Characteristics of Groundwater in East Banat, Pannonian Basin, Serbia

Eastern Banat is the eastern part of Vojvodina Province, southern belt of the Pannonian Basin, a surface area of some 505 km2 in NE Serbia (Fig. 1). It is rolling country at altitudes between 75 and 100 metres. The largest positive morphologic feature is Vrsac Mountains that extend eastward to the Romanian-Serbian border. The Mountains occupy an area of 170 km2 surrounded by Mali Rit and Markovac stream in the north, Mesic and Guzijana ranges in the south, Vrsac suburbs in the west and Serbian-Romanian border in the east.

Similar results for Vrsac Mountains are given in Tab. 3.
Redeposition of natural radionuclides in the heterogeneous environment of Vrsac Mountains is expressed as 232 Th/ 238 U (Fig. 7).
The obtained concentrations of 238 U, 40 K and 232 Th were used to assess the effect of external equivalent of the ionizing radiation dose by Monte Carlo method (Tab.4).Applying conversion factors for ingestion and inhalation, radionuclide intake (determined by radiometry) and the fatal cancer risk were assessed for 100,000 inhabitants for minimum and maximum activities (Tab.5).
The parameters 238 U concentration, pH, Eh and Ep (Tab.6) are determined for each water sample.Moreover, 165 samples were analysed for anion-cation composition, contents of microelements (Pb, Zn, Cu, Mo, Li, Sr, Ni and Co), of radioactive elements (U, 226 Ra and 222 Rn), of F, Br and I, dissolved oxides (SiO 2 ), mineral matter in water, hardness, gases CO 2 , H 2 S, O 2 and Rn, which were measured in the field.The excessive U, Ra and Rn concentrations in water and respective pH are given in Tab.7 for Vrsac Mountains.
Concentrations of U, 226 Ra and 222 Rn in water (Fig. 8 a,c) are detected using two methods: -Laser fluorometry (uranium analyzer Scintrex UA-3); the method (U-Fl-1 "Geoinstitut") measures uranium fluorescence provoked by added fluoran (inorganic phosphorous complex) that acts as a buffer for pH 7; and -Emanometry (emanometer RDU 200 with ionization chamber) measures radium and radon in a scintillation chamber (vol.160-170 ml) made of silver-activated ZnS.The instrument is calibrated to Bq/L unit using radium salt solution of a pre-selected concentration for three standard measures: 1, 10 and 1000 Bq/L.The obtained equivalent of 0.2489 Bq/L for 1 i/min is multiplied by the values read from the instrument.
Relative relationship of U and redox potential in water from excessive uranium areas is shown in Fig. 9, and excessive Zn, Sr, Li and Mo concentrations in relation to natural water are given in Tab. 8.
The analytical methods applied were the following: -AAS (Atomic Absorption Spectrophotometry) for Ag, Au, Bi, Cd, Co, Cr, Cu, Mo, Na, Ni, K, Pb, Sb, V and Zn; -AES (Atomic Emission Spectrophotometry) for Cs, Li and Rb; -ICP-AES (ICP Atomic Emission Spectrophotometry) for B, Ba, Be, P and S.
Samples were prepared with open digestion and mineral acids or their mixtures were used for destruction.The agent used to destroy samples tested on Ag, Au, Bi, Cd, Co, Cu, K, Mo, Ni, Pb, Sb, Zn and V was aqua regia (HNO 3 : HCl).Modified aqua regia was used in destruction of the samples from which P and S were determined, and sample digestion with HF, HNO 3 , HClO 4 to identify B, Ba, Be, Cr, Cs, Li, Rb and Sr.

