A Study Of Organophosphate Pesticide Residue Contamination In Water And Soil/Sediment In The Pearl River Estuary

A long-term intestigation was been carried in Jiaomen river Shawan river of the Pearl RiverEstuary, this study was conducted from March2011to September2012to surveyorganophosphorus pesticides (OPPs) residue contamination in target area. Firstly, the content ofOPPs in water and soil/sediment was determine by GC-MS, and its spatiotemporal change wereanalyzed in target aera. in addition, OPPs’ distribution status, migration, transformation processand fate in different phases were stimulated with Class III multi-media fugacity model.The results showed that8types of OPPs were detected in target area water, among them thephorate, disulfoton,dimethoate and dichlorvos were the main pollutant. The OPPs averageconcentration in Shawan river, Jiaomen river, the irrigation ditchs of vegetable farm were10.07μg/L,3.36μg/L,2.52μg/L, respectively.The average concentrations in surface,middle,bottomwater layer were1.34μg/L、1.04μg/L1.03μg/L,respectively. Besides, the average concentrationsin shiny and rainy day were5.25μg/L and1.04μg/L. OPPs content of sediments and soils in therange of14.76-299.62μg/kg and24.04-790.93μg/kg, respectively.From time distribution, because of seasonal weather factors and local cultivation habit, thepollution of OPPs in water, soild/deposit sediment in June and July were more serious than othermonths. From spatial distribution, the concentrations of OPPs in surface water were higher thanthe deep water layer, and the concentrations of surface soil were lower than deep soil layer. Also,watercourses near the lager agricultural sown area had a higher OPPs concentration.Through the establishment of Class III multi-media fugacity model to simulate migrationand transformation process of dichlorvos and dimethoate in soil, sediment, water, andatmospheric phase in target aera’s Environmental system, overally the running of the model iswell. The model analysis showed that the simulated concentration of dichlorvos were0.33μg/kg,9.05μg/L,0.75μg/kg, and dimethoate as0.25μg/kg,10.63μg/L,11.00μg/kg in soil, water andsediments. The contents of dichlorvos in soil phase and water phase were amounted to84.80%and12.40%of environment, respectively, while the contents of dimethoate were amounted to90.80%and8.20%, respectively. Dichlorvos and dimethoate were degraded directly in soil phaseand water phase. However, they were desorbed in sediment phase, and then became the potentialsource of OPPs pollution.Because of biotoxicity of OPPs, the pollution status of OPPs in Peal River Estuary is severe,which might bring risk to local environment and residents’ health if no measures were taken.