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Hydrogeochemical and isotopic evidences for definition of tectonically controlledcatchment areas of the Konavle area springs (SE Dalmatia, Croatia)

Božo Prtoljan a,⁎, Sanja Kapelj b, Franjo Dukarić a, Igor Vlahović c, Ervin Mrinjek d

a Croatian Geological Survey, Sachsova 2, HR-10000 Zagreb, Croatiab University of Zagreb, Faculty of Geotechnical Engineering, Hallerova aleja 7, HR-42000 Varaždin, Croatiac University of Zagreb, Faculty of Mining, Geology and Petroleum Engineering, Pierottijeva 6, HR-10000 Zagreb, Croatiad University of Zagreb, Faculty of Science, Horvatovac 102A, HR-10000 Zagreb, Croatia

a b s t r a c ta r t i c l e i n f o

Article history:Received 6 April 2010Accepted 16 September 2011Available online 22 September 2011

Keywords:KarstGroundwater hydrogeochemistryTectonicsKonavleCroatia

Increased human activities in the karst areas may result with unwanted impacts on environment, especiallyon groundwaters. This problem fostered reinterpretation of geological and hydrogeological relationships inthe area of Konavle (SE Croatia). Detailed geological mapping enabled better insight into lithological andstructural relationships in the area, especially concerning accumulation of groundwater in the karst under-ground of the hinterland. Thick succession of carbonate rocks of different permeability in the hinterlandresulted in deep and complex reservoirs communicating mainly through tectonically predisposed zones.Aquifer dynamics is especially increased during the periods of high rainfalls and snow thawing in the hinter-land. Four major springs, located along the tectonic contact between thick succession of Mesozoic carbonatesand barrier composed of Palaeogene (and Neogene?) clastic rocks were observed. They show variable hydro-geochemical and isotopic values as a result of different altitudes, but also as a result of different catchmentareas divided by important transversal fault systems. Since sporadically increased orthophosphate contentsindicate anthropogenic influence presented preliminary results request careful monitoring and internationalcooperation to protect these sensitive transboundary catchment systems.

© 2011 Elsevier B.V. All rights reserved.

1. Introduction

The Konavle region represents a relatively small area with highwater potential in the southeasternmost Croatia, where 27 perennialand intermittent springs of different capacities are arranged in zones.The observed springs show, in addition to differences in discharge, sig-nificant temporal variations in chemical contents. The spring areasdrain vast karst areas in the immediate hinterland of the KonavoskaBrda, as well as in the wider hinterland of Bosnia and Herzegovinaand partly Montenegro. These groundwater resources are major strate-gic water potential for future needs in energy, agriculture, tourism andwater-supply in southern Dalmatia.

Study area (Fig. 1) is characterized by a relatively complex geolog-ical structure (Fig. 2), as a consequence of a several thousand metersthick succession of predominantly carbonate deposits of a wide strat-igraphic range (Upper Triassic to Quaternary), very intense polyphasetectonics and significant karstification. Therefore, the catchmentareas are characterized by high relief, complicated structural relation-ships and relatively high elevations.

The potable water demand in the area increases annually due totourism industry growth and development of agriculture in theKonavosko Polje area. Therefore, through analysis and interpretationof new lithostratigraphical and structural data, and recent hydroche-mical and isotopic research, this paper will present a basic knowledgeabout the origin and hydrodynamic conditions within the studiedhydrogeological system which might contribute to the better protec-tion and increased possibilities of exploitation of larger quantities ofgroundwater.

Previous studies of this area mainly focused on water potential re-lated to the hydrogeological projects in the wider region, from theNeretva River catchment to Konavle (unpublished reports by LukaBojanić and his collaborators may be found in the Croatian GeologicalSurvey archive), hydrological analysis of flood events in the Kona-vosko Polje (Bonacci, 1987) and groundwater protection zones(Milanović, 2004). Probably the most comprehensive long-term stud-ies were performed for hydroenergetic utilization of considerablewater potential of the transboundary hydrogeological system be-tween Croatia and Bosnia and Herzegovina (Milanović, 1983).Water quality of the Duboka Ljuta and Konavoska Ljuta springs wasmentioned also within the comprehensive study of Dalmatian waters(Štambuk-Giljanović, 2006).

This paper resulted from investigation funded from 2007 to 2010by the National Foundation for Science, Higher Education and

Journal of Geochemical Exploration 112 (2012) 285–296

⁎ Corresponding author. Tel.: +385 1 6160738; fax: +385 1 6144718.E-mail address: bozo.prtoljan@hgi-cgs.hr (B. Prtoljan).

0375-6742/$ – see front matter © 2011 Elsevier B.V. All rights reserved.doi:10.1016/j.gexplo.2011.09.006

Contents lists available at SciVerse ScienceDirect

Journal of Geochemical Exploration

j ourna l homepage: www.e lsev ie r .com/ locate / jgeoexp

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Technological Development of the Republic of Croatia and KonavleMunicipality through project ‘Geological Map of the Konavle area,1:50,000 Scale — a precondition for a sustainable development’. Oneof the major focuses of the project was detailed lithostratigraphic in-vestigation of the area as a basis for reinterpretation of hydrogeologi-cal relationships of the Konavle area.

2. Geological setting

2.1. Stratigraphy and sedimentology

The Konavle area is situated along the eastern coast of the AdriaticSea, in the SE part of the Dinarides, up to 200 km wide and more than600 km long mountain belt connecting eastern and southern Alps inthe NW and Albanides and Hellenides in the south (Fig. 1). It is mostlybuilt of rocks genetically associated with a vast depositional system ofthe ancient carbonate platform (Dercourt et al., 1993; Lawrence et al.,1995; Vlahović et al., 2005).

In the Konavle area rocks of a very wide stratigraphic range (fromUpper Triassic to Quaternary — mostly shallow-marine carbonate de-posits and some clastic rocks) are present over an area of only210 km2. In places significant lateral lithological variations were de-termined, including frequent late-diagenetic dolomitization and re-crystallization of limestones, which may considerably influencewater flow regimes, and reflect on quantities and chemistry of watersin individual springs.

Generally, the study area may be divided into two parts, separatedby a regionally important reverse fault striking close to the NE margin

of the Konavosko Polje, along which the most important springsoccur. The south-western part is composed of the Upper Cretaceouscarbonates and Palaeogene (and Neogene?) carbonates and clasticrocks, which are overthrusted by a NW part built of a thick successionof older, Upper Triassic, Jurassic and Cretaceous carbonate rocks,representing catchment areas of the studied springs.