Geologic -Structure features
The geotectonic setting of Vrsac and Bela Crkva town areas is a depression formed in the early Miocene with intensive rising of the Carpathians, Dinarides and Alps (Fig. 2).The intermountain subsided and was invaded by the Mediterranean Sea.The communication with the Mediterranean Sea ceased in the late Miocene and the formed Pannonian Sea turned first into a brackish and later into a freshwater water body (Nikic & Vidovic, 2007).Neotectonic positive movements formed the horsts of Fruska Gora (a part of the Vardar Zone) and Vrsac Mountains (part of the Serbian-Macedonian Massif).The Pannonian basin has the floor pattern of minor troughs and horsts.The Vrsac Mountains and Bela Crkva subregion is built largely of Miocene, Pliocene and Quaternary deposits with projecting Vrsac Mountains of crystalline schist and granite (Vukovic, 1965;Rakic, 1978).
Crystalline schist was found in the petroleum test wells on Vrsac Mountains at depths from 890 to 1100 metres under sedimentary rocks.The complex of crystalline rocks dated Precambrian or Lower Paleozoic underwent metamorphism during the Hercynian Orogeny.
It is composed of gneiss, schist, phyllite, granite and granitic gneiss.Pegmatite, and aplite and leptynite associated with finegrained gneiss.
The Miocene (Upper Miocene, Pannonian), unconformable and transgressive over the Lower Paleozoic schist, consists of sands, clays and silts.Lower Congerian Beds or Pannonian (caspibrackish) deposits have the largest distribution east of Bela Crkva.
Fig. 2. Geological map of Vrsac and Bela Crkva areas (Scale 1:100,000) (Vukovic, 1965, Map compilation by Gordanic, 1980) The Pliocene is represented by Pontian and Levantian deposits that form freshwater aquifers, which extend over the southern and central Banat and eastward into Carpathians of Romania (Vukovic, 1987).Levantian deposits with freshwater bodies are unconformable over the Pannonian, composed of gravel and sand tens of metres thick.Their lithofacial character indicates fluvial-lacustrine sediments.Lower Pliocene (Pontian) is exposed in the villages of Gudurica, Markovac, Socica, Kustilj and Jablanka near Bela Crkva, on the northern and southern Vrsac Mountains ridges and from Gudurica to Vojvodinci along the Romanian border.Minor outcrops are located at the Mesic village (IBD-1/01).
Upper Pliocene (Levantian), recognized mostly in boreholes, are gravel and sand, variable in thickness and extensive near Bela Crkva.
The Quaternary, both Pleistocene and Holocene deposits cover some 70% of the geochemically prospected Vrsac-Bela Crkva area.
Two large structural units occupy the region: Rhodope, built of crystalline schist of low metamorphic grade (Rakic, 1978), and Banat or Banat-Morava unit a neoalpine structure, both extending from NE to SW, which is the main trend of the structural features (Askin, 1967) formed in result of the crystalline bedrock fracturing during the Savian and Pyrenean Orogenies.
Tectonic events of different intensities, from the Oligocene-Miocene to the present, formed horst and trough features in numerous faults.The Pavlis source area is in a deep trough that formed between the horst range Velika Greda-Jermenovci-Lokve-Nikolinci-Tilva and Vrsac Mountains, in which different chronostratigraphic units were brought to the same level.Further subsidence and diagenetic processes during the Quaternary developed a shallow surface depression, the Alibunar-Vrsac depression.

Hydrogeological characteristics
Different aquifers are related to the regional geological-structural and geolithological features of the rock masses and their porosity.Bodies of rocks that contain and conduct groundwater are either water-table or artesian aquifers.

Water-table aquifer
Phreatic water in the Vrsac municipality occurs in: alluvial deposits from the Karas (Filipovic, 2003), Guzijana, Boruga, Markovac, Moravica (minor intermittent streams), which are heterogeneous (sand, gravelly sand, clay soil, sandy clay and mud) and have transmissibility coefficient (T) up to 22x10 -3 m 2 /s; Very weak springs of less than 0.1 L/s occur some 50 to 100 metres down the hilltops or their occurrence is secondary.The spring-discharge fluctuation is small because the capacity of aquifers is small.A change in the water-yielding capacity of the aquifer involves other modifications such as water temperature, chemical composition (amount of minerals), etc.
Classified by the water-yielding capacity of aquifers, this area is assigned to the low-yield group from 0.1 to 1.0 L/s per discharge point.
Surface streams that are draining the area run from NE to SW, same as the trends of the structural features.Groundwater flows through the weathering crust mainly in the same direction towards the local base level of erosion.Unconfined water does not occur below the base level, not even in fractures intersecting the area.
Groundwater is dominantly HCO 3 -Ca-Mg, low mineralized (0.4 to 0.5 g/L), neutral (pH 7), contained in an unconfined hydrogeologic body of intensive water exchange, so that individual chemical constituents are susceptible to transformation with the time.

