Occurrence, bioaccumulation, and risk evaluation of selenium in typical Chinese aquatic ecosystems

Selenium (Se), a trace element, is essential for biological growth; however, excess Se in water can harm aquatic organisms, including fish. Thus, increasing attention is being paid to the risk of Se in aquatic ecosystems. However, there has been little research regarding the protection of aquatic organisms from excess Se in China. To comprehensively ensure China's ecological safety, research on the water quality criteria (WQC) of Se is urgently required. Herein, water and fish samples were collected from Taihu Lake and Yellow River estuary to investigate Se distribution characteristics and bioaccumulation factors (BAFs) in aquatic ecosystems. Tissue -based toxicity data and BAFs were used to derive the WQC for Se. Quotient and probabilistic methods were used to assess the ecological risk of Se to aquatic life. The results revealed that the average levels of Se in the water samples were 1.54 and 1.07 mu g/L and that the average Se levels in the fish samples were 0.87 and 0.66 mg/kg in Taihu Lake and the Yellow River estuary, respectively. Furthermore, the calculated BAF for Se in fish was 618.69 L/kg, and the calculated WQC for Se to protect aquatic organisms was 0.29 mu g/L. The high levels of ecological risk associated with Se in Taihu Lake and the Yellow River estuary indicate that the aquatic risk of Se warrants further attention. This study provides scientific guidance for setting Se water quality standards to protect aquatic organisms and ensure environmental management in China.