The oldest lithostratigraphic unit cropping out in the area ofKonavle comprises Upper Triassic early- and late-diagenetic dolo-mites topped by megalodon limestones (Fig. 2). A thickness of thisunit in the wider area of the Dinarides is usually 300–600 m, but inthe studied area they crop out only in the form of heavily tectonizedblocks mostly covered by irregular breccia and conglomerates in thehanging wall of the regional reversed fault.

Lower Jurassic deposits have only been found in some tectonicblocks close to the major reversed fault, and only middle and upperpart of the Lower Jurassic have been documented. Approximately700 m thick succession of Middle Jurassic grainy limestones with sev-eral late-diagenetic dolomite interbeds cover wide areas of the NEKonavle. Up to 900 m thick succession of Upper Jurassic (Oxfordian–Tithonian) deposits is characterized by a continuous succession ofwell-bedded micritic limestones with some diagenetic cherts (closeto the Oxfordian/Kimmeridgian boundary) and dolomites (most fre-quent in the Upper Kimmeridgian and Lower Tithonian).

Jurassic rocks are concordantly overlain by Lower Cretaceous car-bonates, best visible in the central part of the NE Konavle area. Low-ermost, thick-bedded to massive Berriasian deposits are intenselydolomitized, and the overlying succession is typical for shallow-marine Valanginian to Barremian of the Dinarides. The younger part

Fig. 1. General tectonic setting of SE Europe with position of the Dinarides (lower left), position of the studied area within Croatia (lower right, after Prtoljan et al., 2007)and location map of the Konavle area with studied springs.

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of deposits, close to the border with Bosnia and Herzegovina, is stillunreachable because the area is heavily polluted by landmines.

The southwestern part of the Konavle area is composed of rocks ofUpper Cretaceous and Palaeogene (and Neogene?) age, but only theyoungest part of this succession composed of clastic rocks is impor-tant for this study because it represents a barrier to the groundwaterflows. Therefore, it should be only mentioned that below clastic rocksthere is more than 1200 m thick succession of carbonate depositsranging in age from Santonian–Campanian to Middle Eocene, includ-ing more or less continuous transition from Cretaceous to Palaeogeneand emergence between Palaeocene and relatively thin succession ofEocene foraminifera limestones.

Eocene limestones are covered by more than 600 m thick succes-sion of marls and deeper marine clastic rocks which are croppingout in the Konavosko Polje area. Their traditional interpretation hasbeen seriously questioned recently, both from the stratigraphical(they might be younger than Middle to Upper Eocene/Lower Oligo-cene — see discussion in Mikes et al. (2008), supported by our ownpreliminary data) and palaeoenvironmental point of view (lowerand upper part of these deposits are shallower than usually reported).

These rocks were deposited during beginning of the final compres-sion and uplift of the Dinarides.

The youngest deposits in the Konavle area are Quaternary depositsof a relatively small thickness, mostly consisting of terra rossa andclays, silts, sands and gravels.

2.2. Geomorphological and structural–tectonic characteristics

Geomorphologic forms of studied catchment areas are mostlycaused by tectonic deformation of lithologically heterogeneous de-posits which started in the Late Mesozoic (Prtoljan et al., 2007) andculminated during Late Palaeogene, Neogene and Quaternary.

Three separate geomorphologic units of Dinaric strike (NW–SE) areclearly distinguished in the Konavle region. The coastal part is composedof Upper Cretaceous carbonates with mostly inaccessible, steep coastwith cliffs, small capes, and submarine caves. The central part is Kona-vosko Polje, approximately 15 km long, and up to 2 km wide, coveredby Palaeogene (and Neogene?) clastic rocks into which the Ljuta,Konavočica and Kopačica streams are cut with their numerous intermit-tent torrential tributaries. Sinkholes are encountered in the lowermost

Fig. 2. Schematic geological map of the Konavle area. Legend: 1) Upper Triassic alternation of early- and late-diagenetic dolomites topped by megalodon limestones; 2) Lower andMiddle Jurassic grainy limestones; 3) Upper Jurassic micritic limestones; 4) Uppermost Jurassic and Lower Cretaceous limestones and dolomites; 5) Lowermost Upper Cretaceouslimestones; 6) Upper Cretaceous (Santonian–Campanian) limestones and dolomites; 7) Upper Cretaceous (Campanian) early- and late-diagenetic dolomites with weathered red-dish palaeosoils; 8) Upper Cretaceous (Maastrichtian) massive limestones and dolomites and Maastrichtian–Palaeocene micritic limestones; 9) Eocene foraminifera limestones;10) Upper Eocene–Lower Miocene(?) clastic deposits; 11) Palaeogene/Neogene tectogenic breccia; 12) Quaternary deluvial–proluvial deposits; I–II simplified geological profile.

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part of the polje, along its SWmargin, where clastic and carbonate rocksare in contact. The third geomorphologic unit is an uplifted highlandpart in the NE, which is vertically strongly articulated, with high rockygrounds, ridges and summits on average more than 700 m high.Among them, several summits in the central part are higher than1000 m (the highest peak is Snježnica, 1234 m a.s.l.). The far easternpart of Konavoska Brda area is delineated by the Prapratno valley predis-posed by a fault. The valley strikes in N–S direction, and its eastern sloperepresents a morphological barrier rising very steeply towards Mt. Orjenin Montenegro.

In high karst parts of the spring area catchments, i.e. in the area ofthe orographic sequence of Konavoska Brda, numerous dolines of di-verse genetic types, dimensions, shapes and stage of developmenthave developed.

Structural–tectonic relations in the Konavle region are determinedby regional overthrust of Mesozoic carbonate complex over youngerPalaeogene (and Neogene?) clastic rocks along the relatively gentlefault plane striking close to the NE margin of the Konavosko Polje, dip-ping 20–40° towards NE. However, overthrusting has not been uniformalong the entire fault front, since it is cut by numerous transversestrike-slip faults, the most important being two regional diagonal faultsstriking in N–S direction— in the western part, near Cavtat, the Slivnicafault, and in the eastern part, near Dubravka, the Zubac fault. Right-hand movements occurred along these faults, and they have an impor-tant hydrogeologic function, since spring areas of Duboka Ljuta,Konavoska Ljuta and Vodovađa are associated with their zones. TheSlivnica fault runs from Trebinje in Bosnia and Herzegovina, acrossthe Duboka Ljuta gorge, and further to the sea. It is a straight linewater divide between the catchments of the Ombla spring area in thewest and the Duboka Ljuta spring area in the east. The Zubac faultstrikes from Grab and Dubrava polje in Bosnia and Herzegovinathrough the Prapratno valley to Vodovađa. This fault is a water dividebetween catchments of the Konavoska Ljuta and Vodovađa springs.The area along important faults is marked by tectonized and karstifiedrocks, fracture systems striking N–S, and numerous dolines and smallpoljes of the same orientation. Along these faults, right diagonal blockmovements and lateral overthrusts occurred, which resulted in forma-tion of a number of minor secondary faults striking NE–SW. Fault zonesare marked by numerous springs since affected rocks are frequentlycharacterized by different permeabilities.