Artesian aquifer
A Neogene complex of Miocene lithological varieties more than a thousand metres thick forms an artesian water body between Miocene or Paleozoic crystalline schist and intrusive granite, where Miocene deposits are lacking, and 30-100 metres thick Quaternary.
A shallower artesian aquifer, less than 200 metres deep, is formed by Upper Pliocene waterbearing rocks that are not clearly differentiated from other rocks, because water-bearing layers occur at different depth intervals in boreholes within short distances.(Milivojevic, 2004).
On the profile of the borehole (Fig. 4), there was found four water-bearing horizons, which are mutually hydrogeological different.Deeper than these lithological members, there are water-bearing layers, which are not included from the point of these studies.The main groundwater reservoir (both artesian and subartesian) is replenished directly by percolating atmospheric precipitations on Vrsac Mountains margin and Bela Crkva area, and in Romanian side by infiltration from rivers.Indirect replenishment by precipitations occurs from water-table aquifer in the Deliblato Sands and on the loess plateau.Groundwater recharge during piestic low of the main reservoir in the Alibunar-Vrsac depression is small, indirect from the overlying semipermeable layer and from drainage canals.
Groundwater circulation is slow, decreasing from the Neogene basin borderland where water 14 C dated was 1100 years old (Gudurica).Further from the edge of the basin, the water age increases to 6950±160 years in Potporanj and 9900±100 years at Pavlis.
Groundwater in the main reservoir is chemically characterized by low TDS, with dry residue 280-420 mg/L, locally about 600 mg/L, pH 7.4-7.6units.Total hardness varies from 12 to 16.5 ºdH.The KMnO 4 rate is low, not exceeding 5 mg/L.Ammonia is always higher (0.6-1.2 mg/L) than MAC, and local concentrations of iron and manganese are 2.2 and up to 0.15 mg/L, respectively.Other mineral constituents are within the standards for drinking water.

Hydrochemical exploration of main groundwater reservoir
Results of the hydrochemical exploration are presented for the main reservoir in the Pavlis source and aquifers in the Mesic areas.

Pavlis source area
Groundwater in Pavlis area is used for municipal water supply to Vrsac and to small communities in the surroundings.Water production started in 1961 in an area bordered by the Keveris and Veliki Kanal and the village of Pavlis.A Feasibility Study was prepared in 1987, a water supply projection to 2005 needed by the growing town and its industry, from the main groundwater reservoir.On the basis of the Study, the source area has been extended to the present 17 wells (B-1 to B-17).
The production of 10 L/s at first increased to 180 L/s.When the Study was prepared, a drawdown of about 0.5 m/yr was recorded in the Pavlis area.The exploitation regime at Pavlis is considered to be "relaxed", about 16 hours per day on average.Chemical composition of water was analysed previously in relation to the regime of production.Before 1977, only wells B-7 and B-8 in the main reservoir were analysed.After 1977, seven new wells were drilled from which natural water from the main aquifer has been analysed.The parameters analysed are: Na + , K + , CaO, Ca 2+ , MgO, Mg 2+ , Cl -, SO 4 2-, HCO 3 -, Fe, Mn, NO 3 -, NO 2 -, NH 3 , F, SiO 2 , pH, hardness, Ep, KMnO 4 consumption and M (mineralisation).
Water quality deterioration has not been registered for any parameter in the given period.
Chemical composition of groundwater in Pavlis source area is expressed by Kurlov formula (1) (Slimak, 2005)  In Alekin classification, groundwater from the Pavlis main reservoir is hydrocarbonatecalcium-magnesium water, its chemistry in the reported period (Fig. 5 a, b and c).

