Abstract VolumeAbstract Volume

MexicoMexico--City, 20 City, 20 -- 24 June 200624 June 2006EditorsEditors

Jochen BundschuhJochen Bundschuh(Germany/Argentina/Costa Rica)(Germany/Argentina/Costa Rica)

MarMaríía Aurora Armientaa Aurora Armienta(Mexico)(Mexico)

Peter BirklePeter Birkle(Mexico)(Mexico)

Ramiro RodrRamiro Rodrííguezguez(Mexico)(Mexico)

Prosun BhattacharyaProsun Bhattacharya(Sweden)(Sweden)

JJöörg Matschullatrg Matschullat(Germany)(Germany)

CongressCongress

International Society ofGroundwater for Sustainable Development

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Welcome to the International Congress

“Natural Arsenic in Groundwaters

of Latin America”

Dear Participant,

On behalf of the whole organisational team, we welcome you heartily to this congress which tands in the tradition of the San Diego confer-ences and the conference held in Santiago de Chile – all dedicated to a better understanding of arsenic-related problems and challenges.

At the same time, we welcome you to Mexico-City, and we hope that you will enjoy both the enlightening atmosphere of the congress and the relentless dynamics of this fascinating capital.

The Congress In many parts of the world groundwater resour-ces – a backbone for human development – natu-rally contain elevated levels of arsenic (As). These As-concentrations often exceed the World Health Organisation (WHO) guideline value of 10 µg L-1. Severe health effects have been asso-ciated with elevated As-concentrations in groundwater used for drinking purposes. Many people in low income countries, particularly in South East Asia and Latin America, are most severely affected. There is increasing evidence of various susceptibility factors, e.g., malnutrition.

Arsenic in groundwater poses one of the most important environmental health risks of the present century. Several million people depend-ing on arsenic-containing groundwater for drinking purposes are at increased risk of arse-nic-related health effects. So far, most research focussed on As-related cancer effects. More information about other health effects is needed and on susceptibility.

During the last decade, As-rich groundwaters in South and South-East Asia have received much attention. However, the situation seems to be equally important in Latin America, where the number of studies is still relatively low, and the extent and severity of As-exposure in the popu-lation only marginally evaluated. Arsenic occur-rence in groundwater in Argentina, Bolivia, Brazil, Chile, Mexico, Nicaragua, Peru, and other Latin American countries need to be in-

vestigated. Recently, in Nicaragua – a country where the groundwater arsenic problem was not assumed to exist – elevated groundwater As-concentrations as well as As-related health ef-fects were detected. However, the actual number of people at risk for chronic As-toxicity is not yet known. This current status of insufficient knowl-edge on As-occurrence and related health risks deserves attention.

The sustainable land-use and agricultural prac-tices in the Latin American countries are region-ally threatened by the use of As-contaminated irrigation water. Elevated levels of natural As in groundwater from geogenic sources is therefore an issue of primary environmental concern, which limits the use of these resources for drink-ing or other purposes, and hinders socio-economic growth. Hence there is a need to im-prove our understanding of the genesis of As-rich groundwaters, constraints on the mobility of As in groundwater and other environmental com-partments, As-uptake from soil and water by plants, As-propagation through the food chain, health impacts on human beings, life stock, and other animals, assessment of environmental health risks and impacts, and As-removal tech-nologies, to improve the socio-economic status of the affected regions.

Interdisciplinary Platform Objective

The goal of the international congress "As 2006" is to bring together geo-scientists, specialists from public health, from chemical and engineer-ing sciences involved in arsenic-related issues. The regional focus of attention is dedicated to Latin America.

The conference serves as a platform for discus-sion and exchange of scientific knowledge and ideas to identify future research targets needed to improve the understanding of (1) the occurrence and mobility of arsenic in groundwater, (2) the health impacts and risks when using this water for drinking or irrigation purposes, and (3) to develop, evaluate, select and apply the most suitable remediation methods, which means adapted to the hydrogeological and hydrogeo-chemical properties of the aquifer, the specific hydrochemical composition of the groundwater, the social conditions and the economic situation

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of the affected population and the respective water service providers.

The international congress is designed to (1) create interest within the Latin American coun-tries, affected by the presence of arseniferous aquifers, (2) to address the international scien-tific community in general, (3) to update the current status of knowledge on the dynamics of natural arsenic from the bedrock and soils via aquifers and groundwater to food chain, (4) to continue the important worldwide forum on improved and efficient techniques for As-removal in regions with elevated arsenic levels in groundwater, and (5) to increase awareness among administrators, policy makers and com-pany executives, and to improve the interna-tional cooperation on that topic. However, we strongly encourage all other researchers work-ing on arsenic elsewhere in the world to con-tribute, which would strengthen this global issue.

On behalf of the organizing comittee

Jochen Bundschuh, María Aurora Armienta, Prosun Bhattacharya , Jörg Matschullat, Peter Birkle and Ramiro Rodríguez

Content

Welcome address 1

Author list 3

Abstracts 7

Topic list 89

International Society ofGroundwater for Sustainable Development

3

Alphabetical list of authors with page location in this abstract volume

Acarapi C J ................................................... 21 Acosta-Saavedra L ....................................... 79 Aguilera-Alvarado AF.................................. 15 Aguirre RJ ...................................................... 7 Aguirre V...................................................... 22 Agusto M...................................................... 29 Ahmed KM......................................... 7, 11, 39 Alam MGM .................................................. 80 Alfaro-De la Torre MC................................. 53 Alonso MS.................................................... 50 Altamirano Espinoza M.................................. 8 Andrade G .................................................... 83 Aranyosiová, M............................................ 19 Arenas H MJ................................................. 21 Armienta MA ................................... 10, 36, 52 Avena M................................................. 43, 64 Ávila Carrera ME ......................................... 28 Balczewski A.................................................. 7 Bandara A..................................................... 84 Banerjee K...................................................... 7 Barberá R...................................................... 42 Barahona F ................................................... 44 Barnes RM.................................................... 88 Barrera A...................................................... 33 Bastías JM .............................................. 36, 83 Bastida M ..................................................... 79 Beltrán-Hernández RI................................... 45 Berdón V ...................................................... 62 Bhattacharya P...................... 11, 12, 39, 59, 80 Bianco de Salas G......................................... 28 Billib M ........................................................ 37 Birkle P .................................................. 12, 13 Blesa MA...................................................... 24 Bonorino G................................................... 43 Boochs PW................................................... 37 Bovi Mitre G .......................................... 28, 69 Briones-Gallardo R................................. 46, 82 Bruha T......................................................... 27 Bundschuh J ....................11, 12, 13, 44, 54, 80 Caetano LM.................................................. 20 Caldeira C L ................................................. 20 Calderón-Aranda ES..................................... 79 Calderón-Hernandez J ............................ 46, 62

Cama J...........................................................15 Cano-Aguilera I ............................................15 Canyelles C ...................................................16 Carrizales Yañez L..................................46, 62 Caselli AT .....................................................29 Castro de Esparza ML.............................16, 18 Castro-Larragoitia J.......................................53 Caussy D .......................................................19 Cebrián ME.................................26, 45, 52, 79 Cerbon M ......................................................62 Čerňanský S ..................................................19 Chandrajith R ................................................84 Charlet L .................................................64, 65 Chavez C.......................................................22 Choi H...........................................................60 Ciminelli VST.........................................20, 77 Conde P.........................................................79 Cornejo P L.............................................21, 88 Corona M ......................................................70 Cortina JL......................................................16 Cruz L ...........................................................52 Cumbal LH.............................................. 22 (2) d´Hiriart J ......................................................24 Dahmke A ...............................................40, 41Daus B...........................................................40 De Haro-Bailón A .........................................31 de Oliveira Couto e Silva N ..............23, 47, 53 de Oliveira Vilhena MJ .................................48 Del Razo LM. 28, 33, 34, 35, 38, 45, 55, 69, 81 Del Río-Celestino M .....................................31 del Valle Hidalgo M................................24, 32 Deschamps E...............................23, 43, 48, 51 Deshpande L .................................................23 Díaz Sch O ....................................................25 Díaz-Villaseñor A ...................................26, 52 Doušová B...............................................26, 27 Driehaus W .....................................................7 Ebert M ...................................................40, 41 Espinosa M................................................8, 28 Esteller MV...................................................49 Estévez J .......................................................81 Etchichury MC..............................................50 Falcón CM ....................................................50 Farías SS .....................................28, 29, 54, 69 Farré R ..........................................................42 Fazio AM ......................................................29

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Fernández DS ............................................... 32 Fernández RG............................................... 30 Fernández-Cirelli A...................................... 53 Fierro V ........................................................ 88 Figueroa L .................................................... 88 Flores-Valverde E......................................... 10 Font R........................................................... 31 Freitas SHD.................................................. 77 Fuitová L ...................................................... 26 Gabrio T ....................................................... 48 Gaiero D ....................................................... 65 Galindo MC .................................................. 32 Gallaga-Solorzano JC................................... 48 García JW..................................................... 50 Garcia ME .............................................. 13, 54 García MG.............................................. 24, 32 García-Chavéz E........................................... 33 García-Montalvo EA ........................ 28, 34, 81 García-Rico L......................................... 40, 69 Garcia-Vargas G........................................... 81 Germolec DR................................................ 81 Giarolli F ................................................ 40, 41 Giménez E .................................................... 49 Giordano M .................................................. 35 Giuliano G .................................................... 85 Gonsebatt ME......................................... 35, 62 Grygar T ....................................................... 26 Guadarrama JC............................................. 33 Gutiérrez Ospina G....................................... 35 Gutiérrez-Ojeda C ........................................ 35 Gutiérrez-Ruiz M ................................... 44, 65 Haque N........................................................ 15 Hasan MA .............................................. 11, 39 Hasan MT..................................................... 59 Helal Uddin M.............................................. 59 Hernández JC ............................................... 51 Hernández H................................................. 36 Hernández M ................................................ 62 Hernández-Ramosa I .................................... 48 Hernández-Zavala A............................... 34, 81 Herrera C ...................................................... 36 Hiriart M................................................. 26, 52 Holländer HM .............................................. 37 Hossain MA.................................................... 9 Hossain MM................................................. 59 Hugo M ........................................................ 57

Izquierdo-Vega JA ........................................38 Jacks G.................................................... 11 (2) Jakariya M...............................................11, 39 Jara-Marini ME.............................................40 Jiménez I .......................................................33 Jonsson L ......................................................11 Kanel S..........................................................61 Kanel SR .................................................60, 61 Kannel PR .....................................................61 Kinniburgh DG .............................................76 Köber R...................................................40, 41 Koloušek D .............................................26, 27 Königskötter H..............................................66 Korban Ali M..................................................9 Krüger T........................................................37 Kumar M.......................................................59 Laparra JM....................................................42 Lara-Castro RH.............................................53 Leonhardt Palmiere HE.................................43 Lienqueo A H................................................21 Limbozzi F ....................................................43 Limón JH ......................................................35 Litter MI........................................................24 Lòpez DL ......................................................44 Lopez-Bayghen E..........................................70 López-Carrillo L ...........................................79 López-Sánchez JF ...................................67, 68 López-Zepeda JL ..........................................44 Lucho-Constantino C ..............................45, 55 Luna AL........................................................79 Lundell L.......................................................11 Machado-Estrada BP.....................................46 Machovič V.............................................26, 27 Maciasa AE...................................................48 Madé B..........................................................85 Mahlknecht J.................................................68 Maldonado Reyes A......................................47 Mansilla H...............................................21, 88 Marcus M......................................................44 Marijuan L ....................................................51 Mariño E .......................................................73 Martaus A................................................26, 27 Martin RA ...............................................12, 80 Martín Romero F.....................................44, 65 Mata E...........................................................63 Matin Ahmed K ............................................38

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Matschullat J .......................................... 23, 48 Mattusch J .................................................... 40 Mejia JA ....................................................... 63 Merchant H................................................... 33 Merino MH................................................... 50 Micete S........................................................ 10 Monroy-Fernández MG................................ 82 Monroy-Torres R.......................................... 48 Montero A .................................................... 81 Montero Ocampo C ...................................... 47 Monterrosa J ................................................. 44 Montoro M R.............................. 25, 31, 42, 69 Morales L ..................................................... 16 Morales VR .................................................. 62 Morell I......................................................... 49 Moreno C...................................................... 32 Morrison GM................................................ 15 Moscuzza C .................................................. 53 Mridha MAU................................................ 59 Mugica V...................................................... 52 Muñoz O................................................. 36, 83 Nahar S......................................................... 39 Navarrete R .................................................. 35 Navarro C ME .............................................. 62 Nazim Uddin M............................................ 59 Nicolli HB .............................................. 50, 76 Novák M....................................................... 80 Núñez S N .................................................... 25 Oberdá SM ................................................... 51 Orihuela DL.................................................. 51 Ortega MA.................................................... 70 Ortiz E .......................................................... 52 Ostrosky-Wegman P......................... 26, 52, 70 Oswaldo R .................................................... 57 Pande S......................................................... 23 Pant, KK................................................. 71, 72 Pastene O R .................................................. 25 Pauli C.......................................................... 64 Pažout V ....................................................... 27 Pelallo-Martínez NA .................................... 53 Pérez-Carrera A............................................ 53 Pérez-Mohedano S ....................................... 51 Petrusevski B................................................ 30 Pflüger JC..................................................... 54 Pilar Asta M ................................................. 15 Pimentel A.................................................... 55

Poggi-Varaldo HM..................................45, 55 Ponce RI........................................................28 Pradhan B......................................................56 Preziosi E ......................................................85 Prieto-García F..............................................45 Puigdomènech AP.........................................16 Punti A ..........................................................16 Pupo I ............................................................81 Queriol H ......................................................35 Quintanilla J ..................................................57 Rahman IMM................................................59 Ramanathan AL ............................................59 Ramírez E......................................................52 Ramirez P......................................................62 Ransom L......................................................44 Raßbach K.....................................................48 Recabarren G E .............................................25 Rema P............................................................9 Reséndiz I......................................................52 Reyes Agüero JA ..........................................46 Rinderknecht-Seijas N ..................................55 Rocha CA......................................................51 Rocha-Amador DO .......................................62 Rodríguez R ............................................36, 63 Rodríguez V..................................................35 Román-Ross G ........................................64, 65 Ruales J .........................................................69 Rubio R ...................................................67, 68 Rüde TR........................................................66 Ruiz-Chancho MJ ...................................67, 68 Ruiz-Gonzalez Y...........................................68 Sacchi G........................................................64 Sancha AM........................................16, 68, 69 Sánchez-Peña LC ..............................33, 38, 69 Sánchez-Soto M ............................................26 Sandoval M ...................................................70 Santiago-Garcia EJ........................................48 Sarvinder Singh T ...................................71, 72 Sastre-Conde I...............................................45 Schulz CJ ......................................................73 Segura B........................................................33 Selim HM......................................................74 Senapati K.....................................................75 Sen Gupta AK...............................................22 Servant RE ....................................................28 Ševc J ............................................................19

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Shi F ............................................................. 11 Silva A.......................................................... 77 Silva J ........................................................... 43 Silva JCJ....................................................... 77 Smedley PL .................................................. 76 Sordo M........................................................ 70 Soria de Paredes GN..................................... 78 Soriano T ...................................................... 44 Soto-Peña GA............................................... 79 Soto-Peredo CA............................................ 38 Sracek O ..................................... 11, 12, 32, 80 Stummeyer J ................................................. 37 Sulovsky P.................................................... 80 Tineo A......................................................... 50 Tipan R......................................................... 22 Tofalo OR..................................................... 50 Tokunaga S................................................... 80 Torres E ........................................................ 16 Tripathi P...................................................... 59 Urík M.......................................................... 19 Valcárcel L ................................................... 81 Valenzuela OL.................................. 28, 34, 81 Vasconcelos O.................................. 23, 43, 77 Vázquez-Rodríguez G .................................. 82 Vega L.......................................................... 79 Vélez P D ................................... 25, 31, 42, 69 Vieira Alves T .............................................. 51 Vilches S ...................................................... 83 Villaamil E ................................................... 69 Villalobos M........................................... 44, 65 Vithanage M................................................. 84 Vivona R ...................................................... 85 Von Brömssen M.......................................... 11 Wajrak M...................................................... 85 Wallschläger D....................................... 86, 87 Weerasooriya R ............................................ 84 Weidner U .................................................... 48 Welter E.................................................. 40, 41 Yadav PK ..................................................... 87 Yañez J ................................................... 21, 88 Zhang H........................................................ 74 Zuñiga O....................................................... 62

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1. Me arsenic adsorption technology – A review of long-term performance in full-scale applications from Stadtolden-

dorf to Phoenix Roman J. Aguirre1, Kashi Banerjee1, Aaron

Balczewski1, Wolfgang Driehaus2

1U.S. Filter, 1728 Paonia Street, Colorado Springs, CO 80915, USA

2GEH, Germany

In anticipation of the upcoming lower limit of 10 µg L-1 for Arsenic issued by the USEPA many utilities and private water companies are investigating their treatment options. A recent search of arsenic removal solutions on the internet identified 307,000 websites pages offering ‘arsenic treatment’. It can be stated that while most websites promised the ‘latest and greatest’ solution to arsenic removal, full scale experience and commercial availability of many prod-ucts is non-existent or extremely lacking.

As the plethora of adsorption media and revolutionary treatment approaches have gained most of the attention in the market place, successful, full-scale long-term oper-ating experiences have not been published for many new technologies.

This paper will in detail focus on long-term, full-scale arsenic adsorption installa-tions in Germany, United Kingdom, India and the United States. Overall operating performance, influent and finished water quality, waste disposal options employed, site conditions and regional challenges will be examined and compared. Included in the analysis are comments from the operating staff providing their view point of the over-all system.

2. Management of shallow groundwater arsenic: Bangladesh experiences

K M Ahmed

Department of Geology, University of Dhaka, Dhaka 1000, Bangladesh kmahmed@udhaka.net

Presence of arsenic at concentrations above Bangladesh drinking water standards has emerged as serious public health hazard where at least 30 millions people are ex-posed. This is because of about 30% of country’s domestic hand tube wells pumping water with arsenic concentrations above 0.05 mg L-1. Despite enormous variability in spa-tial and vertical distribution of arsenic in groundwater, there are certain geological provinces which are less affected compared to some severely affected ones. Also there are certain aquifers which are almost fully safe compared to others which are almost entirely unsafe. There are forecasts of sig-nificant increase in cancer and other arsenic related diseases in the coming years. Access to safe water coverage has come down to 70% from 97% due to arsenic occurrences in shallow groundwater which is the main source of potable water in the country.

Since first detection in 1993, lots of activi-ties have been carried out by GOB, UN agencies, development partners and NGOs. A large number of research initiatives have also been taken by local and overseas uni-versities and institutions. A large number of papers have been published covering various aspects of the arsenic in groundwater which have certainly the enhanced the knowledge base about occurrences, distribution and remediation of the menace. However, still there are debates about the origin and release mechanism and possible consequences of drinking high arsenic water. And the scale of mitigation does not match with the magni-tude of the problem.

This paper aims to review the existing knowledge base on various aspects of arse-nic occurrences in Bangladesh groundwater along side critically reviewing the efforts by

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government and other agencies. As the arsenic problem occurs in many other coun-tries, particularly in South and East Asia, Bangladesh experiences would be useful in designing mitigation strategies in other countries. For example, Bangladesh has adopted a National Arsenic Policy and Ac-tion Plan for mitigation of the issue. Such a policy can be adapted to other countries. Another commendable task carried out by the World Bank supported Bangladesh Arsenic Mitigation Water Supply Project is testing of more than 5 million wells all over the affected regions of the country. Despite questions about the validity of such tests using field kits, there good examples of using these data is designing village based mitigation strategy. Also various other re-search initiatives and mitigation options can be useful to countries who are trying to understand and manage the problem.

3. Distribución de la contaminación natural por arsénico en las aguas

subterráneas de la subcuenca Suroeste de El Valle de Sebaco-Matagalpa,

Nicaragua M. Altamirano Espinoza

Centro para la Investigación de Recursos Acuáticos –Universidad Nacional Autónoma de

Nicaragua (CIRA/UNAN), Managua 4598 Nicaragua; maximinaa@hotmail.com

Un problema ambiental serio en Nicaragua es la concentración natural de arsénico en las aguas subterránea próximos a áreas mineralizadas por procesos hidrotermales producto de la dinámica de Nicaragua Oc-cidental, donde el proceso de subducción de la placa de Cocos por debajo de la placa del Caribe es el motor principal de la for-mación de la Depresión de Nicaragua, la principal estructura geológica regional, en cuyo margen oriental externo ocurre el Valle de Sébaco y el área de estudio en la parte SW. Entre estas áreas podemos ubicar la parte suroeste del Valle de Sébaco, con

una extensión de 52 km2. El área comprende 15 comunidades con un total de 3225 habi-tantes (INEC,1995) y una tasa de cre-cimiento del 2.6% anual.

Características generales. Las rocas expues-tas presentan una intensa alteración hidro-termal. Fallas y fracturas NE y NW próxi-mas a la superficie son verdaderos conductos y fuentes para que el contaminante entre al medio acuífero.

Métodos de investigación. Se realizaron análisis físico-químicos del agua subterránea y arsénico total en rocas, suelos y aguas. Se hizo reconocimiento geológico, para conocer las condiciones geomorfológicos, estructura-les y la zonificación de la alteración hidro-termal. Se usó geofísica (magnetometría) para identificar posibles estructuras aso-ciadas a las concentraciones de As en las aguas subterráneas.

Principales hallazgos.

1- Las principales concentraciones de arsé-nico en roca, suelo y agua se asocian a procesos singenéticos (primarios) y epigené-ticos (secundarios), evidenciados a lo largo de fallas y fracturas NE y E-W principal-mente.

2- Desde el punto de vista físico químico, las muestras analizadas en los 25 pozos estudiados son consideradas aguas de buena calidad. (CAPRE,1994). Un total de 16 po-zos (64%) se clasifican como aguas bicar-bonatadas cálcicas.

3- Las mayores concentraciones de arsénico se encuentran asociadas a sistemas de fallas secundarias E-W las cuales favorecen la formación de micro estructuras que influen-cian las características propias del acuífero especialmente el espesor y la profundidad del basamento.

4- De los 57 muestras de agua captadas, el 36% presentan concentraciones de arsénico total (10 a 122 µg L-1) que sobrepasan el valor guía establecidos para agua de con-sumo humano. En el 93% de las muestras de

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aguas, el arsénico se encuentra como ar-senatos con un estado de oxidación (V) y el 7% se encuentran como arsenito (III), el cual es la especie más toxica y móvil de arsénico.

5- En la comunidad de El Zapote se encon-traron las mayores concentraciones de arsénico. En rocas y suelos, las concentra-ciones de arsénico total detectadas fueron de 14.98 µg g-1 y 57.19 µg g-1 respecti-vamente, en el agua fue de 122.15 µg L-1. Dos muestras comparativas de suelo, ubicadas fuera del área de estudio, en la entrada a Mina La India y en los alrededores de la comunidad Agua Fría, presentaron concentraciones mayores y similares a la de El Zapote con concentra-ciones de 95.2 y 59.5 µg g-1 respectiva-mente

6- La presencia de arsénico en los suelos evidencia el origen desde fuentes naturales. El contacto de la población con el xeno-biótico ocurre de forma permanente no solo en la ingesta de agua si no en su actividad cotidiana incrementando el riesgo toxi-cológico.

4. Unacceptability of the Two Bucket Arsenic Removal Filter in Dhobawra,

Bangladesh

M. Anwar Hossain1, Pulok Rema2 and M. Korban Ali2

1Department of Farm Structure, Faculty of Agricultural Engineering & Technology, Bang-ladesh Agricultural University, Mymensingh-

2202, Bangladesh 2Faculty of Agricultural Engineering &

Technology, Bangladesh Agricultural Univer-sity, Mymensingh-2202, Bangladesh;

anwar_bau@yahoo.com

This study aimed to determine the reasons why people unaccepting the arsenic re-moval technology (two bucket filter) and the causes why people return back for using tubewells water instead of arsenic removal technology’s water. Data were collected by

using an interview schedule from 85 users from Ghosh Gaon union under Dhobawra upazilla of Mymensingh district, Bangladesh between the times of Jan/2004 to Feb/2005. The most of the users are middle aged illiter-ate low income farmers. The large percent of respondent (50.3%) has no knowledge about arsenic diseases. There were no social/family problem faced by the users during using of two bucket filter and has no arsenic patients. Only 12.9% of the tubewells are bearing arsenic concentration over danger level. The unacceptability index (U.I) of 10-items of arsenic removal unit (two bucket filter method) ranged from 110.6 to 295.3 against a possible range 0 to 300. The score of 6 U.I exceeded 250. Among the causes ‘Very low flow of water through two bucket filter’ was found high unacceptability index (U.I) of 295.3, while, ‘Repair-Maintenance and Re-placement of Sand, Coal and brick particles is not available’ was second ranked order (UI =287.2), ‘More time required to fill up a Jar of water’ the third (U.I = 286) and ‘Eas-ily Block out of filters and Screens’ the fourth ranked order (U.I = 284.9). However, all the remaining indices of unacceptability were found above 150 except one which was 110.6. From the overall unacceptability of the users revealed that 18.8 percent of users shown medium high unacceptability, 63.5 percent users high and 17.6 percent very high unacceptability. There is 100 percent users’ currently consuming tubewells water from their own tubewells. The acceptability index (A.I) revealed that the No. 1 rank or-der obtained by the statements of ‘water is clean and pure’ with an acceptability index of 298.4. The No. 2 and No. 3 rank order obtained by the statements of ‘Water is safe for use and ‘Easily available in all time’ with the acceptability index of 296.5 and 268.1 respectively. From the overall acceptability it is found that 32.9 percent of users have highly accepted the tubewells water instead of two balti method, 64.7 percent users’ me-dium highly and only 2.4 percent users’ me-dium accepted.

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These research findings has recommended to the decision makers and NGO for evalu-ating the unacceptability and sustainability before supplying or install the arsenic re-moval technology in a particular area.

5. Feasability of arsenic removal from polluted water using indigenous geologi-

cal materials M.A. Armienta1, S. Micete2, E. Flores-

Valverde2

1Instituto de Geofísica, Universidad Nacional Autónoma de México. Circuito Exterior C.U.,

México 04510 D.F. victoria@geofisica.unam.mx

2Posgrado en Ciencias e Ingeniería Ambien-tales, Universidad Autónoma Metropolitana,

México D.F.

Arsenic concentrations above the Mexican drinking water standard have been meas-ured in deep wells used for potable supply at Zimapán, México. Arsenic contamina-tion in these wells is produced by natural processes. Lack of productive non-contami-nated wells and surface water bodies in the area, gives few alternatives to As pollution. Currently, good quality water from a well located about 25 km from Zimapán, is pumped 400 m height and mixed with wa-ter from a well (Z5) containing 0.5 mg L-1 As, to supply potable water. Variations on the proportion of water from each source results on variable As concentrations, being 0.15 mg L-1 in February 2005. Iron oxides and zeolites are the geological materials most used to remove arsenic at other pol-luted sites. However, the geology of Zi-mapán with abundant limestone outcrops, prompted to study their As removal poten-tial. Besides, previous studies have shown the capacity of limestones from this area to remove arsenic.

The feasibility of the Soyatal limestone to produce clean water from the deep well Z5 was determined with batch and column tests. Batch tests were performed varying

time, rock: water ratio, and rock sizes. Re-sults showed a 90% decrease on the arsenic concentration treating 1 liter of water with 10 g rock of a size <0.5 mm. Experiments were run during one hour, but removal took place within the first minutes. Clean water was removed and contaminated water was again added to the same rocks. This proce-dure was repeated several times, obtaining the same efficiency of As removal up to the fifth addition of water. Use of rock particles 0.84-1.00 mm decreased As content to 0.057 mg L-1 or less, within 5 minutes. Particle size played a relevant role in the column experi-ments. Use of particles <0.5 mm hindered the water flow. Packing with rocks 0.84 mm to 1.00 size allowed an adequate water flow, and produced an As concentration of 0.025 mg L-1 in the outflow.

Use of the Soyatal limestone rocks at Zi-mapán has several advantages: this type of rock is abundant in the area, is of easy har-vesting and of easy milling. Limestones may be used for a domestic water-treatment. The same rocks may be used five times to clean new batches of contaminated water. Packed columns may be used on site to treat the water pumped from the polluted wells. Waste rocks may be disposed on tailings located at Zimapán town, and contribute to increase their pH and control acid mine drainage.

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6. Targeting safe aquifers in Matlab Up-zila, Bangladesh – Validating the initia-

tives of local drillers

P. Bhattacharya1, M. von Brömssen1, M. Jakariya1,2, L. Jonsson1, L. Lundell1, G. Jacks1, K.M. Ahmed3 and M. A. Hasan3

1KTH-International Groundwater Arsenic Research Group, Department of Land and Water Resources Engineering, KTH, SE-

100 44 Stockholm, Sweden; prosun@kth.se 2NGO-Forum for Drinking Water Supply and Sanitation, 4/6, Block-E, Lalmatia,

Dhaka 1207, Bangladesh 3Department of Geology, Dhaka University,

Dhaka 1000, Bangladesh

Natural arsenic (As) is encountered in groundwaters from the shallow aquifers of Holocene age in Bengal Delta Plain (BDP) of Bangladesh above the safe drinking wa-ter standard of WHO (10 µg L-1). Ground-waters with elevated As levels are ab-stracted. In our ongoing studies in Matlab Upazila of SE Bangladesh, it is observed that local drillers prefer to install tube wells based on the characteristics of the aquifer sediments. The present paper attempts to link the groundwater composition to the redox characteristics of the sediments that would validate the initiatives of the local drillers to identify and target the relatively oxidized aquifers for installation of As-safe tube wells.

The Holocene aquifers in Matlab Upazila is characterized by a sequence of sediments with considerable heterogeneity in terms of grain size, color and mineralogy. In gen-eral, a thick layer of grey (herein after re-ferred to as black) sediments with thickness varying between 40-50 m, overlies a se-quence of sediments characterized by white, off-white and red colors. The groundwater is near-neutral (pH = 6-7) and predominantly of Ca-Mg-HCO3 or Na-Cl-HCO3 type. The groundwater was generally reducing with low concentrations of SO4

2- and NO3

- but with high concentrations of

Fetot and Mn. The concentration of Astot range between below detection limit to 355 µg L-1. The groundwater samples were clas-sified in accordance with the four groups of the color of the sediments (black, white, offwhite and red) at the screen depths of the wells. Four different groups of sediments were characterized by a distinct scale of groundwater composition governed by the redox characteristics.

Groundwater extracted from black sediments was most reduced, followed by white, off-white and red where the groundwater was less reduced. The reddish/yellowish color of the sediments and low concentrations of dissolved Fe in groundwater at these depths suggest a relatively oxidised condition. In these sediments, most of the Fe is likely to be present as coatings on the framework grains as oxyhydroxides, which impart red-dish/yellowish colour to these sediments, thereby have the ability to adsorb As. We believe that it is possible to target safe aqui-fers by combining the indigenous knowledge and techniques of the local drillers along with modern geological and hydrogeochemi-cal expertise.

7. Groundwater characteristics in the shallow aquifers of Huhhot region in In-

ner Mongolia, PR China: Implications on the mobilisation of arsenic

Prosun Bhattacharya1*, Fei Shi1, Ondra Sracek2, Gunnar Jacks1 and Jochen Bundschuh3

1KTH-International Groundwater Arsenic Re-search Group, Department of Land and Water

Resources Engineering, Kungliga Tekniska Hög-skolan, SE-100 44 Stockholm, Sweden;

prosun@kth.se2Institute of Geological Sciences, Faculty of

Science, Masaryk University, Kotlařská 2, 611 37 Brno, Czech Republic

3Instituto Costarricense de Electricidad, Apartado Postal 10032, 1000 San José, Costa Rica

Elevated arsenic (As) concentration in groundwater is becoming a worldwide prob-lem. In Huhhot Alluvial Basin (HAB) in

12

Inner Mongolia, People’s Republic of China, a population of over a million is exposed to severe health risk due to the consumption of groundwater with high As concentration. In some arsenic seriously affected areas, As concentration reach 1491 µg L-1, 149 times over WHO’s drinking water guideline value for As and exceed the Chinese drinking water standard by a factor of 30 times. Due to the acute shortage of safe water supply and inefficient water management system, people are compelled to drink groundwater with high As concen-tration. Long period ingestion of water with high As concentration have lead to chronic arsenic poisoning among the residents of the region. This present work deals with the hydrogeochemical characterisation of the groundwater of the shallow alluvial aqui-fers and their implications on the chemistry and its relation to the mechanism of As mobilization in the HAB.

Groundwater samples were collected dur-ing October 2003, from 29 sites in the vil-lage of Tie Men Jing, located about 100 km from Inner Mongolia’s capital Huhhot. The pH, redox potential (Eh), temperature and electrical conductivity were measured at sites while major ions, trace elements in-cluding As total and As (III) were analyzed in laboratories at the Royal Institute of Technology and Stockholm University in Sweden. Groundwater is generally neutral to alkaline and the pH varies from 6.67 to 8.7. The redox potential (Eh) lies between 74 and 669 mV. The electrical conductivity (EC) range varies from 581 to 5200 µS cm-

1. Temperature ranges from 9.1 to 13.5 °C. Depths of wells are from 4 m to 75 m. Groundwater is mostly of Na-Mg-HCO3-Cl-type and dominated by HCO3

- and Cl- as the predominant anions. The concentrations of SO4

2- range between 0.3 and 172.8 mg L-

1 and there is a trend of decreasing sulfate concentrations with increase in well depth. The levels of NO3

- were lower than the WHO´s guideline value of 50 mg L-1 in 27 wells. These high NO3

- concentrations

could have been caused by anthropogenic contamination due to the sanitation practices. The PO4

3- concentration ranges between 0.04 to 2.6 mg L-1.

Total As concentration ranged from below detect limit (5.2 µg L-1) to 141 µg L-1. In 28 of the investigated wells, As levels exceeded WHO’s guideline value 10 µg L-1 and 17 wells exceeded Chinese standard 50 µg L-1. Among the 42 groundwater samples of the shallow aquifers only three complied with the WHO drinking water guideline value for As. The dominant species in the groundwater was As (III). In the 29 wells of Tie Men Jing, the concentration of Fe and Mn –exceeded the WHO’s guideline value by a factor of 10.

The aquifers are composed of Quaternary (mainly Holocene) fluvial and lacustrine sediments. High As occurring in anaerobic groundwater in low-lying areas is associated with high concenrations of dissolved Fe and Mn. Improved water supply system, em-ployment new water and energy resources, poverty fighting and expertise cooperation are recommended to solve Huhhot basin rural area’s drinking water problem.

8. The abundance of natural arsenic in deep thermal fluids of geothermal and

petroleum reservoirs in Mexico Peter Birkle1 and Jochen Bundschuh2

1Instituto de Investigaciones Eléctricas, Gerencia de Geotermia, Avenida Reforma 113, Col.

Palmira, Cuernavaca, 62490 México; birkle@iie.org.mx

2Instituto Costarricense de Electricidad ICE, Apartado Postal 10032, 1000 San José, Costa

Rica

In general, little data is available on the metal and non-metal composition of thermal groundwater in Mexican geothermal and petroleum reservoirs. The abundance of hydrothermal minerals at the volcanic reser-voir of the Los Azufres geothermal field (State of Michoacán, Central Mexico), as

13

well as arsenic concentrations between 5.1 mg/L and 24.0 mg L-1 in geothermal brines indicate the importance of dissolution and exchange processes between hot fluids and arsenic-enriched host rock. Elevated natural arsenic concentrations of up to 3.9 mg L-1 in surface manifestations - hot springs and fumaroles - are probably related to the ver-tical ascent of convective fluids towards the surface. Deep waters from the Los Hu-meros geothermal field, located in the east-ern part of the Transmexican Volcanic Belt, show a depth-related increase of arsenic concentrations from 3.9 mg/L (e.g., Well H-1) towards 162 mg L-1 (Well H-12). Lower mineralized waters form part of a liquid-dominated, bicarbonate reservoir type at a depth from 1,025 m to 1,600 m a.s.l., whereas deeper wells (800 – 100 m a.s.l.) produce a two-phase fluid. Arsenic-bearing minerals are not reported. The dominance of sandstones in the sedimen-tary basin of the Cerro Prieto geothermal field, State of Baja California, NW-Mexico, explains the presence of relatively low As-concentrations from 0.25 to 1.5 mg L-1 in reservoir fluids, although bottomhole tem-peratures are extremely elevated (max. 370°C). In order to avoid environmental impacts of arsenic-enriched, deep geother-mal fluids with the surface environment, it is essential to maintain a closed production cycle between extraction wells, energy generation and reinjection wells.