Considering the hydrogeological aspect, the most important faultis the one cutting the major fault front near the Lovorno village, form-ing the Konavoska Ljuta spring area.

Highland hinterland NE from the spring areas is marked by openfissure systems and deep dolines, indicating their allochthony andsubsequent extensional stress regime.

3. Hydrological characteristics of the Konavle springarea catchments

Twenty-seven springs of different discharge are documented inthe Konavle area (Table 1). These springs are distributed withinthree sub-catchments — Duboka Ljuta, Konavoska Ljuta–Dragavineand Vodovađa spring recharge areas, which encompass large karstareas of the Konavoska Brda range and wider hinterland (Fig. 3).The water divides delineating the catchments are mostly of orograph-ic nature, with exception of the part of overthrust front, wherePalaeogene (and Neogene?) clastic rocks create a hydrogeologicalbarrier. The water divides are almost completely situated in carbon-ate deposits, and they pass over the highest ridges, crests and sum-mits of the Konavoska Brda hills.

In the case of springs located in very complex structural settings inthe karst areas water movement is usually modeled using a largenumber of variables, from hydrological to geochemical natural tracers(Mazor, 2004; Buljan et al., 2006). Especially important is the fact thatthe aquifers in the studied inflow areas are very quickly discharged,

so the main spring areas, Duboka Ljuta, Dragavine, Konavoska Ljutaand Vodovađa, have relatively high amplitudes of minimum andmax-imum discharges during the hydrological cycle. The highest dis-charges are recorded in winter (December) and spring (March andApril), in periods of prolonged and intensive precipitation and/or dur-ing the snow thawing in the highland inflow areas of the catchments.The lowest discharges are recorded in the late summer/early autumn(August, September, rarely October) and they last until the beginningof the autumn rains (Fig. 4). Such hydrologic variability causesmajor differences in chemical and isotopic contents in particularspring waters (Mazor, 2004; Appelo and Postma, 2005). Due to thehigh permeability of karstified carbonate catchments, water dividesbetween sub-catchments move zonally, depending on hydrologicalconditions.

Since tectogenesis of the study area was polyphase, carbonate de-posits are partly modified and in complex mutual relationships, soeach catchment has specific hydrodynamic relations. In this case,hydrogeological and structural relations lead to a conclusion thatmain and major groundwater inflows are related to diagonal andtransverse faults striking N–S, which cut the major overthrust front.This is a belt where a densely fractured zone with numerous corro-sional caverns and interwoven systems of fractures and siphons cre-ate a complex hydrodynamic system in the subsurface. On the otherhand, the catchment area belongs to both Mediterranean and inlandpluviometric regime, which means that measured annual precipita-tion ranges from 1200 to 2000 mm. It should be highlighted that pre-cipitations in catchment inflow areas increase with altitude and theirseasonal maximums are as much as 40% higher than in the coastalarea.

3.1. The Duboka Ljuta spring occurrence and regime

Duboka Ljuta (also known as Robinzon spring; Figs. 1–3) is a typ-ical coastal karst spring. The spring is tapped and included in thewater supply system servicing the Konavle region. It is located atthe bottom of a semi-circular wide ravine called Duboka Ljuta, atthe foothill of a very steep coastal slope of the westernmost part of

Table 1Springs of the Konavle catchments; major springs discussed in text in bold letters.

Springs Discharge(l/s)

Rate ofoutflow

Springs Rate ofoutflow

Discharge(l/s)

DubokaLjuta

165–2,000

Ascending-persistent

Dubravčić Downward-persistent

0.1–10

Klimar 0.1–1.0 Ascending-persistent

Kukurjek Downward-persistent

0.1–10

Dobra voda 0.1–10 Downward-persistent

Zvekavica Downward-temporary

0.1–1.0

Smokovjenac 0.1–1.0 Downward-persistent

Bundinavoda

Downward-temporary

0.1–1.0

Sisina voda 0.1–10 Downward-temporary

Picet voda Downward-persistent

0.1–10

Lisica 0.1–1.0 Downward-persistent

Vojska Downward-persistent

0.1–10

Godjej b1.0 Downward-persistent

Puc Downward-temporary

b1.0

Urnak 0.1–1.0 Downward–persistent

Vrbica Ascending-persistent

10–100

Dragavine 0.1–3.0 Downward–persistent

Vodovađđđa Ascending-persistent

15–100

Badri 0.1–1.0 Downward–temporary

Bani Downward-temporary

b1.0

Dramanje 0.1–1.0 Downward–temporary

Daljevik Downward-persistent

0.1–10

KonavoskaLjuta

100–31,000

Ascending–persistent

Mala voda Downward-temporary

1–10

Smrdelj 0.1–1.0 Downward–temporary

Gunjina Downward-temporary

1–10

Ušljivac 0.1–10 Downward–persistent

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Konavle. The groundwater upward discharge (siphon) creates a smallpond, about 10 m wide, approximately at 0.70 m a.s.l., 70 m from thesea (Buljan et al., 2006). The outflow opening is not morphologicallydeveloped, since it is covered with spring and marine deposits andclasts and blocks of neighboring rocks.

During the last glaciation period, when the sea level wasmore than100 m lower than today (D'Ambrosio, 1969; Šegota, 1982), Duboka

Ljuta spring was a typical inland spring. After the thawing of ice, thelevel of the Adriatic Sea increased and intrusion of sea water pushedthe fresh water into the deep karstic inland aquifers. This resultedin a spring being covered with marine sandy gravel material that, to-gether with the sea-level rise, has a backwater effect. Under such con-ditions, the spring is characterized by the upward outflow, whichduring dry periods sometimes results in increased chloride content.

Fig. 3. Hydrogeological map of Konavle and neighboring area. Legend: 1) Permeable karstified carbonate rocks; 2) Low permeable dolomites; 3) Generally impermeable Palaeogene(and Neogene?) clastics — hydrogeological barrier; 4) Quaternary deposits of heterogeneous composition; 5) Normal boundary; 6) Transgressive boundary; 7) Regional fault;8) Reverse fault; 9) Studied karst springs; 10) Ponor (swallow hole); 11) Kunak Cave; 12) General groundwater flow; 13) Underground water zone divide; 14) Undergroundwater connection ponor–spring; 15) Duboka Ljuta catchment area; 16) Konavoska Ljuta–Dragavine catchment area; 17) Vodovađa catchment area.

