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Journal of Hydro-environment Research 5 (2011) 169e176www.elsevier.com/locate/jher

Research paper

Distribution of Pb, As, Cd, Sn and Hg in soil, sediment and surface waterof the tropical river watershed, Terengganu (Malaysia)

Khawar Sultan a,*, Noor Azhar Shazili b, Stefan Peiffer a

aDepartment of Hydrology, University of Bayreuth, 95440 Bayreuth, Bavaria, Germanyb Institute of Oceanography, University Malaysia Terengganu, Mengabang Telipot, 21030 Kuala Terengganu, Malaysia

Received 2 March 2009; revised 13 March 2011; accepted 14 March 2011

Abstract

Hydrogeochemistry and distribution of Pb, As, Cd, Sn and Hg in soils (n¼ 53), sediments (n¼ 42) and surface waters (n¼ 51) of the tropicalTerengganu River basin, northeast coast of Peninsular Malaysia, were investigated. The order of abundance of the elements in soils followedgranite>metasedimentary>Quaternary deposit[ volcanic with slight enrichment as compared to the upper continental crust. Both soils andsediments registered the order of concentration of Pb> Sn>As[Cd[Hg with an enrichment factor (EF)< 6 for sediments indicatingslight enrichment representing the regional background and less likely due to the anthropogenic activity related input. SEM analysis revealed thepresence of Malayaite (CaSnOSiO4) explaining elevated Sn concentration (up to w34 mg/kg; 3 times the upper continental crust) in soils. SoilPb distribution showed the geology as the primary control.

Dissolved concentrations of As showed an increasing and Cd decreasing with distance from upstream to downstream along the river flowpath. Lake surface waters registered 16 times higher Cd concentrations (averagew 14.21 mg/L) than the river waters, but lake sedimentsregistered lower Cd concentration than the river sediments (averagew 0.45 mg/kg) revealing Eh, pH and TDS control. Dissolved average Hgconcentration (w0.04 mg/L) was measured to be lower than the tropical river waters from the Central Africa river, but higher than the Mekongand the Amazon Rivers.� 2011 International Association of Hydro-environment Engineering and Research, Asia Pacific Division. Published by Elsevier B.V. All rightsreserved.

Keywords: Tropical; Soil; Sediments; Surface water; Metals; Background; Malaysia

1. Introduction

Environmental management of natural resources (i.e. water,soil, plant) in a world with ever increasing industrial activitiesand urbanization has been the focus of extensive research toprotect and preserve them for future generations across theglobe (Bode and Nusch, 1999; Beck, 2005; Jia et al., 2007).Both natural and anthropogenic factors can impact on theenvironment by producing polluting components which mayenter into the food chain and pose a threat to the ecosystems.However, input from anthropogenic related activities is much

* Corresponding author. Tel.:þ49 (0) 921 55 2170; fax:þ49 (0) 921 55 2366.

E-mail addresses: sultankha@gmail.com, sultan.khawar@uni-bayreuth.de

(K. Sultan).

1570-6443/$ - see front matter� 2011 International Association of Hydro-environment Engine

doi:10.1016/j.jher.2011.03.001

greater than natural ones especially in the world’s industrialregions. According to the Commission for the EuropeanCommunities (CEC, 1986), ATSDR (1989), ANZECC (1992)and USEPA (2000) many heavy metals have been identified ashaving adverse public health effects based on their toxicity.Among these metals, Pb, As, Cd and Hg are well known globalcontaminants and are listed as the most hazardous inorganiccontaminants on the EPA Hazardous Substance Priority Listdue to significant environmental and public health concerns(USEPA, 2000; WHO, 2006).

Equatorial/tropical climates with all year round warmtemperatures and high rainfall enhance both physical andchemical weathering of rocks. High energy conditions (i.e.wind, water discharge) favor the removal and transport ofsolutes and particulates from the source to the sea in a relatively

ering and Research, Asia Pacific Division. Published by Elsevier B.V. All rights reserved.

