Contamination and ecological risk assessment of heavy metals and metalloids in surface sediments of the Tajan River, Iran.

This study's objectives were to evaluate the elements degree of contamination in the Tajan River and the status of contamination in this river for future ecotoxicology studies. Based on geo-accumulation index (Igeo) and contamination factor (CF) indices, Cr, Mn, Fe, Ci, Ni and Zn showed low contamination levels at all stations, while Se showed a very high degree of contamination. Potential ecological risk factor (Eri) and risk index (RI) indices values showed low ecological risk for the river, and this was confirmed by the pollution load index (PLI) results as well as a comparison of the concentrations of these elements with the mean values of the earth's crust and sediments worldwide. Overall, the results showed that the river cannot be regarded as a contaminated river with respect to the elements studied (with the exception of selenium and arsenic) for ecotoxicology studies, but can be considered a reference river.