0.0

50.0

100.0

150.0

200.0

250.0

300.0

Janu

ary

Feb

ruar

y

Mar

ch

Apr

il

May

June

July

Aug

ust

Sep

tem

ber

Oct

ober

Nov

embe

r

Dec

embe

r

Mon

thly

pre

cipi

tatio

n (m

m)

2006 2007 2008

Fig. 4. Variation of monthly average precipitations recorded at the Pridvorje Meteorological Station.

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The spring site is formed by a diagonal Slivnica fault which cutsthe regional overthrust. A widespread underground drainage systemof fractures in karstified carbonate deposits is highly developed inthe fault zone. The spring area discharge is very uneven, and the out-flow regime fluctuations are high. The lowest recorded spring areadischarge is Qmin=0.020 m3/s, and the highest Qmax=20.50 m3/s.However, after a 16.60 km long hydrotechnical tunnel has been builtnear the coast close to the Duboka Ljuta spring area, natural water sys-tem in the spring area hinterland has been disturbed. Construction ofthe tunnel caused decrease in maximum and increase in minimum dis-charges: observed minimum measured discharge is Qmin=0.165 m3/s,and maximum Qmax=2.00 m3/s (Buljan et al., 2006).

3.2. The Dragavine spring occurrence and regime

Dragavine spring is a typical karst spring located in the centralpart of the NE slope of the Konavoska Brda (Figs. 1–3), along thewater divide between Konavoska Ljuta and Duboka Ljuta drainageareas at 185 m a.s.l. It is located at the tectonic contact betweenPalaeogene (and Neogene?) clastic rocks and recrystallized MiddleJurassic limestones with important secondary fracture system strik-ing NE–SW. The spring is gravitational and continuous, discharge isup to 0.003 m3/sec. The spring is tapped and included in the watersupply system servicing the local community.

3.3. The Konavoska Ljuta spring occurrence and regime

By its discharge, the Konavoska Ljuta (Figs. 1–3) is the most im-portant spring in the Konavle region. It is a perennial karst spring lo-cated along the northern edge of the Konavosko Polje below theGruda–Pridvorje road at about 110 m a.s.l., some 13 km ESE from

the Duboka Ljuta spring. The groundwater upflow (siphon) is en-countered at the contact between relatively permeable recrystallizedand fractured Triassic dolomites and impermeable Palaeogene (andNeogene?) clastic rocks, covered with debris. The outflowmechanismis controlled by a transverse fault and secondary fracture systemstriking NE–SW, with associated concentrated groundwater flows.This fault has also predetermined development of the drainage karstsystem within fractured and karstified carbonate rocks. The springconsists of three perennial and several intermittent spring branches.The outflow opening is not morphologically developed, being coveredby debris and blocks of different carbonate rocks. Intermittent springbranches are on somewhat higher hypsometric levels and they occuronly when the groundwater tables are high, i.e. during periods of in-tensive rain and sudden snow thawing in the highland inflow catch-ment areas. When the water levels are low, the water overflows theclastic rocks barrier covered with debris and springs in a lower posi-tion, which suggests that the spring has a gravitational character.

The spring area discharge is very uneven, with high fluctuations inoutflow regime. The minimum recorded discharge was Qmin=0.1 m3/s,and maximum recorded discharge Qmax=31m3/s. The existing intakeenables only a part of water to be used in public water supply for theKonavle Municipality. Minimum spring area discharge is probablymuch higher, since the recorded data do not include water abstractedfor irrigation of arable land.

3.4. The Vodovađa spring occurrence and regime

Vodovađa is a perennial karst spring located 4 km SE of the Kona-voska Ljuta spring (Figs. 1–3), at the bottom of a ravine, directlybelow steep eastern slopes of the Mt. Orjen massif striking towardsneighboring Montenegro. The groundwater discharge (siphon) is

Table 2Hydrochemical spring water data for the Konavle area springs.

Spring Sample code T pH EC TDS Ca2+ Mg2+ Na+ K+ HCO3- SO4

2- Cl- NO3-N NH4-N NO2-N PO43-

Code/day/month/year °C uS/cm (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)