170 K. Sultan et al. / Journal of Hydro-environment Research 5 (2011) 169e176

shorter residence time as compared to the temperate climate. It istherefore important to study the concentration, distribution andmobility of potentially toxic elements in a tropical environmentwhere the health of fauna and flora may be at risk. Whilesignificant research has been carried out in watersheds oftemperate climates, comparatively little or no attention has beenpaid to the potentially toxic elemental background concentra-tions of the tropical watersheds in Asia.

The rapid development of the tropical east coast ofPeninsular Malaysia poses a threat to the food chain system bycontamination from the industrial/municipal effluent, agricul-tural runoff, land clearing and tourism based activities. Thus, itis vital to study the prevailing concentrations and geochem-istry of the potentially toxic elements to understand the nat-ural background/baseline levels to manage and monitor anychanges caused by anthropogenic activities in the future.Hence, this work is significant in documenting the geochem-istry and background concentrations of Pb, As, Cd, Sn and Hgin the soil, sediment and water of the Terengganu River basin,Malaysia.

2. Methods

2.1. Study area

The Terengganu River is located close to the equator (rivermouthw 500N) in the northeastern region of the PeninsularMalaysia and experiences a tropical physical regime duringthe peak monsoon season (dischargew 14.6� 109 m3 year�1;

Fig. 1. Map showing sampling locations

Fig. 1). The upper watershed encompasses Kenyir Lake ina relatively pristine environmental setting separated by a hydroelectric power dam from the lower watershed with an urban-ized and industrialized setting close to the river mouthdraining into the South China Sea. Geographically the Ter-engganu River watershed lies in wet tropics defined by hightemperature (>20 �C) and rainfall (w3300 mm y�1). TheTerengganu River provides major inputs of mass flux (i.e.water, solute, particulate, sediment, organic matter) to theSunda Shelf, South China Sea. This study presents the currentsituation for future reference the geochemical baselines of Pb,Sn, As, Cd and Hg in soils, sediments and surface waters ofthe Terengganu River basin.

This study investigated the concentration, distribution andhydrochemistry of Pb, Sn, As, Cd and Hg in soil, sediment andsurface water samples of the Terengganu River basin.

2.2. Field sampling

Surface water samples (n¼ 51) were collected in acid-washed polypropylene containers from the lake, river andestuary in the Terengganu River basin. Surface water sampleswere filtered through 0.45 mm cellulose acetate filters, acidi-fied to pH� 2 with ultrapure HNO3 for stabilization andstored at 4 �C until analysis. Surface sediment (n¼ 42) andtopsoil (0e10 cm depth, n¼ 53) samples were collected inclose proximity (<10 m circle) of surface water samplinglocations using a plastic scoop and stored in a clean plastic baguntil analysis The sampling locations are shown in Fig. 1 and

in the Terengganu River catchment.

Table 1

Detection limit, accuracy and precision for measured elements.

Elements Unit Detection limit Accuracy (%) Precision (%PRD)

Pb mg/kg 0.006 0.4 1.9

Sn mg/kg 0.004 2.1 3.6

As mg/kg 0.002 3.1 1.7

Cd mg/kg 0.001 0.8 2.2

Hg mg/kg 0.002 1.7 3.4

171K. Sultan et al. / Journal of Hydro-environment Research 5 (2011) 169e176

were chosen randomly along the river flow path keeping inview the geological units, various land uses and accessibility.The sampling locations were recorded using GPS for con-centration distribution map development in GIS software. Thesampling campaign was carried out in November and repre-sented the prevailing environmental conditions.

2.3. Analytical procedures

Sediment and soil samples were oven dried (<40 �C),passed through a 2 mm mesh sieve to remove coarser particlesand ground (Rayment and Higginson, 1992). About 0.1 g ofeach sample was digested in HNO3:HCl:HF (9:3:2, v/v) ina Teflon vessel and heated in a microwave oven at 150 �C for10 min. After cooling, 9 mL of 5% boric acid (B(OH)3) wasadded to remove the fluoride residue. A clear solution with noresidue was obtained at this stage. The acid digest thusobtained was filtered into a 50 mL volumetric flask andbrought to volume with double deionized water. Concentra-tions of elements were determined by inductively coupledplasma mass spectrometry (ICPeMS Perkin Elmer ELAN6100) at the Institute of Oceanography.