In contrast, deep fluids from petroleum reservoirs in SE-Mexico are less enriched in arsenic in comparison to geothermal reservoir fluids in Mexico. The reservoirs of Pol-Chuc, Abkatun, Batab, Caan, and Taratunich, located 80 km off-shore the Gulf coast, reach maximum As-concentrations of 2.01 mg/L at a depth from 2,910 to 4,658 m b.s.l. Formation water from the Cactus, Nispero and Sitio Grande oil reservoirs (State of Tabasco) are located at a depth from 3,670 to 4,315 m b.s.l. Although mineralization of these flu-ids can reach hypersaline conditions (up to

257,000 mg L-1 TDS), arsenic concentrations (< 0.003 to 0.047 mg L-1) are relatively low. This effect can be attributed to the carbonate host rock type – calcareous sandstone, dolo-mitized mudstone and brecciated and frac-tured dolomite units from lower-upper Cre-taceous period - with little ore content and hydrothermal mineralization. Relatively low-temperature reservoir conditions around 130°C prevent major geochemical reactions.

Concluding remarks about the origin of ar-senic in Mexican deep reservoirs, the studied geothermal fluids are strongly affected (Los Azufres and especially Los Humeros fluids) by water-rock interaction processes under elevated temperatures conditions (> 280°C). Although fluid salinization is relatively low (maximum TDS: 15,000 and 2,000 mg L-1, respectively), the combination of physical and chemical conditions causes an enrich-ment in metal and non-metal concentrations In contrast, low saline to hypersaline waters in Mexican oil reservoirs (maximum TDS: 257,000 mg L-1) are less concentrated in arsenic, which must be attributed to the sedimentary host rock type and lower tem-peratures conditions.

9. Rural Latin America —A forgotten part of the global groundwater arsenic

problem?

J. Bundschuh1, M.E. García2, P. Birkle3

International Technical Cooperation Program, CIM (GTZ/BA), Frankfurt, Germany —Instituto Costarricense de Electricidad (ICE), UEN, PySA,

Apartado Postal 10032, 1000 San José, Costa Rica; jochenbundschuh@yahoo.com

2Instituto de Investigaciones Químicas, Universidad Mayor de San Andrés, P. Box

10201, La Paz, Bolivia, maugegarcia@hotmail.com

3Instituto de Investigaciones Eléctricas, Gerencia de Geotermia, Avenida Reforma 113, Col.

Palmira, Cuernavaca, 62490 México

In different countries of Latin America as Argentina, Chile, México, and Peru at least 4 million people are permanently drinking

14

water with elevated arsenic concentrations in a magnitude, which converts the issue in some of the countries as in Argentina and Mexico into a public health problem. So e.g. in Argentina and Chile over 1% of the population is exposed to the problem, whereas in Bolivia, Brazil, Ecuador, Costa Rica, El Salvador, and Guatemala, arsenic in drinking water is proved, but the numbers of persons affected are yet unknown. In other Latin American countries, the existence of the groundwater arsenic problem is not yet known. This was for example the case of Nicaragua where the arsenic exposure of population from groundwater and related severe health effects, was detected just two years ago. Additionally it must be taken into account that with advances in the modern analytical methods for arsenic at low levels of concentrations, and with the introduction of new national arsenic limits of 0.01 mg L-1, as already introduced by Nicaragua and being planned to be implemented Mexico, it is expected that in future arsenic will be detected also in several countries with elevated concentrations, where it was presumed until now to be arsenic safe, and that numbers of people exposed will significantly increase.

Although that the arsenic drinking water problem is already solved in most urban areas by installing corresponding treatment plants, practically no action was performed by the authorities or international and bilateral cooperation agencies to mitigate the arsenic problem for the rural population, making especially the dispersed living rural population, which drinks arsenic-contaminated water — often without being aware of its toxicity — to the most disadvantaged group and to an emerging target for further actions to reduce the arsenic exposure.

In most of the these countries, the problem is of natural origin, related to arsenic occur-rence in groundwater containing up to several mg As L-1, used for drinking water.

In decreasing order of importance, it is either related to (1) the presence of arsenic in the aquifer sediments, related to volcanism (Argentina, Bolivia, Chile, Peru, Nicaragua, Mexico, El Salvador), (2) mining activities (Chile, Bolivia, Peru, Mexico), (3) electro-lytic metal producing processes (Brazil), and (4) agricultural activities (arsenic containing pesticides).

This paper comprises of 3 parts: First it gives a country-by-country state of art overview on the occurrence of arsenic in the groundwaters and surface waters used for drinking purposes in Latin America, including the respective arsenic sources, the numbers of persons exposed and affected, and the respective already observed and future possible health effects. In each case the need and the possibilities of mitigating the impact are discussed.

The second part discusses the experiences from the until now applied remediation methods for both, applications in urban and rural areas, and the third block deals with future needed measures to mitigate the drinking water arsenic problem of "Rural Latin America". Therefore remediation methods as well as the identification of safe water resources free of arsenic are addressed as possible solutions.

Special emphasis is drawn on the fact, that —at first— it is not a technological problem to be solved. First, the local, national au-thorities of the affected countries and the bilateral or international cooperation agen-cies must recognize groundwater arsenic in the rural areas of Latin America as one of the most important natural health risks of the present century. They must recognize that groundwater arsenic is an issue and a prob-lem that would challenge the UN Millen-nium Development Goals of sustainable development on a global scale, and therefore consider doing its utmost to better equip people for life in those parts, where ground-water arsenic affects population and their sustainable development.

15

In order to mitigate the groundwater arsenic problem in rural areas, it must be consid-ered, that the most sustainable strategies for the management of water supply systems are executed by the communities itself. Such is especially applicable in rural areas with small communities. It requires partici-patory development strategies comprising community consultation for problem defini-tion, involvement in investigation and plan-ning and in the execution and maintenance of the constructions. This needs a strong technical assistance or expertise. Often with little education and assistance, communities can be highly motivated to take action to develop and manage local water infrastruc-ture in a sustainable way. If this is not achieved, even successful arsenic remedia-tion programs may be abandoned soon by the local users, as it could be recently ob-served in the case study of Nicaragua.

10. Preliminary results on the dissolution kinetics of arsenopyrite (FeAsS)

Jordi Cama and Maria Pilar Asta

Institute of Earth Sciences “Jaume Almera”, CSIC; Barcelona, E-08028 Catalonia, EU

Arsenopyrite oxidative dissolution contrib-utes arsenic to waters. The effects that envi-ronmental factors (e.g., pH, content of iron and sulphate, dissolved oxygen and surface reactivity) exert on the arsenopyrite de-composition are studied by means of non-stirred flow-through experiments at pH from 1 to 3 and variable DO content. Steady-state dissolution rates are calculated based on the release of arsenic and iron into solution. In the pH range studied proton concentration has no or little influence on the arsenopyrite dissolution. On the con-trary, the decrease in dissolved oxygen concentration up to PO2 approx. 0% strongly diminished the arsenopyrite rate at pH 3.

Arsenic and iron species in solution (e.g., As(III), As(V), Fe(II), and Fe(III)) may be

present in solution and affect the arsenopy-rite dissolution. Moreover, the toxicity of an arsenic rich solution will depend on the oxy-gen content interacting with either the ar-senopyrite surface or with solutions.

Ongoing experiments are aimed to obtain the temperature effect on the arsenopyrite disso-lution rate. Nanoscale techniques, such as in situ AFM experiments and XPS surface analysis will be used to understand the mechanisms governing the overall oxidative dissolution reaction.

11. Fe-modified light expanded clay ag-gregates (LECA) for the removal of arse-

nic from aqueous solutions Irene Cano-Aguilera1*, Nazmul Haque1,2, Al-berto F. Aguilera-Alvarado1 and Gregory M.

Morrison2. 1Facultad de Química, Universidad de Guana-juato, Noria Alta S/N, C.P. 36050, Guanajuato,

Gto., México; irene@quijote.ugto.mx 2Water Environment Transport Department,

Chalmers University of Technology, SE-41296, Göteborg, Sweden

Iron modified materials have been proposed as a filter medium to remove arsenic com-pounds from groundwater. This study was investigated the removal of arsenic from aqueous solutions by iron-coated light ex-panded clay aggregates (LECA). Kinetic ex-periments were performed to investigate the sorption mechanisms. More than 80% of ar-senic adsorbs to Fe-LECA within one hour. Equilibrium is slowly approached within the next 5 hours. At equilibrium, low redox po-tential and a pH value of >6.0 clearly repre-sents a favorable media (iron hydroxides) to adsorb arsenic by Fe-LECA. The experimen-tal data fitted the pseudo-first-order equation. For a 1 mg L-1 of arsenic concentration, the rate constant k1 of pseudo-first-order was 0.098 min-1 that represents a rapid adsorption to reach equilibrium early. Surface complexa-tion and ion exchange proposed to be the major arsenic removal mechanisms. Column

16

experiments were conducted under different bed depths, flow rates, coating duration and initial iron salts concentration for coating were tested to optimize the arsenic removal efficiency by Fe-LECA column. Volumetric design as well as higher hydraulic detention time was proposed to optimize the efficiency of the column to remove arsenic. In addition, concentrated iron salts and longer coating duration was also found very influencing parameter for arsenic removal. The maxi-mum arsenic accumulation was found 3.31 mg of As g-1 of Fe-LECA when the column was operated at a flow rate of 10 ml min-1 and the LECA was coated with 0.1M FeCl3 suspension for 24 h coating duration.

12. Evaluación de alternativas a la mejora de la calidad del agua de pozos

en las comunidades rurales de San Juan de Limay, Nicaragua

Caterina Canyelles1, Ester Torres1, Laura Morales1, Clàudia Puigdomènech1, Anna Punti1,

Jose Luis Cortina1, Ana Maria Sancha2

1Department of Chemical Engineering , Univer-sitat Politècnica de Catalunya, ETSEIB, Av. Diagonal, 647, E-08028 Barcelona (España);

jose.luis.cortina@upc.edu 2 División de Recursos Hídricos y Medio Ambiente, Facultad de Ciencias Físicas y

Matemáticas, Universidad de Chile, Santiago, Chile

En los últimos años el centro de Salud de San Juan de Limay, que atiende a decenas de miles de persona anualmente, ha esta-blecido que el agua de algunos pozos de las comunidades del municipio está contamina-das. La población tiene enfermedades con síntomas característicos de elevada presen-cia de microorganismos patógenos, y muy posiblemente de arsénico, además de otros contaminantes. Con objeto de tomar medi-das urgentes, el centro de salud del MINSA (Ministerio de Salud) promovió el estudio de evaluación de la calidad del agua de diferentes pozos ubicados en las comunida-des campesinas afectadas, estudiar la apli-

cación de algunas medidas de fácil uso y bajo costo para mejorar la calidad del agua en esta zona rural de bajos ingresos.

El presente trabajo presentará los estudios realizados para determinar el nivel de con-taminación de una serie de pozos de las comunidades afectadas de San Juan de Li-may y una primera aproximación a la iden-tificación del origen del As en las aguas.

Finalmente el trabajo proporciona una serie de recomendaciones para la remoción de las aguas de los contaminantes identificados, especialmente del arsénico.

13. Presencia de arsénico en el agua de bebida en América Latina y su efecto en la

salud pública María Luisa Castro de Esparza

Asesora Regional en Aseguramiento de la Calidad y Servicios Analíticos. CEPIS / SDE /

OPS; Calle Los Pinos 259, Urbanización Camacho, La Molina, Lima, Perú;

mesparza@cepis.ops-oms.org

En varios países de América Latina como: Argentina, Chile, México, El Salvador; Nicaragua, Perú y Bolivia por lo menos cuatro millones de personas beben en forma permanente agua con niveles de arsénico que ponen en riesgo su salud en tal magnitud que en algunos de los países se ha convertido en un problema de salud pública.

Este trabajo constituye una recopilación bibliográfica de la problemática del arsénico en el agua de bebida y sus efectos en la salud de las personas expuestas. Situación que se necesita atender a fin de minimizar sus efectos y disminuir el arsenicismo en las zonas afectadas.

Se describe la presencia del arsénico en el ambiente y en las fuentes de agua para consumo humano se debe a factores naturales de origen geológico (México, Argentina, Chile, Perú, Nicaragua) a actividades antropogénicas que involucran la explotación minera y refinación de metales

17

por fundición (Chile, Bolivia y Perú), procesos electrolíticos de producción de metales de alta calidad como cadmio y cinc (Brasil), y en menor proporción en la agricultura en el empleo de plaguicidas arsenicales orgánicos (México).

Como se conoce en la mayoría de los casos la presencia de arsénico en aguas superfi-ciales y subterráneas de América Latina es natural y está asociada al volcanismo terci-ario y cuaternario desarrollado en la Cordil-lera de Los Andes. Proviene de la disolución de minerales, la erosión y desin-tegración de rocas y por deposición atmos-férica (aerosoles). En el agua puede encon-trarse en su forma trivalente y pentavalente.

En el agua de bebida, por lo general el arsénico se encuentra en la forma de arsenato y puede ser absorbido con facilidad en el tracto gastrointestinal en una proporción entre el 40 y 100%. El arsénico inorgánico ingerido es absorbido por los tejidos y luego se elimina progresivamente por metilación a través de los riñones, en la orina. Cuando la ingestión es mayor que la excreción, tiende a acumularse en el ca-bello y en las uñas.

Las principales rutas de exposición de las personas al arsénico son la ingesta e inha-lación. Es acumulable en el organismo por exposición crónica, y a ciertas concentra-ciones ocasiona alteraciones de la piel con efectos secundarios en los sistemas nervioso, respiratorio, gastrointestinal, y hematopoyé-tico y acumulación en los huesos, músculos y piel, y en menor grado en hígado y riñones.

Estudios toxicológicos y epidemiológicos confirman la información anterior e indican que la ingestión crónica de arsénico en el agua de bebida genera lesiones en la piel, la hiperpigmentación e hiperqueratosis palmo plantar; desórdenes del sistema nervioso; diabetes mellitus; anemia; alteraciones del hígado; enfermedades vasculares, cáncer de piel, pulmón y vejiga.

El consumo de agua con arsénico a largo plazo conlleva a efectos crónicos y a la gen-eración de arsenicismo. El tratamiento in-volucra proporcionar al paciente agua de bebida libre de arsénico. El siguiente paso es monitorearlo y asegurarse de que no esté expuesto a este elemento. Otros tratamientos propuestos son la quelación y la mejora de la nutrición.

Su toxicidad depende del estado de oxidación, estructura química y solubilidad en el medio biológico. La escala de toxicidad del arsénico decrece en el siguiente orden: arsina > As+3 inorgánico > As+3 orgánico > As+5 inorgánico > As+5 orgánico > compuestos arsenicales y arsénico elemental. La toxicidad del As+3 es 10 veces mayor que la del As+5 y la dosis letal para adultos es de 1-4 mg As kg-1. Para las formas más comunes como AsH3, As2O3, As2O5 esta dosis varía en un rango entre 1,5 mg kg-1 y 500 mg kg-1 de masa corporal.

Se ha demostrado que los niños son más sensibles que los adultos a la toxicidad por el arsénico y son los más afectados por el ar-senicismo, por problemas de desnutrición y precario saneamiento en las zonas rurales dispersas (pobres). La población más afectada es la población dispersa ubicada en el área rural que consume agua sin ningún tratamiento y desconoce el riesgo al que está expuesta. Se requiere que las autoridades de salud, ambiente y saneamiento planifiquen los servicios de aprovisionamiento de agua y promuevan e intervengan en la ejecución de programas de prevención y control de ries-gos del consumo del agua de bebida con niveles de arsénico superiores a los re-comendados. Los programas deben involu-crar la participación de las autoridades, comunidad y sistemas locales de salud.

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14. Remoción del arsénico en el agua para bebida y biorremediación de suelos

María Luisa Castro de Esparza

Asesora Regional en Aseguramiento de la Calidad y Servicios Analíticos. CEPIS / SDE /

OPS; Calle Los Pinos 259, Urbanización Camacho, La Molina, Lima, Perú;

mesparza@cepis.ops-oms.org

Varios países de América han reportado la existencia de población expuesta crónica-mente a concentraciones de arsénico en agua de bebida, superiores a las previstas por la normatividad de los países. Es el caso de Canadá, Estados Unidos, Chile, Perú, Bolivia, México, El Salvador y Nica-ragua. Algunos de estos países han resuelto total o parcialmente el problema de dis-posición de tecnología, dependiendo de que la población afectada fuera rural o urbana.

Existen alrededor de 14 tecnologías para remover arsénico del agua con eficiencias del 70 al 99%. Los métodos de coagu-lación-floculación y ablandamiento con cal, son los más usados en grandes sistemas y no exclusivamente para remover el arsé-nico. En pequeños sistemas pueden ser aplicados el intercambio iónico, alúmina activada, osmosis inversa, nanofiltración y electro diálisis inversa. Las tecnologías emergentes son: arena recubierta con óxi-dos de hierro, hidróxido férrico granular, empaques de hierro, hierro modificado con azufre, filtración con zeolita, adición de hierro con filtración directa y remoción convencional de hierro y manganeso.

En Latinoamérica los estudios han estado orientados al uso de la coagulación química: con sulfato de aluminio, cal hidratada y poli electrolito de sodio y han logrado tenores de arsénico a 0,12-0,15 mg L-1. Con coagulación directa sobre filtro y con coagulación-floculación han logrado alcanzar valores bajo 0,05 mg L-1. En la remoción mediante adsorción han em-pleado hematitas y materiales con alto con-tenido de hierro y superficies de carga posi-

tiva (arcilla verde natural, arcillas activadas, zeolita natural y activada y carbón de hueso.

Chile es el país con más experiencia en el tratamiento de agua para distribución urbana, cuentan con cuatro plantas de remoción de arsénico del agua de abastecimiento (0,40 µg L-1) que tratan en conjunto 2000 L s-1 y producen agua potable con 0,040 mg As L-1. Han evaluado la mejora del sistema agre-gando osmosis inversa (postratamiento) y desalinización. En Perú hay una planta de remoción de arsénico que trata el agua con cloruro férrico y ácido sulfúrico.

El CEPIS/SDE/OPS, ha desarrollado y pat-entado el producto ALUFLOC que es una mezcla de un oxidante, arcillas activadas y un coagulante (sulfato de aluminio ó cloruro férrico). Es una metodología simple y de bajo costo que permite remover a nivel domiciliario el arsénico natural presente en las aguas subterráneas que son usadas como agua de bebida por la población rural. Se lograron niveles de remoción de hasta un 98%, usando como coagulantes Al2(SO)3. and FeCl3.

Para la remediación de suelos de zonas con-taminadas se ha estudiado la capacidad de algunos vegetales para absorber y concentrar las sustancias tóxicas. La Universidad de Florida ha identificado un helecho que ab-sorbe arsénico del suelo contaminado que hiper acumula este elemento.

Las tecnologías de recuperación y estabili-zación de arsénico en lodos, suelos y residuos de actividades industriales por lo general son precipitados con cal y soda cáus-tica. Luego separación por sedimentación y/o filtración. En México han obtenido un compuesto de arsénico insoluble y que tam-bién se puede emplear como materia prima en la formulación de productos solidificados para ser usados en construcción o dispuestos en un relleno sanitario.

Para afrontar la problemática del agua de bebida, se debe tener en cuenta las caracte-rísticas de las fuentes, la adecuación del

19

agua, forma de distribución y/o consumo y las variantes de la tecnología a emplear considerando las características propias del lugar.

En los países de Latinoamérica existe ex-periencia y capacidad para el desarrollo de tecnología, pero limitada por la carencia de recursos financieros, facilidades y sobre todo políticas de estado que faciliten y ori-enten el desarrollo de la tecnología que conlleve a la solución efectiva de proble-mas o satisfacción de las necesidades exis-tentes.

La población más afectada se encuentra dispersa en el área rural consume agua sin ningún tratamiento y desconoce el riesgo al que está expuesto. Es necesario desarrollar estudios piloto en forma permanente y sos-tenida hasta lograr una solución definitiva que pueda ser recomendada para su imple-mentación en los programas nacionales de remoción de arsénico en el agua de bebida.

15. The World Health Organization nor-mative roles in mitigating health impacts

of arsenic in South East Asia Deoraj Caussy

Department of Sustainable Development and Healthy Environment, Department of Evidence for Information and Policy, World Health Or-

ganization, Office of the South East Asia, World Health House, Ring Road, New Delhi

110 002, India; caussyd@searo.who.int

Ground water contamination, in excess of the World Health Organization (WHO) guideline value of 0.01 mg L-1, has been observed in many parts of the world includ-ing India, Bangladesh, Thailand, Myanmar, Nepal, China, Taiwan and Vietnam among others. In the South East Asia Region of WHO, it is currently estimated that about 40 million persons may have been exposed to contaminated ground water at various concentrations of arsenic and almost a quarter of a million exposed subjects are already showing overt symptoms of chronic

arsenic poisoning. A review of the epidemi-ological data shows that there is a need for internationally accepted criteria based on evidence in the following areas: Exposure assessment, case-definition and case man-agement. This paper reviews the existing epidemiological evidence for standard case definition and management and presents WHO strategic goals to meet these objec-tives. Data will be presented on the formula-tion and validation of standard regional pro-tocol for case definition and case manage-ment. Other mitigation strategies including applied research and community empower-ment will also be presented.

16. Microbial volatilization of arsenic Čerňanský S, Urík M, Ševc J1, Aranyosiová M2

1Institute of Geology, Faculty of Natural Sci-ences, Comenius University in Bratislava, Mlyn-

ská dolina G, 842 15, Bratislava, Slovakia, cernanskys@fns.uniba.sk

2International Laser Center, Bratislava, Slovakia

Microorganisms have evolved diverse strategies to overcome the toxic effects of arsenic including microbial volatilization through biomethylation and bioreduction. The biological volatilization may be possibly applied as method for arsenic removal from contaminated localities. Microscopic fila-mentous fungi participate in this process as a part of microbial community. Because of their low nutrition demand, adaptability, high intensity and diversity of metabolism represent dominant biopotential for envi-ronment, which is realized in effecting of transformation and mobility of arsenic.

Our studies have shown that the efficiency of arsenic removal is influenced by tempera-ture, pH value, presence of oxygen, bioavail-ability and concentration of arsenic, and dominant species of filamentous fungi. For quantification of arsenic removal and identi-fication of arsenic metabolites in vitro the cultivation system of different fungi (Neosartorya fischeri, Aspergillus clavatus,

20

A. niger, Talaromyces wortmanii, T. flavus, T. viride, Penicillium glabrum) and cultiva-tion media enriched by desired amount of arsenic (0,25 – 15 mg) was prepared. Fun-gal strains were originally isolated from sediments from locality Pezinok – Kolársky vrch (Slovakia) that is contaminated with arsenic. Total arsenic concentrations of sediments were 363-1650 mg kg-1. After a desired time of cultivation (10, 30 and 60 days) under different conditions (pH value, temperature) the total arsenic in cultivation medium and mycelium was measured using Hydride Generation Atomic Absorption Spectrometry (HG AAS). The removal of arsenic from cultivation system through microbial volatilization varied between 10 – 70% of the initial amount of arsenic de-pending on cultivation conditions and fun-gal species.

For detailed chemical analysis of biological samples (mycelia) with focus on specific arsenic metabolites was used Secondary Ion Mass Spectrometry (SIMS), an analyti-cal method based on the time of flight prin-ciple. Instrument ION-TOF, SIMS IV with unique parameters (spatial resolution 100 nm, mass resolution > 9000 m/Dm) was used in cooperation with International La-ser Center in Bratislava.

Volatile arsenicals have been identified during a cultivation period from myceliar head gas in cultivation system by using sorption tubes Anasorb CSC (USA).

17. Enriched arsenic precipitates ob-tained from diluted industrial solutions Ciminelli, Virgínia1, Caldeira, Cláudia Lima1;

Lara, Michelle Caetano1 1Dept. of Metallurgical and Materials Engineer-ing, UFMG, Rua Espírito Santo, 35, 30160-030

Belo Horizonte, Brazil; ciminelli@demet.ufmg.br claudia@demet.ufmg.br

Arsenic is a frequent toxic element released during processing of sulfide ores. The treat-

ment of As-containing solutions involves As(III) oxidation, followed by fixation of the resulting As(V) in a solid phase. The most common residues are the crystalline ferric arsenates (e.g., scorodite, FeAsO4.2H2O) produced in the hydrothermal processing of refractory gold ores, or the arsenical ferrihy-drites formed by precipitation of arsenic at moderate temperatures. The latter involves a neutralization of arsenic-rich acidic solutions and generates large volumes of ferric hy-droxide/gypsum sludge (e.g., 3-6% As). Arsenic immobilization by scorodite precipi-tation under ambient pressure has been pro-posed as an alternative to the ferrihydrite process but the studies have been mostly limited to relatively concentrated solutions (10 g As L-1) and batch systems. The present work investigated the removal of arsenic from dilute solutions (1 g L-1 As) produced in the washing tower of the gas released in the roasting of a refractory gold ore. It was demonstrated that industrial solutions with low arsenic concentrations (1.1 – 0.1 g L-1) could be treated in one stage of scorodite precipitation under ambient pressure condi-tions, with a removal in a range of 80.5 to 94.6%. Precipitation was carried out at 95°C. In order to reach a molar Fe/As ratio of 1, required for scorodite precipitation, iron (II) sulfate was added, followed by As(III) and Fe(II) oxidation with H2O2. In order to con-trol supersaturation and to avoid homogene-ous nucleation that yields amorphous ferric arsenate pH was adjusted according to the initial arsenic concentration. The removal increased with the increase of the scorodite seed concentration and became approxi-mately constant (85-88%) in a range of 20 to 80 g L-1 of seeds. It was shown that a surface area higher than 270 m2 g-1 As in solution was necessary to promote an arsenic removal of approximately 85%. Gypsum was an ef-fective seed only in concentrated arsenic solutions (10 g L-1). A procedure to achieve high yields of arsenic removal in continuous system was established. Due to the low rate of crystal growth, the recycle of seeds was required. The precipitation was favored by

21

the excess of iron, due to the increase of initial supersaturation obtained under these conditions. For a Fe:As molar ratio of 2:1 and 1:1, 86% and 70% of the arsenic was removed from the solution, respectively. The TCLP tests suggested that ageing plays an important role on scorodite TCLP- dis-solution, which decreased from 13.66 mg As L-1 to 0.1 mg As L-1 after 8 hours of precipitation reaction in batch tests. Scoro-dite was the only phase identified by micro-Raman and X-Ray diffraction analyses of the precipitates. Advantages and difficulties of the ambient-pressure scorodite precipita-tion with respect to industrial applications are discussed.

18. Remoción de arsénico de aguas

desc sos

Lorena Cornej eo A.2, Jorge

1Universi cultad de Ci -

naturales del valle de Camarones mediante procesos inducidos por

radiación solar: tecnología de ontaminación aplicable a recur

hídricos al norte del Desierto de Atacama, Chile o P.1, 2, Hugo Lienqu

Acarapi C.2, Maria J. Arenas H.2, Héctor Man-silla3, Jorge Yañez3

dad de Tarapacá, Faencias, Departamento de Química, Arica

Chile, Casilla 7-D; lorenacp@uta.cl. 2 ntro de Investigaciones del Hombre enCe el

D .

Los poblados de Camarones, Esquiña e

ca ha originado un interés

iento de

, adaptación y

ron los ensayos de

esierto, Universidad de Tarapacá, Arica-Chile3Facultad de Ciencias Químicas, Universidad de

Concepción, Chile

Illapata se encuentran insertos en el valle de Camarones al norte del Desierto de Ata-cama, Chile. Son beneficiados con las aguas naturales de su única fuente de re-curso hídrico el río de Camarones y diver-sos flujos menores de agua, como ver-tientes y pozos que los habitantes utilizan para suplir sus necesidades de consumo personal, animal y riego. Dichas aguas presentan una contaminación natural de Arsénico, proveniente de las zonas cordil-leranas, con concentraciones en el rango de

1200 a 1300 µg L-1. Este tipo de contami-nación ha afectado en forma crónica a las poblaciones rurales asentadas en la zona norte del país, ocasionando diversos proble-mas a la salud de sus habitantes. Debido a la baja densidad poblacional que poseen estos pueblos no es factible la utilización de tec-nologías de alto costo, compleja mantención u operación para lograr abastecer de agua potable a estas localidades, que es el objetivo de este trabajo.

Esta problemáticreciente en el desarrollo de metodologías de remoción útiles para disminuir niveles de arsénico a concentraciones adecuadas para el consumo humano y se ajuste a los niveles máximos de arsénico permitidos, por norma-tivas nacionales e internacionales (NCh 409 = 50 µg As L-1, OMS = 10 µg As L-1).

Este estudio comenzó con el tratamaguas sintéticas que poseían una concen-tración de arsénico de 500 µg L-1 y con ex-posición a luz artificial obteniendo resulta-dos del 80-90% de remoción.

En seguida se trabajó el diseñoposterior aplicación de una metodología de remoción simple y económica mediante en-sayos de laboratorio univariados en la ciudad de Arica. Para ello se realizaron análisis fisicoquímicos a las muestras de aguas natu-rales a fin de conocer su composición, y así trabajar con muestras sintéticas de igual matriz. Las variables estudiadas fueron hierro (FeSO4), citrato (C6H5Na3O7), pH, remoción en presencia y ausencia de luz solar y tiempo de exposición solar. El hierro y el citrato fueron posteriormente reem-plazados por materiales de uso casero acce-sible al poblador rural.

Finalmente, se realizaremoción “in situ”con muestras de aguas reales del valle de Camarones. La informa-ción recopilada fue evaluada, utilizando un software de optimización basado en métodos de superficie de respuesta (MSR).

22

La determinación de la concentración de arsénico remanente en solución, en todos los casos, fue mediante espectroscopia de absorción atómica con generación de hidruros.

En conclusión, con la metodología pro-puesta se obtuvo una remoción de arsénico mayor al 99% en terreno, presentándose como una interesante alternativa que rinde logros favorables en la descontaminación del recurso hídrico para consumo de los habitantes del Valle de Camarones.

19. Monitoring concentrations, speci-ation, and mobility of arsenic in geo-thermal sources of Ecuador´s North-

Center Andean Region Luis H. Cumbal, Vladimir Aguirre, Ricardo

Tipan and Carlos Chavez

Research Center Escuela Politecnica del Ejercito, Sangolqui, Ecuador;

luis.cumbal@espe.edu.ec

It is well known that arsenic contamination has emerged as a worldwide problem due to pollution of groundwater and surface water. In several areas of Mexico and Chile, groundwaters have been contami-nated with arsenic of volcano origin. In Ecuador, the Andean Region is surrounded by volcanoes and geothermal waters and some of them are used as sources of drink-ing water particularly in rural areas. After petroleum contamination of a lake that is fed by geothermal waters, its water was characterized and arsenic concentrations oscillated between 390 and 670 µg L-1. At that time, it was thought that arsenic was petroleum origin; however, our research group recently measured arsenic in that lake and found concentrations in the range of 330 and 900 µg L-1. In addition, it was found that nearby thermal waters such as El Tambo swimming pool, Jamanco reservoir, and Rio Tambo watershed contained be-tween 970 and 5080 µg L-1 of arsenic. These findings eventually indicate that

other thermal sources in Ecuador’s Andean Region can contain this toxic element.

The objective of this study is to determine arse-nic concentrations in thermal waters from the North-Center Andean Region of Ecuador, its chemical speciation and mobilization during the travel towards rivers, lakes, and reservoirs. With this information we will make a map to localize thermal waters with concentrations above the Ecuadorian maximum concentration level (50 µg L-1). In next stage of this study, we will in-vestigate with local sorbents for selective arse-nic removal such as zeolite or allophane rich clay. Our research will be aimed to treat thermal waters that are used as sources of drinking water in rural areas.

20. Polymer-supported Fe(III) oxide nanoparticles: A robust, reusable and

arsenic-selective sorbent Luis H. Cumbal1 and Arup K. Sen Gupta2

1Research Center of Escuela Politecnica del Ejercito, Sangolqui, Ecuador

2Department of Civil & Environmental Engineer-ing, Lehigh University, 13 E. Packer Ave., Beth-

lehem, PA 18015, USA; luis.cumbal@espe.edu.ec

Many nanoscale inorganic particles (NIPs) such as hydrated Fe(III) oxides, Mn(IV) oxides, elemental Fe, magnetite, etc.; show excellent properties conducive to selective removal of target compounds from contami-nated water bodies. Extremely high surface area to volume ratio of these tiny particles offers favorable kinetics for selective sorp-tion and redox reactions. However, these nanoparticles cannot be used in fixed-bed columns, in-situ reactive barriers and in similar plug flow configurations due to ex-cessive pressure drops and poor durability. Harnessing these NIPs within polymeric beads offers new opportunities that are ame-nable to rapid implementation in the area environmental separation and control. While the NIPs retain their intrinsic sorp-tion/desorption, redox, acid-base or magnetic

23

characteristics, the robust polymeric sup-port offers excellent mechanical strength, durability, and favorable hydraulic proper-ties. In this investigation commercially available cation and anion exchangers were used as host materials for dispersing nano-scale Hydrated Fe(III) Oxides (HFO) within the polymer phase using a simple thermochemical technique. The resulting polymeric/inorganic hybrid sorbent parti-cles were subsequently used for arsenic removal in the laboratory. The major find-ing of this study reveals that an anion ex-changer as a support of dispersed HFO particles offered considerably higher arse-nate removal capacity compared to a cation exchanger, all other conditions remaining the same, the difference in selectivity and removal capacity can be attributed to func-tional groups of polymeric supports. In addition, hybrid polymers are amenable to efficient regeneration; thus, assuring their reuse in several sorption/desorption cycles. On the other hand, rubbing tests demon-strate that HAIX-M particles do not lose mechanical resistance and there is no fines formation. Besides, sorption tests using HAIX-M particles reveal an excellent and simultaneous removal of arsenic and per-chlorate. Consequently, HAIX-M sorbents are media with enormous potential to be used in community water supplies to selec-tively remove arsenic and other toxic ligands.

21. Mitigation actions as a result of As exposure investigations in Brazil

Eleonora Deschamps1, Jörg Matschullat2, Olivia Vasconcelos3, Nilton de Oliveira Couto Silva4

1 Environmental Agency of the Minas Gerais State - FEAM, Av. Prudente de Morais 1671,

Santa Lucia,30380-000, Belo Horizonte, Brazil; eleonorad@feam.br

2Interdisciplinary Environmental Research Center, TU Bergakademie Freiberg, Brenn-hausgasse 14, D-09599, Freiberg, Germany;

matschullat@ioez.tu-freiberg.de

3Department of Metallurgical and Materials En-gineering, Universidade Federal de Minas Gerais,

UFMG, Brazil; olívia@demet.ufmg.br 4Fundação Ezequiel Dias-FUNED, Laboratório

de Contaminantes Metálicos, Belo Horizonte,MG,Brazil; niltoncs@funed.mg.gov.br

Globally, millions of people are at risk from adverse health effects of arsenic from both acute and chronic exposure. Although most of the As exposure comes from drinking water, other important sources are through food, soil and air. In Brazil, arsenic anoma-lies are related to geological structures, and the additional dissipation due to centuries of gold mining and smelting activities. Most of the gold is associated with arsenopyrite and to a lesser extend with pyrite. Although not as severe and not exclusively water-related as in Bangladesh and West Bengal, As-enrichments were recently detected in envi-ronmental and biological media in the Iron Quadrangle, Minas Gerais state. This project presents the mitigation actions to improve the situation, starting with an environmental and health perception study which led to an environmental educational program. Next, appropriate tailings deposits management was started to improve control of tailings with very high As concentrations, and to slow down As-dissipation into the environ-ment. Additionally, a water treatment plant is under construction to avoid the ingestion via As-loaded particulates in drinking water.

