Spatiotemporal distribution, sources, and ecological risk of steroids in a large shallow lake and its inflows in central China

Steroids in the aquatic environment, including extremely important natural hormones and numerous synthetic hormones, have garnered significant attention due to their endocrine disrupting effects. This study conducted a comprehensive investigation of steroid pollutants in Lake Chao and its inflows. In summer, 9 steroids were detected in surface water at total concentrations ranging from 1.3 to 6 ng/L, while 8 steroids were identified in winter with higher total concentrations (2.86–15.09 ng/L). In winter, total concentrations of all steroids were significantly higher than those in summer ( p < 0.05). Natural steroids dominated in surface water in summer, whereas steroid metabolites prevailed in winter. Untreated wastewater was identified as the primary source of steroid inputs in both summer and winter, accounting for 56 % and 75 % of the total inputs, respectively. Ecological risk assessments and hazard indices indicated that steroids in Lake Chao pose an overall moderate risk level in both seasons. Progesterone (P) and 17α-trenbolone (17α-TBL) were identified as the highest-priority contaminants in summer, while 4-Androstene-3,17-dione (AED) was determined as the highest-priority contaminant in winter. This research represents the first systematic investigation of steroids and their metabolites in the surface water of Lake Chao, including their spatiotemporal distribution patterns, primary sources, and ecological risks. By employing a multi-criteria assessment approach, the study further identifies priority control pollutants across different seasons, providing critical scientific evidence to support steroid management strategies and precise pollution control measures. • Nine steroids were detected in summer and eight in winter in Lake Chao. • Natural steroids dominated in summer, while steroid metabolites prevailed in winter. • Untreated wastewater constitutes the main source of steroids in Lake Chao. • Steroids in Lake Chao pose a moderate ecological risk. • P and 17α-TBL were the highest-priority contaminants in summer, and AED in winter.