Vodovađa VOD/2/11/06 11.9 7.80 604 302 35 10 2.70 0.24 211 8.0 10.0 1.8 b0.01 b0.001 b0.001Duboka Ljuta DLJ/2/11/06 11.8 7.80 734 367 82 6 5.90 0.46 245 11.0 16.9 1.2 b0.01 b0.001 b0.001Konavoska Ljuta LJ/2/11/06 11.9 7.90 626 313 69 7 2.10 0.32 214 9.2 11.0 1.4 b0.01 b0.001 b0.001Vodovađa VOD/20/4/07 14.9 7.20 489 214 38 10 3.26 0.22 155 2.0 5.6 1.4 b0.01 b0.001 0.140Duboka Ljuta DLJ/20/4/07 13 7.75 325 212 48 3 2.85 0.28 149 2.0 3.9 2.5 b0.01 0.003 0.270Konavoska Ljuta LJ/20/4/07 17.3 7.81 267 201 45 4 1.89 0.20 145 0.5 2.9 1.5 b0.01 b0.001 0.110Vodovađa VOD/4/9/07 14.9 7.20 489 211 36 11 3.46 0.20 151 2.0 6.0 1.2 b0.01 b0.001 0.050Duboka Ljuta DLJ/4/9/07 15.6 7.18 600 202 45 3 2.44 0.25 143 2.0 3.5 2.4 b0.01 b0.001 0.211Konavoska Ljuta LJ/04/9/07 13.3 7.02 408 213 41 7 2.74 1.10 157 0.5 2.5 1.1 b0.01 b0.001 0.130Vodovađa VOD/28/1/08 11.8 7.78 489 205 32 11 3.56 0.20 149 2.0 6.5 0.4 b0.01 b0.001 0.050Dragavine DRA/28/1/08 11.8 7.80 451 335 48 21 6.50 1.34 234 7.0 14.8 1.1 b0.01 b0.001 0.740Duboka Ljuta DLJ/28/1/08 11.7 7.89 450 228 49 4 3.11 0.28 165 1.0 4.7 0.5 b0.01 b0.001 0.050Konavoska Ljuta LJ/28/1/08 11.8 7.82 271 219 45 5 2.52 0.23 161 1.0 4.3 0.5 b0.01 b0.001 0.040Vodovađa VOD/28/8/08 16.2 7.31 302 220 38 11 3.58 0.13 157 3.0 7.3 0.1 0.01 b0.001 0.170Dragavine DRA/28/8/08 18.7 7.10 435 290 51 13 7.24 0.13 188 8.0 20.2 2.3 0.01 b0.001 0.290Duboka Ljuta DLJ/28/8/08 16.3 7.09 330 244 52 5 3.53 0.73 172 3.0 7.4 0.5 0.02 b0.001 0.180Konavoska Ljuta LJ/28/8/08 16.5 7.80 281 220 44 6 2.26 0.13 162 1.0 4.4 0.2 0.01 b0.001 0.110Vodovađa VOD/30/9/08 13.8 7.65 295 220 38 11 3.56 0.12 158 3.0 6.4 0.1 0.02 b0.001 0.140Dragavine DRA/30/9/08 17.7 7.24 438 290 52 13 7.16 0.74 193 8.0 13.1 2.5 0.01 b0.001 0.220Duboka Ljuta DLJ/30/9/08 16.2 7.68 328 235 50 4 2.72 0.20 170 2.0 5.6 0.6 0.01 b0.001 0.170Konavoska Ljuta LJ/30/9/08 12.4 7.53 285 218 43 6 2.29 0.16 161 1.0 4.2 0.3 b0.01 b0.001 0.110Vodovađa VOD/12/2/09 13.4 7.51 448 224 40 11 3.20 0.19 161 2.0 5.3 1.4 b0.01 b0.001 0.070Dragavine DRA/12/2/09 13.7 7.10 642 321 55 14 10 0.87 211 9.0 19.2 1.8 b0.01 b0.001 0.310Duboka Ljuta DLJ/12/2/09 10.6 7.60 424 212 48 3 2.85 0.28 149 2.0 3.9 2.5 0.04 b0.001 0.270Konavoska Ljuta LJ/12/2/09 12.3 7.50 402 201 45 4 1.89 0.20 145 0.5 2.9 1.5 b0.01 b0.001 0.110Vodovađa VOD/2/6/09 15.2 7.31 416 208 35 10 3.11 0.21 149 3.0 5.9 1.6 b0.01 b0.001 0.170Dragavine DRA/2/6/09 14.4 7.10 588 294 49 12 9.50 0.77 198 8.0 14.9 1.9 b0.01 b0.001 0.290Duboka Ljuta DLJ/2/6/09 15.6 7.49 402 201 50 4 2.77 0.27 172 2.0 1.8 2.4 b0.01 b0.001 0.180Konavoska Ljuta LJ/28/8/08 14.5 7.5 402 201 42 5 2.10 0.18 147 0.5 2.9 1.5 b0.01 b0.001 0.110Vodovađa VOD/14/9/09 14.3 7.59 422 211 36 10 3.42 0.14 151 3.0 6.2 1.1 b0.01 b0.001 0.090Dragavine DRA/14/9/09 16.7 7.31 588 294 51 12 7.11 0.80 200 9.0 12.0 2.2 b0.01 b0.001 0.180Duboka Ljuta DLJ/14/9/09 14.8 7.14 506 253 55 5 2.80 0.22 182 2.0 5.5 0.7 b0.01 b0.001 0.200Konavoska Ljuta LJ/14/9/09 13.7 7.55 428 214 44 6 2.14 0.16 158 0.6 2.8 0.3 b0.01 b0.001 0.050

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encountered at elevation of approximately 310 m a.s.l. Water springsat the contact of permeable Upper Triassic carbonates and imperme-able Palaeogene (and Neogene?) clastic rocks. The outflow mecha-nism is controlled by a transverse fault with right-hand movementand secondary fracture system striking NE–SW, with associated con-centrated groundwater flows. Rocks along the fault zone are charac-terized by very different permeability and therefore this fault has avery important hydrogeological role. Since this is a perennial spring,a good connection with the hinterland of catchment inflow areas isimplied. The outflow opening is not morphologically developed, asit is covered with debris. When groundwater level is high, i.e. during

periods of intense rains and sudden snow thawing in highland inflowareas of the catchment, outflows are recorded at somewhat higherhypsometric level. Groundwater spills over rocky hillslope blocks, soit seems to be a gravitational spring. The spring discharge is ratheruniform, with relatively small fluctuations in groundwater outflowregime. The minimum recorded discharge was 0.015 m3/s, and max-imum 0.1 m3/s.

4. Natural tracers as indicators of groundwater origin

Delineation of the large karst catchments in the Dinarides usuallyrequires a comprehensive and detailed geologic study. Basic knowl-edge is usually obtained by application of classical geologic andhydrogeologic methods, from detailed geologic and hydrogeologicmapping, morphological and structural analysis to tracing tests, etc.Because of a quite uniform lithological composition of study area, dis-tinctions of sub-catchments of four observed springs were obtainedby natural hydrogeochemical (main ionic content) and isotopetracers (δ

18O and δ

2H).

4.1. Sampling and analytical methods

Spring water samples have been collected eight times during dif-ferent vegetation and hydrologic seasons. Air temperatures at thePridvorje Meteorological Station range averagely from 10 °C in winterto 25 °C in summer while precipitation during the sampling period ispresented in Fig. 4.

Water temperatures, electrical conductivity (EC) and pH valueswere measured in the field during sampling. Electrical conductivityvalues were converted to total dissolved solids (TDS) using aTDS/EC ratio of 0.5. Cations (Ca2+, Mg2+, Na+ and K+) were analyzedby atomic absorption spectrometry (AAS) on Perkin Elmer Analyst800, anions (Cl−, SO4

2−, NO3−, NO2

−, NH3 and PO43−) by spectropho-

tometer DL/5000 HACH, and HCO3− by alkalinity titration in the Envi-

ronmental Geochemistry Laboratory of the Faculty of GeotechnicalEngineering, University of Zagreb (Table 2).

The stable isotope composition of water samples wasmeasured ona dual inlet Finnigan DELTAplus and continuous flow DELTAplus XPMass Spectrometers with a HEKAtech high-temperature oven at theInstitute of Water Resources Management, Joanneum Research(Graz, Austria; Table 3). The oxygen isotopic composition (δ

18O) was

measured by means of water–CO2 equilibrium techniques, and theisotopic composition of hydrogen (δ

2H, δD) was obtained by using

H2 generated by reduction of water over hot chromium. Results areexpressed in δ-notation, as per mil (‰) of the isotope ratio from the

10

11

12

13

14

15

16

17

18

19

20

2/11/06 20/4/07 4/9/07 28/1/08 28/8/08 30/9/08 12/2/09 2/6/09 14/9/09

day/month/year

Tem

per

atu

re (

oC

)

Vodova a

Duboka Ljuta

Konavoska Ljuta

Dragavine

Fig. 5. Temperature variations in spring waters of the Konavle area.

