Milka Vidović, Zoran Nikić, Boban Milovanović

Water Quality of the North Basal Aquifer System

Milka Vidović1, Zoran Nikić2, composition of the water, its many expla- Boban Milovanović3 Introduction nations are only hypothetical. The quality North Banat of about 2329 km2 in area is the of confined groundwater is not uniform in northeastern part of the Province the study area. An essential characteristic that occupies southeastern margine of the is the high organic content of natural ori- Abstract Pannonian depression (Fig. 1). An organized gin (Čukić et al., 1987, 1994). North Banat, an area of about 2329 km2 ad- public water supply in North Banat began in Earlier examinations focused only on ministered by six municipalities, is the ex- the sixties of the 20th century. Sources of the organic material in the water that could treme northeastern part of the Republic domestic and industrial water supplies are affect its sensory properties (colour, taste of and located in the southeastern confined aquifers about 160 m to 300 m deep. and odour). There are few references to margin of Pannonian depression. Drinking The aquifer depth decreases from the NE to the full chemical composition of this wa- water is supplied under artesian or sub ar- the south, being 300 m at Kikinda. ter (Vidović, 1996). More light has been tesian pressure of Lower Pleistocene (Q1) Water of “uncommon” composition is thrown on the water quality on the last ten or Upper Pliocene (Pl3) from confined aq- the only potable water in the semi-arid area years (Čukić, 1989; Vidović, 1998) through uifers. Tapped water-bearing beds in Ba- of Kikinda. To meet the general demand, it specific explorations for water supply and nat dip from northeast to the south, reach- is withdrawn in excess of the natural re- petroleum and gas resources. ing a depth of some 300 m at surrounding plenishment that results in continuous re- of Kikinda. duction of the pressure head. What causes Materials and method Chemically, these “uncommon” waters the extraordinary chemical composition Interpretation of the given hydrogeologi- are a natural rarity controlled by geologi- of pumped water is probably the character cal section is based on the available pub- cal and hydrogeological characters of the of the water-bearing strata. Reference in- lished information and exploratory drilling water-bearing strata. The quality of water, formation (Vuković et al., 1979) dates this records for northern Banat (Fig. 2). Water periodically tested and examined, is dis- water between twenty and thirty thousand was sampled from pressure pipes of the mu- cussed in this paper and its chemical com- years ago. Notwithstanding the efforts to nicipal water supply wells in each season of position is interpreted in terms of the re- find the cause of the uncommon chemical the year. The analysis covered series of 34-56 gional geology.

Key words: ground water, hydrogeology, water quality, North Banat.

1 IHTM, Scientific Institution, 12 Njegoševa, 11 000 , E-mail: mivibgd@yahoo. com 2 Faculty of Forestry University of Belgrade, 1Kneza Viseslava, 11 030 Belgrade. E-mail: [email protected]

3 Galenika a.d., bb Batajnički drum, Fig. 1 Geographical location of North Banat 10/2006 Pannonica Geographica 43 Water Quality of the North Banat Basal Aquifer System