Mesic source area
Artesian aquifer (the village of Mesic) is located on the southern side of Vrsac Mountains.
Water is pumped from three rock units: crystalline schist, gneiss, Neogene deposits and Quaternary alluvial deposits of the Mesic brook.
A structural feature in the area is a fault with the northern block of some 20 metres relative downthrow.The Mesic Brook runs from the source in southward direction from the fault, then deviates 90º to SW.In context of local geology and hydrogeology, groundwater reservoirs must have formed in an open structure, and in semi-open Pleistocene quartz sand.Based on the geological setting, porosity of lithostratigraphic units and hydrodynamic conditions, the types of groundwater bodies (Lazic, 2010) are the following: -Compact water-table aquifer of considerable water-yielding capacity in alluvial deposits of gravel and sand; -Compact subartesian aquifer of smaller water-yielding capacity in Pontian and Pleistocene sand deposits (IBD-1/01 Mesic); and -Fractured-rock aquifer of low water-yielding capacity in muscovite gneiss.
Table 2 gives chemical data of groundwater from test/production well IBD-1/01 in a lowcapacity aquifer, for period 2008-2009.The water-bearing formation is largely quartz sand in two layers (lower/basal and higher/upper) at different depths, whose total thickness in test/production well IBD-1/01 is some 10 metres.
The main water-bearing formation consists of two (lower and upper) layers of about 10 m total thickness in test well IBD-1/01 area of influence.The formation is overlain by Quaternary clay and sand 10-15 m thick (26.7 m in the well-influence area) and underlain by crystalline schist.Loam is a kind of confining bed for the surface Mesic brook surface water.Groundwater in this formation is under mild subartesian pressure from the mentioned upper layer.
Pressure in the lower layer of quartz sand is somewhat higher, to 1.5 m below the surface, although IBD-1/01 is 2-3 m higher than BD-1/02.This water-bearing layer, where sands under a thin cover lie near the surface, is replenished by atmospheric precipitations that infiltrate from the crushed and fractured contact zone with crystalline schist.The coefficient of stability is determined only for cations and anions and may be expressed by Kurlov formula.Its value does not exceed 5%, viz.: 6.1056% K Ca 2+ , 7.9234% K Mg 2+ , 29.534% K Na + , 4.653% K HCO3 -, 12.268% K SO4 2-and 6.1069% K Cl -.These coefficients indicate stable chemical composition of water in the 'compact low-capacity aquifer' drained by well IBD-1/01.This refers to the dominant anions and cations (HCO 3 -, Ca 2+ and Mg 2+ ) which qualify the type of water.The type of water from IBD-1/01 is hydrocarbonate-calciummagnesium, written as (Kurlov formula): HCO SO Cl M tQ Ca Mg Na

PARAMETER
(2) In relation to the pumping coefficient (Q 0.9 ), the water resource is classified as "economic" or "B reserve" (Lazic, 2010).
Occurrences of deposits and veins of hydrothermal quartz with pyrite, magnetite and chalcopyrite in salbands at the contact with schist were located south of Gudurica in Vrsac Mountains.Geochemical anomalies for W (3000-5000 ppm) and Mo (up to 250 ppm) were detected in granitic gneiss near a granite intrusion, south of Vrsac peak (Botija Plate).Concentrations of 238 U, 232 Th, 40 K, total uranium (Ut) and dissolved uranium (Ud) are determined (Tab. 1) in samples collected during the radiometric profiling (Gordanic, 1980;Spasic-Jokic & Gordanic, 2010a).3. Radiometric results for granite-migmatite and ectinite-gneiss (Gordanic, 1980) Natural radionuclides have a log-normal distribution in the heterogeneous environment of the Vrsac Mountains.Concentrations of uranium in granite-migmatite indicate its redistribution in the older metamorphic rocks during a long geological period, or it resulted from subsequent hydrothermal and metasomatic processes.Dominant character of Th is represented in relation to U on a Th/U diagram in Fig. 7.  Gordanic, 1980) Potassium is twice higher in gneiss than in ectinite, a likely consequence of metamorphism with the supply of magmatic melts and fluids during the Hercynian Orogeny.