Standard solutions were prepared by serial dilution of thestock solution (1000 mg/L; Merck, Darmstadt, Germany) ofvarious concentrations. Both field and laboratory blanks,duplicates and certified reference materials (GBW-07401 andPACS-2) were included in every batch for QA/QC. Thedetection limit, accuracy and precision for the measuredelements are given in Table 1.

Table 2

Summary statistic of element concentration data of soils, sediments and surface w

Media Element Unit Minimum Maxim

Soil Pb mg/kg 0.110 73.96

Sn mg/kg 0.958 34.03

As mg/kg 0.246 14.54

Cd mg/kg 0.026 0.99

Hg mg/kg 0.011 0.25

Sediment Pb mg/kg 0.051 124.85

Sn mg/kg 0.747 29.23

As mg/kg 0.827 23.09

Cd mg/kg 0.347 0.52

Hg mg/kg 0.007 0.59

Water Pb mg/L 0.022 4.54

Sn mg/L 4.355 36.30

As mg/L 0.013 28.90

Cd mg/L 0.362 24.53

Hg mg/L 0.009 0.21

Soil samples were mounted on an aluminum stub with anadhesive tape and coated with gold for the scanning electronmicroscope (SEM, JEOL-JSM 5310) analysis. The concen-tration distribution and sampling location maps were devel-oped using GIS software.

2.4. Geology

Quaternary deposits consisting of gravel, sand, clay and peatare found along the east coast in the lower watershed of theTerengganu River basin. Granite of Permian to Lower Triassicage occurs as the Main Range Granite and contains hydro-thermal veins of economic value (Gobbett and Hutchison,1973). Granite appearing as high peaks forms the upperwatershed and covers about 40% of the surface area. Limestoneoutcrops are restricted and appear only in the Kenyir Lake area.Localized occurrence of volcanic rock of the Carboniferous agecovers <2% surface area and is dominantly andesitic andrhyolitic. Metasedimentary rock (Carboniferous to Permian) isthe most dominant rock type (>43% area) forming the low andundulating areas (Hadi and Fadzali, 2006; Gobbett andHutchison, 1973) and dominantly consists of phyllite and slate.

3. Results

Summary statistics of concentrations of Pb, Sn, As, Cd andHg in soil, sediment and surface water samples of the Ter-engganu River basin are listed in Table 2. The physico-chemical parameters and concentrations of major, minor andtrace elements in tropical soils of the Terengganu River havebeen described by Sultan and Shazili (2009).

3.1. Soil

Lead (Pb) concentrations ranged from 0.11 to 73.96 mg/kgwith an average value of 29.2� 19.5 mg/kg. Soils developed ongranite registered the highest (averagew 42.30 mg/kg) andsoils developed on volcanic rock registered the lowest

ater of the Terengganu River basin.

um Average Median Standard

deviation

Count

29.23 26.45 19.458 53

7.73 6.51 5.714 53

6.83 6.83 2.909 53

0.14 0.12 0.141 53

0.09 0.08 0.041 53

32.10 29.54 26.119 42

9.75 9.09 5.964 42

9.48 9.18 4.694 42

0.44 0.44 0.027 42

0.19 0.16 0.130 42

0.97 0.49 1.212 51

14.68 13.28 5.857 51

3.42 0.05 6.761 51

4.78 1.06 7.425 51

0.04 0.04 0.033 51

172 K. Sultan et al. / Journal of Hydro-environment Research 5 (2011) 169e176

(averagew 2.61 mg/kg) Pb concentrations. The average Pbconcentration is measured to be 1.7 times higher than the uppercontinental crust value of 17 mg/kg of Pb (Taylor andMcLennan, 1995; Wedepohl, 1995). None of the samplinglocations registered Pb concentrations above the Dutch TargetValue of 85 mg/kg of Pb (MHSPE, 1994).

