| The Songyuan Irrigation Area is planning to develop the large area ofsaline-alkali wasteland in Qianguo, QianAn, and DaAn, improve the middle-low yield,and recover the grassland, construct the national commodity grain base. After thecompletion of Songyuan Irrigation Area, the increase in the use of pesticides, with theincrease in rice planting area, will affect the safety of the aquatic ecosystem and rarewild animals in Chagan Lake. Taking Chagan Lake national natural reserve andSongyuan Irrigation Area as the research objects, this study makes full use of thetheories and methods of environmental science, water chemistry, ecology, geography,biotoxicology, mathematical model, mathematical statistics. This study investigates onapplication of pesticides for paddy field and environmental parameters, chooses waterquality mathematical Model to predict the pesticide residues in Chagan Lake by usingthe AHP method, and then evaluate the pesticide impact of Chagan Lake frombiotoxicology and water quality. At last, the measures of preventon and control for thepesticide pollution are presented. It is great important for early intervention ofpollution prevention concept, the environmental protection of Chagan Lake, and thehealth of local residents.At present, the pesticides used in Songyuan Irrigation Area rice fields are mainlychemical low toxicity and micro-toxic pesticides, which have high proportion oftraditional pesticide formulation such as Emulsifiable Concentrate (EC). Two monthsafter pesticide application, the concentrations in water are lower than safeconcentration, which are less impact on aquatic organisms. Based on estimation, inpaddy field after the completion of Songyuan Irrigation Area, the amount ofherbicides are2.69kg/ha, insecticides are0.63kg/ha, and fungicides are0.32kg/ha. Evaluation of biotoxicology: The maximum concentration of each pesticide inChagan Lake after the completion of Songyuan Irrigation Area is lower than safeconcentration, which is less impact on aquatic organisms. Considering the standardindexes of butachlor, prometryn, pretilachlor, abamectin, chlorpyrifos>0.01, ifimproper use of pesticide, there are several environmental risks of pesticide pollutionfor aquatic organisms in some water bodies.Water environmental quality assessment: the pesticide contributions to COD, TN,TP, and anion in Chagan Lake, which are coming from paddy field, are lower than â…¢standard of GB3838-2002<Surface Water Environment Quality Standard>. Theimpact to Chagan Lake is acceptable.Pesticide pollution prevention measures: it includes establishing and perfectingthe technical service system of pesticide, improving pesticide supervision mechanism,increasing the environmental protection consciousnes of local farmers, establishingenvironmental risk-warning mechanism, improving pesticide residual wastemanagement, and constructing wetland wastewater treatment. |
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