| Summary: | This study was performed in the Linshui River Watershed to explore the contents of heavy metals in river water, their species, and health risks. The test results show that the contents of arsenic (As), chromium (Cr), copper (Cu), uranium (U), and thorium (Th) are relatively low and below the limit of class III of the environmental quality standards for surface water. According to the analysis through PHREEQC (version 2.18), the main species of As, Cr, Cu, U, and Th are H2AsO4− and HAsO42−, HCrO4−, Cr2O72− and CrO42−, Cu2+, CuSO4 and CuCO3, UO2CO3, (UO2)2CO3(OH)3−, and UO2(CO3)22−, Th(OH)4, Th(OH)22+, and Th(OH)3+, respectively. Health risk assessment demonstrates that the average total risk value is 5.68 × 10−5 year−1, which is higher than the maximum acceptable level of 5.05 × 10−5 year−1 recommended by International Commission on Radiological Protection (ICRP). Moreover, the average of total radionuclide risk (U and Th) is calculated to be 7.85 × 10−9 year−1, which is five orders of magnitude lower than the standard value of 5.0 × 10−4 year−1. The health risk of chemical non-carcinogenic (Cu) is lower than that of chemical carcinogenic (As and Cr). Human health risk values descend in the order of Cr, As, U, Th, and Cu. Therefore, As and Cr in the study area are labeled as the priority pollutants.
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