Tin (Sn) concentrations varied between 0.96 and 34.03 mg/kgwith an average value of 7.7� 5.7 mg/kg. Soils developed ongranite rock registered the highest (averagew 10.87 mg/kg)and soils developed onQuaternary deposits registered the lowest(averagew 5.04 mg/kg) Sn concentrations. The average Snconcentration in soil was found to be three times higher than theupper continental crust value of 2.5 mg/kg (Wedepohl, 1995).Gobbett and Hutchison (1973) reported Sn mineral Cassiterite(SnO2) and Malayaite (CaSnSiO5) in the local geology, whichhave been mined commercially for tin.

Arsenic (As) concentrations varied from 0.25 to 14.54 mg/kg with an average value of 6.8� 2.9 mg/kg. Soils deve-loped on metasedimentary rock registered the highest (aver-agew 8.05 mg/kg) and soils developed on volcanic rockregistered the lowest (averagew 4.79 mg/kg) As concentra-tions. All sampling locations registered As concentrationsbelow the Dutch Target Value of 29 mg/kg of As (MHSPE,1994).

Cadmium (Cd) concentrations varied between 0.03 and0.99 mg/kg with an average value of 0.14� 0.14 mg/kg. Soilsdeveloped on metasedimentary rock registered the highest(averagew 0.22 mg/kg) and soils developed on volcanic rockregistered the lowest (averagew 0.05 mg/kg) Cd concentra-tions. Only one sampling location (TR5) registered Cdconcentration above the Dutch Target Value of 0.8 mg/kg Cd(MHSPE, 1994).

Mercury (Hg) concentrations ranged from 0.01 to 0.25 mg/kg with an average value of 0.09� 0.04 mg/kg. Soils developedon volcanic rock registered the highest (averagew 0.103 mg/kg) and the soils developed on metasedimentary rock registeredthe lowest (averagew 0.081 mg/kg) Hg concentrations. Boththe upper continental crust value of 0.06 mg/kg (Wedepohl,1995) of Hg and the European geochemical baseline value of0.061 of Hg (Salminen et al., 2005) have been found to be lowerthan the average Hg concentration measured in the study area.

3.2. Sediment

Lead concentrations varied from 0.05 to 124.85 mg/kg withan average value of 32.1� 26.1 mg/kg. River sedimentsregistered higher Pb concentrations (averagew 32.7 mg/kg)than the lake sediments (averagew 30.8 mg/kg). About 40%of the sediment samples registered Pb concentrations abovethe USEPA (2008) freshwater sediment screening benchmarkof 35.8 mg/kg of Pb.

Tin concentrations varied between 0.75 and 29.23 mg/kgwith an average value of 9.8� 6.0 mg/kg. The highest Snconcentration was recorded at a sampling site (TR50) closer tothe granite bedrock. Tin concentration in lake sediments wasmeasured to be higher (averagew 11.91 mg/kg) than the riversediments (averagew 8.78 mg/kg). The European

geochemical baseline value of 4.79 mg/kg of Sn (Salminenet al., 2005) for stream sediments is nearly half the averageSn measured in the study area.

Arsenic concentrations ranged from 0.83 to 23.09 mg/kgwith an average value of 9.5� 4.7 mg/kg. Arsenic concen-tration in lake sediments was found to be slightly higher(averagew 9.98 mg/kg) than the river sediments (aver-agew 9.25 mg/kg). About 40% of the sampling locationsregistered sediment As concentrations exceeding the USEPA(2008) freshwater sediment screening benchmark value of9.8 mg/kg of As.

Cadmium concentrations ranged from 0.35 to 0.52 mg/kgwith an average value of 0.44� 0.03 mg/kg. No significantchange in Cd concentration was observed in river (aver-agew 0.45 mg/kg) or lake sediments (averagew 0.43 mg/kg).No sediment sample measured concentrations exceeding theUSEPA (2008) freshwater sediment screening benchmark of0.99 mg/kg of Cd.