b) Chemical Properties of Water Groundwater in the area was examined on chemical and physial properties with the view to its domestic use, not for hydrody- namic or hydrochemical study of the aqui- fer, groundwater flow or relation between water-bearing horizons. The examinations confirmed specific water quality characterized by extremely low total hardness (1.7ºdH) and high nat- ural organic content (about 27 mg/dm3), which give water the characteristic opal- escent pale-yellow colour, both properties very uncomon of ground water. The obtained properties (Tab. 1) indi- cate stable quality, increased temperature (about 295 K), pH variation within a nar- row range (from 8.1 to 8.2), and negative re- dox potential (-40 mV) from the presence of reductive agents. Water emits ‘sulphure- ous odour’ produced by anaerobic process- es. The type of water, by its inorganic con- tent, is Na+HCO3-. Dominant kation is that of sodium, ex- ceeding the maximum allowed concentra- tion (MAC) for drinking water, whereas calcium and magnesium concentrations are very low whih is rare for ground wa- ters. Concentrations of Fe and Mn, below MAC for drinking water, are also some- what unusual for ground water (Yugoslav Regulations 1998). Hydrocarbonates are dominant anions, Fig. 2 Geological map of North Banat with indicated investigated section A-B followed by silicates, while sulphate, chlo- information for 32 water quality parameters sand-silt-clay) or reduced cycles in several ride and fluoride concentrations are very selected to represent best the problem. sections A heterogeneous body of permea- low. Ammonia nitrogen is higher than Table 1 gives maximum, minimum and ble material separated laterally and vertical- MAC for drinking water, which is com- average results of the groundwater chem- ly by less permeable or impermeable silty mon for ground waters. It is interesting ical analyses for Kikinda area, which are sand, silt or silty clay as a result of depos- to note that organic nitrogen is relative- commented in the text. Standard and gen- its’ origin acts as a water-yielding hydrau- ly high, probably incorporated into the erally accepted examination methods were lic unit or a basic aquifer system (Collective structure of humic substances. used (Merek, 1974; US EPA, 1988; APHA, authorship, 1996). Because the withdraw- In addition to the common free CO2, 1989; Škunca-Milovanović et al., 1990). al is in excess of natural replenishment, the gaseous constituents are methane and free pressure head is continuously reduced. hydrogen sulphide that give water its nasty Results and Discussion Polycyclyc fluvial sediments are con- smell and taste. The absence of oxygen also formably overlain by fluviatile lake depos- effects its sensorial quality. Oligoelements a) Hydrogeological Properties its also of Pleistocene age. Major constitu- are contained either in traces or below the The aquifer tapped for the Kikinda water ents of the fluviatile lake deposits are silt limit of detection, excluding somewhat supply is part of a thick body of sands and and silt-and-fluviatile clays of alluvial and higher arsenic (12 μg/l). Total β-radioac- sandy clay and clays alternating both hor- oxbow facies with intercalations or lenses tivity also is below the allowed limit. izontally and vertically. Water-bearing ho- of dominantly fine sands of the riverbed Concentrations of phenols and miner- rizons are constituents of polycyclic fluvial facies. For explanation of the water quali- al oils are very low (at detection limit), and sediments, fluviatile lake and fluvial sed- ty, an important characteristic of the fluvi- pesticides are undetected, not even in trac- iments of Pleistocene age. Polycyclic sed- atile lake deposits is the local occurrence of es. Total polycyclic aromatic hydrocarbons iments are the oldest Quaternary (Pleis- silt intercalations with remains of the half- (PAH) is below MAC for potable water. tocene) deposits unconformable over the bog vegetation up to 5 m thick (Collective It should be also noted that fresh upper palustrine beds. The Pliocene/Pleis- authorship, 1999). ground water is bacteria-free, which was tocene boundary is not identified, only be- Fluviatile lake deposits are more and has been a strong argument for its use lieved to be at a depth of a few hundred than 100 m thick in the Kikinda-Nako- despite the evident defects. The argument metres (Collective authorship, 1976). Gen- vo- depression. Lithologic logs for is irrelevant under the prevailing distri- erally, its depth decreases southward from Kikinda show “grey-greenish sandy clay, bution conditions, because other intricate the north-northeast Banat, being about 300 coal-intercalated” at depths from 223 m to factors in major distribution systems that m deep in Kikinda area. A basic character- 261 m. Shallower Pleistocene units contain conduct water of the given quality gener- istic of polycyclic fluvial sediments is the su- fluvial and river terrace sediments (sands, ate secondary pollutants. A noteworthy in- cession of riverbed facies (sands, infrequent silts and clays) of relatively small thickness formation is also that potential trihalogen gravels) and alluvial facies (silt and clay) as (about 30 m) and thereby of a marginal hy- methane (dominantly chloroform) varies

Geographica Pannonica 10/2006 Pannonica Geographica a multiple repetition of complete (gravel- drogeologic importance. between 350 and 400 μg/dm3. 44 Milka Vidović, Zoran Nikić, Boban Milovanović

