Source apportionment, ecological and human health risk assessment of potentially toxic elements in Tumet River, Ethiopia

Mining activities are known sources of water pollution by Potentially Toxic Elements (PTEs), and threatening the health of humans and water ecosystem. This study aimed at evaluating the PTE concentrations and sources of PTEs enrichment in Tumet River, and associated human-ecological health risks in children and adults. The concentration of the studied PTEs (9 elements) in Tumet River water were quantified using Atomic Absorption Spectroscopic technique. The average values of the PTEs were found to be 0.02 ± 0.002-43.4 ± 1.4 mg/L, and 0.019 ± 0.001-39.7 ± 0.3 mg/L for dry and wet seasons, respectively. In both seasons the lowest and highest average values were observed for Cr and Fe, respectively. The average PTE concentrations exceeded drinking water (except for Zn and Cr) and ecological quality (except for Cr) guideline values in both dry and wet seasons. The risk assessment showed that the cumulative carcinogenic risk and non-carcinogenic risk results exceeded the USEPA threshold values for cancer (LCR > 1E-04) and non-cancer risks (HQ/HI > 1), indicating that the PTEs could pose both carcinogenic and non-carcinogenic health risks to adults and children from consumption or dermal exposure to water from Tumet River. Estimated Risk Quotient (RQ) values showed the probable ecological risks of the studied PTEs (RQ/HI > 1), in which Cu, Pb, Co and Ni can pose severe ecological risk to Tumet River ecosystem. The findings of this study highlight concerns about the health of the local community and the ecological quality of the river ecosystem due to PTEs pollution. To mitigate these issues, effective legal regulation of mining activities in the region is strongly recommended.