22. Speciation and instrumental analytical methods as effective analytical tools for

quantification of arsenic in drinking water Leena Deshpande and Sunil Pande

National Environmental Engineering Research Institute, Nehru Marg, Nagpur, India;

gem_neeri@rediffmail.com

Arsenic in ground water has been well rec-ognized as a serious public health hazard in various parts over the globe. Despite recent developments in the quantification of arsenic in water, the method involving generation of

24

arsine, colour development with Silver Diethyldithiocarbamate (SDDC) and meas-uring colour spectrophotometrically, still remains the method of choice in the domain of public health laboratories.

This paper presents development of spec-trophotometric method with modified glass assembly for arsine generation. Recovery studies of arsenic have been carried out in presence of various cations and anions. For validation of the method, its precision and accuracy was determined by analyzing synthetic water samples. Also an attempt has been made to study substitute for pyri-dine, which is a hazardous solvent used in the conventional SDDC Method.

A rapid Hydride Generation-Inductively Coupled Plasma (HG-ICP) spectrometric method has been developed using the ICP spectrometer, which serves as an efficient analytical tool for the monitoring of low levels of arsenic in raw and potable waters. The HG-ICP method is precise and accu-rate as per the international norms. This method can be routinely adopted for the analysis of arsenic in water samples.

23. Arsenic removal by solar oxidation in groundwaters of Los Pereyra, Tucumán

Province, Argentina Josefina d´Hiriart1, María Gabriela García2, Margarita del V. Hidalgo1, Marta I. Litter3,

Miguel A. Blesa 3,4 1Facultad de Ciencias Naturales e Instituto Miguel Lillo, Universidad Nacional de Tu-

cumán, Argentina 2Facultad de Ciencias Exactas, Físicas y Natu-

rales, Universidad Nacional de Córdoba, Argen-tina

3Unidad de Actividad Química, Centro Atómico Constituyentes, Comisión Nacional de Energía

Atómica 4Universidad Nacional de San Martín,

Argentina

Shallow groundwaters from Los Pereyra, Tucumán, are normally used for human

consumption. These waters show arsenic concentrations that exceed the Argentine standard requirements for drinking water. The SORAS method (Solar Oxidation and Removal of Arsenic) is based on the photo-chemical oxidation of As(III) to As(V) pro-duced by reactive oxygen species formed in Fe/citrate containing systems, followed by As(V) adsorption onto the precipitated iron(hydroxides). SORAS method provides an economical technology to eliminate arse-nic until the allowable limits.

In the present work, the efficiency of As re-moval by solar oxidation was assessed using synthetic waters of known ionic composition and shallow groundwater samples. As the concentration of iron in the tested waters is very low and the photooxidation of As (III) at pH between 6 and 8 is favoured by citrate, studies changing the sources of iron and amounts of citrate were made. Citrate was added in the form of lemon juice.

Tests carried out with synthetic waters of similar composition to the study waters showed an excellent removal, ranging be-tween 90-60%. The efficiency of removal was much lower in well waters, between 60-30%. Results showed the influence of the water matrix and the source of iron supply, both factors related to the precipitation of iron (hydr)oxides.

The influence of organic matter, HCO3- con-

tent and the initial As concentration on the precipitation of (hydr)oxides and on the AsO4

3- adsorption was assessed. An increase in the concentration of HCO3

- enhanced As removal and Fe(III) precipitation, whereas an increase of organic matter produced only a slight decrease in both factors. Removal efficiency decreased with the increase of the initial As concentration.

The effect of different Fe sources on the efficiency was analyzed using synthetic goe-thite, Fe-oxide rich sandstones and pelites, packing wire, and nails. Removal varied between 30 to 90% depending on the ex-perimental conditions and the nature of the

25

iron source. Results obtained using non-galvanized packing wire are prominent, due to the short solar exposure time and the absence of color or turbidity in the final treated water.

24. Concentración de arsénico total e inorgánico en el sistema agua – alga –

trucha Oscar Díaz Sch.1*, Nelson Núñez S.2, Estela Recabarren G.1, Rubén Pastene O.1, Dinoraz

Vélez P.3, Rosa Montoro M.3 1Universidad de Santiago de Chile, Casilla 40,

Correo 33, Santiago, Chile; odiaz@lauca.usach.cl

2Programa Indígena CODELCO, Chile 3Instituto de Agroquímica y Tecnología de

Alimentos (IATA), Valencia, España

El curso del río Loa, ubicado en la II Región de Chile, presenta condiciones ecológicas especiales, particularmente de-bido a las altas concentraciones de As en el agua, salinidad y drenaje de los suelos. El objetivo de este trabajo, consistió en estudiar el comportamiento del arsénico y su forma inorgánica más tóxica (AsIII + AsV), en el sistema agua – alga –trucha en un área del curso del río Loa. Muestras de agua del río Loa, hábitat natural del alga (Durvillea sp) y la trucha (Orcorhynchus mykiss), fueron recolectadas en el mes de noviembre del 2000 y 2001, en una canti-dad suficiente para asegurar la confiabili-dad de los resultados. Las muestras de agua (500 mL en botellas de vidrio) y del alga fueron obtenidas desde 5 lugares del curso del río. Cinco ejemplares de trucha fueron recolectados desde el río mediante red de captura y luego cada organismo fue evis-cerado y separada la cabeza, tronco y cola. Todo el material biológico fue lavado con agua destilada, envasado en bolsas de poli-etileno y congelado (-20°C) hasta ser liofilizado. La concentración de As en el agua fue medida directamente mediante espectrofotometría de absorción atómica por generación de hidruros (EAA-GH). La

determinación de arsénico total (AsT) en las muestras liofilizadas (0.25 g) se realizó me-diante mineralización por vía seca y medición del analito mediante EAA – GH y flujo de inyección (EAA – GH – FI). La concentración de arsénico inorgánico (AsI), fue determinada a través de digestión ácida, su posterior extracción (CHCl3, 10 mL) y cuantificación a través de EAA – GH – FI. Altas concentraciones de As en el agua re-sultaron en las muestras recolectadas tanto en noviembre del 2000 (0.07 – 0.28 mg L-1) como en noviembre del 2001 (0.05 – 0.92 mg L-1) dependiendo del lugar de recolec-ción. En el alga recolectada en noviembre de 2000 se encontró concentraciones de AsT (54.02 – 98.03 µg g-1 b.s.) y AsI (41.53 – 100.55 µg g-1 b.s.), mientras que las obteni-das en noviembre de 2001 fueron 64.74 – 86.43 µg AsT g-1 b.s. y 36.90 – 59.70 µg AsI g-1 b.s.. Altos valores del factor de bioacu-mulación de AsT en el alga (86 – 1281) y de AsI (42 – 1004) fueron determinados, así como el porcentaje de AsI, respecto al AsT, fluctuó entre 46 – 103%. Se observó que las concentraciones de AsT y AsI, dependen de las respectivas concentraciones existentes en el agua. Los niveles de AsT y AsI en la trucha, fueron mayores en el tronco (16.02 µg AsT g-1 y 2.40 µg AsI g-1 b.s.), observán-dose que el AsI representa sólo el 15% del total, a diferencia de lo que se apreció en el alga. Se concluye que existe transferencia del metaloide, del agua al alga y la trucha, no evidenciándose tal situación entre el alga y la trucha, posiblemente debido a que no existe una relación trófica entre ambos.

26

25. Sodium arsenite impairs insulin se-cretion and transcription in pancreatic

β-Cells Andrea Díaz-Villaseñor1, M. Carmen Sánchez-Soto2, Mariano E. Cebrián3, Patricia Ostrosky-

Wegman1 and Marcia Hiriart2

1Department of Genomic Medicine and Envi-ronmental Toxicology, Instituto de Investiga-

ciones Biomédicas; andreadv@biomedicas.unam.mx

2Department of Biophysics, Instituto de Fisiología Celular, Universidad Nacional

Autónoma de México. 3Section of Environmental Toxicology, CIN-

VESTAV, IPN, Mexico City, México

Chronic arsenic exposure by drinking water has been epidemiologically associated with several complex diseases and recently with type 2 diabetes. In the present study we ana-lyzed the impairment of insulin secretion in single adult rat pancreatic β-cells treated with sodium arsenite. Insulin secretion was evaluated in vitro in a subchronic exposure model during 72 and 144 h in the presence of 1 and 5 µM sodium arsenite, in which cell viability was not significantly affected. Basal insulin secretion was not modified with 72 h treatment, but was reduced with 5 µM sodium arsenite for 144 h. Glucose-stimulated insulin secretion decreased in a dose-dependent manner in such a way that cells were not longer able to distinguish between different glucose concentrations. We further demonstrated that 5 µM sodium arsenite can reduce insulin mRNA expres-sion. Our data indicate that by impairing pancreatic β-cell functions arsenic might contribute to the development of type 2 dia-betes.

26. Characterization of Fe-treated clays and zeolites as effective As sorbents B. Doušová1, T. Grygar2, A. Martaus1, D. Koloušek1, L. Fuitová1, & V. Machovič1

1Institute of Chemical Technology in Prague, Technická 5, CZ-166 28 Prague 6;

Barbora.Dousova@vscht.cz 2Institute of Inorganic Chemistry AS, CZ-250 68 Řež

Adsorption of arsenic from aqueous envi-ronment on clay surfaces becomes more and more important for economic reasons. Most of the considered natural alumosilicates be-long to low-cost and environmentally ac-ceptable materials.

Two methods using FeII and FeIII salts were applied to the alumosilicate pre-treatment to improve their sorption efficiency to AsV and AsIII species. In the first case three samples concerning natural kaoline from the Merkur quarry, Czech Republic, calcined at 550 °C for 3 hours, raw clinoptiolite-rich tuff from the Nizne Hrabovce deposit, Slovakia, and zeolite P prepared from fly ashes were ex-posed to concentrated solution of FeII (0.6 M FeSO4·7H2O) for 24 hours. Within that proc-ess, Fe2+ ions are oxidized to Fe3+ ions and the mineral surface is covered with FeIII (oxido-hydr)oxides whose high affinity for the AsV adsorption is well known. In all investigated systems the efficiency of AsV sorption in-creased significantly after the FeII treatment, i.e. from about 15% to more than 90%.

In the second procedure, the sorbents were prepared from raw bentonite obtained from a mineral deposit in Cerny Vrch, Czech Re-public. The bentonite was pre-treated with solutions of FeIII (0.025 M Fe(NO3)3·9H2O, 10 min; sample a) and partly hydrolyzed Fe(NO3)3·9H2O (0.025 M Fe(NO3)3·9H2O 0.05 M NaOH, overnight; sample b). The sorption efficiency of FeIII-treated bentonite to AsV increased from ~16 % in original bentonite to ~78% (sample a, treated ben-tonite containing Fe3+ in cation exchangeable positions) and to ~95% (treated bentonite with Fe3+ in cation exchangeable positions and in ferrihydrite).

The treatment of clays and zeolites by Fe is a very simple method opening new possibili-ties in effective and cheap decontamination of As-polluted aqueous systems. The indi-

27

vidual Fe species in the sorbents, namely Fe3+ ions in cation exchangeable positions and in hydrous ferric oxides were identified by voltammetry of microparticles, diffuse reflectance electronic spectroscopy, high-temperature X-ray diffraction, and chemi-cal extraction by Ni-edta complex, i.e. by novel methods, which are specific and suf-ficiently sensitive to detect molecular and oligomeric species in the sorbents. The characterization of the solid phase with above mentioned methods will permit to identify the actual As-sorbing species and to tailor the sorbents with the optimal sorp-tion properties.

27. Two-step in situ decontamination of mining water enriched with As and Fe

B. Doušová, T. Bruha, A. Martaus, D. Koloušek, R. Pažout, V. Machovič,

Institute of Chemical Technology in Prague, Technická 5, CZ-166 28 Prague 6;

Barbora.Dousova@vscht.cz

The suggested method enables the effective removal of arsenic from strongly contami-nated mining water, resulting from former ore mining activity at Kutna Hora, central Bohemia. The average chemical composi-tion of mining water is in Table 1.

Table 1: Average composition of the raw mining water from Kaňk locality

Compound Concentration [g L-1]

Fe 5.752 Zn 1.589 Cu 2.7x10-5 As 0.054 Mn 0.166 Cd 2.27x10-4 SO4

2- 17.665 Insoluble comp. 0.295 pH 3.5 - 4.1

The two-step process includes partial pre-cipitation of contaminated water with a small amount of alkaline agent. In the first step the raw water is partially precipitated

with a defined amount of alkaline agent (NaOH, Na2CO3 or Ca(OH)2) to pH value ~ 5.0. The precipitation ran under the summary equation:

2Fe2+ + O2 + 5OH- + H3O+ = 2FeO(OH) + 4H2O (I)

During the first precipitation more than 90% of presented arsenic is adsorbed as AsV on the iron oxihydr(oxides) surface immedi-ately, forming the inner-sphere complexes. About 30 – 40% of precipitated iron enables the quantitative removal of arsenic from mining water. The “arsenic“ mass from the first step is than separated by decantation and/or filtration.

The final treatment of mining water runs in the second step. The liquid residue after the first step is precipitated with lime Ca(OH)2 to the pH value ~ 8.5. While arsenic was substantially removed by the first precipita-tion, the other components including residual iron, manganese, zinc and sulfates are pre-cipitated quantitatively during the second step. The mass of the second precipitate depends strongly on the amount of alkaline agent used in the second step. The first step – second step precipitate ratio varies about 1:4. The higher concentration of sulfates in the final treated water relates to the applica-tion of sodium alkalies in the first step. The water solubilities of NaOH and Na2CO3 are substantially higher in comparison with Ca(OH)2 solubility.

The study of AsV - Fe - SO42- changes in

relation to the pH value enables to estimate the optimal conditions of the process, i.e. to produce the minimal mass of toxic precipi-tate while keeping ecological limits of treated water. The two step decontamination of arsenic enriched mining water improves ecological and economical aspects of the current technology.

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28. Subchronic exposure to fluoride modifies the arsenic metabolism and

renal oxidative damage in mice Maribel Espinosa, Eliud A. García-Montalvo,

Olga L. Valenzuela and Luz M. Del Razo

Toxicology, Cinvestav-IPN, Mexico City

Inorganic arsenic (iAs) and fluoride (F-) are ubiquitous elements. Their co-exposure is frequent in several endemic areas due to the natural contamination of well water sup-plies destined for the human consumption. In Mexico and other areas; has been re-ported that the co-exposure of these two elements in high concentrations in the wa-ter can cause typical toxic effects of arseni-cism and endemic fluorosis.

The aim of this study was to evaluate the oxidative stress of the repeated co-exposure to arsenite (As3+) and F- in renal tissue of female C57BL/6 mice, which were divided in four groups and exposed daily via ga-vage during 6 weeks with: a) water (control group); b) 3 mg As3+ kg-1 day-1 of sodium arsenite, c) 10 mg F- kg-1 day-1 of sodium fluoride, and d) both As3+ and F-, (3 mg As3+ kg-1 day-1 and 10 mg F- kg-1 day-1), respectively. Urine samples were collected every two weeks (2, 4 and 6 weeks) and levels of F- and the trivalent and pentava-lent arsenical species were performed. Fur-thermore, at the end of exposure the arsen-ical species (AsIII+V, MAsIII+V, DMAsIII+V) were determined in kidney homogenate.

Considering the pro-oxidants antecedents associated to the exposure with iAs and F-, oxidative stress biomarkers at renal level were evaluated such as glutathione (GSH) concentrations, also the renal oxidative damage was evaluated through lipid per-oxidation (TBARS).

The results showed that the As3+-F- co-exposure modified the pattern of arsenical species excreted and modified the urinary excretion of the F-. These results suggesting an interaction between the As3+ and the F- through the possible formation of As-F

complex, that can reduce the bioavailability and increase the half life time in the organ-ism for both elements.

The subchronic exposure to iAs or F- caused oxidative stress, the exposure to both ele-ments caused increase levels of renal GSH. Nevertheless, in the As-F co-exposure GSH concentrations were less than those caused by the single exposure to each xenobiotic. Besides this, the renal TBARS was higher in the iAs exposure group, whereas in the ex-posure to F- group the renal TBARS was increase only at the second week of expo-sure; this effect was similar in the co-exposed group to As-F-.

In future studies to evaluate the biotransfor-mation and the toxic effects caused by iAs exposure, the co-exposure to F- need to be considered.

29. Evaluación de riesgo toxicológico asociado a la ingesta de aguas

naturalmente contaminadas con arsénico y otros oligoelementos tóxicos en La Puna,

Argentina Silvia S. Farías1, Graciela Bovi Mitre2, Rebeca I. Ponce2, María E. Ávila Carrera2, Gladi Bianco de

Salas1, Roberto E. Servant1 1 Unidad de Actividad Química, Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica. Av. Gral. Paz 1499. B1650KNA-San

Martín. Pcia. de Buenos Aires. Argentina 2 Grupo InQA- Investigación Química Aplicada. Facultad de Ingeniería. Universidad Nacional de Jujuy. Gorriti 237-(4600) S. S. de Jujuy- Pcia de

Jujuy. Argentina.

El presente trabajo fue realizado entre mayo de 2001 y julio de 2003 en el Noroeste de la República Argentina. A partir de imágenes satelitales, se estudió un área de 20 000 km2 en la zona de La Puna salto- jujeña y otra de unos 10 000 km2 en la zona de los valles y sierras sub- andinas, en las que se realizó un muestreo bajo normas de calidad, para comparar los tenores de As, B, V y F- y estimar el riesgo asociado a su ingesta.

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Las muestras, provenientes de fuentes su-perficiales y subterráneas fueron analizadas mediante ICP-OES, para determinar As, B y V y cromatografía iónica para evaluar F-.

En la Puna se detectaron valores de hasta 2 mg/L As, mientras que en los valles las concentraciones de As nunca fueron may-ores que el límite establecido por el Código Alimentario Argentino (50 µg L-1 As). Las concentraciones de B asociadas a los máximos tenores de As treparon hasta 50 mg L-1 B, las de F- alcanzaron valores de hasta 4 mg L-1 F-, en las muestras captadas en La Puna, superando así los máximos permitidos por dicha Ley (1 y 2 mg L-1, respectivamente). Y, contrariamente a lo descrito en estudios anteriores realizados en Llanura Pampeana, no se ha observado correlación entre As y V, encontrándose concentraciones que nunca fueron mayores que 100 µg V L-1 en las dos zonas estudiadas.

Una vez identificada el área impactada por estos contaminantes se evaluó la dosis de exposición para caracterización de riesgos no- cancerígenos para la población ex-puesta, discriminando entre adultos y niños, que por sus condiciones físicas y su menor peso corporal, constituyen el grupo de mayor riesgo.

Los resultados informados se discuten en relación con una estimación preliminar de riesgo toxicológico al que están expuestos los grupos poblacionales estudiados con-siderando únicamente la ingesta de agua como vía de exposición para estos con-taminantes críticos, especialmente el arsé-nico.

Para ese elemento, en la zona de los valles, los valores de dosis para adultos y niños (0.8-2.0 µg kg-1 peso/día, respectivamente), nunca superaron el LOAEL- mínima con-centración con la que se observan efectos tóxicos (LOAEL para riesgo no- can-cerígeno * = 2.6 µg kg-1 peso corporal / día), mientras que en la zona de La Puna se determinaron valores de estas dosis com-

prendidas entre 1 y 30 µg kg-1 peso/día, para adultos, y entre 4 y 80 µg kg-1 peso/ día, para el caso de niños, valores que podrían llegar a superar en algunos casos el LOAEL para riesgo cancerígeno (15 µg kg-1 peso/día).

Se propone la realización de un mapa de riesgo para estos elementos, la evaluación de los pobladores por médicos dermatólogos y psicólogos que efectúen pruebas neurocon-ductuales, especialmente en niños, así como también la implementación de un sistema de abatimiento sencillo y económico aplicable a poblaciones rurales dispersas.

(*riesgo no-cancerígeno, relacionado con lesiones dérmicas y efectos neurológicos)

30. Arsénico y otros elementos tóxicos en aguas termales, lagos, vertientes y aguas de consumo, en las cercanías del volcán

Copahue, Argentina Ana María Fazio1, Silvia S. Farías2, Alberto T.

Caselli1, Mariano Agusto1 1Departamento Ciencias Geológicas. Facultad de

Ciencias Exactas y Naturales, Universidad de Buenos Aires. Ciudad Universitaria, Pabellón

2.1428EHA Buenos Aires, Argentina 2Unidad de Actividad Química, Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica. Av. Gral. Paz 1499. B1650KNA- San

Martín. Pcia. de Buenos Aires. Argentina

El Copahue, es un volcán activo de 2297 metros de altura, localizado en la parte oriental de la zona volcánica de Los Andes, al Sur-Oeste de la República Argentina. La presencia de un lago ácido en el cráter, fuentes termales ácidas de elevada tempera-tura y un campo geotermal, son las expresiones superficiales de un sistema hidrotermal volcano-magmático. La princi-pal fuente termal, de características ácidas y elevada temperatura emerge alrededor de 100 metros por debajo del lago del cráter y alimenta al llamado “Río Agrio”, que descarga 12 kilómetros más abajo en el Lago Caviahue, un espejo de agua ácida de origen glacial.

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Desde el invierno de 2003 se han venido realizando muestreos estacionales, bajo normas de calidad, para observar las variaciones en las concentraciones de aniones y de cationes presentes en las aguas bajo estudio, de forma de poder establecer tácticas de monitoreo.

Las muestras, provenientes de fuentes su-perficiales y subterráneas fueron analizadas mediante espectroscopia de emisión- plasma inductivo de argón para determinar As, Al, B, Ba, Be, Bi, Cd, Cr, Co, Cu, Fe, La, Mn, Mo, Ni, P, Pb, Sb, Se, Sr, Ti, V, Y y Zn; mediante cromatografía iónica para evaluar F-, Cl-, NO3

-, SO4-, y se empleó

absorción atómica en llama para cuantificar Na, K, Ca y Mg.

Los tenores de As observados superaron en muchos casos valores de 5 mg As mL-1, para muestras captadas durante el invierno. Se hallaron concentraciones significati-vamente menores de este elemento, para muestreos realizados en otras épocas del año. Asimismo, se observaron variaciones estacionales para la mayoría de los otros elementos estudiados, muchos de ellos con niveles de toxicidad comparables al del As.

Una vez identificado el patrón de variación de las concentraciones de los diferentes elementos a lo largo del año se procedió a establecer una frecuencia de muestreo para monitorear las aguas de consumo, y las aguas termales a las que están expuestos miles de turistas que acuden cada año, a este Centro Termal, durante períodos se-manales o quincenales, en busca de alivio para el caso de patologías reumáticas y óseas, de terapias anti- estrés ó simple-mente de merecido descanso y relajación.

Los resultados obtenidos se han informado a las autoridades sanitarias para que alerten a los turistas sobre los peligros inherentes a la exposición prolongada a aguas naturalmente muy contaminadas, durante los baños ter-males que practican diariamente y por largos períodos de tiempo; a evitar la ingesta de esas aguas, consideradas por muchos de

ellos como “curativas”; y a prohibir su utili-zación en el caso que los tenores de As y otros elementos tóxicos, superen los valores establecidos por la legislación vigente al re-specto.

31. Arsenic removal using ferric chloride and direct filtration

R. G. Fernández1, B. Petrusevski2 1Centro de Ingeniería Sanitaria - Facultad de Ingeniería, Universidad Nacional de Rosario.

Riobamba 245 bis – 2000 Rosario – Argentina; cis@fceia.unr.edu.ar

2UNESCO-IHE - Institute for Water Education. PO Box 3015 – NL-2601 DA Delft – The

Netherlands; b.petrusevski@unesco-ihe.org

Arsenic is a carcinogenic metalloid that is currently regulated in drinking water. The levels of arsenic in finished water in an ex-isting water treatment plant are exceeding the current regulation of 10 µg L-1. One of the available technologies for arsenic re-moval from groundwater is adsorption onto coagulated flocs and in this field, ferric chlo-ride is the most commonly used coagulant for arsenic removal. This research work was conducted to explore a suitable conventional treatment technology for arsenic removal from given groundwater in order to reduce the filtrate arsenic concentration to less than 10 µg L-1.

Bench scale jar test experiments and pilot-scale investigations were carried out to evaluate and improve the coagulation / floc-culation process for arsenic removal using ferric chloride. Model water that represented the water from the existing water treatment plant was used to investigate the effects of different conditions of pH, coagulant doses, arsenic speciation, initial arsenic concentra-tion, temperature, and flocculation condi-tions on the arsenic removal efficiency by coagulation / flocculation process. Based on these bench scale experiments, a direct filtra-tion technique to separate the formed flocs was considered as the most suitable floc

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separation system to be applied after coagu-lation/flocculation process. A direct filtra-tion pilot plant was operated to evaluate the efficiency of arsenic removal.

The results of series of jar test experiments showed that As(V) could be completely removed with iron doses higher than 2 mg L-

1 for filtered samples and at pH value about 7.0. The lower efficiencies obtained for un-filtered samples indicate that settling mecha-nisms are not effective enough to ensure complete removal of As(V), even when using very high doses of coagulant. In agree-ment with the results of previous studies, it was found that As removal efficiency in-creased with the coagulant dose. Addition-ally it was also observed that under the given conditions As(III) removal efficiency was much lower (up to 60%) compared to As(V) removal efficiency (90 - 100%).

Direct filtration with iron doses of 2 mg L-1 at pH value about 7.0, could reduce As(V) levels from 50 to 4 µg L-1 or less without any risk of iron or turbidity increasing in the filtered water within a reasonable fil-terrun length.

Direct filtration using ferric chloride as coagulant, could be an appropriate technol-ogy to reduce arsenic levels below 10 µg L-1 for the given groundwater.

32. Rapid, clean and low-cost assessment of inorganic arsenic in the mussel Mytilus

Galloprovincialis Lmk. by visible and near-infrared spectroscopy

Rafael Font1, Dinoraz Vélez2, Mercedes Del Río-Celestino3, Antonio De Haro-Bailón1, Rosa

Montoro2

1Instituto de Agricultura Sostenible (CSIC). Alameda del Obispo s/n. 14080, Córdoba, Spain

2Instituto de Agroquímica y Tecnología de Alimentos (CSIC), Apartado 73, 46100, Burjas-

sot (Valencia), Spain 3CIFA, Junta de Andalucía, Apdo. 4240, 14080

Córdoba, Spain

M. galloprovincialis Lmk. represents an important resource for fishery in Spain. This production places Spain as the second pro-ducer of mussel of the world, after China. In addition, Spanish export trade for mussel is increasing quickly, mainly in Europe, where countries as Belgium imports over 12000 kg of M. galloprovincialis every day.

Among the metals and metalloids present in the environment, arsenic (As) stands out because of its toxicological potential. Arse-nic is found in food in various chemical forms that differ in their degree of toxicity and pathologies associated with it. The most toxic forms of As are the inorganic ones (iAs), i.e., As(III) and As(V), which are con-sidered human carcinogens.

Thus, concern for food safety in relation to iAs occurrence in foods currently calls for exhaustive controls of these molecular forms in a variety of food products. The standard methodologies for iAs determination offer a high level of precision but at the same time show some handicaps, such as high cost of analysis, slowness of operation, destruction of the sample, and use of hazardous chemi-cals. The availability of fast methodologies to quantify iAs levels in different kinds of foods would contribute to the drawing up of legislation to guarantee the healthiness of foods with respect to this metalloid.

One approach to the consecution of such objectives is made through the use of Visi-ble-Near-Infrared Spectroscopy (VIS-NIRS). VIS-NIRS is a valuable technique that offers speed and low cost of analysis, and also the sample is analyzed without using chemicals. The spectral information obtained from sam-ples can be used for prediction of the iAs, once appropriate calibration equations have been prepared from sets of samples analyzed by both VIS-NIRS and conventional analyti-cal techniques.

We present in this work the potential of VIS-NIRS to predict iAs in different matrices of animal and plant origin. Mathematical mod-els (calibration equations) were developed

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over the spectral data jointly with the iAs concentrations in the samples, by using Modified Partial Least Squares (PLSm) regression. On the basis of the coefficients of determination (R2) shown by the equa-tions in the validation, and also of the stan-dard deviation to standard error of predic-tion in the validation (RPD), the equations obtained displayed a high predictive ability to determine iAs in such matrices. Our results suggest that both, the VIS (chomo-phores) and NIR (X-H, where X= C, O, N) regions of the spectrum from the matrices used to conduct this work, contain relevant information that can be related to the iAs concentration in the samples. This pioneer-ing use of VIS-NIRS to predict the iAs content in biological matrices represents an important saving in time and cost of analy-sis.

33. Intermediate to high levels of arsenic and fluoride in deep geothermal aquifers from the northwestern Chacopampean

Plain, Argentina María Gabriela García1, César Moreno2, Diego Sebastián Fernández3, María Cristina Galindo2

Ondra Sracek4 and Margarita del Valle Hidalgo2

1Centro de Investigaciones Geoquímicas y de Procesos de la Superficie. FCEFyN. Universi-

dad Nacional de Córdoba 2Centro de Investigaciones y Transferencia en

Química Aplicada. Tucumán. FCN e IML. Universidad Nacional de Tucumán. Tucumán,

Argentina. Córdoba, Argentina 3Servicio Geológico Minero Argentino, Delega-

ción Tucumán 4Dep. of Geological Sciences, Faculty of Sci-

ence, Masaryk University, Brno, Czech Republic

High levels of natural occurring arsenic and fluoride in groundwaters from the Chaco-pampean plain have been assigned to the presence of volcanic shards spread within the loess matrix. The primary source of these elements has not been determined yet but there is almost a clear understanding about the mechanisms that promote their

mobilization in the aquifers. Geochemical evidence suggests that, after being released into groundwater, the concentration of arse-nic in solution is controlled by pH. Arsenic is preferentially scavenged by adsorption on Fe (hydr)oxide coatings under acidic to neu-tral pH conditions. The concentration of fluoride depends on the fluorite solubility and also on pH-dependent adsorption with adsorption minimum at high pH values.

In the province of Tucumán, the loessic layer is restricted to the first 30 meters of the Qua-ternary sequence. As a consequence, most shallow groundwater is contaminated by high levels of As and F-. Groundwater in deep confined aquifers is considered to be suitable for human consumption. However, in the southern part of the province several wells show from intermediate to high con-centrations of As (between 10 to 79 µg L-1) and high concentrations of F- (between 0.6 and 6.0 mg L-1). These wells that penetrate saturated layers as deep as 500 mbs, show ground water temperatures above the annual average in the region. Some authors pro-posed that the heat is supplied from a basal-tic layer located 7000 mbs.

The geochemistry of As and F- in deep aqui-fers shows certain characteristics that are not completely coincident with those described in the rest of the Chacopampean plain. Unlike in shallow groundwaters, the concen-trations of As increase with increasing depth and temperature. The same trend is observed for F-, but the relation with depth is not such clear. Furthermore, As shows direct linear correlation with sulphate and reverse correla-tion with bicarbonate and calcium. F- is poorly correlated with arsenic, but highly correlated with chloride and sodium. It also shows reverse correlation with calcium. Concentrations of F- increase at increasing pH and decreasing Eh, but this trend is less evident for As.

The primary source of As and F- in the deep confined aquifers can be associated with volcanic Tertiary sediments that are sup-

33

posed to be in the deepest part of the sedi-mentary sequence. The up-flow of geo-thermal fluids through structural conduits is considered negligible because ground water chemistry matches those of volcanic sedi-ments. The mobilization of As does not seem to be controlled only by the pH, but also by other factors such as the presence of As-rich primary source sediments. The concentration of F- is not affected by the precipitation of fluorite as its supersatura-tion is never reached due the removal of Ca2+ by the precipitation of calcite and/or cation exchange.

34. Lipoperoxidative damage, nerve con-duction and histological characteristics

of sensory sural nerves of rats exposed to arsenite

Erika García-Chavéz1; Bertha Segura2; Horacio Merchant3; Luz C. Sánchez-Peña1; A. Barrera1, Jose C. Guadarrama4, Ismael Jiménez4 and Luz

M. Del Razo1

1Toxicology, Cinvestav-IPN, Mexico. 2 FES-Iztacala, UNAM, Mexico,3IIB-UNAM, Mex-

ico,4Physiol., Biophys. & Neurosci., Cinvestav-IPN, Mexico

Although the remarkable interest on toxico-logical properties of inorganic arsenic (iAs), it has limited amount of information on the capacity of this metalloid to interact and cause structural and functional altera-tions of the nervous system. Previous stud-ies have demonstrated that humans exposed to iAs affect the central nervous system and can produce peripheral neurotoxicity. Gen-eration of reactive oxygen species (ROS) is the major mechanism by which arsenic exerts its toxicity in a variety of tissues. ROS has been demonstrated in rat brain exposed to iAs, although their role in the peripheral nervous system is not fully es-tablished. In addition, the adverse effects of arsenical exposure have not been related to the presence of methylated arsenic species (MAs and DMAs) formed during the iAs metabolism and distributed in nervous sys-

tem, which could be in some extent respon-sible for the neurotoxic alterations reported. Our aim was to assess the relation of the distribution of iAs and its metabolites, its oxidative damage, nerve conduction and histological characteristics of the peripheral sural nervous of rat subchronic exposure to arsenite. Wistar male rats (200 g body weight) received sodium arsenite (10 mg kg-1 bw/day, gavage, for 30 days). Thiobarbituric acid-reactive substances (TBARS) and dis-tribution of iAs and its metabolite in sural nerve were evaluated at the end of 30 days of exposure. Sural nerve conduction studies were performed for measurement the com-pound action potentials and transversal sec-tions using standard electrophysiological and histological techniques. The results revealed oxidative damage in sural nerve as compared from control group (p<0.0001). Dimethyl arsenic was the predominant metabolite of iAs (∼95%) in peripheral nervous tissue.

Meanwhile, the compound action potential evoked in exposed nerves showed a consid-erable reduction area (~18%; p<0.05) and conduction velocity (~18%; p<0.05). These electrophysiological finding were well sup-ported by the histological observation of reduction in axon diameter (~34.8%; p<0.01) and myelin sheath thickness of ax-ons (~40%; p<0.01), as compared with those of control nerves.

Our results may indicate that the high con-centration of DMA in rat peripheral nerves causes demyelinating and axonal changes altering the generation and propagation of action potentials in peripheral nerves and those effects could result in decreased transmission of sensory information from peripheral receptors to the spinal cord.

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35. Arsenite biotransformation in mice feed with selenium deficient diet and

exposure to arsenite Eliud A. García-Montalvo, Olga L.Valenzuela, Araceli Hernández-Zavala, Luz M. Del Razo

Cinvestav-IPN, Toxicology; Mexico City, Mexico

Arsenic (As) is a widespread environmental toxicant in several parts of the world, the main way of exposure is through the drink-ing water or industrial emissions. In hu-mans, like in most mammalian species, inorganic arsenic (iAs) is methylated to methylarsonic acid (MMAV) by AsIII-methyltransferase (AS3MT) using S-adenosylmethionine (SAM) as a methyl group donor. The MMAV through alterna-tive reductions form methylarsonous acid (MMAIII) which is methylated by AS3MT and SAM producing dimethylarsinic (DMAV) which again by alternative reduc-tion produce dimethylarsinous (DMAIII). The main mechanism of toxic action related with the exposure to iAs and the produced metabolites, mainly the trivalent arsenicals species are linked with the reactive oxygen species (ROS) who are the responsible of the stress generation and oxidative damage.

On the other hand, selenium (Se) is an es-sential constituent of the antioxidant system that allows the survival of whom in a rich oxygen environment where the free radicals can damage the biological molecules. Is an essential micronutrient for humans because it is an important component of antioxi-dants enzymes as glutathione peroxidase (GPx) and thioredoxin reductase (TrxR).

