Ecological risk assessment of toxic metal contamination in a significant mining basin in Turkey

Abstract

Emet River Basin is a worldwide significant mining area and contains the most important boron and chromium deposits of Turkey. In this study, water and sediment quality of Emet River Basin was evaluated using some toxic element risk assessment indices. Samples were collected seasonally from 8 locations and nickel (Ni), chromium (Cr), arsenic (As), zinc (Zn), lead (Pb), copper (Cu) and cadmium (Cd) accumulations in water and sediment were analysed using an ICP-OES. Water Quality Index (WQI), Heavy Metal Pollution Index (HPI), Heavy Metal Evaluation Index (HEI) and Degree of Contamination Index (C-deg) were applied to the data for assessing the water quality and Biological Risk Index (BRI), Potential Ecological Risk Index (PERI), Geo-Accumulation Index (I-geo), Contamination Factor (CF) and Pollution Load Index (PLI) were applied to the data for assessing the sediment quality. According to the results of WQI, HPI, HEI and C-deg, As and Cr were recorded as the most dangerous toxicants; according to the results of BRI, I-geo, CF and PLI, Cd, As and Pb were recorded as the most dangerous toxicants; and according to the results of PERI, Ni and Cr were recorded as the most dangerous toxicants among the investigated elements. The seasonal average values of applied ecological indices for the water of the basin ranged 71.41-888.29 for WQI, 85.97-915.76 for HPI, 4.04-49.80 for HEI and - 2.95-42.80 for C-deg. The seasonal average values of applied ecological indices for the sediment of the basin ranged 33.72-130.56 for PERI, 0.14-0.93 for BRI, - 3.92-5.99 for I-geo and 0.45-1.20 for PLI. In addition to the intensive agricultural applications around the region, the geological structure of the watershed was considered as the main cause of the high heavy metal accumulations in basin waters and sediments.