Occurrence Characteristics, Source Apportionment, and Ecological Risk Assessment of Pesticides in Plateau Lakes: A Case Study of Dianchi Lake

• • Detection of 37 pesticides out of 160 screened, with total concentrations ranging from 64.2 to 1132.8 ng/L (average 610.0 ng/L), indicating significant contamination in Dianchi Lake. • • Dominance of fungicides (BOS, FPC, DMM) contributing 65.0% of total pesticide load, highlighting the need for targeted monitoring and regulation of fungicide use in agricultural catchments. • • Southern lake region showed 672.5 ng/L average concentration, significantly higher than the north, due to intensive facility agriculture, underscoring the impact of land use on pesticide distribution. • • Source apportionment revealed that inflowing rivers and wastewater treatment plant effluents had pesticide concentrations 7 and 9 times higher than lake water, respectively, identifying them as critical control points for pollution mitigation.