Distribution and risk assessment of organophosphorus pesticides in two suburban watersheds in Eastern China.

The overuse of organophosphorus pesticides (OPPs) has adverse effects on the environment and human health in China. To fully understand the distribution of multiple OPPs in suburban watersheds and their potential ecological impacts, this study selected two watersheds in East China. A total of 41 OPPs were observed by the high-volume solid phase extraction technique. In general, the mean OPP concentrations in the two watersheds were higher in wet season (26.51 ng/L) than dry season (17.52 ng/L). Famphur, bromfenvinphos, and chlorfenvinphos were the most common pollutants, with detection rates all above 83% in the study area. Among the 14 highly detected OPPs, famphur and parathion were the dominant compounds in dry season and wet season, respectively. The highest total concentrations of OPPs were observed around farmlands and planting lands, which indicated that the distribution of OPPs were closely related to the use of pesticides. Parathion, parathion-methyl, fenthion, and famphur were commonly detected in China, which was markedly different from those in other countries. According to the corresponding analysis, there was a strong correlation between formothion and dimethoate in the dry season. Parathion and mevinphos had a strong relationship in the wet season. The total risk quotient values of parathion and fenitrothion were all above 1, which indicated that they might cause high ecological risks in the two watersheds. The average daily dose in the wet season was nearly twice that of the dry season both in the two watersheds, and methyl-parathion, chlorfenvinphos, and bromfenvinphos were the main contributors. The total health indices (His) in the two watersheds (3.90 × 10-3 and 4.90 × 10-3) were both under an acceptable health risk.