GRANITE AUGEN BIOTITE GNEISS (Gb) GRANITE -GNEISS (Gy) i AUGEN MUSCOVITE GNEISS (Gm
The effect of natural nuclides on rural environment was assessed on the Vrsac Mountains using the Monte Carlo method (Spasic-Jokic & Gordanic, 2010a) to establish external equivalent of the ionizing radiation dose 1 m above the ground, which depicts the natural environmental radiation; this in view of the natural uranium concentrations of 99 Applying conversion factors for ingestion and inhalation, radionuclide intake (determined by radiometry) and the fatal cancer risk were assessed per 100,000 inhabitants for minimum and maximum activities (Zupunski et al., 2010;Spasic-Jokic & Gordanic, 2010b) (Tab.5).(Gordanic & Zunic, 1994) The exploration data were used to delineate anomaly zones, for which geological section A-B is drawn Fig. 2 that shows the proportions of radionuclides in water and rocks.Proportions of U, Ra and Rn concentrations in water of the anomaly zones, radioactivity and U and Th concentrations in rocks are diagrammatically represented in geologic section AB, Fig. 8 a, b, c (Gordanic & Zunic, 1994).Waters with excessive concentration of uranium have pH from 6.5 to 7.6.The range of dissolved minerals in water is from 138 mg/L to 4557 mg/L.Uranium-high waters are mainly low in dissolved mineral materials (< 1 g/L), only few are > 1 g/L to 5 g/L, suitable for uranium migration in an aquatic environment.The amount of SiO 2 in water of the anomaly zones is about 30 mg/L, which is related to the weathering zone, and somewhat higher (up to 99 mg/L) in water in contact with structural features.

SOURCE ACTIVITY (Bq
The oxidation-reduction potential (Eh), determined in each water sample, varies within the range from -65 mV to +190 mV.The diagram of relative Eh and uranium relationship (Fig. 9) shows that waters in extreme zones are dominantly oxidizing, with Eh from 130 mV to 170 mV.Such an environment enhances uranium solution from adjacent rocks, which is manifested in the extreme concentration zones.In view of the metallogenic character of the explored area, waters were analyzed on concentrations of the microelements Zn, Pb, Cu, Sr, Li, Mo, Ni, Co, F, Br, I, Fe 2+ , Fe 3+ and SiO 2 .Elevated concentrations of Zn, Sr, Li and Mo can be used as direct indication of concealed ore bodies and of uranium mineral (Tab.8).Other analyzed elements were found in ore or less standard amounts for natural waters.
Elevated Li, Sr, U, Ra and Rn are related to the nearness of a granite intrusion, a zone of fine-grained gneiss with leptynite, aplite and pegmatite veins.The presence of Li in subsurface and surface waters may be an indication of pegmatite deposits in respect of extreme U, Mo, Pb, Zn and Ag contents in gneisses (Hawkes & Webb, 1960), which are potential sources of elevated concentrations of radioactive elements in waters.(Vidovic, 2007).Anionic and cationic compositions of waters are dominantly HCO 3 -SO 4 -Cl to HCO 3 -Cl-SO 4 , and Ca-Mg to Ca-Na, respectively.Particularly elevated are the amounts of NH 4 , NO 3 , NO 2 , SO 4 , K, Ca and F (in Kustilj and other minor communities).Water in all wells is oxygen-high between 3 and 13.1 mg/L.The effect of human activities is manifested at the water-table level.Large communities, such as Bela Crkva, supply water from drilled wells in which the depth to water table varies from 43 to 111 metres.

