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Chemie der Erde 73 (2013) 293– 308

Contents lists available at ScienceDirect

Chemie der Erde

jou rn al homepage: www.elsev ier .de /chemer

eochemical and stable isotopic variability within two rivers rising under theame mountain, but belonging to two distant watersheds

tanislav Franciskovic-Bilinskia,∗, Vlado Cuculic a, Halka Bilinskia, Hermann Häuslerb, Philipp Stadlerb

Ruder Boskovic Institute, Division for Marine and Environmental Research, POB 180, HR-10002 Zagreb, CroatiaUniversity of Vienna, Faculty of Earth Sciences, Geography and Astronomy, Department for Environmental Geosciences, Althanstraße 14, A-1090 Vienna, Austria

r t i c l e i n f o

rticle history:eceived 2 July 2012ccepted 19 February 2013

eywords:upa and Rjecina rivers (Croatia)isnjak National Parkerhumid climatehysical–chemical parametersediment and water chemistrytable isotopes (deuterium and oxygen-18)ransboundary karst aquiferater quality

a b s t r a c t

Complementary geochemical and stable isotope investigations of the Gorski Kotar karst aquifer systemin western Croatia were obtained for the first time, to answer the question whether both studied riversdrain the same aquifer system or not. The two main rivers, the Kupa and the Rjecina, rise under the samemountain range, but belong to two different watersheds (Black Sea and Adriatic Sea). The karst aquifer ofGorski Kotar is a potentially important source of drinking water for two neighboring countries, Croatia andSlovenia (Central and South Europe), and is strongly influenced by both Mediterranean and continentalweather conditions. It is a part of the Dinaric karst, which is “locus typicus” for karst worldwide and oneof the most typical karst areas in the world.

To answer the main question of our research, baseline data were thoroughly collected comprisingstable isotopes, concentration of dissolved and total trace metals in water, and multi-elemental analysesof river sediments, together with other physical-chemical parameters (pH, dissolved oxygen, electricconductivity and temperature). Total dissolved solid (TDS) was not measured but estimated as (EC) 0.67.Such multi-technique approach was applied for the first time in the Dinaric karst systems.

Multi-elemental analysis of fine sediment fraction (<63 �m) of eight samples was performed by ICP-MS.Elemental composition of sediments is quite different in the two studied river valleys, which indicatesdifferent origin of their waters. Also, concentrations of selected metals were compared with existingsediment quality criteria and anthropogenic influence is evaluated and discussed.

Analytical results of major ions determined in three springs (Kupa spring, Rjecina spring, Zvir springin the City of Rijeka) were used to construct a Piper diagram, which showed that they are of aCa–Na–HCO3–Cl type. The highest concentration of Mg is present in the Kupa spring, while the high-est concentrations of Na and Cl are present in the Zvir spring. Groundwaters are underlain by limestone,less by dolomite and are under a maritime influence. There is a big difference with the main groundwatertypes reported in North Africa, i.e. in the south Mediterranean Sea, where two main groundwater typesare Na–Cl and Ca–SO4–Cl.

Concentrations of total and dissolved fractions of trace metals in surface water samples were deter-mined by voltammetry and compared to the European Water Framework Directive values. Concentrationsof total Pb and Zn are significantly higher in the water of the Kupa spring than the Rjecina spring,suggesting that the karst water bodies of the two springs are not of the same origin.

In addition, stable isotope composition (deuterium and oxygen-18) was determined in the springwaters sampled during low and high water conditions. Due to the significant difference in oxygenisotope-ratios it was concluded that the karst reservoir for the Kupa and Rjecina springs is not identical.

The results obtained from the combination of physical–chemical, geochemical (water and sediment)que asame

and isotope multi-technirivers originate from the

∗ Corresponding author. Tel.: +385 1 4561081; fax: +385 1 4680242.E-mail address: francis@irb.hr (S. Franciskovic-Bilinski).

009-2819/$ – see front matter © 2013 Elsevier GmbH. All rights reserved.ttp://dx.doi.org/10.1016/j.chemer.2013.02.004

nalyses pointed out that even though the springs of the Kupa and Rjecina mountain range, they do not drain the same karst aquifer.

© 2013 Elsevier GmbH. All rights reserved.

1. Introduction

In general, karst aquifers in mountain regions, which can beused as potable water, have been receiving increasing attention,particularly to determine the overall water quality pattern. This

study describes an example of the region in Croatia with a largewater dividing zone between the Adriatic Sea and the Black Seacatchments, located in the mountain area of the Risnjak massif.

2 Chemi

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94 S. Franciskovic-Bilinski et al. /

The Upper Kupa river catchment area was studied within theational Park Risnjak, whereas the Rjecina river was investigated

n the whole catchment area. The air distance between the Kupapring and the Rjecina spring is 22 km only. A brief description ofrevious studies in both catchments is given below.

The Kupa spring is located at 321 meters above sea level (m a.s.l.)nd its water wells up from a siphon, which is 80 m deep. Theater flows about 5 km within the forested National Park Risnjak,hich is characterized by its karst phenomena and biodiversity.t the northern edge of the National Park Risnjak, the Kupa rivereets a large tributary, the Cabranka river. The geochemical status

nd the pollution status of stream sediments of the whole Kupaiver drainage basin (except that part within the National Park)as studied in detail by Franciskovic-Bilinski (2005, 2006, 2007,

008) and by Franciskovic-Bilinski et al. (2005a, 2005b, 2007,012). Preliminary study on the weathering of sandstones waseported by Bilinski (2008). Similar studies of stream sedimentsithin the National Park have not been performed either on the

uality of water or with respect to ecotoxic elements. The Kupaiver drainage basin of 10,000 km2 is a large supra regional basin,ith its central position in Croatia, which extends into the twoeighboring countries, Slovenia as well as Bosnia and Herzego-ina. The north-western part of the basin is an important wateresource for Croatia and a potentially important water resourceor Slovenia. This is due to the fact that the Slovenian part of theupa drainage basin is sparsely inhabited, without any significantettlement. Therefore, there are no major water supply systemsn the Slovenian side and there is no data about the quantity ofupplied drinking water. On the Croatian side of the north-westernart of Kupa river drainage basin there are also no major townsthe town of Delnice with 6200 inhabitants is the largest), but therea is much more densely populated than on the Slovenian side.here is therefore a regional water supply system of Gorski KotarRegionalni vodovod “Gorski Kotar”), which supplies that part ofhe drainage basin. Most water in this water supply system is takenrom the Kupica river spring, while there is no spring-water intaket the Kupa river spring itself. According to the data available atttp://www.komunalac.hr/o-nama/djelatnost/vodoopskrba.htmlin Croatian), 1,165,123 m3 of water was supplied from the regionalater supply system in 2008.

The area on the marine side of the Gorski Kotar Mountains,n the Rjecina river watershed, is much more densely populated,

ith the third biggest urban centre in Croatia – the City of Rijeka,hich together with the suburban area has about 200,000 inhabi-

ants. The needed quantities of water are therefore much larger.he Rijeka water supply system uses several spring-water intakes,mong which three are the largest: the Rjecina spring (suppliesaximum of 20,500,000 m3 of water per year), the Zvir I spring

supplies maximum of 31,000,000 m3 of water per year) andhe Zvir II spring (supplies maximum of 7,100,000 m3 of waterer year). More data are available at http://www.kdvik-rijeka.hr/efault.asp?ru=11&sid=&akcija=&jezik=1 (in Croatian).

The Rjecina spring is located at 325 m a.s.l. It was expected thatoth the Kupa spring and the Rjecina spring would show similareochemical and stable isotope characteristics. The spring at Zvir,hich is additionally used for drinking water supply during the dry

eason, is located in the centre of the City of Rijeka. It was studied byahun and Fritz (1987) and Dukaric (2002), who described the karstystem of Zvir as connected with a submerged cave system reach-ng down 48 m below the sea level. The Rjecina river is the main

atercourse north of the City of Rijeka, Croatia. Its catchment areas 218 km2 and the length of its watercourse is 18.3 km. The longi-

udinal slope of the watercourse varies from 1.0% in the upper part,hrough 3.0% in the central part, to a minimum 0.36% in the lowerart. The total quantity of sediment produced in the Rjecina catch-ent area, estimated by parametric methods, is 10,000 m3/year.

e der Erde 73 (2013) 293– 308

2000 m3 are transported by the watercourse, and mainly depositedin the lower Rjecina river, in the section between the closed paperfactory and the river mouth at the sea. The discharge varies largelyduring the year, from a minimum of <0.1 m3/s in the profile directlybelow the spring-water intake (usually for about 30 days duringsummer months) to the maximum ever recorded 440 m3/s at theriver mouth profile (calculated on the basis of observations duringthe disastrous flood on September 19, 1898), while the average flowis 12.9 m3/s (Biondic et al., 1997; Benac et al., 2005; Karleusa et al.,2009). There is only one hydrological station, situated in Drastin,which is halfway from the source to the mouth of the Rjecina.

Benac and Arbanas (1990) as well as Benac et al. (2003)described sedimentation processes in the area of the Rjecina mouth.They found that under the fluvial deposits there exists a fossil val-ley, which is about 1 km long and up to 60 m deep cut in carbonatebedrock. During the last (Holocene) transgression, the sea intrudeddeep into the mainland, and a ria was formed. Sopta et al. (2003)analyzed flood wave propagation along the Rjecina river for theprotection of the City of Rijeka from floods.

