Hydrological and hydrochemical characteristics of the lower part of the river basin of Slatinska Reka, Republic of North Macedonia

Abstract

The lower part of the river basin of the Slatinska Reka river is protected in the category of Monument of Nature and it is placed on the tentative list of UNESCO World Heritage Sites. The chosen locations in which sampling were done are situated within the karstic part of the river basin. The hydrological method applied on the surface streams, points out that the karstification has strong influence on the discharges along the streams. The losses of water are constantly increasing in downstream direction. In order to understand the hydrochemical properties of the surface streams, water samples were taken monthly from four points between December 2011 and November 2013. For all water samples, the measurements included temperature, pH and electrical conductivity, as well as mass concentrations of major ions of calcium, magnesium, bicarbonate, chloride, sulfate, potassium, sodium, nitrate, nitrite, ammonium and trace elements (Zn, P, Mn, Fe, Cu, Cd, Pb, Co). HCO₃ - and SO₄ 2- were dominant dissolved species in all water samples. The hydrochemical results showed that the lithology of the area is reflected in the chemical composition of the waters and the anthropogenic impact is very low. In agreement with the current Macedonian Regulations of Natural Mineral Water the overall water quality of Slatinska Reka fits into the 1st quality class.