Investigation of Selected Qualitative and Quantitative Water Parameters Using Correlation Analysis

The paper aims at presenting the results of correlation analysis between concentration of pollutants and minimum monthly discharge and minimum daily discharge respectively measured during 38 years. Considered pollutant concentrations were nitrate nitrogen, ammonium nitrogen and biochemical oxygen demand. Their values were measured once a month at three hydrometric stations, i.e., Svit (River Poprad), Košické Olšany (River Torysa) and Ižkovce (River Laborec), in the period from year 1975 till 2013. It was found that the concentration of ammonium nitrogen in the rivers of eastern Slovakia has a decreasing trend but in Torysa river in Košické Olšany, it exceeded the limit value during the whole monitored period. In Torysa river, the concertation of nitrate nitrogen also exceeded the limit value. Concentrations of BOD 5 at all hydrometric stations showed a decreasing trend and a significantly decreasing trend was well visible for hydrometric profiles in Ižkovce (River Laborec) and Svit (River Poprad).