The water quality of the Rjecina river is routinely controlled byHrvatske Vode, but elements in waters and sediments have notbeen monitored so far (Hrvatske Vode, 2007). Recent research onsediments from the Rjecina river, from the spring-water intaketo the polluted prodelta (Franciskovic-Bilinski et al., 2011) and inRijeka Bay (Cukrov et al., 2011) were the first attempts to investi-gate sediments in that region.

Furthermore, isotopic composition (deuterium and oxygen-18)of river waters has not been intensively studied, despite the factthat this method has been known since Friedman et al. (1964).New investigations of stable isotopes in European rivers werereported on the River Danube by Rank et al. (2009) and on theRiver Weser by Koeniger et al. (2009). Biondic (2000) reported onfirst measurements of stable isotopes in the Rijeka catchmentsand Biondic (2003) on those in the Kupa catchments. Horvatincicet al. (2005) performed a study of tritium and stable isotopedistribution in the atmosphere at the coastal region of Croatia.Kapelj et al. (2002) and Biondic et al. (2006) investigated theisotopic composition of several springs in the Kupa and Rjecinacatchments. Häusler et al. (2012) reported preliminary resultsfrom stable isotope investigations of river waters in the wholeKupa Drainage Basin, Western Croatia, based on one samplingcampaign during a wet autumn period.

The aim of the present work is to investigate groundwater–riverinteractions, using chemistry of sediments and waters in additionto stable isotopes (deuterium and oxygen-18) in the uppermostsection of the Kupa river and in the whole length of the Rjecinariver. Our goal is to obtain the basic data set for stable isotopesand for elements in sediments and waters, and use some of themas traces of the extent of environmental changes. Also, we want tocompare origins of the Kupa and Rjecina spring waters. Our hypoth-esis is that the springs of the Kupa and Rjecina rivers (belongingto the Black Sea and Adriatic Sea watersheds, respectively) bothoriginate from the same recharge area situated at the boundaryof the two watersheds under the mountain Risnjak. The knowl-edge of their connectivity is needed for the efficient managementof water resources in the transboundary karst area of South-CentralEurope.

2. Study area

2.1. Climate characteristics of the study area

The main climate characteristics of the study area will be sum-marized using data from the Climate Atlas of Croatia 1961–1990and 1971–2000 (Zaninovic et al., 2008).

S. Franciskovic-Bilinski et al. / Chemie der Erde 73 (2013) 293– 308 295

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ig. 1. (a) A sketch map of the investigated section of the Kupa river with samplinroatia. (b) A sketch map of the Rjecina river with sampling stations and also show

According to the Thornthwaite climate classification, based onhe relation between the amount of water necessary for poten-ial evapotranspiration and obtained from precipitation, there areve types of climate, from perhumid to arid. Croatia has perhumid,umid and subhumid climates. In the highlands, including Gorskiotar Mountains, the perhumid climate prevails. In coastal Croatia,

here are perhumid, humid and subhumid climates. In the Kvarneray, besides the cyclogenetic effect, the mountainous hinterlandenerates high amounts of precipitation, because of its orographicffect that intensifies precipitation, which is especially manifest inhe wider region of Rijeka. Therefore, according to the Thornth-aite index values, Rijeka has a perhumid climate, similar to thathich is prevalent in the highland part of Croatia. So, both river

alleys studied within the current paper have perhumid climate.The largest annual amounts of precipitation in whole Croatia

all in Gorski Kotar Mountains (in some places from 3000 mm/yearo more than 3500 mm/year). In the Rijeka area, amounts of pre-ipitation are around 1500 mm/year and they increase going inlandnto the mountains. So, the Rjecina river valley has somewhat lowermounts of precipitation than the Upper Kupa valley, even thoughhey are still very high. For comparison, it is important to mentionhat the Lower Kupa river course (not studied within this paper),hich is under a predominant continental influence, has precipita-

ion of only about 800–900 mm/year.To give more details about climate characteristics of two stud-

ed river valleys, two meteorological stations are chosen, for whicheveral data will be presented. Regretfully, a network of meteoro-ogical stations is very sparse in the whole region, so the numberf stations which could be used to present the climate of those two

ions and also showing simplified lithology and position of the river valley withinplified lithology and position of the river valley within Croatia.

river valleys is limited to two: Parg on the mainland side, represen-tative for the Upper Kupa river valley, and Rijeka, representativefor the Rjecina river valley. Even though both stations belong tothe perhumid type of climate, they are of different sub-type, asthe coastal side is predominantly under the Mediterranean influ-ence and has much warmer climate. The mean annual temperaturesare 7.0 ◦C in Parg and 13.6 ◦C in Rijeka, which is much higher. Themean temperatures in January (the coldest month at both stations)are −2 ◦C in Parg and 5.3 ◦C in Rijeka. The mean temperatures inJune (the warmest month at both stations) are 16.2 ◦C in Parg and22.8 ◦C in Rijeka. Precipitation does not differ much between thosetwo stations; in the Kupa valley it is slightly higher than in theRjecina valley: Parg has 1849 mm/year, while Rijeka has 1561 mm.But, the ET (evapotranspiration) value is much lower in Parg (only462 mm/year), while in Rijeka it is about double (950 mm/year).The relative annual average of air humidity is higher in Parg (80%)than on the coastal side in Rijeka (62.9%).

These climate characteristics of our study area at the north-ern side of the Mediterranean basin are completely opposite tothe characteristics of important aquifers on the southern side ofthe Mediterranean, on the African side (Hamed et al., 2008). Insouth-western Tunisia there is semi-arid type of climate, with meanannual precipitation of only 165 mm, the mean annual temperatureof 22 ◦C and potential evapotranspiration of 1680 mm/year.

2.2. Geologic setting

The study area in Western Croatia belongs to the central Dinar-ides, a mountain range comprising folded Paleozoic to Mesozoic

296 S. Franciskovic-Bilinski et al. / Chemie der Erde 73 (2013) 293– 308

Table 1Generalized lithostratigraphic profile, maximum thickness in m according to legend of the official geologic maps 1:100,000, and hydrogeologic characteristics of the formationsin the study area of the Gorski Kotar and its southern foreland.

Legend Stage Lithology Thickness (m) Hydrogeologic characteristics

Pg Paleogene Calcarenite (Flysch) 1000 AquitardC Cretaceous Limestone and dolomite 2300 Karst aquiferJ Jurassic Predominantly dolomite 2000 Karst aquifer

ite 450 Karst aquiferrate 1000 Aquitardrate 380 Aquitard

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Fig. 2. Hydrogeologic map of the study area with hydrological water divide betweenthe Kupa catchment in the north and the Rjecina catchment in the south. Gen-eral flow direction of karst groundwater and general discharge at prominent karstsprings. Dotted line marks hydrogeologic profile in northeast-southwest direction

T Triassic Predominantly dolomPe Permian Sandstone, conglomeCa Carboniferous Sandstone, conglome

ormations, which were partly thrusted to the southwest and whichre unconformably overlain by Palaeogene deposits. The Palaeo-oic formations are predominantly of continental origin and consistf 380 m thick sandstones and conglomerates of Carboniferousge, which are overlain by Permian coarse-clastic rocks of about000 m in thickness. Mesozoic formations predominantly consistf dolomites, which are 300 m in thickness. In total about 2000 mf Jurassic dolomites build up the central part of Gorski Kotar; thesere overlain by thick Cretaceous dolomites in the northeast, border-ng Slovenia, and in the southwest, close to the Adriatic Sea, theyverthrust Paleogene deposits. More details are available in Table 1,hich presents a generalized lithostratigraphic profile, the maxi-um thickness in m according to the legend of the official geologicaps 1:100,000 and hydrogeologic characteristics of the forma-

ions in the study area of Gorski Kotar and its southern foreland.In a few regions it is problematic to draw geologic sections,

ecause the relation of Mesozoic dolomite formations to each othernd to clastic rocks of the Permian age is sometimes not clearue to dense fault tectonics and missing outcrops in the karsti-ed plateaus. In former times the geologic section of the officialeologic map Delnice 1:100,000 (Dimitrijevic et al., 1975) wasrawn as faulted domain, where Permian sandstones and Triassicolomites were drawn in upright sequences, bordering the Juras-ic series. Hydrogeological investigations by Herak (1962, 1980)roved, however, that outcrops of Jurassic dolomites in the upperupa river, e.g. around the village of Brod na Kupi, occur in a tec-

onic window, surrounded and overlain by Permian sandstones. As result, large areas of Permian sandstones and Triassic dolomitesan be drawn as tectonic slices thrusted over Jurassic (and partlyretaceous) formations.

Simplified lithology of both studied river valleys is presented inig. 1a and b.

.3. Hydrogeologic setting

The fundamental papers on karst groundwater of the Rjecinaatchment were published by Biondic et al. (1997) and Biondic1988) and on the Kupa catchment by Biondic et al. (2006). In gen-ral, the aquifer characteristics of Gorski Kotar are quite simple,he coarse-clastic continental Paleozoic and lower Triassic forma-ions are hardly permeable or impermeable acting as aquitardsr aquicludes, and the overlying dolomites of Triassic to Jurassicges are major karst aquifers (Fig. 2). Where such continen-al Paleozoic to Mesozoic formations were thrust over karstifiedurassic formations, however, the overlying Permian sandstonesocally camouflage the karst water flow below (Fig. 3). Hydro-eologic conditions become more difficult, where a sequence ofermian sandstone in contact with Triassic dolomite overlies Juras-ic dolomites, because then two karst aquifers can occur, whichre separated by impermeable Permian rocks. Recently Stadler andäusler (2012) described such a complex hydrogeological situa-

ion at Zeleni Vir, where intensively folded Jurassic dolomite of theeleni Vir window forms the basal karst aquifer with its famouseleni Vir Spring (which runs a small hydropower station), andhe overthrusted Permian formation is overlain by an upper karst

(Fig. 3; modified based on the hydrogeological map of Croatia 1:300,000; courtesyof the Croatian Geological Survey).

aquifer, which locally discharges at the foothills of Skradski vrh(1043 m), forming the spring of the Upper Dobra.