Table 3Stable isotope content in spring waters of the Konavle area.

Spring Sample code δ18O δ

2H

(‰ SMOW) (‰ SMOW)

Duboka Ljuta DLJ/02/11/06 −6.85 −42.0Duboka Ljuta DLJ/20/04/07 −7.40 −43.2Duboka Ljuta DLJ/01/09/07 −7.34 −45.5Duboka Ljuta DLJ/28/01/08 −7.19 −42.8Duboka Ljuta DLJ/28/08/08 −6.72 −38.7Duboka Ljuta DLJ/12/02/09 −6.92 −42.8Duboka Ljuta DLJ/02/06/09 −7.14 −41.6Duboka Ljuta DLJ/14/09/09 −7.16 −35.0

Average value −7.09 −41.4

Dragavine DRA/28/08/08 −6.05 −36.3Dragavine DRA/12/02/09 −6.09 −38.8Dragavine DRA/02/06/09 −6.17 −36.7Dragavine DRA/14/09/09 −6.42 −39.1

Average value −6.18 −37.7

Konavoska Ljuta LJ/02/11/06 −7.19 −47.5Konavoska Ljuta LJ/20/04/07 −7.72 −48.4Konavoska Ljuta LJ/01/09/07 −7.52 −44.7Konavoska Ljuta LJ/28/01/08 −7.40 −44.3Konavoska Ljuta LJ/28/08/08 −7.11 −40.3Konavoska Ljuta LJ/12/02/09 −7.08 −41.0Konavoska Ljuta LJ/02/06/09 −7.46 −44.9Konavoska Ljuta LJ/14/09/09 −7.37 −45.0

Average value −7.36 −44.5

Vodovađa VOD/02/11/06 −6.94 −42.2Vodovađa VOD/20/04/07 −7.10 −42.7Vodovađa VOD/01/09/07 −7.00 −39.5Vodovađa VOD/28/01/08 −7.09 −40.8Vodovađa VOD/28/08/08 −6.86 −37.5Vodovađa VOD/12/02/09 −7.03 −39.6Vodovađa VOD/02/06/09 −7.06 −40.5Vodovađa VOD/14/09/09 −7.12 −40.3

Average value −7.03 −40.4

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international V-SMOW standard. The δ values are calculated fromconventional relation

δ ‰ð Þ ¼ Rsample−RSMOW

� �=RSMOW×1000

where Rsample is mass ratio for stable isotope, and RSMOW is the valueof Standard Mean Ocean Water. Measurement reproducibility of du-plicates was better than ±0.1‰ for δ

18O and ±1‰ for δD (Table 3).

4.2. Hydrogeochemical features of spring waters

The physical and chemical characteristics of the spring water sam-ples are shown in Table 2. The spring water temperatures range from11.7 to 18.7 °C (Fig. 5), and pH values range between 7.02 and 7.90(Table 2). Temperature variations reflected seasonal changes in airtemperature; water infiltrated during the colder period of the yearhad lower values, while higher temperature of spring waters was ob-served during warmer months — April, August and September.

Spring waters are slightly alkaline corresponding to groundwaterfrom carbonate aquifers. Low pH value recorded in two springs,Vodovađa and Duboka Ljuta, indicates increase in acidity due to con-tribution of CO2 from soil due to the first precipitation after dry sum-mer period (end of August, September). Total dissolved solids werequite uniform during drier seasons, with evident slight increase inthe Duboka Ljuta spring in autumn (Fig. 6).

According to their hydrogeochemical type, spring waters have allfeatures of groundwater originating from carbonate rocks — lime-stones and dolomites (see e.g. Hem, 1985; Appelo and Postma,2005). Dissolution of carbonate rocks forms predominately Ca–HCO3

to CaMg–HCO3 geochemical types of water depending on particularlithological contribution. In the Dinarides, main ionic ratio in surfaceand groundwaters could be changed due to the influence of seaor evaporite dissolution, mainly of gypsum and anhydrite deposits(Slišković et al., 1998; Štambuk-Giljanović, 2006). In lithologicallyvery homogenous areas delineation of particular catchments orsubcatchments by geochemical methods is possible only by calciumand magnesium ratio and natural isotope distribution and theirtemporal hydrological and seasonal variations (Biondić et al., 2006;Lukač Reberski et al., 2009).

Ratios for Konavoska Ljuta spring are lower than for Duboka Ljutaspring because each particular spring drains lithologically differentparts of the studied hydrogeological system — catchments of Konavlesprings (Fig. 7).

Also, Vodovađa spring water composition is more uniform thanDragavine, Konavoska Ljuta and Duboka Ljuta springs, what is in ac-cordance with dominant lithological composition and hydrodynamicregime of a particular recharge area, since considerable content of do-lomites within the Vodovađa spring drainage area cause certaingroundwater retention. Predominantly diffuse underground flow re-sults in smaller but stable discharges during the year and better ho-mogenization of water chemical composition. Conduit underground

150

200

250

300

350

400

450

500

day/month/year

TD

S (

mg

/L)

Vodova a

Duboka Ljuta

Konavoska Ljuta

Dragavine

2/11/06 20/4/07 4/9/07 28/1/08 28/8/08 30/9/08 12/2/09 2/6/09 14/9/09

Fig. 6. Total dissolved solids in spring waters of the Konavle area.

2.00

2.50

3.00

3.50

4.00

4.50

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00

n(Ca/Mg)

n(H

CO

3- )

Vodova a

Dragavine

Konavoska LjutaDuboka Ljuta

Fig. 7. Calcium and magnesium molar ratio vs. hydrocarbonate alkalinity in spring waters of the Konavle area.

292 B. Prtoljan et al. / Journal of Geochemical Exploration 112 (2012) 285–296

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flows prevail within the Konavoska Ljuta and especially within theDuboka Ljuta spring recharge areas. However, every change in hydro-logic conditions during the year influences chemical composition ofthese spring waters.

Spring waters are oversaturated to unsaturated with respect tocalcite, and unsaturated with respect to dolomite (Fig. 8). Saturationindices and pCO2 have been calculated by NETPATH computer programfor geochemical calculations and geochemical modeling (Plummeret al., 1994).

Increase in CO2 partial pressure in spring waters as a consequence ofthe leaching throughout the soil zone, mainly during the vegetation sea-son, caused decrease in saturation indices for calcite and dolomite.