Table 1 Maximum, minimum and average results of the groundwater chemical analyses for Kikinda area Parameter Unit Medium Maximum Minimum Values of drinking water parameters values values values according to regulations Water temperature K 295,16* 295,66 294,66 281,16-285,16 Odour - On sulphide* On sulphide On sulphide Without odour Turbidity NTU 1,6* 1,8 1,4 1,0 Colour °C0-Pt 28,0* 32 24 5 pH value - 8,2 8,2 8,1 6,8-8,5 Dry residue (105°C) mg/dm3 485 550 448 Consumption of KMnO4 mg/dm3 28,5* 31,0 26,8 8,0 Dissolved O2 mg/dm3 0,0 0,0 0,0 Conductivity (20°C) µS/cm 945 989 791 do 1000 Redox potential mv -40 -49 -31 Total hardness mgCaCO3/dm3 28,6 30,43 26,85 Total alkality mgCaCO3/dm3 422,4 451,8 398,6 p- alkality mgCaCO3/dm3 0,0 0,0 0,0 0,0 Free CO2 mg/dm3 2,5 2,6 2,3 H2S(free) mg/dm3 0,19* 0,20 0,17 bez UV extintion (254nm) 1/m 31,4 32,4 29,6 Total α -radioactivity Bq/ dm3 0,087 0,088 0,085 0,1 Total β -radioactivity Bq/ dm3 <0,037 0,039 0,034 1,0 NH3 mgNH3/ dm3 0,58* 0,72 0,49 0,1 Ca mg/dm3 10,2 12,0 8,6 200,0 Mg mg/dm3 2,74 3,1 2,4 50,0 K mg/dm3 0,93 1,1 0,8 12,0 Na mg/dm3 219* 225 205 150,0 Fe (total) mg/dm3 0,12 0,18 0,09 0,3 Mn(total) mg/dm3 0,03 0,04 0,02 0,05 Zn mg /dm3 0,007 0,0079 0,0064 3,0 Cu mg /dm3 0,0090 0,011 0,0083 2,0 Cd mg /dm3 <0,0001 <0,0001 <0,0001 0,003 Pb mg /dm3 <0,002 <0,002 <0,002 0,01 Ni mg /dm3 <0,001 <0,001 <0,001 0,02 Cr (total) mg /dm3 <0,001 <0,001 <0,001 0,05 As mg /dm3 0,012 0,014 0,011 0,01 Hg mg /dm3 <0,0002 <0,0002 <0,0002 0,001 Nitrates mgNO3/ dm3 0,015 0,023 0,010 50,0 Nitritеs mgNO2/ dm3 0,004 0,006 0,002 0,03 Sulphates mg/dm3 1,12 1,18 1,09 250 Chlorides mg/dm3 4,45 4,60 4,21 200 Phosphates (orto) mgP/ dm3 0,053 0,057 0,050 0,15 Cyanides mg/dm3 <0,005 <0,005 <0,005 0,05 Fluorides mg/dm3 0,5 0,6 0,4 1,2 Silicates mg/dm3 12,4 13,2 11,9 Total organic carbon mg/dm3 13,2 13,8 11,2 - Detergent (anionian) mg/dm3 <0,005 <0,005 <0,005 0,1 Phenoles (4-A method) mg/dm3 <0,002 <0,002 <0,002 0,001 Total oils and fats mg/dm3 0,019 0,0199 0,0186 0,1 Mineral oils mg/dm3 <0,010 <0,010 <0,010 0,010 Polycyclic aromatic hydrocarbon Σ 0,0002 Fluoroanthene mg/dm3 0,06 0,07 0,04 Benzo-3,4fluoroanthene mg/dm3 xnd Benzo 3,4-pyrene mg/dm3 nd 0,00001 Benzo 1,12 perylene mg/dm3 nd Indeno(1,2,3,cd)pyrene mg/dm3 nd Halogen Organic Compounds Chloroform mg/dm3 nd 0,04 Dibromochloromethane mg/dm3 nd 0,0015 Dichlorobromomethane mg/dm3 nd Bromoform mg/dm3 nd Geographica Pannonica 10/2006 Pannonica Geographica 45 Water Quality of the North Banat Basal Aquifer System