Drawing of the geological profile (Fig. 3) is based on the geo-logical maps of Delnice 1:100,000 (Dimitrijevic et al., 1975; Savicand Dozet, 1985) and Ilirska Bistrica 1:100,000 (Dimitrijevic et al.,1975). Fault tectonics is simplified in this profile and for thenew tectonic interpretations we refer to the hydrogeological map1:100,000 of Rijeka (Biondic and Dukaric, 1997), the geological mapof Croatia 1:300,000 (Croatian Geological Survey, 2009), and thehydrogeologic map of Croatia 1:300,000, all of which clearly reflectthe conceptual hydrogeologic model of Herak (1962, 1980).

The lower, middle and upper Jurassic formations of the geolog-ical profile reveal a smooth anticline, and therefore we draw twogroundwater flow directions in the karst aquifer below the Risn-jak National Park (Mt. Risnjak, 1526 m), one to the Kupa Valley tothe northeast, and another one to the Rjecina Valley to the south-west. The most prominent karst springs of the Kupa catchment arethe Cabranka spring (probably also draining the Slovenian side),Zamost, Kupa, Kupica and Zeleni Vir springs (Fig. 2). In the coastalforeland the most prominent springs are the Rjecina spring, and theZvir spring in the City of Rijeka. Basically, the two major springsdescribed in this paper flow out at nearly the same altitude, butcompared to the Rjecina spring (325 m), the Kupa spring forms asmall lake at an altitude of 321 m, but the spring itself dischargeskarst water from an 80 m deep siphon below.

Except for the discharge of groundwater at the karst springs,little is known on the recharge areas and the subterraneous flow

of the karst water because the dense cave system of the karstifiedTriassic and Jurassic dolomites has hardly been explored (Bozic,2009). A first hydrogeologic karst model of the Adriatic karst of

S. Franciskovic-Bilinski et al. / Chemie der Erde 73 (2013) 293– 308 297

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ig. 3. Generalized hydrogeologic cross section of Gorski Kotar from the Kupa catijeka (exaggeration approximately 1.5). Lines with arrows indicate major thrusts t

varner Bay was published by Biondic (1988). Due to the fact thatong-term monitoring of the most important karst wells in Westernroatia has not been conducted, and a network of meteorologicaltations and hydrographs in the region is missing, no estimates onransmissivity are available as e.g. published by Giudici et al. (2012)or a fractured and karst aquifer in south-eastern Italy or by Powersnd Shevenell (2000) for shallow karst and fractured aquifers in theastern United States. In the Kupa and Rjecina river valleys, a piezo-etric network does not exist yet. The Croatian water authorities

lan to establish such network of piezometers in the future.There are surprisingly few data published from project studies

nd expertise dealing with the discharge of karst wells northeastnd southwest of Gorski Kotar. For the Rjecina spring the maximumischarge is about 120–150 m/s but during summer times the wellearly dries out, and its recharge area is hardly known (Biondict al., 1997). The discharge of karst springs discharging from Gorskiotar to the northeast varies between 10 l/s and 1000 l/s, and only

he Kupa spring exceeds 1000 m3/s (Biondic et al., 2006).To sum up, hydrogeological studies of potential recharge areas,

stablishment of hydro-meteorological stations, and monitoring ofhe discharge of karst springs, combined with monitoring the yearlyariation of hydrochemistry and stable isotopes, would be urgentlyeeded for understanding the reservoir characteristics of differentarst aquifers.

. Sampling

The position of each studied river valley within Croatia and theroader region and simplified lithology of our study area is pre-ented in Fig. 1a and b with sampling locations in the valleys of theupa and Rjecina rivers, respectively. The sampling site coordinatesere determined by a GPS instrument (Garmin GPS Map 72, Kansasity, USA) with an accuracy of ±5 m and are presented in Table 2,

ncluding the exact locations and names of the rivers. Surface waternd sediment samples for trace ecotoxic metals and elemental anal-sis respectively were taken in March 2010 at in total 12 locationsn both drainage basins: 6 surface water samples (K1–K6) wereaken at locations along the uppermost section of the Kupa river andts tributaries (Cabranka, Gerovcica) within the Risnjak National

ark and 6 surface water samples were taken along the Rjecinaiver and its tributary Zvir Spring. Surface water samples were col-ected using a clean sampling technique described by Horowitz1997). Water samples were collected in pre-cleaned high-density

t in the Risnjak National Park to the Rjecina catchment in the coastal foreland ofsouthwest.

polyethylene (HDPE) bottles (1 L), which were used as samplers andcontainers. Bottles were zipped in plastic bags and kept maximumone day at 4 ◦C before preparation and analysis. Sediment sampleswere taken at 5 locations in the Kupa river drainage basin (K1–K5)and at 3 locations in the Rjecina river drainage basin (R2, R3 and R4).Sediment sampling sites were chosen to be on representative loca-tions for all parts of the river flow. Also, locations where fine grainedsediment accumulates along the river bank were chosen. On eachsampling site, at least three grab samples of active fine-grained sur-face sediment (0–5 cm deep) were collected from different placesin an area of 5 m2. From this material a composite sample wastaken weighing up to 1.5 kg. This procedure decreased the pos-sible bias caused by local variability. Sediments were wet sievedusing river water from sampling sites by standard sieves (Fritsch,Germany) to obtain the silt + clay fraction (<63 �m). The obtainedfraction was air dried at room temperature. That fraction was usedbecause it is usually used in environmental studies; also anotherreason was to be able to compare results with the results of pre-vious studies from those drainage basins, which were performedon that fraction (Franciskovic-Bilinski, 2005, 2007; Franciskovic-Bilinski et al., 2011). Additional sampling of water was performedin November 2010 at some locations in the Kupa and Rjecina valleysand was used only for stable isotope analysis, to compare isotopesituation between the two seasons. March was the most represen-tative month to abstract waters which were influenced by snowmelting in the mountains of Gorski Kotar, while November was themost representative month to abstract waters influenced by heavyautumn rains.

4. Methods

4.1. Determination of physico-chemical parameters

Physical-chemical parameters (pH, dissolved oxygen concentration, electricconductivity and water temperature) were measured in situ (probes submergeddirectly in flowing stream) at all sampling sites (Table 2) by using a Hach HQ40Dinstrument (Loveland, USA). Prior to each sampling event the instrument waschecked and calibrated. The pH electrode was calibrated with standard pH 4 and 7buffer solutions with precision of 0.01 pH unit, while the oxygen probe has automaticinternal calibration with accuracy of 0.01 mg L−1. Accuracy of electric conductivitymeasurements was 0.1 �S cm−1, while of temperature was 0.3 ◦C.

4.2. Sediment analysis using ICP-MS

Determination of elements was carried out in an ACTLABS commercial labora-tory, Ontario, Canada in fraction <63 �m, using ICP-MS (Inductively Coupled Plasma

298 S. Franciskovic-Bilinski et al. / Chemie der Erde 73 (2013) 293– 308

Table 2Location details, geographic coordinates and physico-chemical parameters measured in March 2010.

No. Location Coordinates pH O2 (mg L−1) (oxygen dissolved) T (◦C) EC (�S cm−1) TDSa (mg L−1)

Kupa river and tributariesK1 Kupa Spring/Kupa N 45◦29′28′′

E 14◦41′29′′8.14 11.7 7.3 204.4 137.0

K2 Bridge/Kupa N 45◦30′37′′

E 14◦42′15′′8.37 11.5 7.5 214.4 143.7

K3 Hrvatsko/Kupa N 45◦32′00′′

E 14◦42′10′′8.38 11.6 7.6 217.8 145.9

K4 Kupa-Cabranka confl./Kupa N 45◦31′31′′

E 14◦42′02′′8.37 11.5 7.3 211.3 141.6

K5 Kupa-Cabranka confl./Cabranka N 45◦31′34′′

E 14◦42′01′′8.68 11.2 7.9 246.0 164.8

K6 Zamost/Gerovcica N 45◦31′36′′

E 14◦41′27′′8.43 11.4 7.0 210.1 140.8

Rjecina river and tributariesR1 Rjecina Spring/Rjecina N 45◦25′31′′

E 14◦25′28′′8.30 – 7.3 229.0 153.4

R2 Kukuljani/Rjecina N 45◦24′16′′

E 14◦25′03′′8.36 11.5 7.8 214.1 143.5

R3 Martinovo selo/Rjecina N 45◦23′11′′

E 14◦26′28′′8.40 11.7 7.9 215.4 144.1

R4 Pasac/Rjecina N 45◦21′30′′

E 14◦26′54′′8.47 10.9 9.7 336.0 225.1

R5 Rijeka town/Rjecina N 45◦19′35′′

E 14◦26′57′′8.32 11.7 8.4 228.0 152.8

◦ ′ ′′ 10.9

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R6 Zvir Spring N 45 20 06E 14◦27′15′′

7.98

a TDS ∼ EC × 0.67.

ass Spectroscopy), with program “Ultratrace 2”. The procedure was as follows:.5 g of sample is dissolved in aqua regia at 90 ◦C in a microwave digestion unit.he solution is diluted and analyzed using a Perkin Elmer SCIEX ELAN 6100 ICP-MSnstrument. For analysis, the following reference materials were used: USGS GXR-1,XR-2, GXR-4 and GXR-6, which were analyzed at the beginning and after analyzingach series of samples.