Like As, Se is a metalloid which undergoes similar metabolic conversions, the inor-ganic species as selenate (SeIV) and selenite (SeVI), are reduced by glutathione (GSH) to yield hydrogen selenide (H2Se), H2Se serves to produce the organic selenium compounds of interest in health and nutri-tion. Since the metabolic interactions be-tween As and Se are complex and it would

represent a practical significance because many human populations are simultaneously exposed to As through drinking water and different levels of Se mainly in the diet. The aim of this study was to evaluate the bio-transformation and distribution of As and their relationship with stress oxidative events in function of the deficient SeMet concentra-tion in weanling female C57BL/6 mice feed by 42 days with Se deficient diet (0.02 mg Se kg-1) and exposed daily to 6 mg As kg-1 day-1 for 9 consecutives days. Oxidative stress biomarkers at hepatic level were evaluated such as GSH and GPx concentra-tions; also the renal oxidative damage was evaluated through lipid peroxidation (TBARS).

Se deficiency group had not alteration in the urinary and liver concentration of arsenicals comparing with diet Se sufficient (0.2 mg Se kg-1) but, increases the urinary relative pro-portions of iAsIII, iAsV, MMAIII, and MMAV accompanied by decreases in DMAIII and DMAV. In addition, increases the relative proportion of iAs and decreases DMA pro-portion in liver.

The Se deficient group exposed to arsenite decreases the concentration of hepatic GPx. However, this decrease was not associated to the presence of hepatic oxidative damage suggesting the possibility of DMA metabo-lite could be the responsible of oxidative damage observed in mice exposed to arsenite and feed with Se sufficient diet.

Se deficiency in the diet affected the arsenite biotransformation pattern and its relation with stress oxidative markers.

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36. Neurotoxicity of arsenic María E. Gonsebatt, Verónica Rodríguez, Jorge H. Limón, Roxana Navarrete, Hielen Queriol, Magda Giordano, Gabriel Gutiérrez Ospina y

Luz Maria Del Razo

Instituto de Investigaciones Biomédicas e Insti-tuto de Neurobiología, UNAM, CINVESTAV,

IPN México; margen@servidor.unam.mx

Epidemiological studies demonstrate that inorganic arsenic exerts other adverse ef-fects that do not involve the induction of cancer such as injury to the peripheral and central nervous systems. Arsenic crosses the blood brain barrier and might accumu-late in brain where it could be metabolized to monomethyl (MMA) and dimethyl (DMA) arsenic forms. In mammals, bio-methylation by the arsenic methyltrans-ferase (As3MT) occurs in two steps: 1) the reduction of pentavalent species to triva-lency in the presence of glutathione (GSH) or thioredoxin and 2) the oxidative methy-lation whereby inorganic arsenic is con-verted to MMA, DMA and trimethyl (TMAO) arsenic forms using S-adenosyl methione (SAM) as the main methyl donor. To investigate the possibility that arsenite was methylated in brain, we treated mice with different doses of sodium arsenite and observed the generation of methylated spe-cies not only in the animals but also in brain organotipic cultures. Arsenic is me-tabolized in mouse brain, mostly to DMA in a dose related manner. Also, contrary to what have been shown in “vitro” inhibition of glutathione reductase, a key enzyme in the maintenance of GSH pool, was ob-served only at very high doses of arsenite. Besides the toxic effects of the accumula-tion of methylated arsenicals in neural tis-sue, both GSH and SAM are important molecules not only in the biochemistry of arsenic but in the physiology of the nervous system. Thus, arsenic metabolism could diminish the GSH pool in the central nerv-ous system, a condition that is associated to neurodegenerative processes such as Alz-

heimer’s, Parkinson and schizophrenia. Bio-transformation of arsenic in brain could also alter the homeostasis of SAM and its inter-mediate metabolites, including methionine, choline, folate, and vitamins B6 and B12, some of which are important substrates or cofactors in neurotransmitter metabolism or in the development of the CNS especially in more susceptible individuals such as children and older people.

37. Arsenic origin determination by geo-chemical modeling: Region Lagunera

aquifer system, Mexico Carlos Gutiérrez-Ojeda

Instituto Mexicano de Tecnología del Agua, Paseo Cuauhnáhuac 8532, Jiutepec, Morelos,

62550 México.; Tel (+52 73) 194000 ext 793/805; Fax (+52 73) 194341 / 193422

The elevated arsenic concentrations found in the groundwater of the alluvial aquifer of the Region Lagunera, northern Mexico, have been attributed to several potential sources: hydrothermal activity, use of arsenical pesticides, mining activities and sedimentary origin.

Arsenic concentrations range from 0.003 to 0.443 mg L-1 (mean of 0.074 mg L-1; stan-dard deviation 0.099). Extensive areas of the alluvial aquifer have concentrations quite above 0.03 mg L-1, the Mexican Maximum Contaminant Level (MCL) for drinking wa-ter. The highest concentrations are found in the lagoonal deposits located in the north-eastern part of the basin, as well as towards the northwestern and southeastern areas.

Previous studies have showed that arsenic is naturally occurring and its most probable origin is due to extinct intrusive hydrothermal activity. Geochemical modeling were used in this work to show that under natural and unchanged conditions, the evaporation of surface water carried by the Nazas and Aguanaval Rivers (0.00201 < As < 0.01766 mg L-1) could have contributed to the elevated

36

groundwater arsenic concentrations (0.003 < As < 0.443 mg L-1) found in the lower parts of the closed basin.

The idea was to select two water samples; one representative of the surface water (from reservoirs) and the other of the groundwater of the area where elevated arsenic concentrations have been found. Then, artificially evaporate the surface water by multiplying its analytic chemical data by the chloride ratio between both samples. A modified version of the aqueous speciation program WATEQF was used to determine the saturation indices of plausible minerals (phases) of both the evaporated surface water and the groundwater. The geochemical program NETPATH was then used to deter-mine the net geochemical mass-balance reactions between the evaporated surface water (initial water) and the groundwater (final water).

The results show that evaporation of 51.51 liters of surface water from the Nazas River would produce one liter of well 1387; this would require the precipitation of calcite (43.86 mmol) and fluorite (1.46 mmol), dissolution of gypsum (6.60 mmol), outgas-sing of CO2 43.19 mmol), and an exchange of 1 mmol of calcium (entering the aqueous solution) per every 0.42 mmol of sodium, 2.46 mmol of potassium and 4.01 mmol of magnesium (leaving the aqueous solution).

38. Arsenic distribution in the multi-layer aquifer of Salamanca, México

H. Hernández, R. Rodríguez and A. Armienta

Geophysics Institute, UNAM; Earth Sciences Postgraduate Program UNAM, Mexico

Salamanca is located in Central Mexico, Guanajuato state, in the Subprovince Bajio Guanajuatense in the Physiographic Prov-ince Eje Neovolcanico. The geologic envi-ronment is defined by volcanic and sedi-mentary rocks from Tertiary to Recent. Groundwater is the only water supply for

Salamanca. There are not alternative water supply sources.

The local aquifer is composed by 3 perme-able units, forming a multilayer aquifer sys-tem. A shallow formation, an intermediate one, semi confined, and a deep unit, con-fined. The shallow water table is located 18-19 m depth. The intermediate water table is found to 35-45 m. Clay, gravel and sand composed the shallow and intermediate aq-uifers, whereas volcanic material formed the deep unit.

The arsenic concentration in the 3 units is variable. The space distribution looks to be controlled by a fault originated by subsidence. A local fast recharge through the fault system can affect the As concentration.

The deep aquifer As could be associated to the sequence of volcanic rocks. Its ground-water is thermal. The As detected in the in-termediate formation, exploited for urban supply could be natural and anthropogenic.

Taken into account these chemical character-istics some alternatives for aquifer manage-ment are proposed.

39. Estudio del efecto de los procesos termicos sobre la concentración de

arsénico total, arsénico inorgánico en los productos pesqueros

C. Herrera†; O. Muñoz*†; J,M. Bastias‡;

†Centro de Estudios en Ciencia y Tecnología de Alimentos, Universidad de Santiago de Chile,

Casilla 33074, Correo 33 Santiago; omunoz@lauca.usach.cl

‡ Departamento de Ingeniería en Alimentos, Universidad del Bío-Bío, Casilla 447, Chillán,

Chile; jobastias@ubiobio.cl

El presente estudio determinó el efecto de los procesos térmicos utilizados en el cocinado habitual sobre la concentración de arsénico total, y arsénico inorgánico en cinco especies marinas de mayor consumo en la ciudad de Santiago (Choritos, Almejas, Cholgas, Jurel y Congrio negro), Se

37

utilizaron cinco muestras de cada especie y tres tratamientos (crudo, hervida y al horno). La determinación de Arsénico total se realizó por digestión por vía seca, En el caso del arsénico inorgánico, se utilizó un procedimiento de extracción por solventes, obteniendo en todos los casos resultados reproducibles y representativos.

Para la determinación analítica se utilizó un Espectrofotómetro de Absorción Atómica (AAS) Varian A 55 acoplado a generación de hidruros.

En las muestras crudas, la mayor concen-tración de metales se encuentra en los bi-valvos (6.18-15.19 µg g-1, base seca (bs) de As total; 0.11-0.23 µg g-1, bs de As inor-gánico), los peces obtuvieron menores con-tenidos de ambos metales (1.69-5.61 µg g-1, bs de As total; 0.08-0.12 µg g-1, bs de As inorgánico).

El Análisis de ANOVA por especie (Chori-tos, Almejas, Cholgas, Jurel y Congrio negro), de los resultados obtenidos en relación a los tres tratamientos utilizados (crudo, hervida y al horno), tanto para arsé-nico total como para arsénico inorgánico, presentaron un valor de P<0.05 indicando que existen diferencias estadísticamente significativas entre los tratamiento. Por lo tanto, al someter los productos pesqueros a procesos térmicos se producen modifica-ciones en el contenido de Arsénico total, las que se atribuyen a la suma de efectos con-trarios: concentración debido a la pérdida de peso del alimento, la cual es mayor en el caso de productos horneados, y por pérdida del arsénico soluble debido a la eliminación de exudados. Con respecto al arsénico inor-gánico se suma el efecto de transforma-ciones que pueden ocurrir en las especies orgánicas a inorgánicas.

40. Subsurface treatment of arsenic in groundwater – laboratory scale

experiments Holländer, H.M.*; Boochs, P.-W.*; Stummeyer,

J.**; Billib, M.*; Krüger, T.* *Institute of Water Resources Management, Hy-

drology and Agricultural Hydraulic Engineer-ing, University of Hannover, Germany;

hollaender@iww.uni-hannover.de **Federal Institute of Geosciences and Natural

Resources (BGR), Hannover, Germany

Objectives. High arsenic concentrations in groundwater (up to 8500 µg L-1) have been found at a military site. It should be investi-gated whether a subsurface groundwater treatment (in-situ treatment) can be applied to remove the arsenic. The procedure is based on the injection of iron and oxygen enriched water into the aquifer to precipitate the arsenic together with the iron.

Methods. Laboratory experiments were carried out at batch reactors using natural groundwater with high arsenic concentra-tions from the contaminated site. Different iron compounds containing Fe(II), Fe(III) or Fe0-particles have be mixed with the water and were aerated for several hours. The de-tection of arsenic was separated into As(III), As(V) and organic As.

Results. The results showed that it is impos-sible in this case to precipitate the arsenic without adding additional iron (removal of arsenic was below 2%) because the iron which is naturally in the groundwater is too low. Fe(II) showed the best results. The re-duction of arsenic was nearly 80%. The pre-sents of ammonium was reducing the arsenic to only 40%. This is caused by the oxygen demand of the nitrification process. The precipitant Fe(III) had only a small effect in reducing the arsenic concentration (less than 10%). Fe0-particles can be also used to re-duce the arsenic. The reduction was ob-served of 60%.

Conclusions. The removal of arsenic by injecting oxygen into the aquifer without an

38

additional precipitant is impossible at the contaminated site because the natural iron content is very low. But first laboratory experiments showed that it is possible to remove high arsenic concentrations with adding additional iron as participant. Best results were observed using Fe(II) or Fe0-particles.

Further investigations will be carried out to optimize the iron concentration and to transfer the results to a field experiment at the military site.

41. Effects of selenium deficiency on dia-betogenic action of arsenite in rats

Jeannett A. Izquierdo-Vega1, Claudia A. Soto-Peredo2, Luz C. Sánchez-Peña1, and Luz M. Del

Razo1 1Toxicología, Cinvestav-IPN, Mexico

2Sistemas Biológicos, UAM-Xochimilco, Mexico

Selenium (Se) is an essential trace element for animals and humans, it play important role in the protection against oxidative damage. In addition, it is an insulin-like trace mineral that regulate homeostasis of the glucose.

Selenium deficiency is one of the factors related to diabetes, malnutrition, low corpo-ral weight, muscular dystrophy, rheumatoid arthritis and diseases associated to the pres-ence of oxidative stress. The metabolic and toxicological interactions between arsenic (As) and Se have been reported in many experimental studies. It would represent a practical significance because many human populations are simultaneously exposed to As through drinking water and different levels of Se mainly in the diet. There are recent epidemiologic studies that have as-sociated chronic exposure to inorganic arsenic with an increase in the prevalence of diabetes mellitus. In a previous study, we showed that the subchronic exposure to arsenite in rats causes insulin resistance. Our aim was evaluate if deficiencies of Se,

therefore, can have a detrimental effect on insulin resistance caused by subchronical arsenite exposure.

In the present study we evaluated the endo-crine function and oxidative damage in pan-creas of male Wistar rats (200 g body weight) feed with Se deficient diet (0.02 mg Se kg-1) and exposed to sodium arsenite at 1.7 mg kg-1 12 h by gavage for 90 consecu-tive days. Rats received the Se deficient diet twenty days before the administration of first dose of arsenite and continued for 90 days of arsenite exposure. At the end of the treat-ment, glucose, insulin and glucagon concen-tration in serum were quantified. A simple method to quantify insulin resistance was assessed through the measurement of glu-cose and insulin (fasting glucose [mmol/L] X fasting insulin [mU L-1]/22.5). Oxidative stress biomarkers at pancreatic level were evaluated such as glutathione and the activ-ity of seleno-enzyme thioredoxin reductase (TrxR); also the pancreatic oxidative damage was evaluated through lipid peroxidation (TBARS).

The insulin resistance caused by subchronic arsenite exposure in rats feed with Se suffi-cient diet (0.2 mg Se kg-1) was no exacer-bated in Se deficiency. Rats exposed to ar-senite and fed with Se deficiency had value of insulin resistance of 14.10 ± 5.04 vs 13.17± 4.79 obtained in Se sufficiency; these values were significantly higher than those of their respective Se-deficient and Se-sufficient control groups (1.84± 1.35 vs 3.34± 1.19).

Independent of arsenite exposure, the Se-deficient diet caused stress and oxidative damage in pancreas. Besides, pancreatic oxidative damage was significantly higher in rats subchronically exposed to arsenite with low Se status than rats with Se adequate diet. The changes may be related to the decreased activity of TrxR, selenoenzyme with anti-oxidative functions.

Se deficiency in the diet intensifies the pan-creatic oxidative damage but did not alter the

39

hiperinsulinemia caused by subchronic arsenite exposure.

42. Occurrence, distribution and tempo-ral variation of the concentrations of arsenic in groundwater from Jhikor-

gachha Upazila, Bangladesh M. Jakariya1*, Kazi Matin Ahmed2, M. Abul Hasan2, Sultana Nahar2 and P. Bhattacharya3

1Research and Evaluation Division (RED), BRAC, 75 Mohakhali, Dhaka 1212, Bangla-

desh; jakariya@ngof.org, prosun@kth.se 2Department of Geology, Dhaka University,

Dhaka 1000, Bangladesh 3KTH-International Groundwater Arsenic Re-search Group, Department of Land and Water

Resources Engineering, KTH, SE-100 44 Stockholm, Sweden

Arsenic contamination, in fact, has become a global issue of public health as it has been encountered in many countries and regions under varying conditions. The presence of arsenic in groundwater has lead to wide-spread concern in Bangladesh. According to the information gathered through the extensive work of various agencies, at least one third of the countries domestic hand tube wells yield water at concentrations above the Bangladesh limit of 50 µg L-1 and more than 60% of the wells exceed the WHO provisional guideline value of 10 µg L-1. Since detection of arsenic contamina-tion in 1993, various studies have provided useful information regarding origin, occur-rence, distribution and the factors control-ling the mobilization of arsenic in ground-water. Studies have been undertaken to find sustainable mitigation of the arsenic prob-lem in Bangladesh. In the process, new concerns such as change of arsenic concen-trations with time and transfer of arsenic through irrigation need proper attention.

BRAC completed a community based arse-nic mitigation study in Jhikorgachha Upazila, which was started in early 1999 and completed in December 2001. One of

the main objectives of the project was to test all the tube well water of the study area and to develop recommendation about the influ-ence of time series and seasonal fluctuation of arsenic concentration in tube well water. The current study synthesizes the data gen-erated from the BRAC’s community-based arsenic mitigation pilot study in Jhikor-gachha Upazila with financial support from UNICEF and the Department of Public Health Engineering (DPHE) of the Govern-ment of Bangladesh. In the present study, we present the salient characteristics about the occurrence, distribution and time trends of the variations in arsenic concentration in the tube wells of Jhikorgachha Upazila in southwestern Bangladesh.

The present study reveals subtle changes in the levels of arsenic concentration in the tube well water. The decrease in the concen-tration of arsenic occurred in almost 50% of the wells of Jhikorgachha Upazila while 46% of the wells showed an increase in the levels of arsenic. However in 4% of the wells the no change in the arsenic concentra-tion was observed. The highest concentration increase in the analyzed tube well water was 91 µg L-1 with a mean increase of 15.7 µg L-

1 and the lowest decrease was ca. 128 µg L-1 with a mean decrease of ca. 19 µg L-1. Therefore, it can be said from the findings of the present study that arsenic concentration in tube well water might increase or decrease with time; however these results indicate that there is a strong tendency of a reduction in the levels of arsenic concentration with time depending on the local hydrogeological con-ditions.

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43. Distribution of arsenic in three geo-chemical fractions of surface sediments

from coastal sites of Sonora, Mexico M.E. Jara-Marini and L. García-Rico

Centro de Investigación en Alimentación y Desarrollo, A.C; Division of Food Science, km

0.6, Carretera a la Victoria, PO Box 1735, Hermosillo, Sonora 83000 Mexico

Arsenic is widely distributed in marine environments and their interaction proper-ties are determined by chemical and physiochemical parameters, as well as its toxic effects in the marine organisms. An indirect metal toxicity evaluation has been performed by operational fractionation using selective chemical extraction solu-tions. Sonora is one of the principal fishery producers in Mexico and in a previous study, a range of 0.09-7.71 µg g-1 of total arsenic was detected in surface sediments of oyster farms of the Sonora state. For this reason, the aim of this study was evaluate arsenic distribution in geochemical frac-tions of surface sediment of four oyster culture sites in the Sonora coast using a three step microwave sequential extraction scheme. Fifty-four surface sediment sam-ples were collected from February to Au-gust 1999. A microwave selective extrac-tion scheme was used. Arsenic concentra-tion was determined in exchangeable (EF), bound to organic matter (OMF) and resid-ual (RF) fractions by hydride vapour gen-eration coupled to an atomic absorption spectrophotometer. Duplicates, blanks and standard reference material were analyzed during the procedure. Statistical analysis were performed using ANOVA-General Linear Model, Fisher´s LDS mean com-parison and Pearson correlations. The total mean arsenic range of concentration (EF-RF) was 0.10-6.59 µg g-1. By study sites wide ranges were also detected (µg g-1): Puerto Peñasco 0.08-6.20, Caborca 0.11-5.35, Hermosillo 0.14-7.30 and Guaymas 0.07-8.68. No significant Pearson correla-tions (p>0.05) were detected. Furthermore,

the sites show a similar concentration of arsenic in the EF and OMF fractions, but slightly higher in Caborca and Hermosillo sites. Both sites are associated to agricultural districts, it is possible that arsenic has been mobilized from deep volcanic deposits into the watertable that is used for agriculture and drinking needs in the cities. Arsenic concen-trations detected may be also related to fertil-izers that could be used in intensive agricul-ture. These arsenic concentrations ranges were similar to those reported in non-polluted sediments. Highest (p<0.05) mean concentration of arsenic (>95%) was de-tected in the RF and then potentially bioavailable arsenic was of minimal toxic risk. However, arsenic may mobilize to bioavailable fractions by changes in envi-ronmental factors (e.g., pH, salinity and re-dox potential), increasing its toxic potential to biota and producing bioaccumulation. In conclusion, the sites studied are pristine in arsenic levels but is important to keep moni-toring sediment, water, and biomonitor or-ganisms to detect alterations of arsenic bioavailability.

44. Using permeable compost barriers for accelerated release of arsenic from con-

taminated sites Ralf Köber1, Jürgen Mattusch2, Birgit Daus2, Edmund Welter3, Francesca Giarolli4, Markus

Ebert1 & Andreas Dahmke1

1Institute of Geosciences, University of Kiel, Ohlshausenstrasse 40, 24118 Kiel,Germany;

rk@gpi.uni-kiel.de 2UFZ – Environmental Research Center

Halle/Leipzig, Germany 3HASYLAB/DESY, Hamburg, Germany

4Agency for Environmental Protection and for Technical Services, Rome; Italy

The bulk of arsenic (As) in the solid phase is frequently associated with iron (hydr)oxides at contaminated sites. Slow desorption of As from iron (hydr)oxide sorption sites can be problematic because this contaminates ground water for decades and longer. Vari-

41

ous studies ascribed increasing dissolved As concentrations to the transformation of iron (hydr)oxides into iron sulfides which was initiated by dissolved sulfide that originated from microbial sulfate reduction. We investigated if this processes can be utilized as a source treatment approach using compost based permeable reactive barriers (PRB) which are located upstream of contaminated areas and promote micro-bial sulfate reduction, or if sulfide supply rather causes precipitation of arsenic sul-fides which would decelerate the As re-lease.

Two sets of column experiments, composed of sequential columns connected by tubing were performed. The first column of sys-tem 1 was filled with organic matter (40% compost, 33% chaff, 27% wood chips), the second with As bearing aquifer sediment from a former fuchsine production site and the third with ZVI. In system 2 (reference), which was run to compare the As release without preset organic matter, the first col-umn contained As contaminated sediment and the second ZVI (As removal by ZVI shall be discussed in a separate presenta-tion).

The As bearing aquifer sediment showed no significant decrease in As content after 420 days of percolation with sulfide-free artificial ground water. In contrast, water that previously passed through organic matter and exhibited sulfide concentrations of 10-30 mg L-1 decreased the As content in the sediment for 87% within 360 days. X-Ray diffraction (XRD) and X-Ray absorp-tion spectroscopy (XAS) investigations showed that no arsenic sulfides precipi-tated, although saturation indices for arse-nic sulfides occasionally were near equilib-rium. The speciation of dissolved As (measured by IC-ICP-MS) changed from initially As(V) dominated to As(III) domi-nated immediately after starting the sulfide flushing, which increases the mobility of As. The resulting solution could appropri-ately be treated by zerovalent iron. Because

sulfide can be supplied not only by compost based PRBs but also by direct injection of solutions with high sulfide concentrations, sulfide flushing has a wide range of applica-tion for source treatment of arsenic.

45. Sulfide – A controlling species for treatment of As by zero valent iron R.F.Köber1, E. Welter2, F. Giarolli3, M. Ebert1 &

A. Dahmke1

1Institute of Geosciences, University of Kiel, Ohlshausenstrasse 40, 24118 Kiel,Germany;

rk@gpi.uni-kiel.de 2HASYLAB/DESY, Hamburg, Germany

3Agency for Environmental Protection and for Technical Services, Rome

Several investigations showed an encourag-ing potential for the removal of arsenic (As) from groundwater by granular zero-valent iron (ZVI). Even though microbial sulfate reduction (MSR) is a known and omnipres-ent process in ZVI-PRBs, most of these stud-ies did not consider the presence of dissolved sulfide. These studies showed that sorption of As to iron (hydr)oxide corrosion products is the predominant mechanism under such conditions. Contrasting to those former stud-ies, we investigated the applicability of this method and the nature of the As bonding under conditions with dissolved sulfide. Sulfide can lower the corrosion rate by pre-cipitation of iron sulfide layers and thereby decrease the formation of new iron (hydr)oxide sorption sites for As. Secondly As can get incorporated in these iron sul-fides. Thirdly As and sulfide could be pre-cipitated as As sulfides like realgar, orpiment or arsenopyrite. And fourthly the formation of thio-arsenic (As-S) species can either diminish the removal from solution by in-creasing the solubility of As, or otherwise it can enhance the As removal by sorption of negatively charged thio-arsenic species to positively charged surfaces. Because of those divergent effects on the long-term

42

performance, it was important to investi-gate the influence of MSR and sulfide.

Three column tests containing ZVI were performed for the term of one year (with cis-DCE as a co-contaminant). The input solutions contained either predominantly As(III) (2-200 mg L-1) or predominantly As(V) (4-10 mg L-1). Arsenic outflow con-centrations decreased from initially 30-100 µg L-1 to concentrations of below 1 µg L-1 as a result of decreasing outflow pH with time. XANES and EXAFS spectra indi-cated that As in the solid phase was not only directly coordinated with oxygen like in adsorbed or coprecipitated arsenite and arsenate. Samples with high sulfur content showed an additional bonding for which EXAFS data exhibited a peak between 2.2 and 2.4 Å. This bonding most likely origi-nated from direct coordination of sulfur or iron with As that is incorporated in iron sulfides or from adsorbed thio-arsenic spe-cies. The formation of this sulfidic bonding supports removal of As by ZVI since sul-fide production by MSR is ubiquitous in ZVI-PRBs. Whereas degradation of cis-DCE significantly decelerated with time half life-times for As removal were rela-tively constant. Association of As with sulfur is likely to account for the fast and constant As removal that makes As re-moval by ZVI-PRBs a much more durable process than degradation of chlorinated aliphatics.

46. Bioavailability of arsenic species in food: practical aspects for human health

risk assessments Laparra, J.M.1, Vélez, D.1 *, Barberá, R.2, Farré,

R.2, Montoro, R.1 1 Institute of Agrochemistry and Food Technol-ogy (CSIC), Apdo. 73, 46100 - Burjassot (Va-

lencia), Spain 2 Nutrition and Food Chemistry. Faculty of Pharmacy, University of Valencia, Avda.

Vicente Andrés Estellés s/n, 46100 - Burjassot (Valencia), Spain

Humans are fundamentally exposed to arse-nic, a metalloid widely distributed in nature, through the ingestion of food. The toxicity of arsenic depends on its chemical form – hence the importance of As speciation in the assessment of toxicological risk. The studies of arsenic in foods have mainly focused on the characterization of As species in raw products. However, to date there have been no antecedents of studies on the bioavailabil-ity of arsenic and its chemical species in foodstuffs.

Three groups of foods have been selected for estimating the bioavailability of arsenic: algae (due to their high As content); fish (due to its important contribution to As in-take); and rices (since the latter constitute the main source of As for over 50 million people). Simulated gastrointestinal digestion has been used to assess bioaccessibility (maximum soluble concentration of the ele-ment) as a prerequisite to absorption, with the incorporation of an in vitro cell culture (Caco-2 cells, a validated intestinal epithelial model) to estimate retention and transport, with the purpose of affording an improved approximation to the actual in vivo situation.

The bioaccessibility of arsenic and its chemical species in the analyzed foods is high (>60%) – thus reflecting high solubility and availability for absorption in the gastro-intestinal medium. Cooking does not modify the chemical species or reduce bioaccessibil-ity. Based on the bioaccessible fraction of the foods studied, the cellular retention of arsenic is seen to be very low (1-6%), with comparatively superior transport perform-ance (4-18%) of the different species.

The studies conducted may be regarded as a pioneering effort in the evaluation of the toxicological risk posed by arsenic and its chemical species in foods, by contemplating the bioavailability of As as it is found in food prepared for actual consumption.

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47. Investigation of arsenic accumulation by vegetables and ferns from As-

contaminated area in Brazil Helena Eugênia Leonhardt Palmiere1, Olivia

Vasconcelos2, Julio Silva2, Eleonora Deschamps3

1Nuclear Technology Development Centre/ National Commission for Nuclear Energy

(CDTN/CNEN) Belo Horizonte, Minas Gerais, Brazil; help@cdtn.br

2 Department of Metallurgical and Materials Engineering, Universidade Federal de Minas

Gerais, UFMG, Belo Horizonte, Brazil; olivia@demet.ufmg.br

3Fundação Estadual do Meio Ambiente-FEAM, Av.Prudente de Morais, 1671, 30380-000,Santa

Lucia, Belo Horizonte,MG, Brazil; eleonorad@feam.br

In Brazil hydrothermal gold deposits in the state of Minas Gerais, contain varying pro-portions of gold bearing sulfides, such as arsenopyrite, pyrite and pyhrrotite. Soil and sediments around gold ore deposits and mining areas present positive anomalies (median concentrations > 100 mg kg-1) and wide ranges (<20 to 2000 mg kg-1) even in densely populated area. Total arsenic con-centrations in soil, plants and vegetables were determined by graphide furnace atomic absorption spectrometric (GFAAS), inductively coupled plasma mass spec-trometry (ICP-MS), neutron activation (NA), and by energy dispersive spectrome-try (EDS). The ferns Pteris Vittata and Pity-rogramma calomelanos extract arsenic from the soi and translocate it onto their fronds showing higher arsenic concentration in the leaves (from 102 to 2585 µg g-1) than in the rhizoid (from 55 to 128 µg g-1). All vegeta-bles from private gardens investigated pre-sent increased As-uptake in both their edi-ble and non-edible parts. Enrichments dif-fered between species but reached elevated values.

48. Hydrogeochemistry of arsenic in the regional Loessic aquifer in the southwest

of Buenos Aires Province, Argentina Fabiana Limbozzi1, A. Guillermo Bonorino2 and

Marcelo J.Avena1

1Departamento de Química, Universidad Nacional del Sur, Av. Alem 1253; (B8000CPB)

Bahía Blanca, Argentina; limbozzi@criba.edu.ar, mavena@uns.edu.ar

2 Departamento de Geología, Universidad Nacional del Sur, San Juan 670; (B8000ICN)

Bahía Blanca, Argentina; bonorino@uns.edu.ar

The phreatic water of the regional aquifer in the southwest of Buenos Aires province is the source of water for both the agricultural production systems and the supply of drink-ing water of all the rural populations of the region. Much of the water witdrawaled from the aquifer contains naturally occurring As from the plio-pleistocene loessic sediments in levels higher than WHO guideline value and the Argentine national standard.

An investigation has been carried out to ex-amine occurrence of arsenic and mecha-nisms of As release to groundwater at the Napostá Grande drainage basin of the Sierras Australes’ occidental drainage slope.

Total arsenic, iron, major cations and anions were measured in water samples collected from holes and/or wells with windmills or submergible pumps and interstitial water extracted from sediments of vadose zone through immiscible liquids displacement method. Arsenic contents were determinated also in sediments, volcanic glass and cal-cretes to delineate interrelationships.

Total arsenic concentrations range between 1.5 and 204.6 µg L-1 (mean value: 72.2 µg L-1) in groundwater, 10.7 and 375.4 µg L-1 (176.8 µg L-1) in interstitial water, 3.0 and 10.0 mg L-1 (5.8 mg L-1) in sediments, 7.6 and 21.3 mg L-1 (14.0 mg L-1) in calcrete, and between 2.2 and 5.0 mg L-1 (3.2 mg L-1) in volcanic glass. Among the investigated groundwater samples, 90% exceed the WHO guidelines value at full length of the basin, including the upper basin.

44

Very weak correlations with iron contents suggest that redox processes containing iron and arsenic are not dominant mecha-nism controlling As release to groundwater. Instead, arsenic groundwater correlates positively with alkalinity, so that bicarbon-ate leaching could be the main mechanism to mobilize arsenic in a loessic aquifer.

49. Volcanic pollution of Arsenic and Boron at Ilopango Lake, El Salvador

D.L. López1, L. Ransom1, J. Monterrosa2, T. Soriano3, F. Barahona3, J. Bundschuh4

Department of Geological Sciences, Ohio Uni-versity, Athens, Ohio 45701, USA;

lopezd@ohiou.edu 1Fundacion de Amigos del Lago de Ilopango, San Salvador, El Salvador, Central America

2Departamento de Fisica, Facultad de Ciencias y Humanidades, Universidad de El Salvador 3, 4International Technical Cooperation Pro-gram, CIM (GTZ/BA), Frankfurt, Germany;

jochenbundschuh@yahoo.com 3Instituto Costarricense de Electricidad (ICE), UEN, PySA, Apartado Postal 10032, 1000 San

José, Costa Rica

Ilopango lake in central El Salvador, Cen-tral America, has an area of 184.9 km2 and maximum depth of 240 m.

More than 300,000 inhabitants live in the drainage basin of the lake and use its water even when high concentrations of B and As make this water unsuitable for human con-sumption. High deforestation, fertilization, and industrialization in the lake basin con-tribute to the environmental degradation of Ilopango. The lake has seasonal stratification. Between November and March the lake shows almost isothermal and oxygenated conditions. High wind velocities and slightly lower air temperatures during this time of the year produce convective water movement and mixing of the water column. In compari-son, from March to November, high air tem-peratures and low wind velocities produce a mild thermal stratification. The water and

sediments of Ilopango lake have been sampled and analyzed for main cations and heavy met-als, especially B and As. For the waters, B con-centrations range from 1.5 to 8.7 mg L-1 and As concentrations from 0.15 to 0.77 mg L-1, with the higher values to the South and lower values close to Cerros Quemados Islands (at the lake center), where the last volcanic activ-ity happened in 1880. In comparison, the As concentrations in the sediments was high at Cerros Quemados (86 mg kg-1 sediment), which also has the lowest concentration of or-ganic matter. The sediment sample collected close to the confluence of Rio Chaguite show high concentrations of B, As, and Li (3.4 g kg-1, 103 and 55 mg kg-1 of sediment respectively) as well as other heavy metals. These results suggest that two sources of As and other heavy metals can be identified for Ilopango waters. One is the internal sediments of the lake that contain the volcanic products of the last erup-tions of this caldera and are rich in As and B, and the other is the material transported to the lake by the Chaguite River. Leaching and ero-sion from the volcanic deposits of the lake basin as well as possible anthropogenic inputs could be the sources for the river loads. The ash of the last calderic eruption of Ilopango (about 2000 years ago) cover all El Salvador and part of Central America and could be the source of As contamination for other aquifers.

50. The use of synchrotron-based micro-X-ray techniques to determine arsenic

speciation in contaminated soils Jorge Luis López-Zepeda1, Mario Villalobos1, Matthew Marcus2, Margarita Gutiérrez-Ruiz1,

and Francisco Martín Romero1

1Grupo de Bio-Geoquímica Ambiental, LAFQA, Instituto de Geografía, UNAM, 04510, D.F.,

México; jllz@servidor.unam.mx 2Advanced Light Source, Lawrence Berkeley National Laboratory, MS 2R0222, Berkeley,

California, 94720-8199 USA

Molecular-scale speciation of environmen-tally relevant trace elements in soils is of utmost importance to understand their bio-

45

geochemical behavior, including prediction of their mobility and fate in the environ-ment. In the case of arsenic, extensive evidence exists on the commanding role of iron oxides in the regulation of arsenic mo-bility in aqueous environments, such as soils, through mechanisms that range from adsorption to precipitation. Recently, the involvement of other trace metals in co-precipitation processes of arsenic is under investigation.

Mining and mineral processing activities alter the natural stability of arsenic mainly via oxidation, rendering wastes containing arsenic species that are more mobile than the originally reduced counterparts. Never-theless, we have found a greatly reduced mobility of oxidized arsenic in soils con-taminated by these kinds of wastes com-pared to that in the original wastes, in three different areas of México, regardless of their specific origin: Real de Ángeles, Zacatecas, contaminated by mine tailings from mining of Pb, Ag y Zn ores; San Luis Potosí, capital of the state with the same name, near Cu, As and Pb refinement plants; and Monterrey, Nuevo León, sur-rounding a Pb smelting plant where cal-cium arsenate wastes were generated.