The nitrate concentration in Vodovađa and Konavoska Ljutasprings is lower in comparison with concentration of the DubokaLjuta spring (Fig. 9). Values in Duboka Ljuta were especially higherduring 2007 and 2009, more than twice higher than typical naturalvalues for karst waters in the Dinarides (b1 mg N/L).

Orthophosphates are a reliable indicator of anthropogenic impacton groundwater, especially waste waters from settlements withoutproper sewage systems and agricultural activities — application of fer-tilizers. The highest orthophosphate concentrations, only slightlybelow permitted values, were found in the Duboka Ljuta spring waters(Fig. 10). Some studies found out that even in a conduit flow situation,

phosphate can be retained within the karst aquifer due to multipledesorption/sorption reactions in soils or geochemical transformationsfrom soluble to insoluble forms (Karstrinos and White, 1986; Wiersmaet al., 1986; Hardwick, 1995). Although the concentrationsof orthophosphates in other springs are lower, there are some solidevidences (tracing tests, occasional microbiological contamination)that all observed spring drainage areas could be subjected to wastewaters from inland settlements of SE Bosnia and Herzegovina(Štambuk-Giljanović, 2006).

Probably due to the influence of the evaporites which have beenfound in the vicinity of the Dragavine spring (Marković, 1971), sulfateand chloride contents recorded in this spring are higher than in otherthree springs. Dragavine spring composition is presented togetherwith main ion composition of other springs in Fig. 11.

4.3. Isotopic results

The δ18O and δD values for Vodovađa spring range from −6.86 to −

7.12‰ and from −37.50 to −42.65‰, for Duboka Ljuta spring from −6.72 to −7.40‰ and −34.99 to −41.99‰, for Konavoska Ljuta springfrom−7.08 to−7.72‰, and from−40.30 to−48.35‰, and for Draga-vine spring from −6.05 to −6.42‰ and from −36.30 to −38.80‰,respectively (Table 3).

-2.500

-2.000

-1.500

-1.000

-0.500

0.000

0.500

1.000

VO

D/0

2/11

/06

VO

D/2

0/04

/07

VO

D/0

4/09

/07

VO

D/2

8/01

/08

VO

D/2

8/08

/08

VO

D/3

0/09

/08

VO

D/1

2/02

/09

VO

D/0

2/06

/09

VO

D/1

4/09

/09

LJ/0

2/11

/06

LJ/2

0/04

/07

LJ/0

4/09

/07

LJ/2

8/01

/08

LJ/2

8/08

/08

LJ/3

0/09

/08

LJ/1

2/02

/09

LJ/0

2/06

/09

LJ/1

4/09

/09

DLJ

/02/

11/0

6D

LJ/2

0/04

/07

DLJ

/04/

09/0

7D

LJ/2

8/01

/08

DLJ

/28/

08/0

8D

LJ/3

0/09

/08

DLJ

/12/

02/0

9D

LJ/0

2/06

/09

DLJ

/14/

09/0

9

DR

A/2

8/01

/08

DR

A/2

8/08

/08

DR

A/3

0/09

/08

DR

A/1

2/02

/09

DR

A/0

2/06

/09

DR

A/1

4/09

/09

log

SI c

alci

te,

log

SI d

olo

mit

e

-3.000

-2.500

-2.000

-1.500

-1.000

-0.500

0.000log SI calcite

log SI dolomite

log pCO2

log

pC

O2

Fig. 8. Saturation state and logpCO2 of spring waters of the Konavle area.

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

day/month/year

NO

3-N

(m

g/L

)

Vodova a

Duboka Ljuta

Konavoska Ljuta

Dragavine

2/11/06 20/4/07 4/9/07 28/1/08 28/8/08 30/9/08 12/2/09 2/6/09 14/9/09

Fig. 9. Nitrate content in spring waters of the Konavle area.

293B. Prtoljan et al. / Journal of Geochemical Exploration 112 (2012) 285–296

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The precipitation isotope content is usually presented by meteoricwater line on a global level (GMWL— Global Meteoric Water Line) oron a local level (LMWL — Local Meteoric Water Line) (Kendall andMcDonnell, 1998; Gat et al., 2001; Geyh et al., 2001). The position oflocal meteoric water line is controlled by several effects: air temper-ature, continental and rain shadowing, altitude and amount effects.The aforementioned effects are very important for application of iso-topes as natural groundwater tracers. Their influences may changethe isotope ratio, making precipitation enriched or depleted withheavier isotope content. Its distribution in groundwater can provideinformation about groundwater origin, recharge rate, hydrodynamicconditions within the aquifer, mean residence time of water in theaquifer and interconnections between aquifers.

A δ2H and δ

18O values in springs water mostly lies between the

Global Meteoric Water Line (δ2H=8δ

18O+10) and Local Meteoric

Water Line obtained from the precipitation monitoring on the Du-brovnik station (Krajcar Bronić et al., 2003). For south Adriatic sta-tions the slope of the LMWL is lower than for continental meteoricstations and the continental precipitation influence can be observedin the samples mainly from the Konavoska Ljuta spring (Fig. 12).

Average values are highest for Dragavine spring (−6.18‰), some-what lower for Vodovađa (−7.03‰) and Duboka Ljuta (−7.09‰)springs and the lowest for Konavoska Ljuta spring (−7.36‰), as a re-sult of predominant drainage area elevation of particular springs(Table 3).

Dragavine spring is a local spring of a low discharge draining avery small sub-catchment in between Duboka Ljuta and KonavoskaLjuta sub-catchments. Vodovađa spring has relatively small drainageareas but due to considerable dolomite content it has good retentioncapabilities and very stable outflow. Duboka Ljuta spring catchment issituated on higher elevation, while the Konavoska Ljuta spring pre-vailing recharge area is mostly located at the highest elevation farfrom the coastal zone.

Quantification of the average elevation of predominant rechargeof particular spring could be based on the altitude effect because pre-cipitation gets isotopically lighter (depleted in heavier isotope) withincreasing altitude. After the four year precipitation monitoring onselected stations the decrease of 0.37‰ δ

18O per 100 m altitude differ-

ence was obtained for continental stations, while for the stations inthe coastal region the decrease was 0.26‰ δ

18O per 100 m altitude dif-

ference (Krajcar Bronić et al., 2004).Because of the relations shown in Fig. 12 that isotope ratio of ob-

served springs reflects partly a more significant sea influence andpartly the continental regime of precipitation within the rechargearea, 0.26‰ δ

18O per 100 m was applied for altitude calculations.

