HYDROCHEMICAL CHARACTERISTICS OF THE GROUNDWATERS IN PRILEP’S PART OF PELAGONIA VALLEY – REPUBLIC OF MACEDONIA

This paper presents the results of hydrochemical investigations of groundwater from the Prilep part of Pelagonia Valley -Republic of Macedonia. These investigations were carried out by analysing 12 samples of groundwater, taken from exploitation wells. Samples were taken once, during August 2013. The values of pH were determined with a eld digital pH meter, while cations were determined by inductively coupled plasma-atomic emission spectrometry (ICP -AES). For the determination of anions standard EPA methods were used (gravimetric -TDS, volumetric -Cl -, spectrophotometric -NO 3 -, NO 2 -, NH 4+ and turbidimetric -SO 4 2-with the spectrophotometer 6715 UV / VIS, Jenway). Maps with spatial distribution of the hydrochemical components were prepared using the IDW (Inverse Distance Weighting) method for map generation (Geographic Information System software (GIS) ESRI ArcGis 9.2 and its extension Geostatistical Analyst). Graphical methods, Piper diagram and Chadha's diagram, were applied in order to determine the hydrochemical properties of the groundwater. The results indicate that the groundwater samples have di erent hydrochemical properties. Ca 2+ >Na + >Mg 2+ for the cations and HCO 3 ->Cl ->SO 4 2-for the anions were dominantly dissolved ions in the majority of the water samples. Generally, increased values of Ca 2+ , Mg 2+ , Na + , K + , HCO 3 -, K + and Cl -occur in the groundwater from deeper artesian wells, as a result of the longer retention time of water underground and its interaction with the geological environment. Dominant groundwater in Prilep eld is water from the hydrocarbonate class (HCO 3 ), calcium group (Ca), the rst type of water. Groundwater from the shallow wells shows an increased content of K + , NO 3 -and PO 4 3-which indicates water pollution from fertilization of the cultivated areas, livestock farms as well as communal wastewater. Although hydrochemical data is obtained on the basis of water samples taken only once, they provide an indicative insight into the hydrochemical composition of the water.