Mercury concentrations ranged between 0.01 and 0.59 mg/kgwith an average value of 0.19� 0.13 mg/kg. River sedimentsregistered higher Hg concentrations (averagew 0.20 mg/kg)than the lake sediments (averagew 0.16 mg/kg). The averageHg concentration was measured to be 2.3 times higher than theEuropean geochemical baseline value of 0.08 mg/kg of Hg(Salminen et al., 2005) in stream sediments. About 30% of thesampling locations measured concentrations above the fresh-water screening concentration of 0.18 mg/kg of Hg by USEPA(2008).

3.3. Surface water

Dissolved Pb concentrations varied between 0.02 and4.54 mg/L with an average value of 0.97� 1.2 mg/L. Riverwater Pb concentration was measured to be higher (aver-agew 1.08 mg/L) than the lake water (averagew 0.70 mg/L).No water sample registered Pb concentrations exceeding theWHO (2006) drinking water guideline value of 10 mg/L of Pb.Huang et al. (2008) reported a higher range from 2.52 to15.2 mg/L of Pb concentrations in the Mekong River waters.

Dissolved Sn concentrations ranged between 4.35 and36.3 mg/L with an average value of 14.7� 5.9 mg/L. Thehighest Sn concentration was recorded at a sampling site(TR29) closer to the river mouth. River water Sn concentrationwas measured to be higher (averagew 16.25 mg/L) than thelake water (averagew 10.9 mg/L).

Dissolved As concentration varied from 0.01 to 28.9 mg/Lwith an average value of 3.4� 6.8 mg/L. River water Asconcentrations were found to be higher (averagew 4.3 mg/L)than the lake water (averagew 1.32 mg/L). The highest Asconcentration was recorded at a sampling location (TR28)closer to the river mouth and a heavily urbanized area. Fivesampling locations registered As concentrations above theWHO (2006) drinking water guideline value of 10 mg/L of As.

Dissolved Cd concentrations varied between 0.36 and24.53 mg/L with an average value of 4.8� 7.4 mg/L. Theaverage lake water Cd concentration (w14.21 mg/L) wasmeasured to be sixteen times higher than the river water

173K. Sultan et al. / Journal of Hydro-environment Research 5 (2011) 169e176

(w0.85 mg/L). About 10% of the sampling locations registeredconcentrations above the WHO (2006) drinking water guide-line value of 3 mg/L and the majority of locations from thelake.

Dissolved Hg concentrations varied between 0.01 and0.21 mg/L with an average value of 0.04� 0.03 mg/L. Riverwater Hg concentration (averagew 0.05 mg/L) was found tobe 1.7 times higher than the lake water (averagew 0.03 mg/L).No sampling location registered water Hg concentrationsabove the WHO (2006) drinking water guideline value of6 mg/L and ANZECC (1992) guideline value of 1 mg/L. Dis-solved average Hg concentration was measured to be lowerthan the tropical river waters from Central Africa (0.68 mg/L;Ikingura et al., 1997), but higher than the Mekong River(<0.001 mg/L; Huang et al., 2008) and the Amazon River(4.5 ng/L; Fadini and Jardim, 2001).

4. Discussion

Overall, the order of abundance of measured metals in soilswas granite>metasedimentary>Quaternary deposit[ vol-canic. The concentrations of metals were slightly enriched ascompared to the upper continental crust (UCC) and reflected onthe geology ofmaterial fromwhich soilswere derived. TheUCCnormalized patterns of metals in soils showed that soils derivedfrom the volcanic rock were the most depleted in terms ofelemental budget. The soils derived from the Quaternarydeposits plot in the middle revealing the heterogeneity in thesource material comprising the upper watershed geology(Fig. 2). This can be explained as the source of Quaternarydeposit is dominantly granite and metasedimentary rocks.Among the metals, Pb showedmore variation in soils developedin volcanic rock which is possibly due to the preferentialweathering of soil minerals.