Although this digestion is not total, its use is justified because the interna-ional standard methods for determining action limits are based on aqua regia leachSalminen and Tarvainen, 1997).

Total mercury analysis was performed from the same extracts at 90 ◦C, using 1Grogram by atomic absorption spectrometry and flow injection techniques. Detec-ion limit for Hg is 5 ng g−1.

.3. Determination of selected trace metals in waters

Trace metals in waters were determined in Ru –der Boskovic Institute, Croatia.oncentrations of total Cu, Cd, Pb and Zn were measured in unfiltered water sam-les. Total dissolved fractions (hereafter named dissolved) were determined afterltration under nitrogen pressure through 0.45 �m cellulose nitrate membrane fil-ers (Sartorius, Göttingen, Germany). Prior to analysis, unfiltered and filtered wateramples for determination of trace metals were acidified with Suprapur® nitriccid (Merck, Darmstadt, Germany) to a pH < 2 and UV irradiated for 24 h (150 Wercury lamp, Hanau, Germany). Trace metal concentration measurements were

erformed by the ECO Chemie �AUTOLAB multimode potentiostat (Utrecht, Theetherlands) connected with a three-electrode system Metrohm 663 VA STAND

Herissau, Switzerland). A hanging mercury drop was used as a working electrodeVA stand 663, Metrohm, Herissau, Switzerland), with a drop surface of 0.25 mm2.

platinum wire was used as a counter electrode and Ag|AgCl with saturated NaCls a reference electrode. The standard addition method was used for determina-ion of trace metal concentrations. In the first step concentrations of Cd, Pb and Cuere determined, and after adjusting pH to about 3–4 by the addition of 0.2 ml of

uprapur® sodium acetate (Merck, Germany), Zn concentration was determined.he electrochemical method used (Branica, 1990; Bard and Faulkner, 2001) was dif-erential pulse anodic stripping voltammetry (DPASV). Limits of quantification, LOQ,btained in acidic Milli-Q® (Millipore, Billerica, USA) water were 1, 2, 5 and 10 ng L−1

or Cd, Pb, Cu and Zn in water samples, respectively. Uncertainties (±) of trace metal

oncentrations in water samples were given as 95% confidence intervals.

Quality control of the applied voltammetric method was verified by determiningrace metal concentrations in the River Water Reference Material for Trace MetalsSLRS-5) of the National Research Council Canada. All measured metal concentra-ions were within 10% of certified values.

9.7 242.0 162.1

4.4. Stable isotope (deuterium and oxygen-18) analysis of waters

The stable isotope composition of water samples was measured at the Univer-sity of Vienna, Department for Environmental Geosciences. The used set up of aPicarro Inc. Isotopic Water Analyzer (Picarro L1115-i) combined with a CTC HTC-Pal autosampler (LEAP Technologies) is similar to the one described by Gupta et al.(2009). The Picarro “Cavity Ring-Down Spectroscopy” (CRDS) uses a near-infraredlaser to define �18O and �2H stable isotope-ratios out of liquid water samples (PicarroInc., www.picarro.com). CRDS is a direct absorption technique (Berden et al., 2001)that offers results for pure water samples highly comparable in precision with clas-sical mass spectroscopy (Brand et al., 2009). Stable isotopes analyses are reportedin the usual � notation relative to Vienna Standard Mean Oceanic Water (VSMOW)standard, where ı = [RS/RSMOW − 1] × 1000; RS represents either the 18O/16O or the2H/1H ratio of the sample, and RSMOW is 18O/16O or the 2H/1H ratio of the StandardMean Oceanic Water. Using the Picarro CRDS measurement, precision of ı18O is±0.1‰, and measurement precision of ı2H is ±0.5‰. Each value reported in thispaper is a mean of 6 measurements.

5. Results and discussion

5.1. Physico–chemical parameters

Spatial variations of water temperature, dissolved oxygen, pHand electric conductivity in both rivers were measured and arepresented in Table 2. Measurements at the Rjecina river were per-formed from the source to the mouth. In the Kupa river catchment,measurements were performed from the Kupa spring down to thetributaries Cabranka and Gerovcica, at a slight distance from theRisnjak National Park. Generally, higher water temperatures wereobserved in March 2010 in the Rjecina river (7.3–9.7 ◦C) comparedto the Kupa river (7.0–7.9 ◦C).

It is interesting that the Kupa (K1) and Rjecina (R1) springs

showed identical water temperatures (7.3 ◦C) in March 2010, sim-ilarly as presented in the paper of Biondic et al. (2006). Accordingto these authors, similar water temperatures may indicate a com-mon catchment area in the highest and the coldest mountain area

Chemi

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lwia(b(aii(eica

dHbtTT

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S. Franciskovic-Bilinski et al. /

f Gorski Kotar. The highest water temperature (9.7 ◦C), the lowestissolved oxygen concentration (10.9 mg L−1) and the lowest pH7.98) were recorded in the Zvir spring (R6).

All measured dissolved oxygen concentrations were above0.9 mg L−1, which shows good aeration of waters of both river.he pH values of the Kupa river varied from 8.14 in K1 samp-ing site (Kupa Spring) to 8.68 in K5 (Cabranka river) samplingite. Also pH values in the Rjecina water were similar (8.32–8.47),howing that both studied rivers are slightly alkaline. These valuesre within the highest desirable limit (HDL: pH 8.5) prescribed byhe World Health Organization (WHO, 1973). The pH value is onlylightly above the HDL in K5 river site. Electric conductivity values204–246 �S cm−1) were slightly lower in the Kupa river, comparedo those measured in the Rjecina river (214–336 �S cm−1).

The highest value of 336 �S cm−1 was observed in R4 samp-ing site Pasac, in the Rjecina river, during a period of a lowered

ater level when the river was diverted to a hydropower plantn the City of Rijeka. Higher electric conductivity values indicate

higher content of dissolved minerals, e.g. in the river waterAbdullah and Musta, 1999), and the electric conductivity also cane taken as a good measure for water quality of different aquifersRoscoe Moss Company, 1990). Taking the Nif Mountain karstquifer system in western Turkey (Simsek et al., 2008) for compar-son, electric conductivity ranging between 200 and 350 �S cm−1

n western Croatia is lower than that determined in Turkish wells752 �S cm−1) and springs (555 �S cm−1). Since no standards forlectric conductivity are suggested by the WHO, Turkish drink-ng water standard TSE266 (1997) for maximum allowable electriconductivity (2000 �S cm−1) can be taken for comparison with rel-tively very low values detected in the Rjecina and Kupa rivers.

The amount of mineral and salt impurities in water is called totalissolved solids (TDS). This useful parameter is not measured byrvatske vode in the studied region. The measured value of EC cane converted to approximate TDS value in mg L−1. A conversion fac-or commonly used has a value of 0.67. Drinking water should haveDS less than 500 mg L−1. All values of approximately calculatedDS are much below 500 mg L−1.

.2. Elemental composition of sediments

Chemical composition of sediments in the two studied catch-ents is not expected to be similar, as they are formed by theeathering of different source rocks. The Rjecina is a typical alo-

ene karst river, flowing first through flysch and later througharbonates and sandstones. Therefore sediments deposited inhe upper flow of the Rjecina are composed of quartz, feldsparnd mica group minerals (Franciskovic-Bilinski et al., 2011). Theupa is in the upper flow a karst river, flowing through lime-tones and dolomites. Hence these sediments are composedf quartz, calcite, dolomite and feldspars (Franciskovic-Bilinski,007). Concentrations of ecotoxic elements will be comparedegarding available sediment quality criteria and their natural ori-in.

Table 3 presents concentrations of 52 elements, which wereetermined in sediment fraction (<63 �m). Only 12 of them (Hg, Cr,n, Fe, Ni, Cu, Zn, As, Ag, Cd, Ba, Pb) are included in the list of exist-

ng sediment quality criteria issued by SMSP and FALCONBRIDGEC SAS (2005).

