Determination of sources, pollution status and health risks of dissolved metals in Tohma Stream (Malatya)

This thesis study was carried out to determine the levels, spatial and seasonal changes, potential sources and human health risks of 10 metals (As, Cd, Cr, Co, Cu, Fe, Mn, Ni, Pb and Zn) in water samples collected seasonally from 13 stations in Tohma Stream, which has a significant water potential among the streams feeding the Karakaya Dam Lake. When the spatial distributions of metals recorded in water samples of Tohma Stream were examined, it was determined that the levels of metals except As, Cu and Pb showed statistically significant changes among the 13 sampling stations (P <0.05). When seasonal changes in dissolved metals were examined, it was determined that only As and Cu levels showed statistically significant seasonal changes (P <0.05). The highest average As and Cu levels were recorded in spring. This situation is probably due to the fact that spring rainfall carries these elements to the stream via surface runoff. It was determined that the average metal concentrations of water samples taken from Tohma Stream did not exceed the maximum values allowed by drinking water quality criteria and fresh water quality criteria for the protection of aquatic life. In addition, according to the results of metal indexes (HEI and HPI), no significant contamination was detected in the water samples. Carcinogenic and non-cancer risk assessment results have shown that metals in Tohma Stream water will not pose a health problem to humans. According to the results of factor, correlation and clustering analyses, it was determined that human activities were effective on the levels of Cr, Ni, Co and Mn in the stream, while both human activities and natural resources were effective on the levels of other metals. KEYWORDS: Tohma Stream, metals, water quality, spatial and seasonal changes, source identification, health risk assessment