A comprehensive assessment of water quality in a shallow lake in Eastern China: occurrence and environmental risks of emerging contaminants

Rapid industrialization and urbanization in China have resulted in challenges related to contaminants of emerging concern in the environment. Dianshan Lake, which is adjacent to the economically developed region of the Yangtze River Delta, is an important freshwater resource for people living in Shanghai and Jiangsu, China. Identification and source tracing of contaminants of emerging concern in Dianshan Lake is important. In this study, the occurrences, temporal and spatial distributions, source apportionment, and environmental risks of these contaminants were investigated. Fifty-three contaminants were detected in the dry season (0.08–89.52 ng/L, mean: 17.72 ng/L), and 57 contaminants were detected in the wet season (0.49–79.45 ng/L, mean: 13.33 ng/L). Pharmaceuticals and personal care products, organic pesticides, and alkylphenols were identified as the predominant contaminants, with contributions of 23%, 25%, and 35%, respectively, to the total contaminant concentrations in both seasons. The contaminant concentrations in surface water during the wet season were higher than those in the dry season. Positive matrix factorization analyses showed that the main sources of pollutants in Dianshan Lake were agricultural drainage and wastewater treatment plant effluents. Pentabromophenol, potassium nonafluoro-1-butanesulfonate, perfluorononanoic acid, and perfluorooctanoic acid were possibly associated with the electronics factories around the lake. A risk assessment showed that no sampling site was classified as high risk. However, ofloxacin, salicylic acid, difenoconazole, dichlorvos, 4-nitrophenol, bisphenol A, bis(2-ethylhexyl) phthalate, and carbaryl posed moderate risks to the environment in wet season. Ofloxacin, difenoconazole, dichlorvos, carbaryl, 4-nitrophenol, salicylic acid, tetrabromobisphenol A, pentabromophenol, and octylphenol posed moderate risks in dry season. This research provides scientific guidance for periodic monitoring and regulation of contaminants of emerging concern in shallow lakes.