For better illustration of concentrations of toxic elements�g g−1 for all elements except Hg, which is in ng g−1) in the sed-ments of the Kupa and Rjecina rivers, the results are plotted asistograms in Fig. 4a–j. The concentration of total mercury in all

ediments (Fig. 4a) is below the value that might cause the low-st toxic effect (200 ng g−1), except in K5 river sample, wheret is slightly above it. This elevated concentration of Hg can bexplained due to natural background. The village Trsce is located in

e der Erde 73 (2013) 293– 308 299

the vicinity of the Gerovcica river where an HgS mine was closed.There was no ore processing, which would add to anthropogenicimpurity. The preliminary determination of Hg in the water of theGerovcica river (Kwokal, unpublished) shows higher concentra-tions of total mercury, which is planned to be investigated within anongoing project. These results can be compared to the Hg concen-trations in sediments, as determined in the whole Kupa drainagebasin by Franciskovic-Bilinski et al. (2005b). Concentrations of totalcadmium (Fig. 4b) are below those reported for the lowest toxiceffects in all stations. At stations K1, K2 and K3 concentrationsof total chromium (Fig. 4c) reach 26 �g g−1, which is the thresh-old for the lowest toxic effects. The values of total chromium inthe Rjecina river are more than double but still below the valuesof 110 �g g−1 that might cause significant toxic effect. Concentra-tions of total manganese (Fig. 4d) are lower than those which mightcause the lowest toxic effects (460 �g g−1) in stations K1–K5. In sta-tion R4 the value is much higher than 1100 �g g−1, which mightcause significant toxic effect, while in R3 and R2 it is near thisvalue. High values of manganese in sediments (374–1090 �g g−1)from the Rjecina delta to near the Rjecina spring were obtainedearlier (Franciskovic-Bilinski et al., 2011). Concentrations of totaliron (2.5–3.7%) show that it is one of the most abundant elements.Its concentration is slightly higher in the Rjecina compared to theKupa, due to local geological conditions (flysch and sandstones, richin iron, in the Rjecina Valley), as shown in Table 3. Concentrationsof total nickel (Fig. 4e) are below the values that might cause thelowest toxic effects (35 �g g−1) in all stations of the Kupa region,while in Rjecina sediments the values of nickel are above the values(75 �g g−1) that might cause significant toxic effects. The values ofcopper (Fig. 4f) in the Kupa are below the values that might causethe minimal toxic effect (28 �g g−1). In sediments of the Rjecinariver the values of copper are above the value reported for moder-ately contaminated sediments (37.5 �g g−1). Concentration of zinc(Fig. 4g) shows values above 90 �g g−1 in all stations, except slightlybelow this value in K4, which is reported for moderately contam-inated sediments. Concentrations of arsenic (Fig. 4h) are higher insediments of the Kupa than of the Rjecina and are above the valuesthat might cause the lowest toxic effects (6 �g g−1), except in R4,where the value is lower. Higher concentrations of As in the baritebearing rock (176 �g g−1) were observed in the Lokve region, con-nected to previous barite mining (Franciskovic-Bilinski et al., 2007).This paper was the first multidisciplinary study which includedmedical-geology investigations in the Gorski Kotar region. A pre-liminary study of diseases diagnosed in Lokve shows that about 18%of the total inhabitants have serious medical problems. Diseases ofthe circulatory system, endocrine, nutritional, and metabolic dis-eases, neoplasms, and respiratory diseases predominate. This papercalls for further multidisciplinary research on the health effects ofbarium and trace elements, as well as for bioremediation of con-taminated gardens and for watershed management of vulnerablekarst aquifers. Barium concentrations (Fig. 4i) in all sediments havevalues above 60 �g g−1, as reported for very contaminated sedi-ments. However, the mean concentration of Ba in the whole Kupadrainage basin was 144 �g g−1 (Franciskovic-Bilinski, 2007). Thehighest value of Ba (207 �g g−1) in sediments was found at K1 (KupaSpring) station. The values of silver (Table 3) are very low in all sta-tions. The concentrations of lead (Fig. 4j) are higher than 250 �g g−1,which might cause significant toxic effects in the uppermost loca-tions K1–K3. It is below this value in other stations, but also abovethe value of 31 �g g−1, which might cause the lowest toxic effect.Because of these higher values of Zn, As, Ba and Pb found in the sed-iments within the National Park Risnjak, and of Cr, Mn, Ni and Cu inthe sediments of the Rjecina river, continuous monitoring of sedi-

ments is recommended, in order to distinguish between elementsof natural or anthropogenic origin. Based on available literaturefrom this region, we are of opinion that higher values of some heavy

300 S. Franciskovic-Bilinski et al. / Chemie der Erde 73 (2013) 293– 308

Table 3Multi-elemental analysis of sediment samples (fraction <63 �m), taken in March 2010 (D.L. = det. limit).

Element D.L. K1 K2 K3 K4 K5 R2 R3 R4

Hg (ng g−1) 5 67 59 132 126 207 70 82 56Li 0.1 34.1 33.9 36.8 31.5 30.2 47 39.4 45.3Be 0.1 1.2 1.2 1.3 1.2 1 1.2 1 1B 1 7 8 9 4 3 14 12 23Na (%) 0.001 0.039 0.042 0.052 0.041 0.045 0.036 0.035 0.044Mg (%) 0.01 2.35 2.25 2.05 1.84 1.77 1.06 0.99 0.91Al (%) 0.01 1.94 1.86 1.99 1.85 1.43 2.82 2.68 2.6K (%) 0.01 0.29 0.29 0.32 0.25 0.21 0.48 0.42 0.61Ca (%) 0.01 4.06 4.35 4.01 3.04 3.03 2.29 2.01 12.4V 1 34 39 36 33 30 62 53 62Cr 0.5 26.7 26.7 30.4 25.3 21.1 83.6 80.9 56.6Mn 1 436 416 435 350 405 984 1030 2910Fe (%) 0.01 2.63 2.57 3.08 2.6 2.83 3.68 3.47 2.86Co 0.1 10.1 9.8 11.5 9.3 11.1 20 20.2 23Ni 0.1 29.8 29.8 34.2 28.2 29.4 130 118 135Cu 0.01 21.8 20.6 25 19.5 24 39 35 37.3Zn 0.1 97 96.9 116 87.3 96.4 102 98.4 121Ga 0.02 5.96 6.03 6.26 6.09 4.82 8.8 7.92 7.04As 0.1 8.6 7.9 10.6 10.2 13 7.8 6.8 4.7Se 0.1 0.8 0.8 1 0.7 0.7 0.7 0.7 1.5Rb 0.1 23.2 23.5 25.1 22.2 17.9 38.2 32.6 43.3Sr 0.5 25.8 29.9 31.1 28 26.3 66.2 53.2 512Y 0.01 9.51 10.3 8.8 9.85 7.57 11 10.1 8.59Zr 0.1 2 2.1 2.2 1.7 1.6 3 2.2 3.8Sc 0.1 4 4.3 4.7 4 4.2 7.8 6.3 6.5Pr 0.1 2.9 3.7 2.5 3.5 2.4 3.7 3.7 2.3Gd 0.1 3.3 3.5 3.1 3.6 2.9 3.5 3.5 2.2Dy 0.001 2.39 2.52 2.14 2.46 2.06 2.55 2.41 1.72Er 0.1 1 1.1 0.9 1 0.8 1.1 1 0.8Mo 0.01 0.8 0.68 0.98 0.6 0.5 0.24 0.28 0.17Ag 0.002 0.066 0.055 0.071 0.067 0.054 0.088 0.069 0.23Cd 0.01 0.22 0.23 0.2 0.19 0.14 0.19 0.22 0.17In 0.02 0.04 0.04 0.04 0.03 0.04 0.05 0.04 0.04Sn 0.05 0.99 0.89 1.03 0.87 0.92 1 1.07 0.79Sb 0.02 0.44 0.42 0.47 0.45 0.48 0.28 0.31 0.37Te 0.02 0.11 0.11 0.11 0.07 0.09 0.12 0.17 0.4Cs 0.02 2.31 1.98 2.37 2.17 1.96 1.89 1.68 2.25Ba 0.5 207 140 127 141 101 76.9 71.7 83.8La 0.5 10.7 14.4 9.6 13.5 9.2 12.1 12.6 8.5Ce 0.01 23.6 31.5 20.7 29.1 20.5 30.1 30.6 21.5Nd 0.02 11.9 14.9 10.2 14.3 9.74 16 15.8 9.22Sm 0.1 2.8 3.3 2.5 3.3 2.4 3.6 3.5 2.1Eu 0.1 0.6 0.6 0.5 0.6 0.5 0.8 0.7 0.5Tb 0.1 0.4 0.5 0.4 0.5 0.4 0.5 0.4 0.3Yb 0.1 0.8 0.7 0.6 0.7 0.6 0.8 0.7 0.6Au (ng g−1) 0.5 1.4 1.5 1.3 1.1 1.4 2 2.1 0.6Tl 0.02 0.29 0.26 0.21 0.24 0.14 0.2 0.2 0.05Pb 0.01 734 593 477 234 164 42.1 55.3 30.7Bi 0.02 0.28 0.27 0.28 0.28 0.29 0.31 0.27 0.29Th 0.1 5.9 7.2 5.8 7 6.1 6.8 6.1 5.1

A

mo

toceteiHtPMotKh

U 0.1 1.2 1.4 1.1

ll values with no mentioned unit are in �g g−1.

etals found in the National Park Risnjak are of anthropogenicrigin.

Miko et al. (2000) analyzed the pollution of soils and have foundhat the effect of probably both long-range and local transportf air-borne pollution on the region of the Risnjak National Parkan be seen in the concentrations of Pb and As, and to a lesserxtent of Cd and Zn. According to these authors, the spatial dis-ribution pattern of the air-borne Pb–Zn–As–Cd–P association oflements in soils is generally controlled by the geomorpholog-cal boundary of the Western Croatian coastal mountain range.owever, there can be another reason for elevated concentra-

ions in the sediments of the Kupa river, like the formation ofb-carbonate hosted deposits (Cooke et al., 2000; Leach et al., 2010;atic et al., 2012). In further steps, research on bioavailability

f those elements is necessary to see if the higher concentra-ions of total elements in river sediments (as analyzed from theupa and Rjecina catchments) can cause any harm to humanealth.