Parameter Unit Medium Maximum Minimum Values of drinking water parameters values values values according to regulations 1,2 dichloroethane mg/dm3 nd 0,003 Carbon tetrachloride mg/dm3 nd 0,005 1,1,1trichloroethane mg/dm3 nd 2,0 Trichloroethilene mg/dm3 nd 0,07 Tetrachloroethilene mg/dm3 nd 0,04 Organic Chlorides Insecticide Lindan µg/dm3 nd 0,2 DDT(DDE+DDT) µg/dm3 nd 1,0 Aldrin/ Dieldrin µg/dm3 nd 0,03 Triazine herbicide Atrazine µg/dm3 nd 0,1 Simazine µg/dm3 nd 0,1 Prometryn µg/dm3 nd 0,1 PCB mg/dm3 nd 0,0005 xnd -no detected exceeding * -exceeding the maximum allowed concentration Conclusion ological and ecotoxicological research in North Banat). Water Quality Interna- Geological formations overlying the tapped the identification of geopathogenic zones of tional Conference Proceedings), Čačak, aquifer in the Kikinda area contain much toxic elements and natural radioactivity in pp. 69-73. organic vegetative material. A reasonable storage reservoirs for domestic water sup- Čukić, Z., Vidović, M., Perišić, M. 1989. Ef- assumption is that organic matter in well ply in the Republic of Serbia, funded by the fects of Water THM Potential Reduc- water originates from the strata contain- Ministry of Science and Environmental pro- tion by Mildly Alkaline Macroporous ing vegetable irganic material, which exist- tection of the Serbian Government. Resins. Water and Sanitation 4, 31-35. ed in the paleoenvironment of marshes. MERCK 1974. The Testing of Water. Darm- Beause aquifers of North Banat are the References stadt, Federal Republic of Germany. only source of drinking water in this arid APHA, AWWA, WPCF 1989. Standard “Official Gazette of the Republic of- Ser district, explorations in the extent of the Methods for Examination of Water & bia” no 42/98, Hygienic Standards for aquifer that yields water of the described Wastewater (18th Ed.). Drinking Water. quality may produce information on its or- Colective authorship 1999. Conceptual De- Škunca-Milovanović, S., Feliks, R., Đurović, igin and provide useful guidelines for se- sign of Water Supply in Vojvodina, Stage B. 1990. Drinking Water, Standard San- lection of the water-treatment technology. Two. Ministry og Agriculture, Forestry itary Examination Methods. Federal Consumed natural and fresh this wa- and Water Resources, Belgrade. Health Agency. NIP Privredni pregled, ter is harmless, but its massive use for do- Collective authorship 1976. Geology of Ser- Belgade. mestic supply is questionable under the bia, Hydrogeology. Belgrade University, US EPA, 1988. Methods for the Determina- conditions of its present delivery (man- Faculty of Mining and Geology. tion of Organic Compounds in Drink- datory clorination): organic carbon, ex- Collective authorship 1996. Water Man- ing Water, 600/4-88/039, Cincinnati, tremely high in water, allows generation of agement Plan - Draft. Ministry of Ag- OH, 5-29. trihalomethane and other cancerous orga- riculture, Forestry and Water Resourc- Vidović, M. 1996. Water Treatment by Ad- nochlorine substances which enhance de- es, Belgrade. sorption-Removal of Organic Com- velopment of microorganisms and sapro- Čukić, Z. 1987. Kikinda Source Water pounds on Macroporous Resins. Mas- phytes in the water distribution system. Quality Examination. “Jaroslav Černi” ter thesis, University, Faculty Institute for Development of Water Re- of Natural Sciences and Mathematics, Acknowledgement sources. Belgrade. Novi Sad. This work was executed under the basic re- Čukić, Z., Vidović, M., Janać, M., Vulić, D. Vidović, M. 1998. Trihalomethane Con- search programme, Project 146021B: Ge- 1994. Deep Ground Water Quality in centrations and Formational Poten- tial in Humin.Rich Waters. Specialist Thesis. Belgrade University, Faculty of Pharmacy, Belgrade. Vidović, M. 2002. Heavy Metals in Hu- man Material as a Result of Environ- mental Pollution, Doctoral Thesis. Faculty of Technology and Metallut- gy, Belgrade. Vuković, M., Pušić, M., Soro, A. 1979. Wa- ter Supply to Banat North of the Begej and Old Begej Rivers, Feasibility Study. “Jaroslav Černi” Institute for Develop- ment of Water Resources, Belgrade.

Geographica Pannonica 10/2006 Pannonica Geographica Fig. 3 Hydrogeological section A-B (Novi Kneževac-Hetin) 46