The present work reports the kind of infor-mation provided, and procedures followed to determine the molecular-scale speciation of arsenic in heterogeneous soil samples, by using micro-X-ray techniques from syn-chrotron sources, including µ-XRF (X-ray fluorescence), µ-XRD (X-ray diffraction), and µ-XAS (X-ray absorption spectros-copy). Suitable soil samples with high total arsenic contents, but low aqueous arsenic levels were processed at the Advanced Light Source of the Lawrence Berkeley National Laboratory, in California, USA. Synchrotron facilities provide extremely bright X-rays obtained from circular mo-tions of electrons accelerated to near speeds of light. These X-rays allow structural de-terminations of trace element local envi-ronments to very accurate levels, including

interatomic distances to 0.03 Å, and nature and number of neighbors in first few atomic shells surrounding the element of interest. The data obtained through simultaneous processing of adequate arsenic standards provided structural information on the corre-lation and involvement of other metal cations such as Fe, Pb, and Zn, in the immo-bilization processes of arsenic in soils. The latter include formation of adsorbed species and surface precipitates on mineral oxides surfaces.

51. Effect of Irrigation with Wastewater on Arsenic Concentration in Soils and

Selected Crops of Irrigation District 03, Hidalgo State, Mexico

C. A Lucho-Constantino1,2, L.M. Del Razo3, R.I. Beltrán-Hernández,4, I.Sastre-Conde5, M. Ce-brián3, F. Prieto-García4, H.M. Poggi-Varaldo1

1CINVESTAV del IPN, Dept. Biotechnology and Bioengineering, Environmental Biotechnology R&D Group, P.O.Box 14-740, México D.F.,

07000, México; hectorpoggi2001@yahoo.com 2UTTT, Tepeji del Río, Hgo. México

3CINVESTAV del IPN, Section of Toxicology, México D.F., México

4UAEH, Chemistry Research Centre, Pachuca, Hgo, México

5Conselleria d’Agricultura i Pesca, Government of Islas Baleares, Palma de Mallorca, Islas

Baleares, Spain

The accumulation and distribution of arse-nic, boron, selected heavy metals and several major elements in 31 agricultural soils of the District 03 (DR03) in the State of Hidalgo, Mexico, irrigated with raw wastewater for 0 to 90 years, was evaluated. Also, four con-trol soils (rainfed) were analyzed. Samples of topsoils (0-30 cm depth) were extracted using a modified Tessier method. As a com-plementary study, arsenic and heavy metal concentrations were determined in selected crops harvested in soils of DR03.

Total concentrations of the species tested fell in the following ranges: 10- 9009 mg K kg-1, 144 – 1002 mg Na kg-1; 9.3 – 123.8 mg B

46

kg-1, 0.06 – 5.6 mg Cd kg-1, 7.63 – 256.6 mg Cr kg-1, 4.0 – 660 mg Pb kg-1. The con-centrations of As were below the detection level of the method (0.03 mg kg-1) in all soils, whereas soils S3 (Ixmiquilpan1), S4 (Ixmiquilpan2), S11 (Rosario) and S18 (San Juan Tepa) showed Hg contents above the detection level of the method, with val-ues 0.77, 0.03, 5.59, and 3.15 mg kg-1. The concentrations of total Cd, and Cr were generally below the maximum permissible levels set by the regulations of the Euro-pean Union. By contrast, cadmium and lead in several soils were in the middle to the high side of European Union maximum ranges. Moreover, contents of Pb in the most mobile fractions (soluble and ex-changeable) were significant in a range between 3 to 28%. This distribution trans-lates into concentrations of soluble plus exchangeable lead around 2 mg Pb kg-1 or higher in several soils, significantly supe-rior to the Swiss tolerance limit of 1.0 mg Pb kg-1 for mobile fractions of lead in soils. Contents of arsenic in alfalfa (Medicago sativo) ranged between 0.003 to 0.09 mg kg-1, depending on the soil and the part of the plant (i.e., stem, leaves) whereas As concentrations in nopal (Opuntia robusta) were up to 0.54 mg kg-1 for irrigated soils. By contrast, As content in nopal grown in control soils (rainfed) was in the range between detection level to 0.003 mg kg-1. Yet, lead concentration in alfalfa and nopal reached values as high as 30 - 46 mg kg-1, whereas the corresponding levels in nopal harvested in control soils was 0.04 mg kg-1. It seems that long term irrigation with wastewater of agricultural soils in Irrigation District 03 of Mexico does not pose an immediate risk from the standpoint of arse-nic accumulation in soils and crops, al-though lead contents in several soils, alfalfa and nopal seem to be of concern. Further monitoring and research are required to have a more complete assessment, although it seems that lead accumulation would jus-

tify the implementation and enforcement of crop restriction regulations in some soils.

52. Identification of arsenic tolerant plants in the mining district of Villa de la

Paz, S.L.P. B.P. Machado-Estrada1, J. Calderón-Hernández2,

L. Carrizalez-Yañez2, J.A.Reyes Agüero3, R. Briones-Gallardo1

1Facultad de Ingeniería, Instituto de Metalurgia, U.A.S.L.P., San Luis Potosí, S.L.P., México;

briones@uaslp.mx 2Laboratorio de toxicología ambiental, Facultad

de Medicina, U.A.S.L.P., San Luis Potosí. México

3Instituto de Investigaciones de Zonas Desérticas, U.A.S.L.P, San Luis Potosí, S.L.P., México

The identification of native plants that are both tolerant to arsenic and phytocumulator of arsenic is of main importance in remedia-tion and restoration of soils impacted by mining activity. This work shows the results obtained after the analysis of nine physiog-nomical predominant plants in the mining district of Villa de la Paz-San Luis Potosí, Mexico. All plants were identified taxo-nomically Five sampling areas were defined by isoconcentration maps of arsenic (Razo, 2004). Total arsenic concentrations in the sampling areas are in the range of 10 µg.g-1

S to 10224 µg.g-1

S. Total arsenic concentration measurements in dry biomass (DB) were the result of the sum of independent arsenic concentration analysis in different sections of the plant (root, stem and leaves). Total digestion of plants was performed using both the hotplate method and total soil digestion by the microwaveoven method.

Arsenic was determined using a flow injec-tion analysis system (FIAS) coupled to an atomic absorption spectroscopy system (AAS). Sampling areas with a concentration of up to 10224 µg.g-1

S of arsenic, showed that accumulated concentration in Solidago scabrida biomass (330 µg.g-1

DB) was 3.5 times higher than accumulation in Viguiera

47

dentata (95 µg.g-1DB) and Brickellia ve-

ronicifolia (90 µg.g-1DB) and 4.7 times

higher than in Flaveria appositifolia (70 µg g-1

DB). Also, it was observed that the accu-mulation of arsenic in root on Solidago scabrida was of 89%; Viguiera dentata accumulated 82% of As in leaves; Brickelia veronicifolia accumulated 56% and 36% of As in leaves and root, respectively; while Flaveria appositifolia accumulated 49% and 48% of As in leaves and root, respectively. For Brickellia veroncifolia a linear relation-ship was observed between the arsenic concentrations in biomass and the total arsenic concentration in soil.

The results suggest that the mechanisms of arsenic accumulation in all plants analyzed are different. These differences can be at-tributed to several factors: physicochemical processes or biological mobilization at the rhizosphere of the plant; possible symbiotic associations; exposure to the biological surface; and local physical processes (e.g., atmospheric mineral dispersion). This work shows the importance of defining the arse-nic distribution in different sections of the plant as a selection criterion for the poten-tial use of such plant for remediation treat-ment.

53. Effect of current density in the arse-nic removal by electrocoagulation from

groundwater A. Maldonado Reyes1, C. Montero

Ocampo1 1CINVESTAV. U. Saltillo, P.O. Box 663,

Saltillo Coah, México 25000; araceli.maldonado@cinvestav.edu.mx

Elevated concentrations of arsenic (As) are found in groundwater in many regions of the world due the anthropogenic activities and natural process. Arsenic drinking water con-tamination occurs is a world wide concern because millions of people may be affected in several. In the central part of northern of México this problem is severe because re-

cently underground sources of water have been located with approximate arsenic contents of 120 µg L-1, which is approximately a magni-tude order higher than the maximum value admissible for drinking water (<10 µg L-1).

Exist important methods for removal As from drinking water, but one of the more promising methods of total As removal from drinking water is the electrocoagulation (EC) method due to several advantages that pre-sents respect with other conventional meth-ods as for example, it does not requires addi-tion of chemical reagents and produces very small amount of sludge. In natural ground-water, inorganic soluble As is normally pre-sent in oxidation states 5+ (As(V)) and 3+ (As(III)) (2). As(V) species (H2AsO4

- and HAsO4

2-) are the most easily removed by any method because of their ionic nature. The opposite case found for As(III) species (predominantly H3AsO3) which are difficult to remove. However, generally is assumed that small amounts of As(III) are present along with As(V) in groundwater

This study compares the total arsenic re-moval from contaminated (120 µg As L-1) groundwater degree by EC using five differ-ent currents densities. The experiments were carried out using iron electrodes in gal-vanostatic conditions for 1 hour and five current densities, 1.5, 3, 4.5, 6 and 12 mA cm-2 at constant temperature (30°C). The results have shown that As content was re-moved reaching values lower than 10 µg L-1 at the end of the EC process when the cur-rent was greater than 4.5 mA cm-2, that can be explain as follow: when the current in-creases, the amount of iron dissolved also increases and therefore the insoluble iron species which form complexes with the ars-enates present in the underground water are also increased. This evidence that the ratio Fe/As is very important in the As removal by this EC process, its means that when the iron dissolves anodically increase, the As total removal by this EC process is also increased.

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54. Long-term environmental impact of As-dispersion in Minas Gerais, Brazil Jörg Matschullat1, Eleonora M. Deschamps2, Thomas Gabrio3, Nilton de Oliveira4, Kirstin Raßbach1, Marcelo José de Oliveira Vilhena5,

Ursula Weidner3

1Interdisciplinary Environmental Research Center, TU Bergakademie Freiberg, Brenn-hausgasse 14, D-09599 Freiberg, Germany;

joerg.matschullat@ioez.tu-freiberg.de 2Fundacao Estadual do Meio Ambiente

(FEAM), Avenida Prudente de Morais 1671, CEP 30380-000 Belo Horizonte, Minas Gerais,

Brazil 3Landesgesundheitsamt Baden-Württemberg, Department of Toxicology, Widerholdstr. 15,

D-70174 Stuttgart, Germany 4Fundacao Ezequiel Dias (FUNED), Instituto

Octávio Magalhaes, Rua Conde Pereira Carneiro 80, CEP 30510-010 Belo Horizonte,

Minas Gerais, Brazil 5Companhia de Saneamento de Minas Gerais

(COPASA), Br 356, km 4, Trevo de Nova Lima, Bairrio Belvedere, CEP 31950-640 Belo

Horizonte, Minas Gerais, Brazil

To answer the question whether up to 250 years of continual gold mining, and related activities in parts of the Iron Quadrangle, Brazil, have lead to arsenic-pollution prob-lems, a comprehensive research project was launched in1998. Within this project, air, soils, surface and groundwater, suspended particulates and fresh, unconsolidated sedi-ments were sampled and investigated to-gether with home-grown vegetables, human urine and hair, and private water supplies. All sampling, sample processing and ana-lytical work has been done until today by the same people with the same methods applying strict quality control measures.

Elevated to very high soil As-concen-trations (50–1000 mg As kg-1) in living quarters, and extremely high (percentage range) As-values on derelict industrial sites, including old tailings surfaces characterize the areas. Soil dust, As-enriched vegeta-bles, and partly As-contaminated water from private wells and unauthorized sur-

face sources explained the partially high As-load particularly in children of the area (up to 60 µg As L-1 urine). This load was suc-cessfully lowered over the past few years, although the exposure of some families could not be improved. The complex evalua-tion of all environmental compartments and their interactions allows for a thorough un-derstanding of the dominating processes and As-pathways. Thus, a detailed risk assess-ment is possible and, following the results, additional action to improve the situation is being suggested.

55. High level of arsenic in children’s hair from communities exposed to well water

contaminated with arsenic despite its lim-ited use as drinking water

Rebeca Monroy-Torresa, Alejandro E. Macíasa, Juan Carlos Gallaga–Solorzanob, Enrique Javier

Santiago-García, Isabel Hernández-Ramosa aUniversity of Guanajuato School of Medicine at

León, Mexico bState Public Health Laboratory, Guanajuato,

Mexico

Objective: To know the level of arsenic absorption in children chronically exposed to contaminated well water.

Design: Cross sectional study to compare arsenic level in hair of children exposed and unexposed to contaminated well water.

Subjects/setting: We recruited school chil-dren with at least two years of residency in four rural communities in Guanajuato, México on 2004; two villages had arsenic contaminated well water.

Main outcome measure: Arsenic in hair measured by hydride generation atomic ab-sorption spectrophotometry.

Statistical analyses performed: Chi square, Fisher’s exact test, t test or Wilcoxon, used as appropriate.

Results: Overall, 110 children 10 years old on average (range 7-14) were included; half

49

were males. Neither age, sex, nutritional status nor total water consumption were different between exposed and unexposed groups. Among 55 exposed children, mean arsenic level on hair was 1.3 mg kg-1 (range <0.006 - 5.9); 49 had abnormal levels (>0.05 mg/kg) and only six had undetect-able values. All unexposed children had undetectable arsenic levels on hair. Cate-gorical analysis showed a statistical rela-tionship between the high level of arsenic in water and hair (p< 0.0001). However, compared to unexposed children, exposed kids drank with less frequency well water at school (3.6% vs. 58.2%, p < 0.0001) or at home (7.3% vs. 38.1%, p < 0.0001).

Conclusion: The use of contaminated well water to cook or for agricultural purposes may play an important role in chronic population exposition to arsenic.

Application: Analyses of local practices that enhance the exposure might help un-derstand and limit the problem.

56. Presencia de arsénico en areniscas: Caso de estudio en un acuífero del

Mediterráneo Español I. Morell1, M.V. Esteller2, E. Giménez3

1Departamento de Ciencias Experimentales -Universitat Jaume I de Castellón, España;

morell@exp.uji.es 2CIRA - Universidad Autónoma del Estado de

México, México; esteller@uaemex.mx 3Universidad Católica de Ávila, España;

elena.gimenez@ucavila.es

El acuífero de areniscas del Buntsandstein (Triásico) es una fuente de abastecimiento de agua potable para varias poblaciones de la costa del Mediterráneo, en concreto de las provincias de Castellón y Valencia. La explotación de este acuífero se inicio de-bido a los problemas de calidad (presencia de nitratos y salinización) que presentan los acuíferos costeros detríticos.

Este acuífero está constituido por una ho-mogénea y potente secuencia de areniscas silíceas (cuarzoarenitas), localmente pueden observarse en contadas ocasiones alguna intercalación de lutitas rojas, muy compactas y de escasa potencia. Los componentes prin-cipales son granos de cuarzo monocristalino, aunque también se observan otros cuarzos policristalinos y algunas láminas de mica. También se ha reconocido la presencia de feldespato potásico, moscovita, turmalina, circón y óxidos de hierro. La matriz es clorítica y procede de la alteración de micas, sobre todo biotita, proceso en el que se libera hierro ferroso que es posteriormente oxidado y fijado como cemento o matriz, y es el que de el color rojizo característicos de estas rocas.

La permeabilidad del acuífero es debida a la fisuración, la cual presenta diversos grados de intensidad y penetración que ha dado lugar a que no toda esta formación conforme un acuífero y que exista una alta comparti-mentación. En cuanto a la hidroquímica, se trata de aguas bicarbonatadas cálcico-magnésicas.

Últimamente, y debido a los cambios en la normativa sobre calidad del agua de con-sumo humano que ha fijado un limite de 10 µg L-1 para el As, se ha prestado especial atención a la presencia de este elemento en las aguas, habiéndose detectado concentra-ciones de hasta 14 µg L-1. Por otro lado, altas concentraciones Fe (830 µg L-1) y Mn (25 µg L-1) también han sido detectadas en algunos pozos aunque en otros pozos con As, la con-centración de estos elementos es minima. Otro dato a tener encuenta es que la concen-tración de As ha aumentado con el tiempo, pasando de concentraciones inferiores a 2 µg L-1 hasta de más de 10 µg L-1, en unos 3 años.

Para establecer cual es el origen de este arsénico se está planteando dos hipótesis: la oxidación de pirita (cuya presencia ha sido detectada) por la entrada de oxigeno atmos-férico originada por el descenso de los nive-

50

les piezométricos de la zona (la oxidación del sulfuro podría liberar el As contenido en él) y/o la desorción de As que esté fijado en los óxidos de Fe.

57. Hydrogeochemistry of arsenic in groundwaters from Burruyacú basin,

Tucumán province, Argentina H. B. Nicolli1,2, A. Tineo1, C. M. Falcón, J. W.

García1, M. H. Merino1, M. C. Etchichury1, M S Alonso and O. R. Tofalo

1Instituto de Geoquı´mica, Av. Mitre 3100, 1663 San Miguel, Provincia de Buenos Aires,

Argentina 2Consejo Nacional de Investigationes

Cientı´fı´cas y Te´cnicas (CONICET), Buenos Aires, Argentina

hbnicolli@fullzero.com.ar

The Burrucayú basin (2700 km2 area) in the Eastern Plain, Tucumán Province, Argen-tina, has been filled by loess deposits from Tertiary and Quaternary ages and substan-tially reworked by fluvial and aeolian proc-esses. Three well-differentiated hydrologi-cal environments have been defined: 1) a lower hydraulic system (below a 200 m depth) in Tertiary quartzose sands with thermal anomalies (up to 40ºC); 2) a middle hydraulic system in Quaternary reservoirs in alluvial fans with confined levels; and 3) an upper hydraulic system (between 10 and 40 m depth) corresponds to a low perme-ability unconfined aquifer made up of silty-clayey sediments. This groundwater is used by the local rural population.

Groundwaters have a highly variable chemical composition. Their salinity pre-sents a wide range of variation (TDS from 451 to 4830 mg L-1). Major ion composi-tion is controlled by the reaction of the silicate minerals and by the carbonate equi-librium. Most groundwaters are hard or very hard (hardness ranges up to 1130 mg L-1 CaCO3). Sodium is the dominant cation (maximum content 1040 mg L-1) and bicar-bonate the dominant anion (maximum con-

tent 1080 mg L-1), but in more saline waters sulphate and chloride contents are high. So-dium mainly results from the dissolution of sodium plagioclase and is concentrated by evaporation. Bicarbonate concentrations are high, the same as the pH values that vary from 7.2 to 8.6. High nitrate contents are restricted to shallow groundwaters (maxi-mum 64.8 mg L-1) and lower values, in deep aquifers. The highest contents result from agricultural pollution.

Trace-element contents in groundwaters from Burruyacú basin exhibit a high vari-ability with an observed range of 15.8-1610 µg L-1 in shallow groundwaters. Fluorine variation range is also high (149-8740 µg L-1). Arsenic correlates positively with several other trace elements that also reach a high concentration: vanadium contents reach up to 1090 µg L-1; uranium, up to 155 µg L-1; boron, up to 6740 µg L-1; molybdenum, up to 90.1 µg L-1 and antimony, up to 0.46 µg L-1 in shallow groundwaters.

There is no regional trend in the distribution of trace elements, and local phenomena play a fundamental role: geomorphological fac-tors (small slope variations) influence the flow velocity of the waters as well as the variations in the composition of the host sediments. The trace elements are strongly concentrated in materials of volcanic origin, the Quaternary loess being their source. The main components are feldspars, quartz and volcanic glass shards, with minor amounts of muscovite, calcite and lithic fragments, with opal and chalcedony. Heavy minerals (<5%) are pyroxene and amphibole, with minor amounts of epidote and biotite, and scarce zircon. The clay minerals have a low degree of crystallinity and illite prevails over smec-tites and interstratified illite-montmoril-lonite.

Sorption processes of arsenic and other trace elements onto Al and Fe oxide and oxi-hydroxide surfaces tend to restrict the mobil-ity of those trace elements and consequently control their distribution in groundwaters.

51

However, sorption processes are limited in waters with high pH values and high bicar-bonate contents. Under such conditions, desorption processes may occur, increasing their mobility and trace-element contents in shallow groundwaters.

58. Evaluation of the human contamina-tion by arsenic in the municipal district

of Santa Bárbara, MG, Brazil Nilton de Oliveira Couto e Silva1, Clélia Aparecida Rocha1, Tatiana Vieira Alves1,

Eleonora Deschamps2, Sandra Maria Oberdá2

1Laboratório de Contaminantes Metálicos, Divisão de Vigilância Sanitária, Instituto

Octávio Magalhães, Fundação Ezequiel Dias, Rua Conde Pereira Carneiro, 80, CEP: 30510-010, Gameleira, Belo Horizonte,MG, Brazil;

niltoncs@funed.mg.gov.br 2Fundação Estadual do Meio Ambiente-FEAM,

Av. Prudente de Morais,1671, CEP: 30380-000, Santa Lucia, Belo Horizonte,

MG, Brazil; eleonorad@feam.br

Santa Bárbara, located in the Iron Quad-rangle, is rich in iron ore and hydrothermal gold deposits, which contains several sul-fides as principal accompanying minerals, among them the arsenopyrite (FeAsS), principal mineral arsenic bearer. With the intense activity of gold mining in the area, the arsenic minerals are liberated to the external compartments, contaminating the waters, soils and sediments. The objective of this research was the evaluation of the contamination of the local population by the arsenic and the identification of the main sources of contamination. Five places of the area were studied between 2002 to 2005: Barra Feliz, Brumal, Sumidouro, Santana do Morro and "Rua do Carrapato", occasion when 6 campaigns were carried out by collecting samples of the residents’ urine, mainly the children, who were the most affected. During the collecting time the participants were invited to answer an epidemic questionnaire containing informa-tion about the lifestyle, feeding and situa-

tion of health, which were later used to study the results. Approximately 700 samples were collected and were analyzed through atomic absorption spectrometry with hydrite genera-tion. The results were corrected by the creatinine, correlated with the answers of the questionnaires, and it was evident that the arsenic content of the urine samples in-creased with the arsenic enrichment in the different environmental compartments.

59. Factores de transferencia (FT) suelo-hojas de As en Prunus persica L. modifi-caciones por la aplicación de sulfato de

hierro monohidratado (SFM) bOrihuela, DL. aHernández, J.C.; bPérez-

Mohedano, S. bMarijuan, L. aEscuela Politécnica Superior La Rábida. Univer-

sidad de Huelva. Huelva. España; bHUNTS-MAN-Tioxide. Madrid. España; orihuela@uhu.es

La cantidad de un elemento que la planta es capaz de absorber de un suelo ha sido objeto de numerosos estudios científicos. El Factor de Transferencia (FT) se define, conceptual-mente, en la literatura científica, como la relación entre la concentración en la planta, o en un órgano de ella, de un elemento de-terminado y la concentración de ese ele-mento en el suelo. Esta definición desde una óptica matemática sería un modelo lineal muy simplista. Los modelos matemáticos que expresan los datos experimentales del Factor Transferencia (FT) serán, por lo general, más complicados, pero siempre tienen la notable ventaja de ayudar a entender parte del proceso de traslocación de los elementos nutritivos desde los suelos a las plantas cuantitativa y temporalmente.

El objeto de este trabajo es estudiar en un cultivo de melocotones, Prunus persica L. los FT del As cuando la solubilidad del suelo se altera por un proceso de corrección de pH. Concluimos que los modelos de transfe-rencia de As expresados por el valor de FT desde suelos calizos hacia las hojas en cul-tivos de melocotón (Prunus persica L.) son

52

por lo general modelos lineales y casi hori-zontales expresando el hecho de que las concentraciones de este elemento en hojas son independientes de las concentraciones en el suelo, y que las alteraciones del pH modifica escasamente los valores de FT.

60. Desarrollo de un sistema de información geográfica para el

municipio de Zimapán Hidalgo, México E. Ortiz1, I. Reséndiz1, E. Ramírez1, M.A. Ar-

mienta2, V. Mugica1 1Universidad Autónoma Metropolitana-

Azcapotzalco, Av. San Pablo 180, Col Rey-noza, México D.F. 02200

2Instituto de Geofísica, UNAM, México 04510 D.F.

En este trabajo se desarrolla la metodología para el diseño de un sistema de información geográfica que permita la identificación de sitios y fuentes potenciales de contami-nación de agua y aire en el municipio de Zimapán Hidalgo. En el sistema se incluye a nivel AGEB: Ubicación geográfica de la zona de estudio, uso del suelo, meteo-rología disponible, fuentes de abaste-cimiento hidrológico, y desarrollo pobla-cional, localización de la industria, servi-cios urbanos y transporte. Con el fin de diagnosticar la exposición al arsénico en pobladores del municipio de Zimapán, aso-ciándolo a las enfermedades como hi-pocromia, hipercromia, hiperqueratosis y zonas verrugosas, se incorpora información publicada en estudios previos.

61. Sodium arsenite increases calpains ac-tivity and induces expression of calpain-10

Patricia Ostrosky-Wegman1, Andrea Díaz-

Villaseñor1, Laura Cruz3, Marcia Hiriart2 and Mariano E. Cebrián3

1Department of Genomic Medicine and Environmental Toxicology, Instituto de

Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México;

ostrosky@servidor.unam.mx

2Department of Biophysics, Instituto de Fisi-ología Celular, Universidad Nacional Autónoma

de México, México 3Section of Environmental Toxicology, CIN-

VESTAV, IPN, Mexico City, México

Type 2 diabetes is a complex disease with genetic and environmental risk factors. Chronic arsenic exposure by drinking water has been epidemiologically associated with with type 2 diabetes. Single nucleotide polymorphisms (SNPs) in calpain-10 gene have been associated with type 2 diabetes in some populations. Calpain-10 is member of the family of calcium-dependent nonlyso-somal cystein protease and plays an impor-tant role in insulin secretion by pancreatic β cells. The capacity of arsenic to alter calcium currents and intracellular concentrations has been shown. This modification of calcium by arsenic could lead to alterations in calpains activity inducing a diabetogenic effect. In the present study we analyzed the interaction between calpains and sodium arsenite. Non cytotoxic sodium arsenite dosis in a sub-cronic exposure model were used to evaluate calpain-10 expression and functionality in RINm5F rat insulinoma cell line. Sodium arsenite (1 µM) increases calpains activity by 60.3% and there was a 2.79 ± 1.02 fold-induction in the expression of one isoforma of calpain-10. Major dosis (5 µM) affected cell viability and cause morphological cell changes. More experiments are going to be realized to evaluate specific calpain-10 func-tionality, alterations in calcium concentration and to discard the involvement of another member of the calpain family. The modifica-tions of calpain-10 by arsenic could contrib-ute to the dysfunction of β-cells present in type 2 diabetes.

53

62. Arsenic mobilization in aquatic sedi-ments of an impacted mining area, north

central Mexico N.A. Pelallo-Martínez1, R.H. Lara-Castro2,

M.C. Alfaro-De la Torre1, J.Castro-Larragoitia3

1Facultad de Ciencias Químicas; UASLP, San Luis Potosí, México;

na_pelallom@yahoo.com.mx; alfaroca@uaslp.mx

2Instituto de Metalurgia UASLP, San Luis Po-tosí, México

3Facultad de Ingeniería/Instituto de Geología; UASLP, San Luis Potosí, México;

gcastro@uaslp.mx

The presence of arsenic in groundwater has been a main environmental research topic in Mexico for over two decades. There are well studied sites as the Lagunera Region near the city of Torreon on the north central zone and Zimapan in the central State of Hidalgo. In those places, concentrations from 8 to 1112 µg L-1 As have been reported, with As(V) as the predominant species. Health risk and some effects in humans have been also stud-ied.

Previous studies on the mining district of Villa de la Paz-Matehuala located in the semiarid Altiplano of Central Mexico re-ported polluted soils, and aquatic systems and associated them to the dispersion of historical and active tailings impound-ments, waste rock dumps and historical refining activities. Arsenic was identified as the most important pollutant at this site and reported concentrations in groundwater exceed more than 100 times the Mexican Drinking Water Standard.

Our work focuses in elucidating the mecha-nism of arsenic mobilization between sedi-ments and groundwater in sites (dug wells, springs and channels) where residues of mining and smelting activities may have polluted the groundwater. The results may conduct to information about the source or sources of pollution.

Porewater and overlying water concentra-tions of As and other chemical were ob-tained using dialysis samplers (peepers) placed in sediments of three contaminated sites. Sediment cores were also taken at those sites. Data showed that total As con-centrations in porewater are different from site to site ranging from 26 to 123 000 µg L-

1. However, concentration profiles suggest As mobilization from sediments to the water column associated with the sulfides dissolu-tion or the sulfate/sulfide redox process. The concentrations of total dissolved As change among the sites probably related to the pol-lution source or sources but this relationship with the source has not been demonstrated.

High Arsenic(III) concentrations were de-termined in two sediment and water sam-pling sites. Sediment and porewater concen-tration profiles of As suggest mobilization from the solid phase followed by diffusion from the sediment to the water column in one site. Our results suggest this mechanism because the maximum concentration of As occurs near to the maximum of sulfides [ΣH2S] in pore water. Decreasing concentra-tions of total As in the more recent sedi-ments occurs near the maximum of dissolved As in porewater suggesting not only that As is lost to the water column but also that the emission of this chemical has probably de-creased in the last years.

63. High arsenic in drinking water of dairy cattles in Cordoba, Argentina and

its transfer to milk Alejo Pérez-Carrera, Carlos Moscuzza and Alicia

Fernández-Cirelli

Centro de Estudios Transdisciplinarios del Agua. Facultad de Ciencias Veterinarias, Universidad de Buenos Aires. Av Chorroarín 280 (C1427 CWO). Ciudad Autónoma de Buenos Aires,

Argentina; ceta@fvet.uba.ar

The Chaco Pampean Plain of central Argen-tina constitutes one of the largest regions of high arsenic groundwaters known, covering

54

around 1x106 km2. The high-As groundwa-ters derive from Quaternary loess deposits (mainly silt) with intermixed rhyolitic or dacitic volcanic ash. One of the most af-fected region is the province of Cordoba, where As concentrations that exceed the maximum level of 50 µg L-1 for drinking water have been reported. The southeast of Cordoba is an important milk production zone in Argentina, where dairy products consumption is up to 192 equivalent milk L/inhabitant/ year. As an excretion of the mammary gland, milk can carry numerous xenobiotic substances, which constitute a technological risk factor for dairy products and above all for the health of the con-sumer. Nevertheless no studies on the inci-dence of high-As livestock drinking water in livestock health and its transfer to milk have been performed in Argentina.

The aim of the present study was the de-termination of arsenic content in livestock drinking water and milk from dairy farms located in an area of high arsenic ground-waters, to analyse the relation between As uptake through water and its transfer to milk. Groundwater is the main source of livestock drinking water. In 54% of the analysed wells, the phreatic water was found between 3 and 8 m, with extreme depths of 2 and 15 m, while the remaining wells range in depth from around 80 to 150 m (deep wells). Arsenic concentration in all phreatic water samples was over the sug-gested level for occurrence of chronic in-toxication in cattle (0.15 mg L-1) and 53% of them showed higher values than those rec-ommended for livestock drinking water (0.5 µg L-1). Arsenic concentration in deep wells was under 0.15 mg L-1. As milk con-tent ranged from 2.8 to 10.5 ng g-1 for dairy farms using phreatic groundwater, while a mean value of 0.5 ng g-1 was obtained for farms using deep wells.

In order to analyse the relation between As uptake through water and its transfer to milk, four farms (Holstein dairy cows) were selected. Two of these stablishments

where medium size (100-120 dairy cows) and two were small (10-20 dairy cows). One medium size stablishment with As water concentration of 0.04 mg L-1 was also se-lected for comparison. If As water content is considered as the only exposure dosis of As to milk, assuming steady state conditions, a biotransfer factor (BTF) may be calculated as: concentration of As in milk (mg L-1) / daily animal intake of As (mg day-1). The values obtained ranged from 5.2 x 10-5 to 1.8 x 10-4. No significant differences were found between the five farms analyzed, where food is the same in all cases and one of them has very low As water content.

Although As transfer to milk is a complex process, the fact that a BTF may be esti-mated through As water contribution rein-force the importance of dairy cattle drinking water quality not only from a productive point of view but also because of its inci-dence in the agricultural food chain.

64. Arsenic in Argentina groundwater: need to develop methodologies to define problems and arrive to actual solutions J. Pflüger1, S.S. Farías2, J. Bundschuh4, M. E.

Garcia3

1Ente Nacional de Obras Hídricas de Saneamiento. Av. L. N. Alem 628 pisos

10/11/12/13. Capital Federal. Buenos Aires. Argentina; pfluger@enohsa.gov.ar

2Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Av. Gral. Paz. 1499

(1650). San Martín. Provincia de Buenos Aires. Argentina; farias@cnea.gov.ar

3International Technical Cooperation Program, CIM (GTZ/BA), Frankfurt, Germany - Instituto

Costarricense de Electricidad (ICE), UEN, PySA, Apartado Postal 10032, 1000.San José, Costa

Rica; jochenbundschuh@yahoo.com 4Instituto de Investigaciones Químicas, Universi-dad Mayor de San Andrés. P. Box 10201, La Paz,

Bolivia; maugegarcia@hotmail.com

In Argentina, water quality is affected in more than a half of its provinces by the pres-ence of anomalous, high contents of arsenic

55

and other toxic trace elements. This fact was well known since the beginnings of 1900, and studies developed during last century identified that the source was in most of the cases due to the natural pres-ence of these contaminants in soils and their migration to aquifers through time. These aquifers have supplied groundwaters to first inmigrants and nowadays provide cities, towns and disperse rural populations with this valuable resource all around Chaco-Pampean Plain and also in some Argentinian Western and North-Western areas.

Although the situation has been thoroughly described and divulged, it has not been treated in a systematic manner in the whole country. In this way, there are some coun-ties that develop and perform their own mitigation programs and there are some other that disregard this situation with the subsequent damage of affected population health.

A number of Argentinian government or-ganisations are devoted to arsenic and other toxic trace elements studies about occur-rence and remediation; Water Resourses Office, Health and Environment Depart-ment and Federal Planning Department can be mentioned; even though their works are sometimes overlapped.

The present work appoints to the organiza-tion of resources to carry out a detailed analysis of the situation, through to knowl-edge of contamination levels, their geo-graphic limits and localization, the state-ment of remediation tecnologies adequate to each particular case, fitting the budget and cost-benefit equations.

This survey also mention the programs that are being performed, the fulfilled invest-ments and those that are going to be real-ized by the organisms mentioned above, in order to supply well-being to inhabitants and, the need to develop innovative pro-jects involving new treatment strategies and remediation technologies that can be ex-

pensive but may be trivial compared with potential health- care costs. This work also mention that social concience about health risks and consequences of environmental circumstances have to be developed and the actual situation must be taken into account by authorities to achieve a final and definite solution for this old problem.

65. A review of suitable technologies for treatment of waters contaminated with

arsenic in Mexico Héctor M. Poggi-Varaldo1; Carlos Lucho-

Constantino1,2; Luz María Del Razo3; Abigail Pimentel1; Noemí Rinderknecht-Seijas4

1Cinvestav-IPN, Dept. Biotechnology and Bioen-gineering, Environmental Biotechnology R&D

Group, México D.F. México 2UTTT, Dept. Environmental Technology, Te-

peji, Hgo., Mexico 3Cinvestav-IPN, Toxicology, México D.F.,

México.4 ESIQIE-IPN, Division Basic Sciences, México D.F., México

In México, several regions have been identi-fied whose communities rely on fossil groundwater contaminated with inorganic Arsenic (iAs) for drinking water supply. There is a pressing need for supplying treated, low iAs drinking water to hundreds of thousand people in our country. Then, the objective of this review is to critically evalu-ate the most feasible modern technologies of water treatment that could comply with the WHO limit for As (< 10 µg L-1) and to iden-tify a few niches of further research and development adapted to the needs of Mex-ico.

The chemical speciation of iAs is crucial for the treatment of polluted waters. The iAs can exist as tri- and pentavalent species. The speciation and predominance of the species mainly depend on the pH. Arsenic removal is favoured when the chemical species has negative charges, thus, some type of pre-oxidation of iAs(III) to iAs(V) is generally required for all the available technologies.

56

So, the fist step of treatment generally is the preoxidation. Chlorine, hypochlorites, ozone, permanganate, and a few patented chemicals are recognized to be effective oxidants for iAs. On the other hand, chlo-rine dioxide, chloramines, UV light alone are not as effective. The combined photo-chemical oxidation consisting of UV light with sulfite seems to be a promising alter-native.