1.4 1.3 0.5 0.6 0.6

5.3. Major elements in spring waters

Analytical results of major ions determined in three springs for2010 were obtained from Hrvatske vode (Croatian water author-ity), which routinely measures those parameters in those threesprings. A Piper (1944) diagram was constructed to describe waterchemistry.

As shown in Fig. 5, major ions are plotted in the diagram inthe two base triangles as cation and anion miliequivalents per-centages. Total cations and total anions are each considered as100%. It should be mentioned that this diagram does not por-tray actual ion concentrations. The Piper diagram in Fig. 5 showsthat the samples from the three studied springs are character-ized to be of a Ca–Na–HCO3–Cl type. Groundwaters are not of

a pure carbonate type, but are under a maritime influence. Thestudy area is generally underlain by limestone, less by dolomites.If the actual concentrations of Na, Cl, Ca and SO4 are compared,they are comparable in the Kupa and Rjecina springs. In the Zvir

S. Franciskovic-Bilinski et al. / Chemie der Erde 73 (2013) 293– 308 301

Fig. 4. Concentrations of ten ecotoxic elements (values for all elements are in �g g−1, except for Hg, which is in ng g−1): Hg (a), Cd (b), Cr (c), Mn (d), Ni (e), Cu (f), Zn (g), As(h), Ba (i), Pb (j) in sediments of the Kupa and Rjecina rivers.

stgTew2

pring, these concentrations are higher. Concentration of Mg ishe highest in the Kupa spring. There is a significant difference inroundwater types in North Africa. The selected examples are from

unisia, where Na–Cl and Ca–SO4–Cl types predominate (Kamelt al., 2008; Hamed et al., 2008, 2010), or from Egypt, where mixedater of Mg–SO4, Mg–Cl and Na–Cl types was reported (El-Fiky,

009).

5.4. Trace metals in waters

The concentrations of trace metals (Cd, Pb, Cu and Zn) deter-

mined in surface waters are presented in Fig. 6a–d. The levelsof total and dissolved fractions of these specific four traceelements can be a suitable parameter for preliminarily distin-guishing natural from anthropogenic influence, even at very low

302 S. Franciskovic-Bilinski et al. / Chemie der Erde 73 (2013) 293– 308

pa riv

ceKabo

Fig. 5. Piper diagram of the groundwater from three springs: the Ku

oncentration ranges, as shown by Cuculic et al. (2009). In gen-ral, all trace metal concentrations determined in the waters of the

upa and Rjecina rivers were in the range characteristic for cleannd unpolluted karst rivers (Cukrov et al., 2008). The differenceetween the two fractions (total and dissolved) shows the amountf trace elements bound to particulate matter of size greater than

Fig. 6. Concentrations of total and dissolved ecotoxic elements in ng/l: C

er spring (K1), the Rjecina river spring (R1) and the Zvir spring (R6).

0.45 �m. These particles can be of different composition, inorganicor organic. However, origin of these particles was not examined

within the present paper. It was possible to get a significant corre-lation between total and dissolved Cu and Zn in waters (R2 = 0.9236and R2 = 0.9168, respectively). Less significant correlations wereobtained for Cd and Pb (R2 = 0.5749 and R2 = 0.4722, respectively).

d (a), Pb (b), Cu (c) Zn (d) in waters of the Kupa and Rjecina rivers.

Chemie der Erde 73 (2013) 293– 308 303

crsdocZpilCdKata

w(opln(Mdwswctiswaab

dtwBPtf

5r

rcraKpRpKiS(at“

Table 4Average and minima–maxima of dissolved trace metal concentrations in watersof Kupa and Rjecina rivers. Comparison with the concentration values from theother Croatian rivers, with the world average for “natural” river systems and withthe acceptable metal concentrations in river water according to the EnvironmentalQuality Standards (EQS) of the European Water Framework Directive (WFD).

Cd (ng L−1) Pb Cu Zn

Kupa (K1–K4), average 1.7 5.3 134 154Min–max 1.2–2.2 4.7–6.0 99–183 134–165Rjecina (R1–R5), average 2.5 6.1 208 432Min–max 1.7–3.7 4.8–8.7 140–308 93.3–1116Krka, Croatia average(Cukrov et al., 2008)

3.1 8 100 275

Sava, Croatia average(Dragun et al., 2009)

11 55 540 2270

World average (Gaillardetet al., 2004)

80 79 1480 600

AAa (CEC, 2006) ≤80 7200 8200b 7800b

S. Franciskovic-Bilinski et al. /

The springs of the Kupa river (K1) and the Rjecina river (R1)ontain very low trace metal amounts. These amounts in the Kupaiver water did not show any significant variations from K1 to K4ampling sites. Dissolved cadmium (Fig. 6a) and lead (Fig. 6b) isecreasing in the downstream Kupa and is higher in K1 than inther stations downstream. Only at K5 site (Cabranka river) con-entrations are significantly higher for Pb (Fig. 6b), Cu (Fig. 6c) andn (Fig. 6d) and their total amounts are 2–4 times higher com-ared to those in the Kupa river. Concentrations of Pb, Cu and Zn

n the Rjecina river are significantly higher at downstream samp-ing sites (R2–R5) in comparison to the values found in its spring.oncentrations of Cu and especially Zn are significantly higher inownstream sampling sites of the Rjecina river compared to theupa river because of numerous settlements along the Rjecina rivernd their anthropogenic input. Concentration of Zn at R2 is sevenimes higher than in the spring (1.22 �g L−1), suggesting notablenthropogenic input from Kukuljani Village surrounding R2 site.

The highest total Pb concentration (∼170 ng L−1) in wateras found in Rjecina R4 site, with very low dissolved fraction

∼9 ng L−1), resulting in low dissolved vs. total concentration ratiof 0.05, pointing out that only 5% of Pb amount in water at R4 isresent in dissolved fraction. It indicates high amount of particu-

ate matter. It is known that Pb has a strong adsorption affinity foratural particles (Bilinski et al., 1991), particularly for Mn oxidesBilinski et al., 1977). At this location, the highest concentration of

n was found in sediment (see Fig. 4d). At sampling site R5, inowntown Rijeka, all measured concentrations of trace metals inater sharply decreased compared to the values found at upstream

ampling site R4. The reason for the dilution can be either mixingith karst water or with seawater. The water of the Zvir spring (R6)

ontains all trace metals in considerably higher amounts comparedo the Kupa and Rjecina springs, due to the influence of a formerndustrial zone in the City of Rijeka. Moreover, the highest Zn dis-olved amount of all sampling sites in both rivers was found in theater of the Zvir spring (almost 1.5 �g L−1). The Zvir spring is used

s an additional drinking water supply source during dry seasonnd for bottling of “Zvir” water, where continuous monitoring cane recommended.

Concentrations of Pb, Cu and Zn in spring waters, whichiffer significantly between springs, can be used as environmen-al indicators for better understanding of groundwater–surfaceater interactions, similarly as major ions chemistry was used byaskaran et al. (2009). Based on the total concentrations of Zn andb in water, which are much higher in the Kupa spring (K1) than inhe Rjecina spring (R1), it can be suggested that their origin is notrom the identical karst aquifer.

.5. Comparison of trace metals in water with other Croatianivers regarding the EU water regulations

The dissolved trace metal average concentrations and theiranges in the Kupa (K1–K4) and the Rjecina (R1–R5) rivers areompared to previously published data of the clean karst Krkaiver and the anthropogenically influenced Sava river, both in Cro-tia (Table 4). The average dissolved metal concentrations in theupa river were the lowest except for Cu, in comparison with allresented values. Average amounts of dissolved Cu and Zn in thejecina river were approximately two times higher compared to theublished concentration values in the pristine waters of the karstrka river, Croatia (Cukrov et al., 2008). However, these levels found

n the Rjecina river were significantly below those reported for theava river, which is considered to be anthropogenically influenced

Dragun et al., 2009), although concentrations are not significantlybove the natural level. Moreover, Gaillardet et al. (2004) reportedhe world average levels of dissolved metals for the so-callednatural” river systems, based on the metal concentrations in

a Annual average (AA) stated by WFD.b Proposed WFD EQS cited by Crane et al. (2007).

the world’s major rivers, but excluding the heavily polluted ones(Table 4). Dissolved metal average levels in the Kupa and Rjecinarivers were considerably below the world average values for allmetals.

Environmental quality standards (EQS) for dissolved metals inthe inland surface waters (Table 3 from CEC, 2006) were used forcomparing our results from the Kupa and Rjecina rivers despitethe fact that the concentrations given in this research refer to onlyone season. Annual average concentration values for Cd, Cu andZn are one order of magnitude higher, and for dissolved Pb eventhree orders of magnitude above the concentrations in the Kupaand Rjecina rivers, which confirms their status as clean and unpol-luted karst rivers. This conclusion can be important not only for thecentral and southern European area, but also more globally, becausethere are not many pristine springs and rivers left in the world. Theconclusion is also in accord with the classification of these waters,determined by local authorities, Hrvatske vode. Based on biologi-cal and physico-chemical parameters, waters were reported to beof quality class I. It means that in natural condition or after disin-fection, water can be used for drinking, or in food industry, or fortrout farming. In the lower course from Bubnjarci to Sisak, the Kupais of quality class II. The Rjecina is also of quality class II below thestation Drastin. Such waters can be used for swimming, recreationand water sports.