The enrichment of Sn seems to be the natural backgroundconcentration in this region. Granite rock is host to mineral-ized zones enriched in metals (e.g. Sn, W) extending northsouth in the study area. A number of Sn minerals occurnaturally of which Malayaite (CaSnSiO4) and Cassiterite(SnO2) are the dominant minerals. SEM analysis revealed thepresence of tin mineral Malayaite explaining enrichment of Snin soils (Fig. 3). The study area has been subject to tin mining

Fig. 2. The upper continental crust (UCC) normalized patterns of the inves-

tigated elements for the Terengganu Basin surface soils (n¼ 53) developed on

various rock units. The UCC values are after Wedepohl (1995).

operations in the past, the scale and extent of which isunknown. The Sn deposits generally occur in the granitepegmatites and have been mined for their commercial value inMalaysia (Gobbett and Hutchison, 1973; Schwartz et al.,1995). The edges morphology revealed that part of Sn ismobilized but largely intact and seems to be stable underprevailing environmental conditions.

Lead concentration in soils was measured to be slightlyhigher than the upper continental crust which seems to benaturally high in soils developed on granite rock. The Pbdistribution map shows a lower concentration of Pb in soilsdeveloped on volcanic rock in the Kenyir Lake area (Fig. 4).A positive correlation (r¼ 0.56, n¼ 53, r< 0.01) between Pband Sn indicated the possible presence of the mineral Teallite(PbSnS2) which is found in hydrothermal tin veins in the studyarea. Gobbett and Hutchison (1973) reported the Pb mineralsincluding Teallite (PbSnS2), Galena (PbS), Franckeite ((Pb,Sn)6FeSn2Sb2S14) and Boulangerite (Pb5Sb4S11) in hydro-thermal veins of the Main Range Granite. Lead concentrationalso showed a positive correlation with Sn in sediments(r¼ 0.64, n¼ 42, r< 0.01) but a very weak correlation wasobserved between Pb and Sn in surface waters. The prevailingEhepH conditions favor the fixation of Pb in the river sedi-ments possibly onto the secondary Fe oxides. A brown to redcolor coating on the sediments was observed which is likelydue to the Fe oxidation.

The enrichment factor (EF) was calculated in order toevaluate anthropogenic activity related input of the potentiallytoxic elements using Al as a reference element and isdescribed as:

EF¼ ð½Me�s=½Al�s=ð½Me�b=½Al�bÞ

where [Me]s and [Al]s represent concentrations of metal andAl in sediments, respectively, and [Me]b and [Al]b representthe upper continental crust concentrations of metal and Al,respectively. The EF value above 1 points to the enrichmentand below 1 points to the depletion as shown in Fig. 5. The EFvalues ranged between 2.3 (for Pb) and 5.7 (for As). However,only significantly high EF value (>5) is considered to beenrichment by anthropogenic related activities (Atgin et al.,2000). All the metals investigated recorded EF< 6 whichindicated a slight enrichment representing the regionalgeochemical background and less likely due to land useactivities. The middle and upper catchment areas of the Ter-engganu River are in a relatively pristine environment andhome to one of the world’s oldest tropical rainforests.

Dissolved concentrations of As showed a multifoldincreasing and Cd decreasing with distance from upstream tothe river mouth along the flow path (Fig. 6). However, Pbconcentrations did not show a systematic change with the flowpath from the upstream lake to the downstream river mouthrevealing heterogeneity in sources and/or hydrochemicalbehavior. Both Sn and Hg registered higher average concen-trations in river waters as compared to the lake waters (1.4 and1.9 times, respectively) but the change in concentrations wasnot systematic along the flow path. Dissolved concentration of

Fig. 3. SEM/BSE images of tin (Sn)-mineral Malayaite (CaSnSiO4) in a soil sample (location TR38). The Fe map is showing the possible secondary Fe-oxide

coating; the other mineral grain on the Si map is quartz.