Conclusion
Controlled by the geological-structural setting of the region, groundwater bodies have formed on Pontian-Levantian deposits that extend over the southern, central and eastern Banat and further to Carpathian offsets in Romania.Zones of groundwater recharge are the following: -Deliblato Sands, percolation of precipitation; -Vrsac Mountains offsets (in water-bearing layer exposures), and -Carpathians offsets in Romania (in aquifer exposures).
Groundwater drainage in the Vrsac-Bela Crkva area operates through groundwater bodies in: overbank deposits from the Nera and Karas streams, or rises through the overlying less permeable layer to the shallower aquifer in a confined area of groundwater (piezometric surface above the land surface), -through many flowing wells and water-intake facilities.
The zones of extreme natural U, Ra and Rn radionuclides are related to the geologicalstructural and metallogenic features of Vrsac Mountains and have no effect on the Pavlis groundwater source for supply to Vrsac and its suburbs.
The identified extreme concentrations of Pb, Zn, Mo, Ag, Au and W in Vrsac Mountains have no effect on groundwater in Pavlis area.
Total concentrations of ΣU, 232 Th and 40 K are used to assess the fatal cancer risk per 100,000 inhabitants exposed to ingestion and inhalation of natural radionuclides in soil.Measured concentrations UNSCEAR, 2000) in the region of Vrsac Mountains are within the allowed range.This information is important for the geomedical status of the region and for other environmental-geochemical research.
Extreme concentrations (above MAC) of Pb, Li, Sr, Mo in groundwater of Vrsac Mountains are noteworthy because this water is used in rural households (Drinking Water Regulations, Official Gazette SRY No. 42/98 and 44/99).Water from tested wells used in the communities near Bela Crkva does not meet the standard for drinking water.The abovementioned elements are below the MAC in the source of the Bela Crkva water supply.No impact of human activities in the nearby communities has been established on the source of Bela Crkva water supply.

Acknowledgment
This work was supported by the Ministry of Education and Science (Project OI 176018).
238 U, 232 Th, 40 K concentrations in rocks (80 samples) used scintillation detector 4x4 Bicron with a NaJ crystal and a multiplier tube (MCA; 4096 channels) Ortec 7500 (Tab.3, Fig. 8 b).The instrument measures flashes of a high-energy (0-3 MeV) agent.The calibration of spectra and the count of natural radionuclides, compared to the standards for uranium and thorium minerals, are NBL No. 103 0.005 % U and NBL No. 107 0.10 % Th and relative Th/U are shown in Fig. 7.The potassium standard used was potassium chloride (p.a., Merck).

Fig. 3 .
Fig. 3. Columnar section for borehole IBD-1/01 in the Mesic village(Lazic, 2002) The groundwater body is difficult to outline, because it extends into Romania on one side and throughout the Pannonian basin on the other side.Its southern boundary is the Danube, and the eastern boundary is Vrsac Mountains (the SW offsets of the Carpathians) and a crystalline massif near Bela Crkva.Characteristic geological and hydrogeological sections beneath Quaternary deposits in Vrsac area near the artificial lake are reconstructed on the data from RB-1 and B-1 test-wells.Lithology of Paludine-Levantian sands under Quaternary deposits consists of the following intervals: 0-23 m Quaternary complex (clay, gravel, sand); 23-42 m grey-green sand; 42-44 m clayey sand; 44-67 m grey-green fine-to medium-grained sand on gravel; 67-73 m grey-green silty to fine sand; 73-96 m grey clay; 96-121 m grey medium-grained sand; 121-174 m grey clay; 174-188 m grey coarse quartz sand; and 188-220 m grey clay.The depth of good hydraulic properties is between 23 and 67 metres, particularly interval 44-67 m, confirmed by pumping test in well RB-1(Milivojevic, 2004).
Fig.4.Columnar section for borehole at the Vrsac artificial lake(Gordanic, 1980) The Vrsac borehole (Fig.2) penetrated four different water-bearing layers: Upper Pontian, Levantian and Pleistocene clay-sand deposits form several confined (artesian and subartesian) aquifers to a depth of 300-400 metres from the surface.Mineral salts and temperature of water are increasing with the depth, yet this is the main source of domestic and industrial water supply.Moreover, the prevailing hydraulic system is complex.Strata of deposits that include confined water bodies are interrelated because of the frequent vertical and lateral variations in facies.Horizontal and vertical communication of confined groundwater has also hydraulic connection with the shallow unconfined groundwater.Artesian water-bearing layers, established on the Vrsac Mountains margin, dip to the central basin along fault zones, which provides for overflow of mineral-high water from deep into the shallow layers.The test hole near the artificial lake at Vrsac produced water from the depth of 200 metres that had mineral content 6.91 g/L and temperature of 24ºC.Groundwater from the same depth in Banat, only unaffected by overflow from deeper aquifers commonly contains 1.1 to 1.6 g/L dissolved mineral material.Water from deep aquifers in Vrsac area moves along the contact of Tertiary deposits and crystalline schists and overflows into the shallower Pliocene aquifers of lower confining pressure.