5.6. Stable isotopes ı2H and ı18O in waters

For comparison of stable isotopes in different waters we haveanalyzed hydrogen (deuterium, �2H) and oxygen (�18O). Results ofstable isotope analysis are presented in Table 5. In first approachwe compare the oxygen-data of our short termed sampling in2010 with the long termed isotopic characteristics of precipita-tion from a station situated about 20 km south of Gorski Kotar, inthe Velebit mountain range, namely at Zavizan, at an altitude of1595 m above sea level. Regrettably, no stable isotope data fromprecipitation at the meteorological station of Mt. Risnjak (1526 ma.s.l.) in Gorski Kotar exist in order to better assess the monthlyvariation, and the effects of air temperature, altitude, and mostimportant-isotopic composition of air moisture during continentaland maritime weather situations in that region. It is evident thatcontinental stations show significant differences in meteorologi-cal parameters and isotopic composition of precipitation compared

to maritime stations along the Adriatic coast (Vreca et al., 2006),and the regional provenance of precipitation in the karst ground-water system of Gorski Kotar is poorly known. Nevertheless, thefirst overview of the composition of stable environmental isotopes

304 S. Franciskovic-Bilinski et al. / Chemie der Erde 73 (2013) 293– 308

Table 5Stable isotope composition of water samples from the Kupa (K1–K6) and Rjecina (R1–R6) catchments, taken in March and November 2010.

Kupa March 2010 Kupa November 2010

�18O (‰) (±0.1‰) 2H (‰) (±0.5‰) d-Excess (‰) �18O (‰) (±0.1‰) 2H (‰) (±0.5‰) d-Excess (‰)

K1 Spring −9.94 −65.40 14.11K2 River −10.12 −67.39 13.59K3 River −10.08 −66.70 13.90 −8.09 −47.50 17.25K4 River −10.05 −66.49 13.91 −8.53 −53.39 14.86K5 River −10.35 −69.94 12.88 −8.07 −46.86 17.73K6 River −9.57 −64.01 12.52 −8.19 −50.31 15.19

Rjecina March 2010 Rjecina November 2010

�18O (‰) (±0.1‰) 2H (‰) (±0.5‰) d-Excess (‰) �18O (‰) (±0.1‰) 2H (‰) (±0.5‰) d-Excess (‰)

R1 Spring −9.24 −59.40 14.53 −7.27 −42.07 16.09R2 River −9.23 −59.32 14.54 −7.35 −42.53 16.31R3 River −9.15 −59.45 13.72 −7.29 −41.54 16.78

–

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R4 River – –

R5 River −8.87 −56.28 1R6 Spring −8.26 −51.50 1

ained during the field campaigns in 2010 gives a preliminarynsight into local hydrology and hydrogeology respectively of thewo distant watersheds. Despite the fact that both investigatedprings, namely the Kupa spring northeast and the Rjecina springouthwest of Gorski Kotar mountain range, discharge at an altitudef approximately 300 m a.s.l., the potential recharge area compriseshe whole Gorski Kotar range. Below, we first describe the stablesotopes from samples taken at the Rjecina (R1), Zvir (R6) and KupaK1) springs, followed by some comments on stable isotopes of theupa river draining Gorski Kotar to the northeast and east, com-ared to those of the Rjecina catchments, draining southward tohe Adriatic Sea.

The hydrogen- and oxygen-isotope ratio-values of the samp-ing periods in springtime and autumn of the Rjecina, Zvir andupa springs match the “Local Meteoric Water Line” (LMWL), whichas calculated as �2H = (7.6 ± 0.4) �18O + (10.5 ± 4.0) by Vreca et al.

2006) for the high altitude meteorological station Zavizan in thet. Velebit range. At this station the long lasting mean yearly pre-

ipitation ranges between 1900 mm and 2100 mm and the meannnual air temperature ranges between 3.5 ◦C and 4.5 ◦C. Due tohe fact that the Gorski Kotar–Kapela mountain range parallels theoastal Velebit range some 20 km in the north, the major weatherituations causing precipitation in these neighbouring mountainanges might be similar, and therefore the values of stable iso-opes in precipitation of Gorski Kotar can be assumed equivalento those of the Velebit Mountains. Based on this hypothesis we usehe oxygen isotope-ratios of precipitation at Zavizan station for thenterpretation of stable isotopes in the groundwater of the Gorskiotar karst system, keeping in mind that the average annual air

emperature in Gorski Kotar is 6 ◦C, as reported by Biondic et al.2006).

As can be seen in Fig. 7, the oxygen isotope-ratio of waterrom the Kupa spring (K1 = −9.94‰) and from the Rjecina springR1 = −9.24‰), taken in March 2010, is different. It is well knownhat oxygen and hydrogen heavy isotope contents in rainwaterecrease with increasing altitude. For 18O, in general the deple-ion varies between about −0.15‰ and −0.5‰ per 100 m rise inltitude (Clark and Fritz, 1997). In a first preliminary attempt weherefore interpret the differing oxygen isotope-ratios in the Kupand Rjecina springs as an altitude effect. If this can be proven, alson altitude effect of about 0.28‰ per 100 m, similar to the mid-nd south-Adriatic stations (Fig. 7 from Vreca et al., 2006), could be

xpected in Gorski Kotar.

When applying the concept of deuterium excess (d), which isefined as d = �2H-8�18O, and which is believed to be mainly relatedo the meteorological conditions at the source region from where

−7.17 −40.47 16.91−7.00 −41.00 15.01−6.82 −39.07 15.52

the sample is derived, the d-excess of 15‰ for Zavizan high altitudestation is the highest one in Croatia (Vreca et al., 2006). Despite thefact that we do not know the annual variation of the d-excess of thestudied springs, their single values (14.5‰ for the Rjecina springand 14.1‰ for the Kupa spring in March 2010) match the d-excessof Zavizan meteorological station very well (Table 5).

The stable isotopes of river waters investigated also match theLMWL, partly with slightly lower deuterium values (Kupa river),and partly with slightly higher values (Rjecina river). The compari-son of the river waters of the two catchments, which were sampledclose to the springs (Fig. 7), shows – as expected – that the isotope-ratios of the Rjecina river plot close to those of the Rjecina spring,and those of the Upper Kupa river plot close to the values of theKupa spring. In addition, there is obviously a shift of both springwaters and river waters from lighter isotope-ratios in springtimeto heavier isotope-ratios in late summer and autumn, respectively.

For example, for the Rjecina river the values of the oxygenisotope-ratio of approximately −9.00‰ (samples taken in March)shift towards −7.00‰ in samples taken in November 2010. Whenthe oxygen isotope-ratio of the Kupa spring in March is about−10.00‰, the oxygen isotope-ratios of the Upper Kupa river plotaround this value. When the oxygen isotope-ratio of the Kupaspring in August is −9.0‰, the river values (sampled two monthslater, however) plot also close to this higher value. A similar trendof shifting from lighter to heavier isotope-ratios was also calcu-lated for the Rjecina catchments. This shift most likely indicatesthe influence of seasonal variations on the composition of stableisotopes.

Our interpretation of stable isotope ratios in spring water isbased on the relation between the weighted mean �18O and thealtitude obtained from stations of the Global Network of Isotopesin Precipitation (GNIP), revealing an approximate vertical �18O gra-dient of −0.30‰ per 100 m, as reported by Vreca et al. (2006). Inaddition, these stable isotope data for the GNIP station Zavizanpredominantly indicate precipitation from the Adriatic coast, con-trary to the GNIP station Zagreb, where the precipitation is moreinfluenced by the continental climate.

5.7. Interpretation of stable isotopes results

In first approach we interpret the difference of 0.70‰ betweenthe oxygen isotope-ratios of the Kupa spring and the Rjecina spring

in March 2010 and of 1.73‰ in November 2010 as significant. Dueto the fact that the average maximum discharge of both springs ingeneral is the highest during springtime, namely 120 m3/s for theRjecina (Biondic et al., 1997), and 195 m3/s for the Kupa (Biondic

S. Franciskovic-Bilinski et al. / Chemie der Erde 73 (2013) 293– 308 305

Fig. 7. Isotope-ratio of water samples taken in March (marked red) and October (marked blue) 2010. The “Local Meteoric Water Line” (LMWL), as calculated from precipitationo t al., 2m

etsibdt2socidKfldswt

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t al., 2006), we interpret the oxygen isotope-values of −9.90‰ forhe Kupa (K1) and −9.24‰ for the Rjecina (R1) as characteristic fortrong influence of melt water. This hypothesis is supported by thencrease of heavier oxygen isotopes in late summer/autumn 2010y 1–2‰ (−9.00‰ for K1 and −7.27‰ for R1), when the spring’sischarge in general is low. In addition, electric conductivity ofhe Kupa spring is slightly lower in spring (204 �S cm−1 in March010) compared to 256 �S cm−1 (not included in Table 2), as mea-ured in August 2010, which might result from a higher amountf melt water in springtime whereas mineralization at base flowonditions is slightly higher. A similar seasonal shift of the oxygen-sotope composition is also visible for the samples taken in riversownstream of both springs at distances of about 10 km (Fig. 7;2–K6 and R2–R6 in Table 5). We assume that the Upper Kupa riverowing to the junction with the Cabranka river in the north pre-ominantly consists of water from the Kupa spring. Consequently,outh of Gorski Kotar, the Rjecina river predominantly dischargesater from the Rjecina spring, but in the City of Rijeka, in addition,

he Zvir spring contributes to the river water near the coastal zone.We compare the shift of stable isotopes from samples taken in

he spring and autumn of 2010 with the seasonal variation in dis-harge of both the Kupa spring north of Gorski Kotar, where theischarge varies between 1.07 m3/s and 195 m3/s (Biondic et al.,006), and the Rjecina spring south of Gorski Kotar, where the dis-harge varies between 0 m3/s and 120 m3/s (Biondic et al., 1997).omparing the shift of stable isotopes with the seasonally chang-

ng discharge of the springs, we conclude that a part of the big karsteservoir of Gorski Kotar rapidly empties through a system of karsthannels, which is locally well known from the caves in the Del-ice region (e.g. Lokvarka Cave) or in the Rjecina region (Bozicevic,973, 1974).