174 K. Sultan et al. / Journal of Hydro-environment Research 5 (2011) 169e176

measured elements is controlled by master variables includingpH (5e8), Eh (�51 to 110 mV), EC (12e1670 mS/cm), waterresidence time and changing bedrock lithology from thedominantly granite in the upstream watershed to the Quater-nary sediments in the downstream areas. Cadmium concen-trations in sediments increased only slightly opposite to thedissolved Cd in surface waters with the distance fromthe upstream lake to the downstream river mouth (Fig. 6). Thiscan be explained as a result of reducing alkaline conditions(i.e. low Ehehigh pH) in the lake favoring the dissolution of

Fig. 4. Distribution of Pb in soils o

Cd, but mildly acidic river water under oxidizing condi-tions favoring precipitation/adsorption of Cd possibly ontosecondary oxides of Fe, Al and Mn. A non-significant changein sediment Cd concentrations between lake and river sedi-ments also pointed to the absence of naturally enriched Cdsource in the upper watershed. In addition to natural weath-ering processes, Cd may be released to water by dischargefrom metal and fertilizer industries, sewage treatment plants,atmospheric deposition and by leaching from landfills or soil(Elinder, 1985; ANZECC, 1992; WHO, 2006). Further

f the Terengganu River basin.

Fig. 5. Bar chart for the enrichment factor (EF) of Pb, Sn, As, Cd and Hg in the

sediments of the Terengganu River basin.

175K. Sultan et al. / Journal of Hydro-environment Research 5 (2011) 169e176

research is required to investigate the potential sources of Cdin the study area.

Both soil and sediment registered metal concentration inthe order of Pb> Sn>As[ Cd>Hg, but surface watermetal concentration followed the order Sn> Cd>As> Pb[Hg pointing to the mobilization of Sn. While Pb was themost abundant metal in soils and sediments, it registered lowerconcentration in surface waters. Overall, no significant threatto the soil or surface water was found with the exception ofa few sampling sites close to the river mouth and in the upperwatershed of Kenyir Lake close to the mineralized zones ofSneW in the Main Range Granite. Sediments in generalshowed enrichment of Pb, As and Hg which exceeded theenvironmental guideline values at locations close to the rivermouth and in the mainstream. This is likely due to the

0

5

10

15

20

25

]gk/g

m[

sA

Kenyir Lake (upstream) Terengganu River

Estuary (downstream)

0

10

20

30

0 20 40 60 80 100

0

10

20

30

0.35

0.4

0.45

0.5

0.55

]L/gu[

sA

]L/gu[

dC

Distance [km]

Surface water

Surface water

]gk/gm[

dC

Sediment

Sediment

Fig. 6. Concentration changes of As and Cd in surface waters and sediments

with the distance from the river mouth to the upstream Kenyir Lake.

agricultural runoff, urban/industrial effluent and past miningoperations in the study area. Sediments seem to play the roleof a sink for Pb, As and Hg due to elevated levels of Fe, Al andMn by providing adsorption sites.

5. Conclusion

The order of abundance of Pb, As, Cd, Hg and Sn in soilsdeveloped on various rock units followed granite>metasedimentary>Quaternary deposit[ volcanic with slightenrichment as compared to the upper continental crust. Both soilsand sediments registered the order of concentration as:Pb> Sn>As[Cd>Hg with an enrichment factor (EF)< 6for sediments indicating slight enrichment representing theregional background and less likely due to the anthropogenicactivity related input in the tropical Terengganu River basin.

Elevated levels of Sn in soils, sediments and surface watersas compared to the global values are due to the presence of Sn-containing mineral deposits. SEM analysis also revealed thepresence of Malayaite (CaSnOSiO4) in soils. Soil Pb distri-bution showed the geology as the primary control.

Systematic multifold increasing in dissolved As and Hgconcentrations with distance from the upstream to downstreamalong the river flow path is possibly due to the variations in Eh,pH and TDS as master control variables. Lake surface watersregistered 16 times higher Cd concentrations than the riverwaters but lake sediments registered lower Cd concentrationsthan the river sediments.

Dissolved Hg concentrations were measured to be lowerthan the tropical river waters from Central Africa but higherthan the Mekong and the Amazon Rivers. Dissolved Pbconcentration was measured to be higher than the river watersof both the Mekong and Amazon. Overall, no significant threatto the environment was found with the exception of a fewsampling sites close to the river mouth and others in the upperwatershed which is due to the mineralized zones.

Acknowledgements

The authors would like to thank INOS, University MalaysiaTerengganu for the funding support.

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