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 Hi-volume Solid Phase Extraction (SPE) 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 their detection rates all above 83% in the study area. Among the 14 highly detected OPPs, famphur and parathion were the dominated compounds in dry season and wet season, respectively. The highest total concentrations of OPPs were observed around the 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 were markedly different from those in other countries. According to the corresponding analysis, there was a strong correlation between formothion and dimethoate in dry season. Parathion and mevinphos had a strong relationship in wet season. The total risk quotient values of the 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 wet season was nearly twice that of dry season both in the two watersheds, and methyl parathion, chlorfenvinphos and bromfenvinphos were the main contributors. The total HIs in the two watersheds (3.90 × 10-3 and 4.90 × 10-3) were both under an acceptable health risk.