Ecological Effects Of Three Pesticides On Aquatic Organisms

In this study,the diflubenzuron,chlorothalonil and diuron were studied.The ecological risk of three pesticides to aquatic ecosystem was evaluated by TOP-RICE model,the test of species sensitivity distribution method,and indoor microcosmic test.Firstly,the potential exposure concentrations in surface water were predicted by TOP-RICE model,and the primary risk assessment was carried out.Secondly,the species sensitivity distribution curve of 13 species of Aqueous and Freshwater organisms exposed to the diflubenzuron,chlorothalonil and diuron was constructed on the basis of acute toxicity test of single species in laboratory and data of ecotoxicology.The 5% hazardous concentration of pesticides to freshwater organisms was calculated,and the acute water quality standardwas deduced.Finally,the mixed microcosmic system of diuron and its main metabolite,3,4-dichloroaniline(DCA),were constructed in the laboratory.The biomass and structure of zooplankton population were investigated by continuously monitoring its concentration in surface water and physicochemical parameters of microcosmic water.By TOP-RICE model,the predicted maximum environmental concentrations(PECmax)of diflubenzuron,chlorothalonil and diuron were 102.93,291.73 and 109.05ug/L respectively.The results of the primary assessment showed that the bioconcentration risks of three pesticides were acceptable.The risks of three pesticides to vertebrates and invertebrates were unacceptable.The further assessment will be caaried on..The acute toxicity of the five common aquatic species exposed to diflubenzuron,chlorothalonil and diuron in aquatic ecosystem were carried on the laboratry,and the toxicity data of the other 7 species were also collected.The benchmark toxicity database of three pesticides was constructed.The species sensitivity distribution curves of the three pesticides are produced by the toxicity database data.The results showed that the most sensitive organisms to diflubenzuron are rotiferas and the most sensitive organisms to chlorothalonil are skeletonema costatums.Duckweed is the most insensitive organism to diflubenzuron and chlorothalonil.The most sensitive organism to dichlorfenidim is Sargassum quadrangularis.Rainbow trout is the most insensitive creature to dichlorfenidim.The HC5 of diflubenzuron,chlorothalonil and diethyluron on 95% freshwater algae are 0.04 1.86 and 5.15 ug/L respectively.The acute water quality of the three drugs(WQC)are 0.02 and 0.93 and 2.575 ug/L respectively.3.The resultshowed that both dichlorfenidim and 3,4-dichloroaniline have an effect on water quality parameters in indoor microcosms.And the concentration,time and interaction of the two compounds have significant effects on the community structure of zooplankton.From 0 to 14 days after dichlorfenidim entering the water,the minimum inactivated concentration(NOECcommunity)of the community is 12.207 ug/L(measured concentration: 11.479 ug/L),781.25 μg/L from 21 to 28 days(measured concentration: 604.97ug/L),195.3125 μg/L from 28 to 35 days(measured concentration: 97.7 ug/L).The NOECcommunity of DCA pair community is 62.5μg/L in 14-21(measured concentration: 0.42333 and 0.16ug/L)and 28-35 period,and the rest time is 15.625μg/L(measured concentration: 0-7d0.5933,7-14d0.19733,21-28d0.09633μg/L).