Due to the smaller number of isotope data Dragavine spring was ex-cluded from altitude calculation (Table 4). Also, the altitude of theVodovađa spring was used as a reference location because of smallisotope content fluctuations and expected smaller recharge area incomparison with other springs (Fig. 13). For calculation we used thefollowing relation:

Altitudespring ¼ δ18OVodovađa spring−δ18Ospring

� �� 100=0:26

þ AltitudeVodovađa spring

In April waters from all four springs had lower δ18O isotope con-

tent (Fig. 13), which probably reflects the contribution of infiltratedprecipitation or thawing of snow from the colder period of the year.

5. Discussion and conclusions

Geological, morphological, structural and hydrogeological rela-tions of the major karst spring areas in the Konavle region were ana-lyzed, along with hydrochemical and isotope characteristics ofgroundwaters. A large part of the catchment is situated in neighbor-ing Bosnia and Herzegovina and partly Montenegro, thus we are

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

day/month/year

Ph

osp

hat

e (m

g/L

)

Vodova a

Duboka Ljuta

Konavoska Ljuta

Dragavine

2/11/06 20/4/07 4/9/07 28/1/08 28/8/08 30/9/08 12/2/09 2/6/09 14/9/09

Fig. 10. Orthophosphate content in spring waters of the Konavle area.

Fig. 11. Piper plot of spring water samples major ion composition.

294 B. Prtoljan et al. / Journal of Geochemical Exploration 112 (2012) 285–296

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dealing with a transboundary aquifer. Important water potential hasbeen recognized decades ago and very comprehensive studies wereperformed for hydroenergetic utilization purposes.

As a typical high karst terrain of the Dinarides, the catchmentareas are marked by poorly developed surface and well developedunderground hydrographic network with groundwater flow and dis-charge regime. One of the main characteristics of this system is a highvelocity of drainage, as a consequence of significant polyphase tecton-ics (Lawrence et al., 1995; Prtoljan et al., 2007) which intensified kar-stification. The most important aquifers are Jurassic grainy limestonescontaining lenses and interbeds of dolomites, which are underlain bya relatively thick sequence of the Upper Triassic dolomites. Complexrelationships between permeable limestones and less permeable do-lomites represent one of the most important moderators of thegroundwaters in the Dinaric karst. In the study area Palaeogene(and Neogene?) clastic rocks, over which Mesozoic carbonates areoverthrust, represent the most important barrier to the undergroundflows.

Geological, hydrogeological, hydrogeochemical and isotope stud-ies determined that all studied spring areas belong to separate sub-catchments with highly complex structural and tectonic pattern.These spring areas drain inflow areas of fully developed karst mor-phological forms.

Hydraulic systems in catchments drained from highland inflowareas at the Duboka Ljuta and Konavoska Ljuta springs, which havehighly fluctuating discharges, react quickly and abruptly during therainy periods and/or during sudden snow thawing. Variable hydro-logical conditions also cause certain seasonal changes in physicaland chemical characteristics of water flowing out at the springs.This confirms that the karst underground is regulated by complexhydrogeological conditions with well and deeply developed drainagesystems in the spring recharge area hinterland.

Higher presence of dolomites in the Vodovađa spring catchmentincreases retention capacity of underground which, consequently,causes lower discharges, smaller discharge fluctuations and ratheruniform chemical and isotopic composition. Predominant rechargearea of Konavoska Ljuta spring is located at the highest elevation

and largest distance from the coastal zone. Groundwater infiltratedat hypsometrically somewhat lower area springs at Duboka Ljuta,and the lowest altitude replenishment area is that of Vodovađa andDragavine spring areas, and drainage areas of these springs are sepa-rated by diagonal fault striking N–S.

Orthophosphate contents measured in spring water indicate thatall three springs are suffering from anthropogenic impacts, probablycaused by wastewater from the settlements situated in the catch-ments, partly in neighboring Bosnia and Herzegovina. The highestphosphate content was recorded at the Duboka Ljuta spring, andthe lowest at the Vodovađa spring. These results completely confirmprevious evidence of anthropogenic impact on Duboka Ljuta springwater quality (Štambuk-Giljanović, 2006).

Considering the above facts, the Vodovađa spring may be suitablefor tapping of new groundwater reserves within the studied area,since it suffered the lowest transboundary impact from populatedareas in the neighboring regions, and although its discharges arelower they are relatively constant.

Because of sub-catchments transboundary character further activ-ities should be extended to Eastern Herzegovina: successful ground-water protection in recharge areas of the Duboka Ljuta andKonavoska Ljuta springs is possible only through bilateral trans-boundary cooperation that would result in appropriate wastewatertreatment in the neighboring country.

Results achieved by presented preliminary investigations indicatea need for continuous monitoring of hydrochemical characteristics ofmain drainage systems in the Konavle area in order to protect and im-prove utilization of potable water. Achieved results may represent agood basis for the future investigation of similar systems in thewider area of the Dinarides.

Acknowledgment

This study was co-funded by The National Foundation for Science,Higher Education and Technological Development of the Republic ofCroatia (70%) and Konavle Municipality (30%) through project ‘Geo-logical Map of the Konavle area, 1:50,000 Scale — a precondition fora sustainable development’ (Principal Investigator B.P.) in the frameof the program ‘Partnership in Basic Research’. The authors are grate-ful to responsible persons from both National Foundation and localcommunity for very professional, but also friendly support in allphases of work. Some works were partially supported by the CroatianMinistry of Science, Education and Sports through projects No. 181–1811096–3061, 160–0982709–1709 and 195–1953068–0242. The

-7.80 -7.60 -7.40 -7.20 -7.00 -6.80 -6.60 -6.40 -6.20 -6.00

Delta 18O (‰ SMOW)

GMWL

LMWL

Dragavine spring

Duboka Ljuta

Vodovada

Konavoska Ljuta spring

-54.00

-52.00

-50.00

-48.00

-46.00

-44.00

-42.00

-40.00

-38.00

-36.00

Del

ta 2

H (

‰S

MO

W)

Fig. 12. Relationship between δ2H and δ18O in spring waters of the Konavle area with GMWL and LMWL position.

Table 4Calculated average altitudes of Konavle springs recharge areas.

Vodovađa Duboka Ljuta Konavoska Ljuta

Mean average δ18O (‰ SMOW) −7.03 −7.09 −7.36

Altitude (m a.s.l.) 800 823 926

295B. Prtoljan et al. / Journal of Geochemical Exploration 112 (2012) 285–296

Author's personal copy

authors are grateful to the journal's Associate Editor and anonymousreviewers whose suggestions and comments improved the papersignificantly.

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Duboka Ljuta

Dragavine

Konavoska Ljuta

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elta

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day/month/year

Fig. 13. δ18O variations in spring waters of the Konavle area.

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