Traditionally, the iAs removal technologies can be grouped in three categories: adsorp-tion, membrane, and precipitation / coagu-lation-flocculation treatments. Several elec-tro-technologies under development seem to fall in the third category. The adsorption of iAs by using ionic exchange resins and zeolites is well established. Yet, it does not remove iAs(III) at the working pH; high iAs concentration can suddenly appear in the effluent; the presence of sulfate and other anions in the water can deteriorate the process performance; liquid wastes are produced by regeneration of the resin; and poisoning and fouling of the resin lead to costly resin replacement. The adsorption using activated alumina does not remove arsenite; it usually requires pH pre-adjustment; an aggressive liquid waste is generated in each regeneration cycle; the medium has to be replaced in the mid-term due to solubilization of the alumina in the regeneration cycles. The adsorption can be also carried out using iron oxide media.

Regarding the removal of iAs by membrane processes, the reverse osmosis (RO) is the standard treatment. It can remove high amounts of iAs(V) and considerable amounts of iAs(III) as well. However, the fouling of the membranes may lead to shut-downs and generation of liquid wastes; it is energy-intensive because of the high pres-sure pumps.

The processes based on precipitation and coagulation-flocculation are increasingly becoming less favoured, since the condi-tioning-handling-and-disposal of the phys-

chem hazardous sludges is cumbersome and expensive.

As a common denominator, all the currently available technologies are expensive for underdeveloped countries. Moreover, very often the treatment selection depends on the water characteristics other than that the mere iAs concentration. Our future work seems to revolve around two axes (i) adapting the existing technologies for making them more simple and cost-effective; or (ii) to find and develop a technological breakthrough. It is foreseen that the most feasible niches for short-term R&D regarding iAs removal from drinking water in Mexico are: (i) develop-ment of patent-free, hybrid or new adsorp-tive media; (ii) optimization studies on de-sign and operation of RO for minimizing the energy and maintenance requirements; (iii) development of patent-free RO membranes that can work at lower pressures and are more resistant to fouling; (iv) coupling solar energy to RO for minimizing costs associ-ated to the energy of pumping; (v) last, but foremost, any strategy of supplying drinking water with low concentration of iAs should be implemented together with effective and strong programs of water conservation and reuse. This is the only feasible approach to a cost-effective, low-iAs drinking water sup-ply.

66. Irrigation strategy in the context of arsenic threat in Nepal

Bandana Pradhan

Department of Community Medicine and Family Health, Institute of Medicine, Tribhuvan Univer-

sity, Kathmandu Nepal; bandana@healthnet.org.np

Arsenic contamination in groundwater and the threat it poses to human health is rela-tively new for Nepal. Groundwater is the main source of drinking and irrigation water for the people living in the country’s south-ern part called Tarai region, a contiguous part of the Indian Gangetic plain, where the

57

number of Arsenic risk population has in-creased during the last few years. Arsenic studies carried out in 29,953 tube wells in the Tarai region have shown that 32 percent tube wells have Arsenic level above the WHO Guidelines (10 µg L-1) and 7 percent above the Nepal interim standard (50 µg L-

1). Further, about 500,000 people living in the Tarai are estimated at risk of Arsenic problem.

The Tarai is the principal region for potential agricultural development of Nepal, where groundwater is the most potential source for irrigation development. His Majesty’s Government of Nepal has recently taken significant initiatives for the exploitation of groundwater in order to increase the production of agricultural crops. If irrigation is relied completely on the groundwater, there is high chance that arsenic may turn out to be disastrous in the future. This situation needs to be taken very seriously and ways and means need to be devised to deal with the Arsenic threat in implementing the government irrigation strategy for agriculture intensification through year round irrigation.

From the irrigation perspective, there is no study conducted in Nepal to explore uptake of Arsenic by different crops from irriga-tion water. Nevertheless, studies conducted elsewhere in the world demonstrate that uptake of Arsenic by a variety of vegeta-bles and cereals that can get into the food chain and ultimately affect the human health. Scientists have argued that the groundwater abstraction from Arsenic-rich aquifers generates water fluctuation and also accelerates weathering process of Ar-senic-rich rocks and therefore creates con-ducive environment for Arsenic to be re-leased and dissolved in water. If this hy-pothesis is true, mining of groundwater in the Tarai region of Nepal will increase the Arsenic content and thus will worsen the existing situation.

This study intends to relate water availability in the Narayani irrigation command area and the arsenic contamination in groundwater in four districts of the central Tarai region, based on the thorough review of the existing studies on arsenic contamination and identi-fies areas for better management for surface water resources through modern irrigation system. The findings of the study have re-vealed that the Arsenic level is high in areas where there is low availability of surface irrigation water and vice versa. Though the analysis needs to be further verified through more investigations, it is assumed that the Arsenic level can be reduced by improving the performance of surface irrigation deliv-ery or less dependency on groundwater or adopting arsenic removal strategy.

67. Arsenico: Evaluación, contaminacion, especiacion; Su incidencia ambiental en la cuenca del Altiplano Boliviano y la ciudad

de Oruro

Jorge Quintanilla1, Ramos Oswaldo1, Medina Hugo2

1Instituto de Investigaciones Químicas, Universidad Mayor de San Andrés, La Paz,

Bolivia 2Instituto Nacional de Salud Ocupacional

(INSO-SNS), La Paz, Bolivia

Varios trabajos se realizaron en el Altiplano boliviano basados principalmente en la de-terminación de los parámetros fisicoquí-micos de aguas superficiales (estado y cali-dad) fuentes de contaminación natural y antrópica. Fundamentalmente en este trabajo trata del arsénico contaminante natural, evaluación de su distribución, modelación geoquímica para determinar su naturaleza primaria y su especiación teórica.

Estudios en aguas superficiales determinaron las fuentes naturales y antropogénicas como medios para el aporte significativo de arsénico. Los estudios del Plan Piloto Oruro (PPO, 1997) en la cuenca de los lagos

58

Poopó, han permitido establecer el origen de la contaminación natural de los metales pesados, concluyendo que el 85% del arsé-nico transportado por el agua superficial al lago Poopó tiene origen natural, en el in-temperismo de vulcanitas del Mioceno en la cuenca colectora del río Mauri y de las vulcanitas del Mioceno tardío/Plioceno en la meseta de Los Frailes, en las cuencas colectoras de los ríos Sevaruyo y Marquez. La contribución de arsénico debida a las minas y al procesamiento de minerales, es poco significativa.

Otros estudios en la cuenca de los lagos Poopó y Uru Uru realizados por la Univer-sidad Mayor de San Andrés (UMSA-IIQ, 2004), indican que las aguas superficiales con y sin actividad minera, en su mayoría se encuentran por encima de los límites permisibles para cualquier consumo (50 µg/L) y puede utilizarse para riego con restricciones, según la Ley de Medio Am-biente de Bolivia Nº 1333, salvo alguna excepción como el río Huaya Pajchi (ver-tiente Huari) muestra valores que están por debajo de los limites permisibles para cualquier uso. Los puntos ubicados en el lago Poopó (sur, centro y norte) y Uru Uru presentan valores que elevadas concentra-ciones de arsénico que las hacen no aptas para ningún uso.

En general en el altiplano boliviano, las aguas subterráneas de las cuencas del lago Poopó y Uru-Uru (PPO, 1997) y del salar de Uyuni presentan poca evidencia de cualquier contaminación relacionada con la actividad minera. Sin embargo, en la escala local, las concentraciones de antimonio, arsénico y cadmio son mucho más elevadas en los sitios impactados que en los sitios de referencia.

Para ésta evaluación se utilizaron datos de trabajos anteriores (Quintanilla, 1992) que permitió realizar la modelización, usando el modelo geoquímico CHIMERE, lo cual permitió determinar las especies secunda-rias y sus concentraciones al equilibrio,

derivadas del arsénico, que muestra pre-dominancia en cinco especies secundarias “mayoritarias” en condiciones reales de pH, presión atmosférica y temperatura, cuya distribución es AsO3-

4 (32%), H2AsO-4

(22%), HAsO-4 (16.5%), As2O5 (17%),

H3AsO-4 (6%) y otros (6.5%).

Además, se cuantifico su incidencia, riesgo ambiental y humano a través del control toxicológico en la ciudad de Oruro (fundi-ciones de Vinto y Peró), en el año 1993, de 201 trabajadores sometidos al control toxi-cológico de arsénico en orina, el 32% pre-sentaron niveles anormales de arsénico; en 1994, 120 trabajadores fueron sometidos a control médico y se detectó que el 28,5% presentaban niveles anormales de arsénico y a fines del mismo año y como seguimiento preventivo, fueron sometidos al control 199 trabajadores, habiéndose establecido que el 63,3% presentaban índices por encima los máximos permisibles para indicadores biológicos.

A objeto de compatibilizar los valores de arsénico en orina, con muestras de arsénico en aire, en diferentes puestos de trabajo se determinó, que el 50% de las evaluaciones en higiene industrial, en las áreas de hornos los índices detectados se encontraban por encima los máximos permisibles estable-cidos por la Conferencia de Higienistas Americanos.

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68. Arsenic assimilation into edible plants grown in homestead garden soil

irrigated with arsenic laden groundwater I.M.M. Rahman*a, M. Nazim Uddina, M.T.

Hasana, M. Helal Uddina, M.M. Hossainb and M.A.U. Mridhac

aApplied Research Laboratory, Department of Chemistry, University of Chittagong, Chit-

tagong-4331, Bangladesh; I.M.M.Rahman@gmail.com

bInstitute of Forestry and Environmental Sci-ences, University of Chittagong, Chittagong-

4331, Bangladesh. cDepartment of Botany, University of Chit-

tagong, Chittagong-4331, Bangladesh.

One of the most important global environ-mental toxicants is arsenic whose high con-centrations in groundwater have been re-ported from many countries. The arsenic calamity of Bangladesh is the largest known mass poisoning in the history, with approximately 35–77 million people being exposed to arsenic-contaminated drinking water. Edible vegetables, medicinal and aromatic plants grown in arsenic contami-nated soil may uptake and accumulate sig-nificant amount of arsenic in their tissue. The plants studied during the present in-vestigation were Lablab niger (Bean), Ly-copersicon esculentum (Tomato), Solanum melongena (Brinjal), Cucurbita maxima (Sweet gourd), Amaranthus gangeticus (Red amaranth), Carica papaya (Green papaya), Capsicum sp. (Chilli), Lagenaria siceraria (Bottle gourd), Momordica cha-rantia (Bitter gourd), Mentha viridis (Mint), Vigna sesquipedalis (String bean), Abel-moschus esculentus (Okra), Trichosanthes dioica (Palwal), Basella alba (Indian spin-ach). Mean arsenic concentration in the selected plants in the area studied was 0.113 µg g-1. The minimum was found in T. dioica (0.026 µg g-1) and the maximum in M. viridis (0.566 µg g-1) followed by V. sesquipedalis, Capsicum sp. (0.400, 0.200 µg g-1, respectively) while arsenic content in A. esculentus, B. alba and C. papaya was below detectable limit. The average dietary

intake of arsenic from the plants in the study area was estimated to be 14.69 µg day-1. Correlation with the groundwater arsenic status and statistical significance of varia-tions has also been determined.

69. Arsenic in surface and ground waters of the Ghazipur and Ballia in the Central

Gangetic Plain of Uttar Pradesh, India AL. Ramanathan1*, Prosun Bhattacharya2 ,P,

Tripathi1 and Manish Kumar1

1School of Environmental Sciences, Jawaharlal Nehru University, New Delhi-110067, India;

alr0400@mail.jnu.ac.in 2KTH-International Groundwater Arsenic Re-search Group, Department of Land and Water

Resources Engineering, Royal Institute of Tech-nology, SE-100 44 Stockholm, Sweden

In the Holocene aquifers of the Indo-Gan-getic plains of the states of Uttar Pradesh, Bihar and Jharkhand elevated concentrations of arsenic (As) have been reported in groundwaters. The present paper reports about the As and related contamination in groundwater and surface water in two dis-trict of Gangetic plain in northern India. Groundwater samples and surface water samples were collected from a 2 km stretch in the flood plain of the two rivers Ganga and Ghagra river over a three year period in Ballia and for one year in Ghazipur. The water samples were collected from surface, shallow and deep aquifers and analyzed for other hydrogeochemical parameters includ-ing major anions and cations, and dissolved trace elements.

Arsenic concentration in Ballia varies from below detection limit up to as high as 80 µg L-1. The concentration of As was very high in the location close to the river basin. The concentration of As near an inland lake was also very high. Concentration of As were found to be moderate to low in the interior flood plains between these two basins. The surface water showed high concentration near the confluence of the two rivers. The

60

Ghagra seems to contributing more As. The groundwater in the intermediate and deeper aquifers has more As compared to As in Shallow aquifers. In the Ghazipur the it is observed that As concentration in ground water is very low in most places expect few locations where it exceed 30 µg L-1, where as the surface water As concentrations is very low. The correlation between Fe and As was low. The sulphate concentration in groundwater was low as compared to sur-face waters. These aquifers seem to be par-ticularly in risk, due to the prevailing geo-chemical conditions in which oxidized and reduced waters mix, and where the amount of sulphate available for microbial reduc-tion seem to be limited. The study needs further refinement and the detailed work is under progress to understand the processes controlling the As concentration in surface and ground waters.

70. Arsenic remediation from groundwa-ter by environmentally reactive iron

nano particles Sushil Raj Kanel* and Heechul Choi

Environmental Nano Particle Laboratory, De-partment of Environmental Science and Engi-

neering, Gwangju Institute of Science and Technology (GIST), Oryong-dong Bukgu, 500-

712 Gwangju, The Republic of Korea; * skanel@gist.ac.kr

It is well established that removal of Arse-nic (As) is the major environmental con-cern due to its existence in groundwater and acute toxicity. Many different methods including precipitation-coagulation, co-pre-cipitation, ion exchange, electro-coagu-lation, oxidation and adsorption are being used for its remediation. Among them, the adsorption method has received more atten-tion due to its high efficiency and cost-effectiveness, and considered as the most suitable technology in the developing coun-tries.

Among different types of adsorbents being used for As remediation, zero-valent iron nano particle (INP) is one of the most com-mon because its capacity to remove both As(III) and As(V) simultaneously. Providen-tially, recent study shows that INP has shown great promise for environmental ap-plication. Due to the extremely small particle size, large surface area, and high in-situ re-activity, these materials have great potential in a wide array of environmental applica-tions such as soil, sediment and groundwater remediation. In addition, due to small size and capacity to remain in suspension, INP can be transported effectively by groundwa-ter and can be injected as sub colloidal metal particles into contaminated soils, sediments, and aquifers.

In this perspective we have utilized for the first time Environmental Iron Nano Particle (E-INP) for the remediation of As. For which we synthesized in laboratory E-INP and tested for the removal of As(III). We used SEM-EDX, AFM, and XRD to charac-terize particle size, surface morphology, and corrosion layers formed on pristine E-INP and As(III)-treated E-INP. AFM results showed that particle size ranged from 1 to 120 nm. XRD and SEM results revealed that E-INP gradually converted to magnetite / maghemite corrosion products mixed with lepidocrocite over 60 d. Arsenic(III) adsorp-tion kinetics were rapid and occurred on a scale of minutes following a pseudo-first-order rate expression with observed reaction rate constants (kobs) of 0.07-1.3 min-1 (at varied E-INP concentration). These values are about 1000?higher than kobs literature values for As(III) adsorption on micron size ZVI. Batch experiments were performed to determine the feasibility of E-INP as an ad-sorbent for As(III) treatment in groundwater as affected by initial As(III) concentration and pH (pH 3-12). The maximum As(III) adsorption capacity in batch experiments calculated by Freundlich adsorption isotherm was 3.5 mg of As(III)/g of E-INP. Laser light scattering (electrophoretic mobility

61

measurement) confirmed E-INP-As(III) inner-sphere surface complexation. The effects of competing anions showed HCO3

-, H4SiO4

0, and H2PO42- are potential interfer-

ences in the As(III) adsorption reaction. Our results suggest that E-INP is a suitable candidate for both in-situ and ex-situ groundwater treatment due to its high reac-tivity.

71. Arsenic crisis in Nepal: Key issues and remediation

Prakash Raj Kannel1, Sushil Raj Kanel2, Sabina Kanel3

1Water and Remediation Research Center, Ko-rea Institute of Science and Technology, PO

Box 131, Cheongryang, Seoul 130-650, South Korea; prakash.kannel@gmail.com

2Department of Environmental Science and Engineering, Gwangju Institute of Science and Technology (GIST), 1 Oryong-dong, Buk-gu, Gwangju 500-712, South Korea;

sushi.kanel@gmail.com3Social Welfare Council Nepal, GPO Box

10907, Kathmandu, Nepal; sanamkane1968l@hotmail.com

Groundwater is a significant source of drinking water in many parts of the world as well-protected groundwater is safer in terms of microbiological quality than water from open dug wells and ponds. Unfortu-nately, water is a universal solvent and hence groundwater is notoriously prone to chemical and other types of contaminations from natural sources and anthropogenic activities. The presence of unwanted con-taminants in water makes it unacceptable to drink for humans from both an aesthetic and a health aspect, and can have severe implications for all life forms. One of the substances that water can dissolve is chemical combination of the element “ar-senic”.

The arsenic contamination is becoming worldwide concern due to its high toxicity and carcinogenic effect. Arsenic has long been known as a poison and is best known

for its harmful acute and chronic effects. Due to long exposer about ten to twenty years, it ultimately leads to cancer. Arsenic in drinking water has been detected in many countries at concentrations greater than the WHO guideline value of 10 µg L-1 or the prevailing national standards. These include Argentina, Australia, Bangladesh, Chile, China, Hungary, Mexico, Peru, the United States of America, Thailand, Myanmar and Nepal. Among them, the arsenic crisis in Bangladesh has been described as one of the worst cases of mass poisoning in the world history. Arsenic occurrence in groundwater in Gangetic plains of Bengal Delta Plains of Bangladesh, West Bengal of India is the largest environmental health disaster areas of the present century, where at least 50 million people is at risk of cancer and other arsenic related diseases due to the consumption of high arsenic contaminated groundwater. The levels of arsenic in the groundwater on these areas are greater than the WHO guideline and have been shown to cause adverse chronic health effects.

Recently arsenic contamination of the groundwater has been detected in Nepal above 50 µg L-1 when arsenic testing was undertaken realizing that it shares some geo-logical features with the Gangetic plains of India and Bangladesh. It is suspected that the groundwater should have been contaminated by natural arsenic source as the districts of the Terai region is the area forming the northern extension of the Indo-Gangetic Plain and is composed of alluvial soil. In such context millions of Nepalese are at risk from diseases caused by drinking water con-taminated with the poison arsenic. The prob-lem is affecting the Terai lowlands, home to 47 percent of Nepal's 26 million people. People are suffering from skin and other serious diseases due to drinking underground water laced with arsenic. It is estimated from the studies that about 3.19 million people may have been affected by arsenic contami-nation in Nepal.

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To tackle arsenic problem, several mile-stones have been achieved in the three years period in at the national level. One of the significant achievement on this issue is the formation of National Arsenic Steering Committee (NASC)) for better co-ordination among the concerned agencies which has formulated a national and a working guideline for all interested con-cerned agencies. Presently, different op-tions are tried for arsenic removal process to the affected households and communities of Nepal. Low cost, effective and socially acceptable systems are still to be investi-gated. In addition, sufficient public aware-ness is still to be raised about the arsenic hazards in Nepal.

72. Arsenite induces cytokeratin expres-sion in mouse liver

P. Ramirez1, Oscar Zuñiga1, Mirna Hernández1 Valeria Berdón3, M. Cerbon2 and M. E. Gonse-

batt3

1Laboratorio de Toxicología Celular, FES Cuautitlán

2Laboratorio de Biología Molecular, Facultad de Química, UNAM, México, DF.

3Departamento de Medicina Genómica y Toxi-cología Ambiental, Instituto de Investigaciones

Biomédicas, UNAM, México, DF.

Cytokeratins (CK) constitute a family of cytoskeletal intermediate filament (IF) pro-teins that are typically expressed in epithe-lial cells. In simple type epithelia such as liver, exocrine pancreas and intestine the two major IF proteins are CK polypeptides 8 and 18. Increased levels of CK18 are observed in human liver disease such as primary billiary cirrhosis and in alcoholic liver disease, related to Mallory body for-mation as a consequence of CK accumula-tion. Modified synthesis and abnormal or-ganization of these intermediate filaments are considered indicators of liver damage. The liver is also the main organ where many carcinogens such as arsenic are me-tabolized. Studies in humans exposed to

inorganic arsenic by the oral route have noted signs or symptoms of liver injury. Also, lipid vacuolation and fibrosis have been reported in rats exposed to arsenic in drinking water. Increased synthesis and dis-ruption of CK 18 cellular organization, have been induced in WRL-68 human fetal he-patic cell line by sodium arsenite. In this work, male BALB/c mice were given orally 2.5, 5 and 10 mg kg-1 per day of sodium arsenite. CK expression was monitored in liver after 2 and 9 days. Significant induction of CK18 mRNA and protein synthesis were observed in those animals exposed to the lower doses when liver samples were exam-ined by RT-PCR and Western blotting re-spectively. We did not observe significant induction at the highest dose employed, sug-gesting that arsenite is inhibiting the synthe-sis of this important protein to hepatocyte architecture. The induction of CK 18 could be considered as an early indicator of liver damage by arsenic. This work was partially supported by PAPIIT IX201004 and CONACYT I38967-N.

73. Effects of arsenic and fluoride on the central nervous system

Rocha-Amador D. O.1, Carrizales Yañez L.1, Morales V. R.2, Navarro C. M.E.2, Calderón H. J.1

1Facultad de Medicina de la Universidad Autónoma de San Luis Potosí

2Facultad de Psicología de la Universidad Autónoma de San Luis Potosí

Million of people around the world are ex-posed to arsenic (As) and/or fluoride (F) through drinking water (DW). In Mexico, approximately 6 million of people are ex-posed to both pollutants; from these 35% are children. Experimental and epidemiological studies, supports the evidence that both pol-lutants are neurotoxic. They have the ability to cross the blood brain barrier and to accu-mulate in the brain. Nevertheless, one of the worrisome effects is the reduction of the intelligence quotient (IQ). In the center-north

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of Mexico the As and F levels in DW are superior to the established values in the Norma Oficial Mexicana (NOM SSA1-027). We designed a cross-sectional study in children, to evaluate the effect of the exposure to As and the F on the IQ and the neurological functions in children. One-hundred thirty two children from 6 to 10 years were included in the study from four communities with different As and F con-centrations in DW: 1) Soledad de Graciano Sánchez, San Luis Potosí, (SLP) (As 6.7 ± 1.2 µg L-1; F 0.7 ± 0.3 mg L-1); 2) Mocte-zuma, SLP (As 4.5 ± 1.5 µg L-1; F 1.1 ± 0.01 mg L-1); 3) Salitral de Carrera, Villa de Ramos, SLP (As 169.5 ± 16 µg L-1; F 5.3 ± 0.18 mg L-1 and 4) 5 de Febrero, Du-rango (Dgo) (As 200 ± 84 µg L-1; F 9.4 ± 1.1 mg L-1). Two neuropsychological tests were applied; 1) The Weschler Intelligence Scale revised version for Mexican children (WISC-RM) to evaluate, the IQ (verbal, performance and full), as well as cognitive functions (like attention, memory, visu-ospatial organization and language), and 2) The Rey-Osterrieth Complex Figure Test (ROCF), to evaluate visuospatial organiza-tion and short term memory. As exposure biomarkers As and F in urine were ana-lyzed by atomic absorption spectropho-tometry. As confounding factors lead in blood (PbS), socioeconomic status (SES) and nutritional evaluation (anthropometric measurements and iron deficiency) were evaluated. After adjusting by confounding factors, inverse associations between As and the F in urine and the scores of Full IQ, verbal IQ, performance IQ and the ROCF were obtained. These results suggest that the chronic exposure to both pollutants affects the higher brain functions in these children.

74. As behavior in an urban aquifer: Chemical, geological and hydrogeological

characterization R. Rodriguez, E. Mata and J.A. Mejia

Geophysics Institute, UNAM, Mexico COTAS, Irapuato valle de Santiago, Mexico

Salamanca is an industrial city where a Pet-rochemical Plant and chemical industries are established. The urban area is crossed by the Lerma River. In most of 80% of the urban wells As was detected. The As concentra-tions are 0.01 to 0.07 mg L-1. Population is been exposed to low, but constant, As con-centrations. There are not evidences of health affectations.

Some urban wells are located inside the ur-ban area, around the industrial zone. The high As concentrations allow the closure of 3 wells. In 2 of them, was detected also hy-drocarbons. There is not a clear correlation between free phase and As content in groundwater.

A hydrochemical, geological and hydro-geological characterization is been realized in order to clarify the origin and factors that control the As mobility.

The aquifer system is composed by sedimen-tary and volcanic rocks, in both environ-ments As was detected. The main recharge mechanism is associated to rainfall infiltra-tions in the Guanajuato range. A regional flow component was inferred to the north were the As concentrations are very low.

The preliminary results show that fault, frac-tures and paleochannels are controlling the As distribution in a shallow aquifer unit. The origin is mainly natural but there are evi-dences that there are also anthropogenic sources.

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75. Arsenic in drinking water in Cór-doba Province, Argentina

G. Román-Ross1, G. Sacchi2, L. Charlet3, M. Avena4, and C. Pauli2

1Department of Chemistry, Faculty of Sciences, University of Girona, Campus de Montilivi, E-

17071 Girona, Spain; groman@obs.ujf-grenoble.fr

2Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria,

5000 Córdoba, Argentina 3 LGIT-OSUG, Université Joseph Fourier, BP

53, F-38041 Grenoble Cedex 9, France 4Departamento de Química, Universidad Na-cional del Sur, Av. Alem 1253, 8000 Bahía

Blanca, Argentina

Arsenic in drinking water can impact hu-man health and is considered one of the prominent environmental causes of cancer mortality in the world. Latin America is among the most affected areas worldwide. As opposed to the now well studied Bang-ladesh case, arsenic contaminated waters in Argentina are well oxygenated waters. Ar-senic affects mainly rural population, which is exposed to arsenic levels of around 5.3 mg L-1 in the most contaminated areas. At present, epidemiological studies are scarce due to the lack of Cancer Registries and to exposure heterogeneity. In Argentina, na-tional and local governments do not have the responsibility for providing safe drink-ing water. Each small local water company is responsible for the quality of the supplied water. In addition, only few local laborato-ries are able to provide quality control ar-senic analyses. The current Argentinean As guideline has been set up equal to 50 µg L-1. However, this guideline can be considered as a temporary measure due to the increas-ing international efforts to lower this limit down to 10 µg L-1. The estimated costs of compliance with more stringent standards are high. In this context, it is worthwhile to examine the arsenic contamination on the basis of these different possible guidelines. In the present study we analysed drinking water supplied by local companies in the

Cordoba Province. The As-contaminated waters in this region are in contact with loess, a thick sequence (generally around 200-300 m) of Tertiary and Quaternary sediments. Borehole depth is highly variable depending on the regional topography. In the western area, where loess deposits are ex-tremely thick and groundwaters rather deep, it may be as deep as 140 m below ground level. In the eastern area wells are shallow, as groundwater level is closer to the surface, and wells depth is typically 10 m or less. In the major towns, groundwater is treated by reverse osmosis to remove dissolved salts and As before to be delivered as drinking water. In the rural areas, this is not possible and water is typically used without pre-treatment, and is thus often arsenic-contaminated. We have collected and ana-lyzed arsenic as well as V, F, U, Se, in drink-ing water from 200 cities and villages across Cordoba Province, during 2004. The number of samples, broad geographic coverage, and consistency of methods produce the most accurate and detailed picture of arsenic con-centrations in drinking water for the region. Maps of the contamination have been pro-duced to show the hotspots and the factors affecting the presence of arsenic (borehole depth, water treatments, etc). Most rivers and streams in Córdoba province contain arsenic concentrations ≤1 µg L-1. Therefore, towns and cities that use this water as source are free of As contamination. In contrast, waters from heavily impacted areas in the E and S exceed the As limit (50 µg L-1). This data contribute to the understanding of the status and trends of arsenic concentrations in drink-ing water in Córdoba Province, and can: (1) assist water managers and users in overcom-ing adverse health effects through avoidance or treatment; (2) provide a basis for evaluat-ing the costs of adopting a particular value for a drinking-water standard; and (3) assist epidemiologists interested in evaluating the intake of arsenic from drinking water.

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76. Arsenic in loess and volcanic ashes of Cordoba Province, Argentina

G. Roman-Ross1, Laurent Charlet2 and Diego Gaiero3

1Dept. of Chemistry, Faculty of Sciences, Uni-versity of Girona, Campus de Montilivi, 17071 Girona, Spain; groman@obs.ujf-

grenoble.fr 2LGIT-OSUG, Université Joseph Fourier, BP

53, F-38041 Grenoble Cedex 9, France 3CIGeS- FCEFyN, Universidad Nacional de Córdoba, Pabellón Geología, Avda. Velez Sars-

field 1611. X5016GCA Córdoba, Argentina

The main objective of this study was to explore whether iron oxides or volcanic ashes are the main arsenic storage material in the sedimentary aquifers of the Cordoba Province, Argentina.

Loess samples were collected from two 14 and 7 m thick natural outcrops. One profile is located in the western region, and the second one in the eastern part of Cordoba province where groundwaters have the high-est As concentrations. Identification and separation of volcanic ashes from loess out-crops is difficult to perform and little amount can be obtained from loess samples to perform laboratory studies. Therefore, we sampled volcanic ashes from a sedimentary lacustrine core which has yielded a continu-ous record of particles deposited over the last 15.0 kyr BP.

Total concentration of As in volcanic ashes samples varies from 5 to 20 mg kg-1. Al-though volcanic ashes represent only a tiny fraction of loess material, the same concen-tration range has been measured in loess materials. Furthermore, the percentage of As linked to the different phases as deter-mined by selective extractions is nearly constant both in loess and volcanic ashes sampled in the lake core. Ionically bounded As is very rare (2% of total As). In Argen-tinian loess, secondary carbonates are abundant as nodules, layers or cements and secondary Mn oxide is also present as nod-ules in some horizons. Arsenic found in the

corresponding fraction represents 18% of total arsenic in loess samples and 22% in volcanic ashes. A special attention was given to Fe oxides since these minerals have been cited in the literature as being the main source of As in Pampean aquifers. Selective extractions performed on volcanic ashes and loess samples show that As is mainly associ-ated to Fe oxides (around 60% of extracted As).

These studies were complemented by incu-bation experiments to investigate As desorp-tion under conditions prevailing during flooding periods, i.e. desorption induced either by excess of bicarbonate ions or by reducing conditions. The quantity of As re-lease in oxic waters is equal to 100 µg L-1 and increase linearly up to 300 µg L-1 in presence of increasing bicarbonate ion con-centrations. Therefore, bicarbonate leaching is presumed to be one important mechanism to mobilize arsenic in bicarbonate dominated oxidizing aquifer of the region.

In Córdoba Province, recent variations in the hydrological budget have lead dry and wet intervals that resulted in distinctive fluctua-tions of lake levels, river discharges and recurrent floods of very productive soils in the low plain. This shift in aeration status of the soils lead to the reduction of As(V) re-duction to As(III), a more mobile and toxic species. Leacheable As(III) concentrations in anoxic conditions may increase up to 400 µg L-1.

77. Sources and transport of arsenic con-taminating shallow groundwater in the historical industrial zone of Monterrey

City, Nuevo León, México Francisco Martín Romero, Margarita Gutiérrez

Ruiz and Mario Villalobos

Instituto de Geografía, UNAM-México, Mexico; fmrch@igiris.igeograf.unam.mx

Arsenic contamination has been detected in a shallow aquifer of the geographical center of

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Monterrey City, in the Northeast of Mex-ico, and where the historical industrial zone of the city is located, reaching concentra-tions of up to 3.1 mg L-1. A metallurgical plant that operated more than 100 years and closed down in 1999 is identified as a pos-sible pollution source because it deposited arsenic-rich wastes in the fields adjoining it, showing total arsenic contents that reach up to 1-2% As in weight. We deem arsenic transport through the soil profile as highly unlikely based on the following experimen-tal and field evidence: water-soluble arse-nic contents in 1:20 soil:water extracts of both surface and subsurface samples is very low, showing values in a majority of sam-ples below 1 mg As L-1; the unsatured zone under the inactive plant is characterized by the presence of two impermeable clay lay-ers (hydraulic conductivities of 2.1 x 10-8 cms-1 to 8.4 x 10-8 cms-1), the first one oc-curring at 0.6 to 1 m below the surface, and the second one at approximately 17 m be-low the surface; arsenic analyses of several core samples from boreholes 40 m deep show that As released at the soil surface is completely retained in the upper clay layer.

Nevertheless, the highest dissolved arsenic concentrations (1.1 to 3.1 mg L-1) were found in wells from shallow groundwater from active industries located to the north of the inactive plant. The groundwater flux in the area goes in a direction west to east, therefore, the source of these arsenic levels cannot come from the inactive plant prem-ises and indicates the occurrence of addi-tional sources of arsenic groundwater con-tamination.

The evidence points to the fact that the most likely cause of shallow groundwater contamination inside the inactive plant is via surface runoff of deposited wastes dur-ing the rainy season, into drilled boreholes in the area. This is supported by a 10-year semester analysis database, which shows a constant seasonal variation in dissolved arsenic concentrations measured at the drilled boreholes, fluctuating between 0.1

and 0.9 mg L-1. Therefore, the authors rec-ommend a suitable and immediate closure of these boreholes.

78. Geogenic arsenic enrichment in histosols Thomas R. Rüde1 and Henrietta Königskötter2

1RWTH Aachen University, Institute of Hydro-geology, Aachen, Germany;

ruede@hydro.rwth-aachen.de 2Ludwig-Maximilians-University Munich, De-partment of Earth and Environmental Sciences,

Munich, Germany; paprikaland@web.de

There is an increasing awareness of natural arsenic enrichments in aquifers and overly-ing soils worldwide. In contrast to anthropo-genic contaminated sites, these geogenic enrichments occupy large areas and cause an often unforeseen threat to humans. There are now several reports in Germany of soils, often histosols, which have very high arsenic concentrations. The example discussed here is an area in southeastern Germany with up to 4000 mg kg-1 As.

There, soils are cultivated since approx. one hundred years and it is discussed that arsenic was enriched in the organic matter due to cultivation. The process in mind is a dewa-tering of the organic rich horizons accompa-nied by shrinking and decomposition of these horizons and enrichment of arsenic on residual matter. Alternatively, arsenic can be enriched on pedogenic iron and/or manga-nese oxides.

We tested both hypotheses on three profiles which were studied in detail. The profiles show organic rich layers on top with total thicknesses of 0.25 to 0.55 m. The humic horizons contain 15 to 35% of organic car-bon. The lower parts of the profiles consist of carbonaceous gravels with up to 70% of calcite and only around 1% of organic car-bon. These lower horizons show redoximor-phic features and the lowermost horizon is saturated by capillary fringe and groundwa-ter. All profiles show concentrations of iron of 5 to 8% in the humic layers which de-

67

crease sharply in the redoximorphic lower layers to values of 1 – 2%. The second uppermost horizon of one profile is a ferric one with up to 30% of iron. Manganese is only a minor constituent with concentra-tions around 1300 mg kg-1 in the humic and approx. 150 mg kg-1 in the calcareous re-doximorphic horizons. Sequential extrac-tions demonstrate that pedogenic iron ox-ides are the dominant iron minerals espe-cially in the humic horizons which make up 80% of iron as a maximum.

Arsenic concentrations in the profiles fol-low sharply the distribution of iron oxides with a fraction of explained variance r2 = 0.914. Using total iron concentrations the correlation is much weaker with r2 = 0.661. There is now distinct relation of arsenic to the organic carbon. We conclude from our observations that arsenic is enriched on iron oxides in the soils and that the organic car-bon is only of minor importance.

