Study On The Behavior And Fate Of Ethiprole In Simulated Aquatic Microcosm

The multimedia environmental behavior of pesticide and the pesticide expousure risk to human health has become more and more concerned by the researchers. Mathematieal simulation is important method used in investigating environmental fate and behavior of pesticide. The fugacity model is one of the most exeellent environmental models for it can give comprehensive, accurate and reliable simulating results despite of its simple structure. Microcosms, are small experimental ecosystems or model ecosystems. Microcosm is more and more popular used in assessment of environmental pollutants and pesticide in ecological toxicology studies. In this study, the environmental behavior and fate of ethiprole in water-fish-sediment microcosm was studied by two approaches: stimulating laboratory microcosm experiments and multimedia fugacity model. It is significant to learn about ethiprole environmental impacts, and provide environmental parameters and new idea for studying the fate of other pesticide. The main results are listed as following:Trace analysis of ethiprole in water, fish and sediment using the modified QuEChERS in the sample pretreatment procedure. The sample were extracted with acetonitrile（containing 1%（v/v） acetic acid） and cleanup by PSA, C18 and Florisil was detected using ultra-performance liquid chromatography/tandem mass spectrometry. The established method exhibited good linearity with R2> 0.99, and the recoveries ranged from 80.2% to 102.62% with all RSDs less than 13.71% The limit of detection（LOD） was calculated at a range of 0.55-1.76 mg kg-1 and the limit of quantification was was calculated range from 5 mg kg-1 to 10 mg kg-1. The developed method was proven to be suitable for the requirement of residue.A Level IV（unsteady state） multimedia fugacity model was established to simtuate the rate anct transfer of ethiprole between water,fish and sediment, The predicted concentrations of ethiprole are in good agreement with the observed ones.when the system reaches steady state, ethiprole mass percentage in three type of aquatic microcosm were: 97.2% in the water phase, 0.1% in the biota phase and 2.7% in the sediment phase in Beijing microcosm; 92.01% in the water phase, 0.09% in the biota phase and 7.9% in the sediment phase in Heilongjiang microcosm; 96.2% in the water phase, 0.1% in the biota phase and 3.7% in the sediment phase in Hunan microcosm. Over 90% of ethiprole stay in water for all microcosm. This finding demonstrates that water plays a key role in the fate of ethiprole, acting as the major sink for contaminants in the stimulation system.The ethiprole was degraded by both photolysis and microorganisms in the water accounts for 86.8%（ account for 90.4% in Beijing microcosm, account for 95.4% in Hunan microcosm） of the total removal, the ethiprole was removed by advective outflow accounts for 0.15%（accounts for 0.05% in Hunan microcosm, account fors 0.1% in Beijing microcosm）, of the total removal, the ethiprole were removed by biodegradation in sediment and fish, accounts for 8.54% and 5.55%（ accounts for 2.52% and 2.03% in Hunan microcosm; accounts for 5.6% and 3.7% in Beijing microcosm） of the total removal respectively in Heilongjiang microcosm. Biodegradation and photolysis in the water phase was the main removal process, and most of the ethiprole was distributed in the water phase.The sensitivity analysis of model show that the Henry’s law constant（H） have significient effect on the calculated ethiprole concentrations in water, sediment and fish for all aquatic microcosm. The degradation rate constant in water(K_WR) and the degradation rate constant in fish(K_BR) have significant influence on the calculated ethiprole concentration in water. The octanol-water partition coefficient(K_ow) has significant effect on the calculated ethiprole concentration in sediment. The degradation rate constant in water. The degradation rate constant in water and organic carbon fraction of sediment have medium effect on the calculated ethiprole concentration in sediment. The degradation rate constant in fish(K_BR) also has significant effect on the calculated ethiprole concentration in fish. However the organic carbon fraction of sediment, the density of the sediment and degradation rate constant in water have little effect on the calculated ethiprole concentration in fish.