Spatial dispersion hot spots of contamination and human health risk assessments of PTEs in surface sediments of streams around porphyry copper mine, Iran

This comprehensive research has been conducted to consider the distribution of PTEs in the surface sediments of a recently developed Dar-e-Allo copper mine in dependence on the potential ecological and human health risks. Field sampling was carried out discreetly at preselected sampling spots including the natural background, the streams around the mine, waste rock drainages, evaporative deposits, sediments containing Fe oxy-hydroxides and secondary phases. Distribution of target elements (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, S, Sb, Se, and Zn) showed high levels of crustal elements. As regards, Fe, Al, and S are identified to exist as the most copious elements in the earth's crust, so have the major portion of potentially toxic elements (PTEs) in the sediment concentrations. Evaluating environmental indices reflected that in general, Cu, S, and Mo have a higher quota of contamination in sedimentary systems. the pollution load index (PLI), modified contamination degree (mCd), Contamination factor (C-f), Sediment potential index (SPI), Geo-accumulation index (I-geo) and Contamination degree (C-d) confirm that sedimentary systems of mining area are heavily contaminated by PTEs and were not found within the guideline acceptable values. The potential ecological risk index (PERI) displayed a high or severe risk level for Cu with a peak in green-blue sediments containing secondary minerals. The results of total carcinogenic risk (TCRs) show that As has high toxicity level and carries a risk of carcinogenicity among children and adults. The TCRs for Cd, Cr, Ni, and Pb with carcinogenic potential are found only in children and they are classified as the prime concern elements that have serious dangers to children's public health. The results of contamination source presumed that the sources of PTEs contamination were principally geogenic along with the anthropogenic sources in the study area. Therefore, the present study has highlighted the implication of human health risks of PTEs in sedimentary systems of copper mining, also will grant advice for prime stakeholders, including mine managers, Environmental Protection Agency, the government and public organizations in connection to protecting the environment, aquatic biota and consumer's health.