The original source of the arsenic is proba-bly a deeper aquifer with well known geo-genic enrichment of arsenic. That aquifer and the one covered by the soils are region-ally connected by hydraulic windows which allow for the transport of arsenic into the upper one and enrichment of arsenic during pedogenesis.

Actually, the mobile fraction of arsenic is very small (less than 1% of the total con-centration) which is proved by small water soluble concentrations, low concentrations in the groundwaters of the area and only a few spots of increased arsenic concentra-tions in grass and crops. The risk is that the pedogenic sink of arsenic will become dis-solved during changes of land use espe-cially renaturalization of bogs and wet-lands.

79. Arsenic determination in soils from a mining zone in the eastern Pyrenees,

Spain M.J. Ruiz-Chancho, J.F. López-Sánchez, R.

Rubio 1Departament de Química Analítica, Universitat

de Barcelona. Martí i Franqués 1, 3ª planta, 08028 Barcelona; roser.rubio@ub.edu

The Vall de Ribes is situated in the Eastern Pyrenees and at the beginning of this cen-tury; the now abandoned mining district produced small amounts of several metals like As, Sb, Au. Nowadays soils with high contents of As can be found in this zone, usually associated with the presence of ar-senopyrite.

Seven soil samples were collected in three differentiated sites of this mining zone, the first sample point belongs to an old Sb mine, the second one to an As and Sb mine and the third one belongs to an old As mine. Soil samples were air dried and sieved to 2 mm and 90 µm. For these soil samples the min-eralogical composition, pH, organic matter estimation and major components were de-termined.

Total arsenic content was carried out in aqua regia extracts by ICP-AES and HG-AFS. For the species extraction a mixture of phospho-ric and ascorbic acid was used and the de-termination of arsenic species was per-formed by using the coupled technique HPLC-HG-AFS.

High levels of arsenic were found in some samples ranging from 51 to 38000 mg kg-1 and with the only presence of inorganic ar-senic (As(III) and As(V)) were detected when the speciation analysis was performed.

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80. Arsenic content in plant samples from a mining contaminated area

M.J. Ruiz-Chancho, J.F. López-Sánchez, R. Rubio

1 Departament de Química Analítica, Universi-tat de Barcelona. Martí i Franqués 1, 3ª planta,

08028 Barcelona; roser.rubio@ub.edu

The Vall de Ribes, situated in the Eastern Pyrenees in Spain, was one of the main producers of iron at the end of the last cen-tury. It is also known the presence of As, Sb, Cu. High levels of As were found in soils of this zone in a range from 51 to 38000 mg kg-1. For this reason it was ex-pected that plants growing on the contami-nated zone could contain relatively high concentrations of As. Arsenic present in these plant samples in determined condi-tions could be bioavailable.

Several plant samples were collected in seven contaminated sites. About 40 plant samples of 20 different species were col-lected, cleaned with deionized water, dried at 40ºC and finally crushed. Total content of As was carried out by acid digestion in a microwave oven and quantification was performed by ICP-MS. Arsenic concentra-tion in plant samples ranged from 0.1 to 5400 mg kg-1 depending on the sample specie as well as the arsenic soil concentra-tion. Uncontaminated terrestrial plants usu-ally contain about 0.2 to 0.4 mg kg-1.

The arsenic species content was determined in several samples by using coupled tech-niques as HPLC-(UV)-HG-AFS and HPLC-ICP-MS. Several extraction media were tested in order to obtain the best ex-traction efficiency and to preserve the original species of the sample.

81. Identification of areas with major arsenic concentration in the Meoquí-

Delicias aquifer, Chihuahua Yadira Ruiz-Gonzalez, Jürgen Mahlknecht*

Centro de Estudios del Agua, Instituto Tecnológico y de Estudios Superiores de

Monterrey; Av. Eugenio Garza Sada No. 2501 C.P. 64849, Monterrey, N.L., Mexico;

jurgen@itesm.mx

It is known that the groundwater of semiarid Meoquí-Delicias area in Chihuahua, North-ern Mexico, consisting of several munici-palities (Saucillo, Rosales, Meoquí, Delicias and Julimes), is affected by arsenic contami-nation. The present study deals about pres-ence, distribution and plausible origin of arsenic in the Meoquí-Delicias aquifer.

Of a total of 47 water samples from deep tubewells of the Meoquí-Delicias aquifer, 68% demonstrate not to comply with the maximum admissible value of the Mexican Standard for drinking water (NORMA OFI-CIAL MEXICANA NOM-127-SSA1-1994; 0.025 mg L-1). A maximum value of 0.45 mg L-1 has been observed in the area of Delicias City, which is 17 times the maximum admis-sible value. This concentration represents a major social risk for the inhabitants of this city.

The tubewells with a major arsenic concen-tration generally lie very near of or in urban-ized areas of the region: in the north of the Meoquí city, in Delicias city, and south to the Saucillo town; those municipalities rep-resent the major population of the study area. It is assumed that the origin of arsenic is geologic, induced by heavy pumping of groundwater resources.

82. Estimate of the current exposure to total arsenic in Chile

Ana María Sancha

Department of Civil Engineering. Universidad de Chile. P.O. Box 228/3; Santiago, Chile;

amsancha@ing.uchile.cl

Exposure to arsenic in Chile results from natural hydrogeochemical conditions and from antropic sources derived from the min-ing activities carried out in some areas of the

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country, mainly in the north and central zone.The arsenic levels found in different environments and the results of epidemiol-ogical studies indicate that this element constitutes an important health risk factor, principally for the inhabitants of the north of Chile.

Current total arsenic “external” exposure was assessed by combining data on the levels of arsenic in water, food and air, with information about food consumption, rates of water ingestion and air inhalation. The results showed that the population’s mean level of exposure to total arsenic fluctuates between 173.85 and 80.99 µg As day-1. Ingestion of water was found to be the most important exposure pathway for population of northern and central Chile and for the southern Chile the largest contribution cor-responds to food. Air is not a significative exposure pathway

A historical estimation of the total exposure of the northern Chile indicates that in the decade of the 70’s the arsenic exposure via water became, in some cities as Antofaga-sta and Calama, ten times as high as it is now. Exposure via air must have been somewhat lower due to less intensive min-ing activity at that time. Exposure via food may be considered similar or slightly higher than the current one.

83. Arsenic removal from water with low initial turbidity: Chilean experience

Ana María Sancha

Department of Civil Engineering. Universidad de Chile. P.O. Box 228/3; Santiago, Chile;

amsancha@ing.uchile.cl

This study presents Chilean experience in arsenic removal from groundwater. Neither the origin of arsenic in groundwater nor the processes responsible for its mobility are known with certainty, but it is suspected that it is a naturally occurring contaminant.

The coagulation process has been used in Chile since the 70’s to remove arsenic from surface waters with high arsenic content. Through previous studies, we know that in the case of water with low arsenic content and low turbidity, this process could be replaced by a simplified treatment consisting of a di-rect coagulation-filtration process. This re-sults in a significant cost reduction in invest-ment, operation and maintenance costs.

Arsenic is removed through chemical sorp-tion and particulate removal processes with a previous oxidation and pH conditioning. The addition of metallic coagulants facilitates the conversion of inorganic arsenic species into insoluble reaction products which are sepa-rated later on by means of filtration. Key factors in arsenic removal by this simple and low cost technology are: pH, oxidant and coagulant dosage mixture speed, retention times and filter washing frequency. During the experimentation period the arsenic con-centration in raw water ranged from 0.05 to 0.07 mg L-1 and the pH ranged from 7.0 to 9.0.

Good correlations exist between particulate removal and arsenic removal. Treated water with residual As <0.010 mg L-1 is obtained during long operation periods.

84. Dietary arsenic and selenium intake by school children in arsenic-endemic

areas of Argentina, Ecuador and Mexico Luz C. Sanchez-Peña1, Silvia S. Farias2, Graciela

Bovi-Mitre3, Edda Villaamil4, Leticia Garcia-Rico5, Jenny Ruales6, Dinoraz Velez7, Rosa

Montoro7 and Luz M. Del Razo1 1Toxicology-Cinvestav-IPN; Mexico City, Mexico

2CNEA, Buenos Aires, Argentina 3Ingenieria-UNJu, Jujuy, Argentina,

4FFyB-UBA, Argentina, 5CIAD, Sonora, Mexico,

6IIT-EPN, Quito, Ecuado, 7IATA, Valencia, España

Arsenic (As) occurrence in the aquifers of several geographic regions such as Argen-tina, Ecuador and Mexico have been identi-

70

fied. Selenium (Se) is an essential micronu-trient with a recommended dietary allow-ance for humans of 50 to 200 µg per day. It functions as an essential constituent of se-lenoproteins. In the Andean regions of Ec-uador, Se deficiency has been reported in children. People in many other areas of the world are selenium deficient, with the con-sequence that they are unable to express their selenoproteins fully. As and Se are metalloids with similar chemical properties and metabolic fates.

The interactions between As y Se are com-plex. The toxic effects of inorganic Se can be ameliorated by exposure to As. In con-trast, inorganic As (iAs) potentiates the toxicity of methylated Se compounds. The metabolism, retention and toxicity of As can be modified by exposure to Se. Be-cause chronic exposure to As has been associated with increased incidences of a variety of cancers and increased risk of morbidity or mortality due to peripheral vascular, cardiovascular or cerebrovascular disease, to hypertension or to diabetes mel-litus, there is considerable interest in identi-fying factors that modify the susceptibility of individuals to the toxic and carcinogenic effects of As. For example, it has been sug-gested that differences among human popu-lations chronically exposed to As in the manifestations of the adverse effects of this metalloid might be related to variation in Se intake. Thus, it can be postulated that individuals with a high intake of Se may be less likely to suffer from a given toxic ef-fect of chronic exposure to iAs than are individuals with a lower intake of Se. Con-versely, a lower intake of Se may exacer-bate the toxic effects of As, increasing the risk associated with chronic exposure to this metalloid.

In order to estimate the intakes of total arsenic, iAs and total Se concentrations, food consumed by school children attend-ing elementary school were evaluated. Four schools whose communities rely on fossil groundwater contaminated with As for

drinking water supply (> WHO limit of 10 µg L-1) were selected. The source of As con-tamination of the groundwater is the subsur-face soil chemical composition and charac-teristics and not the anthropogenic activities. School are sited in Santiago del Estero, Argentina; Quito, Ecuador; Hermosillo and Zimapan, Mexico.

Total As, iAs and total Se levels were meas-ured by AAS. The dietary intakes of these elements were determined by a total diet study. Calculations were carried out on the basis of recent data on the consumption of the selected food items.

Information about Se intake in arsenic-endemic areas will be useful information for identification of factors that affect the toxic effects of As exposure.

85. Exposure to arsenic: Modification of cell proliferation and differentiation mark-

ers in primary human keratinocytes M. Sandoval1, M. Corona1, Moisés A. Ortega, M.

Sordo2, P. Ostrosky2, E. Lopez-Bayghen1

1Departamento de Genética y Biología Molecular, CINVESTAV-IPN, 2Departamento de

Genética y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, UNAM, Mexico

D.F., Mexico

Human exposure to arsenic is associated with an increased incidence of skin patholo-gies as hyperkeratosis and cancer. Different mechanisms have been explored including genotoxicity, cell proliferation changes, al-tered DNA repair or modifications in methy-lation patterns. The proliferation and differ-entiation of skin stratified epithelial cells requires the coordinated expression of struc-tural and regulatory proteins. All modifica-tions in expression patterns of these proteins result of special interest in arsenic-associated-skin pathologies. Here, we test if during arsenic exposure, some changes in the proliferation and differentiation process in human keratinocytes can be mediated by modifications in the expression levels of p53

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and human involucrin (Hi). The tumour suppressor p53 is a potent mediator of cel-lular responses against genotoxic damage, controling normal cell proliferation and may be a modifier of the differentiation process in keratinocytes. The human in-volucrin (Hi) is an important differentiation marker and estructural protein in cornified envelope of terminally differentiated keratinocytes. Based on this premise, we treated human keratinocyte cultures (HKC) with increasing concentrations of sodium arsenite for up to 24 h. We evaluated the effects of arsenic on cell proliferation, genotoxic damage, and changes in Hi and p53 protein levels. Likewise, we examine the effect of arsenite on cyclin D1 protein levels, as an indicator of regulation of cell proliferation.

The arsenite effect on HKC was an increase in proliferation, in cells under treatment with a relatively low concentration (0.1µM). This effect was companied by an increase in cyclin D1 protein levels, when cells are exposure at concentrations of ar-senite less than 0.5 µM. Significantly, using concentrations higher than 0.5µM, we no-ticed a decrease in proliferation and in-creased levels of Hi protein, supporting the idea that arsenic may act as a differentia-tion inducer in our system. Exposure of HKC to different concentrations of sodium arsenite resulted in increased levels of p53 and Hi (in a dose-response manner). These data indicate that sodium arsenite induces an increase in p53 protein levels, probably in response to DNA damage. Increment of micronuclei counts in cells exposed to 1µM of sodium arsenite for 24 hr, indicated a significant cell damage associated with exposure to arsenic.

In order to understand the molecular mechanisms underlying p53 role as modu-lator of gene expression controlling cell proliferation, and even in the control of keratinocyte differentiation, we tested if arsenic may modulate the ability of p53 to act as a transcription factor. Electrophoretic

gel shift assays were performed using a p53-consensus DNA-binding sequence. A dose-dependent response in DNA binding can be noticed under arsenic exposure. Using a reporter system, in which, transcriptional activity is mediated by a p53-driven-SV40 promoter, the augmentation in arsenic con-centrations correlates with a higher tran-scriptional activity. Additional data support the idea that signalling events as Protein Kinase B activation may be important in p53 activation. Current work in evaluating so-dium arsenite effect on p53-regulated genes may result in important data to understand modifications in the differentiation process, via p53, which may be an important altered pathway during skin carcinogenesis.

86. Remediation of arsenic contaminated waters by ferric iron and ferric com-

pounds – a review Tony Sarvinder Singh* and K. K Pant

Department of Chemical Engineering, Indian Institute of Technology,

Hauz Khas, Delhi 110016 INDIA; *: tony_iitd@yahoo.com

Arsenic, a commonly occurring toxic metal in natural ecosystem, is associated with ei-ther natural conditions or the industrial prac-tices of mankind. Arsenic does not often form in its elemental state and is far more common in sulfides and sulfo salts such as arsenopyrite, orpiment, realgar, lollingite and tennantite whereas it readily substitutes for silicon, ferric, iron and aluminium in crystal lattices of silicate minerals. One of the two distinct mechanisms that lead to the release of arsenic on a large scale, is the develop-ment of high pH (>8.5) conditions in semi-arid or arid environments usually as a result of the combined effects of mineral weather-ing and high evaporation rates. This pH change leads either to desorption of adsorbed arsenic and a range of other anion-forming elements from mineral oxides, especially iron oxides. The second is the development

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of strongly reducing conditions at near-neutral pH values, leading to the desorption of As from mineral oxides and to the reduc-tive dissolution of Fe and Mn oxides, also leading to arsenic release. The process is generally aided by the high water table and fine-grained surface layers which impede the penetration of air to the aquifer. Ele-vated concentrations of arsenic (> 1 mg L-1) in groundwater of geochemical origins have been found in many countries such as Taiwan, India (West Bengal), Bangladesh, Chile, North Mexico, Argentina, USA and Nepal. Due to its various carcinogenic and mutagenic effects on human and animals, various regulatory agencies have prescribed different permissible limits for arsenic such as 0.01 mg L-1 (WHO).

Various technologies reported in the litera-ture for the treatment of arsenic are conven-tional co-precipitation, lime softening, fil-tration, ion exchange, reverse osmosis and membrane filtration but due to the exces-sive use of chemicals, bulky sludge, high cost, these techniques are not cost effective at small scale or household level. A thor-ough literature review revealed that adsorp-tion has been extensively used for arsenic removal. Some of the most common ad-sorbents tried for the removal of arsenic are activated carbon, iron oxide, manganese oxides, different polymeric materials and alumina. In recent years, elemental and zero valent iron has received considerable attention as a media for treatment of wide variety of contaminants in water such as chlorinated hydrocarbons, chromium, ni-trates and radionucides. One of the chief advantages of using this media for treat-ment is its adaptability to passive flow through application, which can be signifi-cantly less expansive to operate. This paper is an effort to review the different kinds of Iron and Iron based adsorbents used for arsenic removal.

Several iron (II) oxides such as amorphous hydrous ferric oxide (FeOOH), Hydrous ferric oxide (poorly crystalline ferrihy-

drite), goethite, pyrite, hematite and green rust (an intermediate product of iron oxida-tion that eventually transform to ferric oxy-hydroxide) have shown promising results for both As(V) and As(III) removal from aque-ous solution.

Most of the Fe oxide shows strong sorption affinity toward both As(V) and As(III) through ligand exchange in the co ordination sphere of structural Fe atom. Various inves-tigation into the mechanism of arsenic re-moval revealed that As(III) and As(V) are selectively bound to the oxide surfaces through formation of inner sphere complex. Electrostatic interaction and specific adsorp-tion are also important mechanisms for arse-nic removal by the iron oxides, which form a passivation layer on Feo iron oxides includ-ing poorly crystalline oxide. As(III) is more toxic and difficult to remove from aqueous solution, Attempts have also been made to impregnate this Fe metal/ion on basic mate-rial such as sand, clays to increase its sorp-tion capacity. This paper discusses the ad-sorbent preparation techniques and the com-parisons of Iron and Iron based adsorbents with other sorbents have also been pre-sented.

87. Effect of chloride, sulphate, phosphate and fluoride ions and regeneration studies

on the sorption of arsenic by activated alumina and Iron oxide impregnated acti-

vated alumina Tony Sarvinder Singh* and K. K Pant

Department of Chemical Engineering, Indian Institute of Technology, Hauz Khas New Delhi

110016, India; *: tony_iitd@yahoo.com

Numerous studies regarding the sorption of arsenic have been reported in the literature where different kinds of adsorbents such as Activated Carbon, Iron and Manganese based adsorbents, Lanthanum based adsorb-ents have been used. In most of these stud-ies, synthetic solutions (arsenic solution prepared in distilled water) have been used

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whereas in real ground or surface water, presence of other ions such as Chloride, Sulphate, Phosphate and Fluoride was also observed. As few studies are available in literature on the effect of competing ions moreover the concentrations of competing ions taken in their studies were very less as compared to natural systems.

To simulate the conditions prevailing in natural ecosystems/ environment, the pre-sent study was undertaken to assess the impact of these competing ions on the re-moval As(III) and As(V) by Activated Alumina (AA) and Iron Oxide Impregnated Activated Alumina` (IOIAA). were con-ducted. The concentrations of Chloride (0-600 mg L-1), Sulphate (0-600 mg L-1), Phosphate (0-600 mg L-1) and Fluoride (0-15 mg L-1) ions were studied in the range found in ground water. Effect of these ions on the % As(III) and As(V) removal was investigated. The binding affinity of vari-ous competing ions such as Phosphate, Fluoride, Chloride and Sulphate was de-termined using adsorption kinetics experi-ments.

Investigations on the effect of competing ions revealed that adsorption of arsenic strongly depends on the presence of phos-phate, sulfate and fluoride ions whereas presence of chloride ion had negligible effect on uptake of arsenic in the range studied. The effect of competing ions on arsenic removal followed the sequence as PO4> F- > SO4

-- > Cl-.

To evaluate the performance of regenerated sorbent for arsenic removal, equilibrium studies were carried out with the samples after each regeneration cycle. Exhausted AA was desorbed with different concentra-tion of NaOH (1%, 2% and 4% by weight) for 24 h followed by washing with water and activation with different HCl concen-tration (0.1 M- 0.5M). The treatment was carried out for 12 hours. Each batch was dried in the oven at 378 K for 24 hours and the final weight was measured for weight

loss studies. A known amount of regenerated sorbent from each batch was taken and the remaining sorbent was again subjected to second regeneration cycle. The same proce-dure was repeated for second and subsequent regeneration cycles. Regeneration studies were carried out up to five regeneration cy-cles. Regeneration efficiency was tested for repeated regeneration cycles. Exhausted activated alumina can be effectively regen-erated with 4% NaOH followed by reactiva-tion with 0.5 M HCl. However, higher loss of activated alumina was observed at higher NaOH concentration due to dissolution of activated alumina. Therefore 2% NaOH with reactivation by 0.1 M HCl may be desirable.

88. El arsénico en las aguas subterráneas en La Pampa Central, Argentina.

Hallazgos y consecuencias Carlos J. Schulz1,2,3 y Eduardo Mariño2

1Facultad de Ciencias Humanas (UNLPam). 2Facultad de C. Exactas y Naturales (UNLPam)

3Secretaría de Recursos Hídricos de la Pampa (L.P) Uruguay 153, 6300 Santa Rosa, La Pampa. Ar-

gentina. Tel +54-2954-425166; cjschulz@cpenet.com

La presencia de Arsénico en las aguas sub-terráneas en la región de La Pampa central de la República Argentina plantea una serie de interrogantes que nos lleva a establecer nuevas líneas de razonamiento que tiendan a constituir otras metodologías de reflexión hidrogeológica para la zona.

Es importante destacar que la clásica visión hidrogeoquímica en la caracterización de las aguas subterráneas en lo que respecta a la presencia del Arsénico, como de otros oli-goelementos, constituye en la mayoría de los casos un enfoque parcial o a veces equivo-cado de la realidad. Esta situación induce muchas veces a toma de decisiones total-mente equivocada por los gestores del agua o muchas veces por otras disciplinas que tienen que ver con la saluda de las personas (médicos, odontólogos, etc.).

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A partir de estos conceptos y, de manera preliminar, podemos decir que la presencia del arsénico en las aguas subterráneas en la región de La Pampa central de la República Argentina constituye una incógnita desde el punto de vista hidrogeoquímico ya que, de acuerdo a las distintas regiones se comporta de manera diferente, y su variación en pro-fundidad es errática.

Como puede observarse entonces, no resulta para nada sencillo establecer los mecanismos que gobiernan el aporte de sales por parte de los sedimentos que conforman la zona no saturada (ZNS) y zona saturada (ZS) al agua subterránea en el tiempo de contacto entre ésta y el material que la contiene. Lo que es indudable es que en este fenómeno deben contemplarse una serie de factores y parámetros tales como la alterabilidad de los materiales ante el disolvente universal, las condiciones climáticas, la geoquímica de las aguas de recarga, los tiempos de contacto, la sinuosidad del camino recorrido, los procesos biológicos que se han llevado a cabo en su transcurso, los parámetros hidrogeológicos tales como la Transmisividad, Permeabilidad, Coeficiente de Almacenamiento, etc.

Ejemplos de la anarquía de patrones hidrogeológicos e hidroquímicos que pre-senta el Arsénico en nuestro medio, tanto en lo que respecta a su distribución areal como vertical, se verifican en casos en que en un mismo sector se pueden localizar valores de 0,05 mg L-1 en la parte superior del acuífero y 0,30 mg L-1 en profundidad o exactamente el fenómeno a la inversa. Asimismo, también es importante determinar en que estado de valencia se encuentra, si como arsénico tetravalente o pentavalente, ya que de ello depende en gran parte su nocividad o toxicidad que afecta a la salud humana.

Si bien, la presencia del agua subterránea y las posibilidades de su aprovechamiento se encuentran condicionadas principalmente por tres factores naturales: a) Clima, b) Geología (litología y tectónica) y c) Geo-

morfología, la compleja génesis y presencia del Arsénico en dichas aguas, constituye una incógnita desde el punto de vista hidrogeo-químico y puede deberse, según a algunos estudios realizados, a tres factores preponde-rantes como lo son: los litológicos, hidráulicos y químicos.

Lamentablemente, existe un profundo desco-nocimiento de esta problemática por parte de la población en general, incluyendo a los orga-nismos vinculados a la salud que no registran estadísticas de patologías vinculadas al tema ni han encarado esta cuestión en el sentido de fomentar y desarrollar investigaciones científi-cas que tiendan a morigerar y determinar feha-cientemente el origen y comportamiento de este elemento en las aguas subterráneas.

89. Adsorption-desorption kinetics of As(V) in soils: Multireaction modeling

H. M. Selim and Hua Zhang

Department of Agronomy & Environmental Management, Louisiana State University, Ba-

ton Rouge, Louisiana 70803, USA; mselim@agctr.lsu.edu

Knowledge of adsorption and desorption of arsenic (As) on soil mineral surfaces is a pre-requisite for predicting its fate in the soil en-vironment. Kinetic data have the advantage of taking into account possible time-dependent reactions for adsorption, release, or desorp-tion. Nonequilibrium conditions may be due to heterogeneity of sorption sites and slow diffusion to sites within the soil matrix, i.e. slowly accessible sites with variable degrees of affinities to heavy metals. The focus of this investigation was (i) to quantify the kinetics of adsorption and desorption of As in two different soils: Sharkey clay and Olivier silt loam; and (ii) to present multi-reaction kinetic type models of the nonlinear type and assess their capability of describing the sorption as well as release or desorption behavior of As in soils.

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Recent approaches based on soil heterogeneity and kinetics of adsorption-desorption have been proposed for the purpose of describing the time-dependent sorption of heavy metals in the soil environment. The multireaction (MRM) kinetic approach presented here considers several interactions of heavy metals with soil matrix surfaces. Specifically, the model assumes that a fraction of the total sorption sites is kinetic whereas the remaining fractions interact rapidly with solute in the soil solution. The model accounts for reversible as well as irreversible sorption of the concurrent and consecutive type.

Batch kinetic experiments were carried to determine adsorption and desorption iso-therms for As (V) by our three surface soils having different properties; Sharkey clay and Olivier silt loam, and Windsor sand. The technique used here is kinetic batch type. Six initial As(V) concentrations (5, 10, 20, 40, 80, and 100 mg L-1) of KH2AsO4 prepared in 0.01M KNO3 back-ground solution were used. The reaction times of adsorption ranged from 2 to 504 h. Desorption commenced immediately after the last adsorption time step (504 h) using successive dilutions for 12 days. The amount of As(V) retained by the soil fol-lowing the last desorption step was deter-mined using sequential extraction methods.

Our Results indicated that adsorption of As(V) were highly nonlinear with a Freundlich reaction order N much less than 1 for all soils. Adsorption of arsenate was strongly kinetic, where the rate of As(V) retention was rapid initially and was fol-lowed by gradual or somewhat slow reten-tion behaviour with increasing reaction time. Freundlich distribution coefficients and Langmuir adsorption maxima exhibited continued increase with reaction time for all soils. Desorption of As(V) from all soils were hysteretic in nature which are indica-tions of lack of equilibrium retention and/or irreversible or slowly reversible processes. A sequential extraction procedure provided

evidence that a significant amount of As(V) was irreversibly adsorbed on all soils. More-over, the multi-reaction model with equilib-rium and kinetic sorption successfully de-scribed the adsorption kinetics of As(V) to Olivier loam and Windsor sand. This model with optimized parameters was found to be capable of predicting the desorption of As(V) from these two soils. However, for Sharkey clay, with high adsorption affinity, an additional irreversible reaction phase was required to predict the desorption processes.

90. Community arsenic removal system using ADI media G2

Kiron Senapati

ANANT Technologies Inc., Tampa, Florida, USA; KSenapati@att.net

Several treatment technologies to remove arsenic are available for use, of which “Ad-sorption” has been found to be the most cost effective and easy to implement. ADI Inter-national, Inc., of Canada www.adi.ca / Wa-ter/water.html has developed an arsenic re-moval media called “MEDIA G2” that per-forms with significant advantages over other adsorbent media, and has been determined to be one of the most cost effective technolo-gies from field studies. MEDIA G2 is a highly porous media with an extremely large surface area to volume ratio. The technology proposed allows for the concurrent treatment of multiple contaminants, rendering it more efficient and cost-effective compared to con-ventional treatment methods.

The combined benefits of these attributes will be reflected in lower life-cycle treatment costs combined with removal of other ele-ments of concern that are not targeted for treatment. As such, this technology presents a tremendous opportunity to apply proven technology in Latin America. The objective is to offer affordable arsenic water treatment systems to provide arsenic safe drinking water in remote areas. The need is especially urgent for rural communities, which consti-

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tute 97% of the people affected by arsenic contamination.

For a technology to be effective in arsenic removal, it must be simple, economical, easy to apply, requiring minimal operation and maintenance. The MEDIA G2 selec-tively removes arsenic and is unaffected by common interfering such as fluorides, chlo-rides, sulfates, and iron which are usually found in drinking water. Arsenic removal by adsorption is a simple process, which usually does not require addition of any chemicals during the treatment. Arsenic is removed from water via a combination of adsorption, occlusion (adhesion) or solid-solution formation by reaction with ferric oxide ions. The MEDIA G2 technol-ogy is a novel iron oxide-based media with high surface area and enhanced selectivity for arsenic compared to conventional ad-sorbents. It is ideal for groundwater treat-ment given its physical and chemical prop-erties such as stability, porosity, and high surface area.

The paper proposes to present the results of the study undertaken in India and Bangla-desh and describe the ADI Media G2 arse-nic removal technology and process as applied to small community treatment sys-tems. The paper will also provide capital and operating costs for implementing such treatment systems.

91. Arsenic in groundwater and sedi-ments from La Pampa, Argentina

P L Smedley, H B Nicolli and D G Kinniburgh 1British Geological Survey, Wallingford, Ox-

fordshire, OX10 8BB, United Kingdom; p.smedley@bgs.ac.uk

2Instituto de Geoquı´mica, Av. Mitre 3100, 1663 San Miguel, Provincia de Buenos Aires,

Argentina

Groundwater from the Quaternary loess aquifer of northern La Pampa has spatially variable but often high concentrations of As. Pumped groundwater samples from

boreholes and wells in the region have an observed range of <4–5300 µg L–1. The dis-solved As correlates positively with several other trace elements which also reach unusu-ally high concentrations: V concentrations reach up to 5.4 mg L–1, F up to 29 mg L–1, B up to 14 mg L–1, Mo up to 990 µg L–1 and U up to 250 µg L–1. The groundwater is univer-sally oxic with a neutral to alkaline pH (7.0–8.7) and the dissolved As is present pre-dominantly as As(V). Some of the highest As and associated trace-element concentra-tions are found in topographic depressions which are likely to be zones of groundwater discharge and increased residence time.

Extracted porewater from a cored borehole in one investigated topographic depression (Tamagnoni borehole) had concentrations of As up to 7500 µg L–1. The mineral sources of the As in the groundwater are difficult to identify unequivocally. The aquifer sedi-ments have unexceptional concentrations of As (3–18 mg kg–1), although porewater As concentrations correlate broadly with host sediment As concentrations. Data for selec-tive sediment extracts suggest that secondary iron and manganese oxides are likely to be among the most significant minerals in-volved in the cycling of As.

As the groundwater is oxic, As release from the metal oxides is concluded to be through desorption rather than dissolution reactions. Oxalate-extract data have been used to esti-mate the amount of labile As in the sedi-ments. From an observed linear correlation between oxalate-extractable As and dis-solved As in the cored Tamagnoni borehole, a partition coefficient, Kd, was estimated as 0.94 L kg–1. This unusually low value dem-onstrates the low affinity of the Pampean sediments for As sorption. Modelling of As sorption to hydrous ferric oxide (HFO) sug-gests that competition from other anions can have a significant effect on the amounts of sorbed As, with the biggest effect being from vanadate at the concentrations of solutes observed. Although HFO is probably not the dominant Fe(III) oxide present in the Pam-

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pean aquifer, it serves as a useful indicator of the likely reactions involved in As re-lease to groundwater in the region.

92. Using GIS to define As-anomalous catchment basins considering drainage

sinuosity Ardemirio Silva

State University Of Feira De Santana, Salvador, Bahia, 41940-250, Brazil;

barros@ige.unicamp.br, abarros@uefs.br

Arsenic values in stream sediments of anomalous catchment basins are a function of several geological factors, including average composition of underlying rocks, geochemical controls, such as dispersion processes and scavenging of metal ions by oxides. The influence of all these factors, in turn, is a reflection of sorting of minerals in drainages during sediments accumulation. Drainages with lower gradients and more sinuous paths, are more likely to yield higher As levels, as these factors restrict dispersion. In the study area, 121 As bear-ing basins (above the detection limit of 4 ppb in the <177 µm sieve fraction), out of 385 sampled basins situated entirely in a Archaean volcanic-sedimentary sequences, the Itapicuru Greenstone belt (Bahia State, northeastern Brazil), were modelled in a Geographic Information System (GIS) with respect to total lenghts of drainage and distances from uppermost to lowermost points. Firstly, it was calculated the pres-ence or absence of ouliers, secondly, it was calculated statistical parameters such as, mean, standard deviation, median and mode. To define the behaviour of the data a Kolmogorov-Smirnov test was carried out.

The sinuosity indexes were calculated by dividing total stream lenght by the distance between uppermost and lowermost points. The results were reclassified into three ranges for sinuosity (low, medium and high). To each of those range empirical val-ues of 1, 1.5 and 2 were assigned. As values

for each basin were weighted by classes of sinuosity and reclassified, resulting in a modi-fied As anomaly map. The basins were auto-matically extracted from a Digital Elevation Model (DEM). Some basins otherwise not considered first priority were thus empha-sized, while others which were originally considered anomalous were de-emphasized. Thus, the resulting As anomalous map re-flects more accurately the factors afecting the dispersion of As and filter out the cofounding effects of physical dispersion and accumula-tion of As in stream sediments sampled as part of a exploration program. Basins selected using sinuosity-weighted As anomalies corre-late well with those selected by pathfinder associations, and the two approaches are con-sidered complementary.

93. Determination of arsenic in river sediments from geographical basins in the

state of Minas Gerais, Brazil, using GF-atomic absorption spectrometry

Julio C. J. Silva (PQ), Sandro H. D. Freitas (IC), Olivia V. M. S. Vasconcelos1 (PQ), Virginia S.

T. Ciminelli1 (PQ)

Institutos do Milênio: Água-uma visão mineral, CNPq, CAPES; Department of Metallurgical Engineering and Materials, UFMG, Brazil;

silvajcj@yahoo.com.br

Environmental pollution is a problem of fundamental importance in relation to aquatic life and its quality. This problem is especially critical in the Ferrous Quadrilat-eral in the state of Minas Gerais, one of the most important mining areas in Brazil, which has suffered the effects of predatory mining activities since the XVII century. Among the many chemical pollutants, arsenic is consid-ered to be one of the most concerning, its high toxicity places at risk both the environ-ment and human health. Work has then been carried out to develop a method for the de-termination of arsenic in samples of river sediments by means of graphite furnace atomic absorption spectrometry (GFAAS). The samples of interest were collected from

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five geographical basins in the State of Minas Gerais, Brazil. The samples (ap-proximately 100 mg) were digested in a microwave oven with cavity and closed vessels using an acid mixture (HNO3 + HF + H3BO3). In the experiments graphite py-rolytically covered tubes were used, and integration of signals and chemical modifi-ers (0.015 mg Pd + 0.01 mg Mg(NO3)2). The total volume (sample + diluent + modi-fier) delivery in the graphite tube was 50 µL, the pyrolysis temperatures and atomi-zation was 1400 and 2500°C, respectively. The accuracy of the procedure was evalu-ated with certified reference material (NIST 2780 - Hard Rock Mines Waste and NIST 2780 - Inorganics in Marine Sediment) and recovery and addition tests. The quantifica-tion was conducted using the analyte addi-tion method. Preliminary results for arsenic (λ = 196 nm) showed recoveries around 100% for the certified samples. To compare the obtained values and the certified values two statistical tests were used, the F test and T test matched, and the values obtained were not significantly different within the evaluated interval (P = 0.05). The arsenic concentration obtained in one of the sedi-ment samples (SF 017) was 11.4 mg L-1. Additional studies are being conducted and will be extended to the samples of interest.

94. Causas sociales de la patalogía del hidroarsenicismo en las localidades de Urutau y Benado Solo departamento

Copo – Provincia de Santiago del Estero, Argentina

Gladys N. Soria de Paredes

Programa de Prevención y Control de Hidroarsenicismo (H.A.C.R.E.) – Ministerio de

Salud y Desarrollo Social de la Provincia Santiago del Estero, Argentina, 4200 Santiago

del Estero, Argentina; gladysparedes@infovia.com.ar

El presente trabajo de Investigación apunta a poner de manifiesto que la escasa dispon-

ibilidad de Agua y las Causas Sociales emer-gentes del Medio Ambiente donde habitan los pobladores de Urutaú y Benado Solo, sigue siendo una de las grandes preocupaciones de los pobladores del Departamento Copo en la Provincia de Santiago del Estero – Argentina – desconociendo los mismos la importancia de la calidad para sus vidas.

