Effects of heavy metal contamination on river water quality due to release of industrial effluents

This study seeks to evaluate the quality of Kor River water located in southern Iran, and presents techniques for identifying the main sources of contaminations discharged to the river by neighboring factories. Water quality constituents, including water temperature, pH, total hardness, chloride, phosphate, nitrate, arsenic, cadmium, trivalent chromium, hexavalent chromium, copper, molybdenum, nickel, and zinc in twenty-nine stations along the river were evaluated during two years. The Dunnett statistical test and principal component analysis were employed to determine the most influential constituents on river water pollution. The Kriging method was also applied to analyze the spatial distribution of contaminants in the vicinity of polluting industries. Results of the Dunnett test indicated that the stations located in the vicinity of an industrial area, including petrochemical, pulp mill, home appliances, meat, sugar, tanning, flour, and licorice extraction factories were among the most polluted stations. Water quality index and heavy metal evaluation index were used to determine the contamination level at each station. Stations with water quality indices of 0.9 +/- 5.0 and 87.3 +/- 2.0 had the highest and the lowest contamination levels, respectively, corresponding to very poor (undrinkable) and very good water qualities. Stations with poor water qualities were also found to be highly polluted according to the heavy metal evaluation index, showing high concentrations for arsenic and cadmium. (C) 2020 Elsevier Ltd. All rights reserved.