Fig. 6 .
Fig. 6.Circle graph of the principal anion and cation mean concentrations in water from IBD-1/01 at Mesic village in the observation period (from March 2008 to October 2009) Stability of chemical macro-composition or of individual constituents is based on the proportion of minimum and maximum concentrations of some elements expressed by the stability coefficient (K ) for the period from March 2008 to October 2009.

Fig. 8
Fig. 8. a) Compilation diagram of extreme concentrations of uranium in water and b) U and Th in rocks related to the c) geologic-structure setting(Gordanic & Zunic, 1994)

Fig. 9 .
Fig. 9. Relative relationship of redox potentials in waters of extreme uranium concentration zones(Gordanic, 1980) The depth to groundwater is between five and ten metres.The water table contours are comparable with the topographic contours, only the slope of the water table is gentler than that of the land surface.Water table contours indicate directions of the groundwater drainage to the lower lands where are the local base levels of erosion (the streams Karas and Nera and the Danube-Tisa-Danube Canal).Diffuse aquifers are fractured Paleozoic schistose rocks of Vrsac Mountains and east of Bela Crkva.The complex of schistose rocks had been much deformed by multiple folding of a structure in NE and SW directions with minor local deflections.Rocks heavily fractured at the surface have fractures and cracks mostly filled with weathering waste.The density and size of cracks decrease with the depth nearly to the point of disappearance of water table.Groundwater is recharged almost entirely from precipitations and is discharged to small morasses or at intermittent springs.Most of precipitation runs off or evaporates, with only a very small amount percolating underground.

Table 1 .
Hydrochemical analysis of groundwater for Pavlis source

Table 4 .
Annual effective dose from ingestion of terrestrial radionuclidesThe effective doses for ingestion in Table4are lower than those of UNSCEAR.

Table 5 .
Absolute fatal cancer risk assessments after exposure to radionuclides 238 U, 232 Th, 226 Ra and 40 K

Table 6 .
Water analysis during the regional hydrogeochemical prospectingThe presence of augen biotite gneiss (Gb) around the granite intrusion on Vrsac Mountains, then the presence of granite varieties, largely altered by sericitization, muscovitization and feldspathization a younger phase of which is expressed through albitization, are the reasons for elevated U,226Ra and 222 Rn concentrations in water of the following anomaly zones:

Table 7 .
Concentrations of U, Ra and Rn in well and spring waters of Vrsac and Bela Crkva areas are given in Tab. 7. Concentrations of U, Ra and Rn in waters and pH for Vrsac and Bela Crkva areas

Table 8 .
Amounts of Zn, Sr, Li and Mo in water Unconfined groundwater in Upper Pliocene (Levantian) deposits of Bela Crkva is pumped for domestic water supply in small communities.Water in most wells (3-34 m deep) is below the MAC standard for drinking water (Drinking Water Regulations, Official Gazette SRY No. 42/98 and 44/99) being highly mineralized, elevated amounts of nitrogen compounds, high conductivity and concentrations of heavy metals: Pb, Cd, Ni, Br, Al