De acuerdo a las visitas realizadas en la zona se ha podido comprobar la falta del elemento vital para consumo humano, ganado y cul-tivos condicionando los medios de sustento para esta población rural, poniendo énfasis en contaminación arsenical.

En estas zonas el hombre normalmente con-sumió el agua de represas, pozos perforados extraídos con baldes, molinos de viento, y bombas cuando cuenta con los elementos necesarios o bien ha construido aljibes, cali-cantos de diversos tamaños donde almacena agua de lluvias para consumo.

En estas diferentes formas de almacena-miento muchas veces no cuentan las condi-ciones sanitarias mínimas necesarias para ser usadas en el consumo humano, pero a pesar de esto u ante la necesidad los pobladores continúan consumiendo este tipo de agua, preparando sus alimentos y también usán-dola en la higiene personal.

Esta agua así obtenida satisface sus necesi-dades, una de las fuentes más utilizadas en la actualidad es el agua subterránea o sea de la napa freática con alta concertación de arsé-nico. Ante esta realidad surgió un interrogante ¿desde que época los pobladores de la zona ponen en riesgo su vida al consumir agua contaminada?.

Indagadas estas instancias, las respuestas obtenidas son paralizantes a tal punto que paso a ser un problema social, político y sanitario en la provincia.

En la actualidad se han detectado casos en la población con afecciones contraídas en el medio ambiente donde habitan, enfermedad crónica y agudas, de fácil diagnostico, ob-servables ha simple vista se pueden observar

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las manifestaciones dermatológicas propio de la ingesta de agua arsenicales.

Este trabajo de investigación pretende entre sus objetivos ser un aporte desde la Investi-gación Social en la relación hombre-medio y de que manera influye en estas pobla-ciones rurales el marco histórico, geográfico y cultural, como así también el nivel socio económico y de que manera son validas las alternativas de solución para logra erradicar definitivamente este flagelo que viene condicionando sus vidas desde muchas décadas.

95. Lymphocyte subpopulations and cytokine secretion in an infant popula-

tion exposed to arsenic Soto-Peña GA, Luna AL, Acosta-Saavedra L,

Conde P, López-Carrillo L2, Cebrián ME, Bastida M3, Calderón-Aranda ES, Vega L*.

*Sección Externa de Toxicología, Centro de Investigación y de Estudios Avanzados del IPN. Av. IPN 2508, San Pedro Zacatenco, Mexico D.

F. 07360, Mexico; lvega@cinvestav.mx 2Instituto Nacional de Salud Pública, Cuer-

navaca, Morelos, Mexico. 3Jurisdicción Sanitaria 5, Secretaría de Salubri-dad y Asistencia, Zimapán, Hidalgo, Mexico

In animal models and human cells in vitro, arsenic has shown to modulate some tran-scription factors, cytokine secretion, cell proliferation, and hypersensitivity response, among other cellular and systemic activities that confers arsenic it’s immunotoxic ability. To date, no studies have been conducted with the aim of immunotoxic effects on human, neither on infant populations (that could be more susceptible to arsenic effects). We evaluated some parameters within the immunological status in an infant population in Mexico exposed to arsenic via drinking water.

Peripheral blood mononuclear cells (PBMC) of 66 infants (6 to 10 years old) from an arsenic exposed area were col-lected. Proportion of lymphocyte subpopu-

lations, their mitogenic proliferative re-sponse, and activation capacity were evalu-ated and related with the arsenic levels found in urine. In this study we included children with no clinical history of cancer develop-ment or immune related diseases, children participating in this study were not taken any drugs for at least three weeks before sam-pling and a questionnaire including exposure history, exposure to heavy metals and pesti-cides, socioeconomic status and clinical history was answered by their legal guardi-ans.

Urine samples were collected and kept fro-zen until arsenic concentration was evalu-ated by hydride generation atomic absorp-tion spectrophotometry (iAs, MMA and DMA). Heparinized blood samples were collected and mononuclear cells subpopula-tions were evaluated in whole blood sam-ples, mitogenic response and cytokine secre-tion were evaluated on isolated cultured cells after 24 or 48 h of culture. Also hemoglobin and lead levels were evaluated.

In this infant population we observed a reduc-tion in the proportion of helper T cells (CD4) subpopulation (β = -0.0039, p = 0.097), and in the CD4/CD8 ratio (β = -0.0032, p = 0.090) that was related with arsenic levels in urine. The proportion of cytotoxic T cells (CD8), B cells and Natural killer cells was not modified by arsenic exposure. In isolated lymphocytes we observed a reduction in the proliferative response to PHA-stimulation (β = -0.0016, p = 0.010), and in the IL-2 secre-tion (β = -0.018, p = 0.001) related with an increased in urine arsenic levels. Meanwhile IL-4, IL-10, or IFN-γ secretion was not modi-fied by arsenic exposure. Additionally, we observed an increment in GM-CSF secretion on LPS/IFN-γ activated mononucleated cells associated with increasing arsenic levels in urine (β = -0.0099, p = 0.000). Gender, age, socioeconomic status, or other co-variables evaluated in this study did not modified the relationship of the immune response parame-

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ters evaluated with the arsenic levels found in urine of exposed individuals.

These data indicate that arsenic exposure could alter the activation processes of T cells and macrophages, representing an immunodeppressed status that could favor opportunistic infections and cancer devel-opment in human populations exposed to arsenic. In addition, several reports of in vivo genotoxic effects of arsenic exposure in Mexican human populations had indi-cated a gender differential effect of arsenic exposure. Some in vitro studies of arsenic effects on immune response parameters had also indicated that this susceptibility is related with helper T cells in adult women.

96. Mineralogical study of arsenic-enriched aquifer sediments at Santiago

del Estero, northwest Argentina O. Sracek1*, M. Novák1, P. Sulovský1, R. Mar-

tin2, J. Bundschuh2, P. Bhattacharya3

1Institute of Geological Sciences, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic; srondra@yahoo.com

2Facultad de Ciencias Exactas y Tecnologias, Universidad Nacional de Santiago del Estero

(UNSE), Av. Belgrano 1912, 4200 Santiago del Estero, Argentina

3KTH-International Groundwater Arsenic Re-search Group, Department of Land and Water Resources Engineering, Kungliga Tekniska Högskolan, SE-100 44 Stockholm, Sweden

Shallow aquifer located in an alluvial fan at Santiago del Estero, northwest Argentina, is enriched in arsenic. Sediments from sites with high As concentration were collected by hand auger and studied by X-ray diffrac-tion and by electron microprobe. X-ray diffraction confirmed the presence of quartz and albite. Concentrations of total organic carbon (TOC) in soil are low, but concentration of total inorganic carbon (TIC) may be significant.

The electron microprobe investigation found abundant glass particles with fluidal

structure. The grains show significant weathering (voids, dissolution pits etc.). Biotite grains present in sediments are also weathered. Iron oxyhydroxides occur in isolated spots on the surface of silicate min-erals, but not as continuous coatings. Heavy minerals were represented by altered ilmen-ite, monazite, zircon, and garnet with pre-dominant almandine component.

The primary source of arsenic could not be determined unequivocally, but volcanic glass, and biotite are potential candidates. Ferric oxyhydroxides, which are important adsorb-ents of arsenic, seem to have formed by pre-cipitation of iron released from titano-magnetite, ilmenite, and biotite. However, the amount of precipitated ferric oxides and hy-droxides is limited and, furthermore, their arsenic adsorption capacity depends on fac-tors like pH and ionic strength of ground wa-ter and on concentrations of species compet-ing for adsorption sites.

97. Sorption and desorption behavior of arsenic in a soil

S. Tokunaga* and M.G. M. Alam

National Institute of Advanced Industrial Science & Technology; Central 5, Higashi, Tsukuba,

Ibaraki 305-8565 Japan; s.tokunaga@aist.go.jp

Arsenic carries a +III or +V valence in soil environments. Difference in the behavior of As(III) and As(V) in soils has not been well known. The authors studied sorption and desorption behavior of As(III) and As(V) in Kuroboku soil, one of the typical soils in Japan. Comparison was made between the behavior of As(III) and As(V).

A 0.25 g of soil was contacted with 25 mL of 1.60 mg L-1 As(III) or 14.9 mg L-1 As(V) solution for 16 h under N2 atmosphere. The As(III) sorption was less pH-dependent, only 75% of As(III) ion being removed in the pH range 8 to 10. On the other hand, the As(V) sorption was highly pH-dependent, almost 100% of As(V) ion being removed in the pH

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range 2 to 5 in spite of much higher initial As concentration. Little As(V) was sorbed in the pH range > 11. The sorption rates of As(III) and As(V) ion were measured at pH 8 and 4, respectively, under N2 atmosphere. The kinetic data were analyzed using zero-order, first-order, second-order, third-order, parabolic diffusion, two-constants rate, Elovich-type, and differential rate models.

The soil was artificially contaminated with As(III) or As(V) ion. The contents of As(III) and As(V) were 1,622 and 3,190 mg kg-1, respectively. The desorption rates of As(III) and As(V) ion were measured by controlling pH at 4, 7, and 9 under N2 at-mosphere. The desorption of As(III) reached equilibrium within 3 h. The de-sorption rate of As(III) increased in the order at pH 9 < pH 7 < pH 4. A significant amount of As(V) ion was detected in the leachate at pH 9, indicating oxidation of As(III) ion. Only several µg/L of As(V) desorbed from As(V)-contaminated soil at pH 4. The desorption rate of As(V) in-creased in the order at pH 4 < pH 7 < pH 9. The desorption of As(V) was still much less than that of As(III) at pH 7. At pH 9, the desorption of As(V) continuously in-creased even after 10 h.

98. Estudios de especiacion de arsenico en agua por fluorescencia de rayos X y

voltametría de redisolución catódica L. Valcárcel, J. Estévez, A. Montero, I. Pupo

CEADEN: Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear Calle 30 No

502, Playa, Ciudad de la Habana, Cuba; lino@ceaden.edu.cu

Se implementaron dos métodos para la determinación de las especies inorgánicas de arsénico en agua por Fluorescencia de Rayos X (FRXDE) y Voltametría de Re-disolución Catódica (VRC).

Durante el desarrollo del primer procedi-miento se estudiaron los rendimientos de la

precipitación de As (III) y As (V) con APDC, que posteriormente se determinaron por un método absoluto de capa fina de FRXDE. Se aplicaron además procesos de oxidación reducción para la determinación del contenido total del elemento.

Paralelamente se implementó un método polarográfico alternativo de análisis de las especies de arsénico, utilizando la variante de VRC. El As (III) se reduce a As (0) y se deposita en la gota de Hg en forma de un compuesto intermetálico de As-Cu-Hg. La señal medida corresponde a la reducción de As (0) a As (-3). La determinación del con-tenido total de arsénico inorgánico requirió de un paso previo de reducción de As (V) a As (III).

En el trabajo se reflejan los parámetros metrológicos de los métodos tales como Precisión, Límites de Detección e Incer-tidumbre. La exactitud se evalúa por com-paración de los resultados obtenidos por ambos procedimientos.

Estos métodos fueron aplicados en el análisis de las especies inorgánicas de este elemento en aguas naturales.

99. Transforming growth factor alpha concentration in exfoliated bladder

epithelial cells from Mexican population environmentally exposed to inorganic

arsenic Olga L. Valenzuela1, Gonzalo Garcia-Vargas2, Araceli Hernandez-Zavala1, Eliud A. García Montalvo1, Dori

R. Germolec3 and Luz M. Del Razo1 1Toxicology, Cinvestav-IPN, Mexico City

2Medicin, UJED, GP, Durango, México 3Environmental Immunology Laboratory,

NIEHS, NIH, RTP, NC, USA

Arsenic is a well established human carcino-gen and is associated with a variety of can-cers including those of skin, liver, kidney, lung and bladder. The activation of the pro-liferation cellular-induced growth factor has been linked to the biological effects of arse-

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nic. Recently has been demonstrating that overexpression of growth factors, such as transforming growth factor alpha (TGF-α), promote the formation of skin tumors. TGF-α is secreted by epithelial cells in a variety of normal tissues (including skin, pituitary and brain) and function as a paracrine mediator of epithelial cell prolif-eration. The urinary concentration of TGF-α has often been used as a marker of vari-ous malignancies (e.g., liver, lung, bladder, and skin cancer) or as an indicator of an elevated risk of cancer in humans. In addi-tion, increased TGF-α production has pre-viously been reported in normal human keratinocytes treated with arsenite and in the skin of mice exposed to arsenite in drinking water.

This study examines the relationship be-tween urinary profiles of arsenic and TGF-α concentrations in exfoliated bladder epithelial cells among 90 residents (18-51-year-old) in both high and low inorganic arsenic-exposed subjects of an endemic region of central Mexico.

Previous studies carried out in the local populations have found an increased inci-dence of pathologies, primarily skin lesions that are characteristic of arseniasis. Addi-tionally in this study, we compared the pattern of urinary methylated metabolites between persons with and without skin lesions associated to arseniasis in an en-demic Mexican area.

Urinary arsenic species and total arsenic (TAs) were measured by hydride genera-tion atomic absorption spectrometry method. The concentration of TGF-α in urothelial cells was measured by using an enzyme-linked immunoabsorbent assay. The participants on this study are from areas exposed to different concentrations of arsenic in drinking water (6 – 378 µg L-1). Preliminar results in 75 individuals show a statistically significant positive correlation between the log-normalized TGF-α concen-tration in exfoliated cells and the TAs con-

centration in urine (R = 0.44, P < 0.001). However, this association is higher between TGFα levels and DMA in urine (R = 0.47, P < 0.001). Besides, people exposed to high concentration of arsenic (mean 114 µgAs/g creatinine) was significantly (P < 0.05) greater in TGF α levels than individuals with lower arsenic exposure (mean 26.6 µg As g-1 creatinine). People from areas with high arsenic concentration had a significantly higher TGF α concentrations in urothelial cells than people of areas with low arsenic exposure (P<0.05). In addition, the average TGF-α concentration was significantly higher in exposed individuals as compared to unexposed controls: 67.5 vs. 34.6 pg mg-1 protein (p = 0.020). Notably, exfoliated cells isolated from exposed individuals with skin lesions contained significantly greater amount of TGF-α than cells from exposed individuals without skin lesions: 84.5 vs. 39.1 pg mg-1 protein (p = 0.017). These re-sults indicate that in arsenic-endemic areas, the concentration of TGF-α in exfoliated bladder epithelial cells may serve as a marker of the exposure to inorganic arsenic in drinking water and as an indicator of ad-verse epidermal health effects associated with this exposure.

100. Arsenic mobility in the rhizosphere of the tolerant plant Viguiera dentata

G. Vázquez-Rodríguez, M.G. Monroy-Fernández, R. Briones-Gallardo*

Facultad de Ingeniería-Instituto de Metalurgia, Universidad Autónoma de San Luis Potosí. Av. Sierra Leona 550, Col. Lomas 2ª. Sección. San

Luis Potosí, S. L. P. México; *briones@uaslp.mx

The arsenic (As) mobility or retention in soils as a result of mining activity is directly related to the chemical equilibria between the existing phases (soluble, mineral or bio-logical). In polluted sites, the exposure of plants to arsenic is determined by these equi-libria at the rhizosphere. In this work, arsenic mobilization in the rhizospheric soil (RS) of

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a tolerant plant taxonomically identified, as Viguiera dentate was studied. The plant was collected in the mining district of Villa de la Paz Matehuala- SLP, Mexico. In this site, a total arsenic concentration in rhizospheric soils 3867 µg g-1

RS was found. The analysis of the total arsenic concentra-tion on dry total biomass (DB) of this plant was 94.8 µg As g-1

DB, distributed as 82%, 12% and 6% in leaves, stem and root, re-spectively. This distribution was further studied as available and bioavailable arse-nic fractions for physicochemical and bio-logical mobilization, respectively.

The physicochemical mobilization in the rhizospheric soil was analyzed by two dif-ferent tests of successive sequential extrac-tion (ESS). The results have shown that the available fraction by ionic exchange was 40 µg As g-1

SR while 72 µg As g-1SR were asso-

ciated to carbonates phases. These last sus-ceptible of being mobilized by acidification of soil at a pH value of 5. Also, 687 µg As g-1

SR were adsorbed on iron and manganese oxides. A modified ESS protocol was used in order to favor chemical availability of arsenic for anionic exchange with a soluble phosphate salt. It was observed that the available arsenic concentration, under such conditions, corresponds to 83.4% of the arsenic associated to iron and manganese oxides which might suggests that arsenic is in the form of arsenates. Finally, arsenic bioavailability in the rhizosphere was de-termined using a synthetic solution that resembled the organic acid solution found in plants at a pH value of 4.7. The available arsenic concentration at the interface of the biological surface exposed in the rhizosphere of Viguiera dentata is 147 µg As g-1

SR.

The results of this work show that not all arsenic in soils is available, nevertheless it was found that the arsenic accumulation observed in the plants studied, could be the result of a progressive exposure of low arsenic concentration of the plant that ex-plains its tolerance.

101. Determinación del contenido de arsénico en productos marinos entregados por el Programa de Alimentación Escolar

(PAE), de la Junta Nacional Escolar y Becas (JUNAEB), Vii región, Chile

S. Vilches1, G. Andrade1, O. Muñoz2, J.M. Bastías1 1Departamento de Ingeniería en Alimentos,

Universidad del Bío-Bío, Casilla 447, Chillán, Chile; jobastias@ubiobio.cl

2Centro de Estudios en Ciencia y Tecnología de Alimentos, Universidad de Santiago de Chile,

Casilla 33074, Correo 33 Santiago, Chile; omunoz@lauca.usach.cl

El objetivo del presente estudio fue determi-nar el contenido de arsénico total e inor-gánico en productos marinos entregados por el Programa de Alimentación Escolar (PAE), de la Junta Nacional de Auxilio Escolar y Becas (JUNAEB), VII región, Chile. La determinación de arsénico total e inorgánico se realizo sobre 35 muestras (24 filetes de merluza, 5 pulpas de salmón, 5 Jurel en con-serva y 1 surtido de marisco deshidratado), obtenidas de las empresas concesionarias que atienden el PAE de la VII región. La determinación de Arsénico total se realizó por digestión por vía seca. En el caso del arsénico inorgánico, se utilizó un procedi-miento de extracción por solventes, obteni-endo en todos los casos resultados repro-ducibles y representativos.Para la determi-nación analítica se utilizó un Espectro-fotómetro de Absorción Atómica (AAS) Varian A 55 acoplado a generación de hidruros.

La concentración mínima Arsénico total encontrados en los productos marinos fue de 0.379 µg g-1 base húmeda (bh) y la máxima de 1.404 µg g-1 (b.h.), sobrepasando seis muestras el límite establecido por el Regla-mento Sanitario de los Alimentos de Chile (RSA), para pescados (1 µg g-1). La concen-tración mínima de Arsénico inorgánico ob-tenido fue de 0.012 µg g-1 (bh) y la máxima de 1.130 µg g-1 (bh), no sobrepasando nin-guna muestra el límite establecido por el RSA, ya que sólo establece arsénico inor-

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gánico para mariscos y crustáceos (2 µg g-

1), siendo la muestra con mayor concen-tración la de surtido de mariscos de-shidratados.

El Análisis de ANOVA por especie, pro-ducto y proceso de los contenidos de Arsé-nico total e inorgánico en las muestras analizadas, arrojan que la especie influye en forma significativa en las concentra-ciones obtenidas y en menor grado el tipo de producto, pero los procesos en sí no afectan de manera significativa tales con-centraciones.

102. Natural red earth – an effective sor-bent for arsenic removal

Meththika Vithanage1, Rohana Chandrajith2, Athula Bandara3 and Rohan Weerasooriya1

1Chemical Modeling Laboratory, Institute of Fundamental Studies, Kandy, Sri Lanka;

meththikav@yahoo.com 2Department of Geology, University of

Peradeniya, Peradeniya, Sri Lanka 3Department of Chemistry, University of

Peradeniya, Peradeniya, Sri Lanka

Arsenic is present mainly in water as a natural contaminant mainly in the form of arsenate and arsenite. The natural release of arsenic species into groundwater results in detrimental health effects. Arsenic toxicity leads to a host of problems including skin cancers, Bladder and lung cancers, tumors, keratosis and hyperpigmentation. Therefore attention is focused to determine dominant adsorptive minerals to characterize them systematically for better prediction of arse-nic removal from natural systems. This study was focused on modeling the adsorp-tion of arsenite and arsenate on to natural red earth (here after NRE) found in Sri Lanka.

X-Ray Diffraction (XRD), X-Ray Fluores-cence (XRF) and Scanning Electron Micro-scopic (SEM) analysis were performed to determine the characteristics of red earth. Potentiometric surface titrations of NRE,

were carried out by auto-titration system under inert environmental condition for three different ionic strengths. The retention of As species, both As3+ and As5+ ([As3+] = [As5+] = 0.385 µmol/L =50 µg L-1 of As3+) were examined as a function of pH and ionic strength in single- (As3+ or As5+ only) and dual-sorbate (As+3 and As+5) systems using AAS. Fourier Transform Infra Red (FTIR) studies were performed to study the mecha-nisms of surface complex formation. Ex-perimental results were modeled using dif-fuse layer model.

NRE is found to be dominated with SiO2 (54.15%), Al2O3 (20.73%), Fe2O3 (12.39%) and TiO2 (5.54%). No peaks were obtained for Al and Fe or other constituents from XRD indicating that Al and Fe are in the surface coating, not in the crystal structure. Proton titration data of red earth showed that pHzpc = 8.8, which was fitted well with the modeling, denoting the red earth surface is dominantly positive when pH < pHzpc. Both As3+ and As5+ were adsorbed over 95% on to red earth when initial [As3+] = [As5+] = 0.385 µmol/L in single sorbate systems. In the dual sorbate system, when both As3+ and As5+ are present; the retention of As3+ decreases by about 80% above pH > 7, however pH < 7 adsorption of both species were shown strong. Modeling results showed a competi-tion between arsenic species to the solid binding sites. However both experimental and modeled data showed that there is no dependency of arsenic species on pH or ionic strength in both single and dual sorbate systems, which indicates that the affinity of arsenic species on to NRE is strong forming inner sphere complexes with the NRE sur-face. From the FTIR studies it was suggested that arsenite form monodentate complexes while arsenate form bidentate complexes with NRE surface. As determined by the simple diffuse layer model the binding con-stants were very well fitted with experimen-tal data, proving that red earth can be effec-tively used to remove arsenic from aqueous

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systems by modifying the available filter-ing systems.

103. Natural arsenic in groundwater: a case study from central Italy

R. Vivona1, E. Preziosi1, G. Giuliano1, B. Madé2

1Water Research Institute, IRSA-CNR, 1, Via Reno – 00198, Rome, Italy

2Ecole des Mines de Paris, CIG, 35, rue St Honoré – 77305, Fontainebleau, France

The widespread presence of high concen-trations of natural micro-pollutants is well known in the volcanic aquifers of central Italy where groundwater are largely ex-ploited for agricultural and drinking pur-poses. Their presence is related to the alka-line-potassic volcanism which developed along the Tyrrhenian margin of the Italian peninsula in the Quaternary age.

The aim of this research was to characterize the groundwater system and the geochemi-cal processes by means of an integrated methodology including field activity (col-lection of groundwater samples from wells, springs and rivers), chemical analysis in laboratory, geochemical modelling to study the thermodynamic state of the waters, minor elements origin and their enrichment in the solution in a pilot area about 100 km2 north of Rome.

The interest was pointed out on F and As, the latter being a cancerogenic element which is often above the threshold value for drinking waters (10 µg L-1 fixed by the European Council Directive 98/83/EC) in several Italian aquifers. The study of minor elements allowed us to better understand the hydrogeological setting of the area and to define a local hydrogeological scheme; moreover the analysis of the hydrofacies and the elements contents was useful to shed light on the origin and the processes leading to high concentrations of minor elements, their evolution along the groundwater pathway and possible mecha-

nisms of their natural removal from solution, giving at the same time new insights on the quality of groundwater of the study area.

The integration of a quantitative study (dis-charge measurements along the main streams, piezometric levels in the wells, elaboration of the water table map) with a qualitative analysis (characterization of the hydrofacies and study of the spatial distribu-tion of elements concentration) was a helpful tool to point out the differences in the water-rock interaction along groundwater flow and to understand the concentration variations (in particular of As, F and Ca) observed from the highest sector of the region down-stream along the main flow direction. Two hypothesis were made about the possible geochemical processes responsible of the hydrochemistry observed in the sampled waters: the good correlation between As an F and their decrease with Ca augmentation downstream was related in the first hypothe-sis to the precipitation of As-F-bearing min-erals (fluorapatite); in the second hypothesis a dilution due to mixing processes between waters of different origin and different com-position (volcanic aquifer + sedimentary aquifer) was considered.

104. Infield detection of arsenic using a portable digital voltameter

Magdalena Wajrak

School of Natural Sciences, Edith Cowan Uni-versity Joondalup Campus, JOONDALUP, WA,

6027; m.wajrak@ecu.edu.au

There are a growing number of countries in the world where arsenic in groundwater has been detected at concentrations greater than the WHO Guideline Value of 10 µg L-1. These include; Argentina, Bangladesh, Chile, China, Hungary, India, Mexico, Peru, Thai-land, and the USA. More recently this issue has also become a concern in Western Aus-tralia. A decline in the watertable due to a low period of rainfall and the disturbance of sulfidic peat soils by dewatering and exca-

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vation in some of Perth’s suburbs has re-sulted in widespread acidification of groundwater and has caused the water to be contaminated by arsenic and other metals. Groundwater forms 70% of Perth’s water usage and people use the groundwater to water their vegetable gardens and thus ex-pose themselves to high levels (up to 800 µg L-1) of arsenic.

Of particular concern is the situation in Bangladesh where it is estimated that there are more than 1 million people drinking arsenic-rich water (>50 µg L-1). The con-sequences of arsenic poisoning have al-ready affected many thousands; skin dis-coloration, ulcers and cancer of the skin, lungs and intestines. It is imperative that people stop drinking from wells where arsenic levels are high. However, as yet, there is no reliable, simple, inexpensive and field-based method for arsenic detec-tion.

The current methods of arsenic detection use sophisticated and expensive laboratory based instruments, such as Atomic Absorp-tion Spectroscopy - hydride generation (AAS-HG) and Inductively Coupled Plasma – Mass Spectrometry (ICP-MS)4. With over 6 million wells spread across Bangladesh, using such methods is not only highly expensive, but also time-consuming. What is needed is a method which can be used in-field, is relatively easy to imple-ment, accurate and has a detection limit of 10 µg L-1.

This research involves the development of an infield method for arsenic detection in ground-water using anodic stripping volt-ammetry (ASV). The instrument used is a Portable Digital Voltammeter, PDV6000, designed by Monitoring Technologies In-ternational (MTI) company in Perth, WA. Using solid gold working electrode the instrument can detect down to 5 µg L-

1using arsenic standard solution in ethanoic acid electrolyte with a 5 minute deposition time. The results are reproducible and lin-

ear and speciation between the two stable forms of arsenic, As 3+ and As 5+ is possible. The method is now being validated using ‘real’ ground water samples from Perth sub-urbs by comparing the ASV results to ICP-MS. Initial results are promising, the volt-ammeter values are within +/- 3 µg L-1of the ICP-MS method. The next step in this pro-ject is to implement and validate this method for groundwater samples from Bangladesh (currently awaiting the arrival of those sam-ples).

105. Occurrence of hexafluoroarsenate in fluoride-rich waters – blessing or curse?

Dirk Wallschläger

Environmental & Resource Sciences Program, Trent University, 1600 West Bank Dr, Peterbor-

ough, ON K9J 7B8, Canada; DWallsch@TrentU.ca

The hexafluoroarsenate anion [AsF6]- is an extremely stable compound well known in inorganic chemistry, but to date, it has re-ceived little to no attention in environmental As speciation studies, despite the fact that it is used as a pesticide and in certain types of batteries. Synthetic literature also suggests that [AsF6]- may be formed from arsenate and dissolved fluoride or fluoride minerals.

The lack of studies on the occurrence of [AsF6]- in natural waters is mostly due to the lack of analytical methods for its determina-tion. In this paper, I present a method for the selective and sensitive determination of [AsF6]- in waters by anion-exchange chro-matography coupled to inductively-coupled plasma mass spectrometry (AEC-ICP-MS), and demonstrate that this compound occurs in certain types of waters.

Separation of [AsF6]- from all other known inorganic As species and methyl-As pesti-cides was accomplished by AEC using per-chlorate as the eluant under alkaline condi-tions. Detection limits around 5 ng L-1 As were achieved. The species mass balance (=

87

sum of all detected species vs. the inde-pendently determined total As concentra-tion) in real world samples was excellent (95-110%). I will discuss why other com-mon As speciation methods are unsuitable for waters where [AsF6]- occurs, which may explain why it hasn’t been detected in the environment before.

Hexafluoroarsenate was detected in process waters from an industrial fluorination proc-ess, where it constituted the vast majority (78-100%) of the total As concentration. It was not at all removed by iron hydroxide co-precipitation.

I will present further experiments on the formation and fate of [AsF6]-, and illustrate under what circumstances this species might be encountered in natural waters, with particular reference to ground waters that contain both elevated As and fluoride concentrations. I will also attempt to dis-cuss if the occurrence of [AsF6]- is positive or negative with respect to As toxicity and environmental cycling and fate, and what implications this may have for potential treatment strategies.

106. Interaction between arsenic oxyanions and iron-sulfide minerals

Prabhas Kr. Yadav, Dirk Wallschläger

1Environmental & Resource Studies Program, Trent University, 1600 West Bank Dr, Peter-

borough, ON K9J 7B8, Canada; prabhasyadav@trentu.ca

Arsenic (As) contaminations of groundwa-ter used for drinking water production is among the most severe environmental problems encountered in several parts of world. Studies have shown that As usually originates from geogenic sources, and is mobilized through geochemical changes caused directly or indirectly by human ac-tivities. However, factors of As release and mobilization in the groundwater are still under investigation.

Iron-sulfur (Fe-S) minerals have been recog-nized to play important parts in the overall fate of As in the reducing aquifers. Under-standing the interaction of As with Fe-S minerals is more important when deeper wells are sought as an alternative to the ex-isiting shallow contaminated wells.

In this study, we have investigated As exchange at the interface between water and Fe-S minerals under controlled laboratory conditions. From our experiments, we expect to outline the geochemical reactions affecting the mobilty of the As in these environments.

Batch experiments equilibrating synthetic Fe-S minerals (FeS2 and FeS) with As (ar-senite or arsenate) were performed in oxic, anoxic and sulfidic environment. In the first set of experiments, As oxyanions were equilibrated with Fe-S minerals, while with the second set, As was spiked to the dissolv-ing Fe-S minerals solution after they had partially dissolved for 1, 3 and 5 days. Sam-ples were collected daily for 5 days after spiking. Experimental environments were controlled by standard methods. Total As, Fe and S in the collected samples were analyzed by ICP-MS.

As reported previously, pronounced differences between the solubilities of different Fe-S minerals were observed. As for the corresponding Fe-O minerals, arsenate generally showed a higher affinity for the studied Fe-S mineral surfaces than arsenite, which often remained in solution to a significant extent. Also, FeS adsorbed both As species stronger than FeS2. The kinetics of these reactions will be described, and apparent equilibrium distribution coeffi-cients are determined.

Our results suggest that removal of As from the solution is severely by the constituents of the dissolving minerals (see figure below), likely due to the modification of the surface during the partial dissolution process and/or reactions between the released Fe and S species with the added As species. We also

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observed reddish-brown Fe-O precipitate on the Fe-S mineral surface after 2 days under oxic and anoxic conditions. We believe this new precipitate to be some Fe-O minerals.

Finally, we will combine the results obtained from batch experiment withs flow through experiments and derive result as a simple model which describes the changes in As speciation and mobility as it crosses from one set of geochemical conditions into another in order to simulate the effects of geochemical transition zones.

107. Arsenic exposure in rural population from Atacama Desert, Chile:

Characterization of arsenic species in water, urine, hair and nails

J. Yáñez, H. Mansilla & V. Fierro1, L. Cornejo & L. Figueroa2, and R.M. Barnes3

1Faculty of Chemical Sciences, University of Concepción, Concepción, Chile;

jyanez@udec.cl Department of Chemistry, Faculty of Sciences,

University of Tarapacá, Arica, Chile 2Centro de Investigaciones del Hombre en el

Desierto (CIHDE) 3University Research Institute for Analytical

Chemistry, URIAC, Amherst, MA, USA

Por primera vez se presenta a la comunidad científica un estudio integral de caracteri-zación de arsénico en aguas de consumo humano, su transformación en otras especies químicas y su eliminación en orina, cabello y uñas en una población altamente expuesta del norte de Chile (Illapata). Se determinó que el As(V) fue la especie más abundante en las aguas del río Camarones y vertientes asociadas, constitu-yendo la principal especie ingerida por la población. El río Camarones presentó concentraciones de hasta 1252 µg L-1 de arsénico total, siendo casi exclusivamente As(V). En la orina de la población expuesta, la distribución de las especies As(III), As(V), MMA y DMA fue de 5, 1, 6

y 87% respectivamente. Estos resultados indican que existe una alta capacidad de metilación de arsénico de los individuos de Illapata, en comparación con la población control y con datos de la literatura. El As(V) ingerido también fue transformado y depositado en cabello principalmente a la forma de As(III), que fue la especie más abundante encontrada, 57 y 85% en indivi-duos de la población control y expuesta (Esquiña e Illapata respectivamente). Se relacionó la concentración de arsénico total en cabello y uñas con la edad de los individuos expuestos crónicamente, encon-trándose una mejor correlación con cabello (0.64) en comparación con las uñas (0.44).

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Topic areas with abstract number

Remediation material and technology:

1 – 4 – 5 – 11 – 14 – 17 – 18 – 20 – 23 – 26 – 27 – 31 – 39 – 40 – 44 – 45 – 53 – 65 – 70 – 71 – 83 – 86 – 87 – 90 – 102

Arsenic (biogeo)chemistry and analysis:

10 – 16 – 22 – 24 – 32 – 39 – 45 – 50 – 87 – 89 – 93 – 97 – 98 – 100 – 104 – 105 – 106

Environmental management:

2 – 12 – 19 – 21 – 37 – 51 – 52 – 54 – 60 – 64 – 66 – 67 – 71 – 81 – 92 – 94 – 101 – 107

Geoenvironmental situation and processes:

3 – 7 – 8 – 9 – 21 – 24 – 30 – 33 – 37 – 38 – 42 – 43 – 47 – 48 – 49 – 52 – 54 – 56 – 57 – 59 – 62 – 63 – 64 – 67 – 68 – 69 – 71 – 74 –75 – 76 – 77 – 78 – 79 – 80 – 81 – 82 – 88 – 91 – 93 – 96 – 103 – 107

Public health issues and physiology:

13 – 15 – 25 – 28 – 29 – 34 – 35 – 36 – 41 – 46 – 47 – 54 – 55 – 58 – 61 – 63 – 72 – 73 – 82 – 84 – 85 – 94 – 95 – 99 – 101

International Society ofGroundwater for Sustainable Development

ResResúúmenes Cortosmenes Cortos

MMééxico, 20 al 24 de Junio de 2006xico, 20 al 24 de Junio de 2006EditoresEditores

CongresoCongreso

International Society ofGroundwater for Sustainable Development

Jochen BundschuhJochen Bundschuh(Germany/Argentina/Costa Rica)(Germany/Argentina/Costa Rica)

MarMaríía Aurora Armientaa Aurora Armienta(Mexico)(Mexico)

Peter BirklePeter Birkle(Mexico)(Mexico)

Ramiro RodrRamiro Rodrííguezguez(Mexico)(Mexico)

Prosun BhattacharyaProsun Bhattacharya(Sweden)(Sweden)

JJöörg Matschullatrg Matschullat(Germany)(Germany)