Due to the significant difference in oxygen isotope-ratios weonclude that the karst reservoir for the Kupa and Rjecina springss not identical. Also the variation in water temperature of thesewo springs is different, because temperature of the Kupa springaries between 7.2 ◦C and 7.5 ◦C, whereas temperature of thejecina spring varies between 7.3 ◦C and 8.5 ◦C, as monitored fromeptember 1997 to September 1999 by Biondic et al. (2006), Fig. 2.his shows that the simplified model of a connected karst water

evel under the same mountain range can hardly be encounteredn reality. We suppose that the north-eastern part of Gorski Kotars more the recharge area for the Kupa spring (as well as for allther big springs in the Kupa catchments) and its south-western

006), fits the oxygen isotope-ratio of the springs discharging from the Gorski Kotar

slopes are more the catchment for both the Rjecina spring and theZvir spring. Considering the results from dye tracer tests north ofRijeka (Dukaric, 2002; Biondic et al., 2008), the recharge area ofthe karst water discharging at the Rjecina spring can be located innorth-western Gorski Kotar. Compared to the Rjecina spring, whichoften lacks water during dry summer months, the Zvir spring (R6)is the largest permanent overflow karst spring in the coastal regionof Kvarner Bay. Because of these differing discharge conditions, weconclude that the karst water reservoir of the Rjecina spring andthe Zvir spring is also not identical.

The interpretation of stable isotopes is ambivalent. Takinginto account, however, that the deuterium-excess of the karstgroundwater discharging at springs north and south of the Risn-jak Mountain in Gorski Kotar is quite similar, yearly precipitationat both sides might also result from similar climatic influence.Supposing similar weather situations for the paralleling mountainranges of Gorski Kotar and Velebit, and hence interpreting the oxy-gen isotope-ratio as an altitude effect, the altitude of the averagerecharge area for the Kupa spring might be 250 m higher comparedto that of the Rjecina spring. This hypothesis leads to the conclusionthat precipitation of the lower slopes of south-western Gorski Kotarpredominantly recharges a karst aquifer that discharges towardsthe Adriatic Sea. Consequently the high elevated and wide plateauof Gorski Kotar acts as a big recharge area for the numerous bigkarst springs discharging towards the Cabranka and Kupa rivers inthe north. To sum up, we conclude that the Kupa, Rjecina and Zvirsprings basically discharge water from the same big recharge areaof Gorski Kotar but not from identical karst aquifers.

5.8. Recommendations and significance

In order to meet the international quality requirements, con-tinuous monitoring of Cr, Zn, As, Ba and Pb in sediments isrecommended, especially within the National Park Risnjak. In addi-tion, regional investigations of physical–chemical parameters suchas pH, electric conductivity, dissolved oxygen and water tempera-ture is useful to monitor the seasonal variations of karst waters, asindicated also by Biondic et al. (2006). Despite the fact that theRisnjak karst mountain region discharges groundwater meeting

the rigorous Croatian drinking water quality standards, contin-uous monitoring is suggested, especially at the Kupa spring inthe National Park Risnjak and at the Zvir spring, the lowermosttributary of the Rjecina river, where elevated concentrations of

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race elements were observed. In order to better distinguisheogene trace elements in river sediments from anthropogenic pol-ution, future analysis of bulk rock samples from different rockormations in the catchments is useful. Further trace metal anal-ses in waters at different water regimes and in different sedimentractions, with additional statistical analysis are recommended toistinguish whether metal concentrations are the result of geogenicnomalies or are from anthropogenic source. At locations wherenthropogenic influence is considered as high, such as at K5 (Pb andn in water), R2 (Zn in water) and R4 (Cu, Pb and Zn in water), moreetailed investigations on possible pollution are recommended.

The hypothesis of differing karst aquifers, as concluded fromtable isotope investigations, can be supported by investigating inetail the complex geology of Gorski Kotar, because folded Juras-ic and Cretaceous carbonate formations (acting as karst aquifers)egionally are overthrust by confining Paleozoic formations (com-are Fig. 5 in Biondic et al., 2006). For this reason the area ofhe hydrogeological catchments of smaller rivers (often compris-ng larger cave systems) mostly exceeds that of the orographicalatchments. In order to better understand this complex hydrogeo-ogical situation in western Croatia, we propose a longer lastingarst-hydrological monitoring program. To distinguish the localnfluence of Adriatic and continental weather situations as well aso detect the short- and long-termed variations of stable isotopes inhe karst groundwater, further investigations should contain reg-lar monitoring of the major karst springs and sample campaignsf the river waters. In addition, in a complex karst aquifer system,etailed hydrological and hydrogeological information can also becquired by short-termed monitoring of heavy precipitation eventsy means of stable isotopes (Stadler et al., 2010). To sum up, we pro-ose integrated hydrogeological investigations in Gorski Kotar asave been applied for the conceptual hydrogeological model of thelitvice region by Biondic et al. (2010).

. Conclusions

To evaluate hydrological and geochemical parameters of theomplex and vulnerable karst system it is important to combinearious analytical techniques and tools, such as physical–chemical,hemical and isotope analyses. Such combination of methods waspplied for the first time in the karst region.

Obtained results from the Dinaric karst area of western Croatiaupport hypothesis that the springs of the Kupa and Rjecina rivers,amely the Kupa spring, the Rjecina spring and the Zvir spring,riginate from the same mountain range (Gorski Kotar), but do notrain the same karst aquifer. This hypothesis is also supported byrace element analyses in surface waters, which highly differ in bothatchments, especially concentrations of total Pb and Zn.

Additionally, comparison of dissolved and total fractions of traceetals generally confirms that the water quality of the karst Kupa

nd Rjecina catchments is very good with respect to particulateatter, which is nowadays rare in the industrialized world. The

ame conclusion is obtained from low values of EC and approxi-ately calculated TDS, below 500 mg L−1.Due to a significant difference in oxygen isotope-ratios, it could

e concluded that the karst reservoir for the Kupa- and Rjecinaprings is not identical.

Chemical composition of sediments in the two studied catch-ents is not similar, which was expected as these are formed by theeathering of different source rocks: the Rjecina is a typical alogene

arst river, flowing first through flysch and later through carbonates

nd sandstones and its sediments are composed of quartz, feldsparnd mica group minerals (Franciskovic-Bilinski et al., 2011). Theupa is in the upper flow a karst river, flowing through limestonesnd dolomites and its sediments are composed of quartz, calcite,

e der Erde 73 (2013) 293– 308

dolomite and feldspars (Franciskovic-Bilinski, 2007). From majorelement analyses of the three springs the groundwater was deter-mined as a Ca–Na–HCO3–Cl type, discharging mostly limestone-and less dolomite formations.

Current research of the environmental status and hydrologicalcharacteristics of water supplies in the protected regions of South-Central Europe (Croatia and Slovenia) would be of benefit for theirfurther protection.

Acknowledgments

The research was supported by the bilateral project Croatia-Austria 2010–2011 “Hydrogeological investigations of the upperflow of Kupa river and its tributaries” (principal investigators:Ru –der Boskovic Institute, Division for Marine and Environmen-tal Research: Dr. Stanislav Franciskovic-Bilinski and University ofVienna, Department for Environmental Geosciences: Univ.-Prof. Dr.Thilo Hofmann), and by the Croatian Ministry of Science, Educationand Sport project No. 098-0982934-2720 (principal investigator Dr.I. Pizeta).

Thanks are due to Univ.-Prof. Dr. Ranko Biondic and Univ.-Prof.Dr. Bozidar Biondic (both Faculty of Geotechnical Engineering inVarazdin, University of Zagreb) for useful discussion and for orga-nizing to take samples of Rjecina Spring and Zvir Spring, which wassupported by the Water Supply Company of Rijeka. We are gratefulfor valuable scientific input of Univ.-Prof. Dr. Dieter Rank (Depart-ment for Environmental Geosciences, University of Vienna), and ofDr. Albrecht Leis and Dr. Hermann Stadler (Joanneum Research,Institute for Water, Energy and Sustainability, Department forWater Resources Management, Graz, Austria). We acknowledgeChristian Müllegger for his support measuring the stable isotopesat the Department for Environmental Geosciences, University ofVienna.

We thank Dr. Natalija Matic from Hrvatske Vode for helpingus with construction of Piper diagram. Also, Hrvatske Vode arethanked for providing us necessary data for Piper diagram for threestudied springs.

Mrs. Tatjana Jauk, linguist, has edited and improved English lan-guage of manuscript and we thank her a lot.

Special thanks go to Prof. Younes Hamed for his intensiveand constructive review, whose suggestions greatly helped us toimprove the major revision of the first submitted manuscript.

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