| This paper studied Pendimethalin residue detection methods and Pendimethalin degradation regularity in rice plant and field environment. Studied the toxicological effects of Pendimethalin on Danio rerio and Eisenia foetida.These studies provide a scientific basis for the rational use of Pendimethalin in the rice fields and comprehensive assessment of the ecological environment’s security in the field. The conclusion is as follows:(1)The extraction,purification and HPLC test method of the Pendimethalin has been preliminary established from the rice,paddy plant,straw,rice field water and soil samples.The minimum detectable amount of this method is5.0×10-1g;the minimum detectable concentration of Pendimethalin in rice,puddy plants,straw and soil are0.01mg/kg;the minimum detectable concentration of Pendimethalin in rice field water is0.005mg/L.When the additive concentration of Pendimethalin in plants,straw,soil,water are0.01(in rice is0.05)mg/kg,0.10mg/kg,1.00mg/kg,the percent recovery of the test method is greater than89.79%and the coefficient of variability is less than7.0%.The test method is sensitive,accurate and stable,which can be applied for detecting the residues of Pendimethalin in rice, rice field water and soil samples.(2)Under different natural ecological environment in Changsha,Changchun and Guiyang in2012and2013.Studied by high-dose (1.5times the recommended dose) use16%Pendimethalin WP216g/ha watered75L/ha diluted spray pesticide on rice and field1time,degradation dynamics of pendimethalin in rice plants,rice field water and soil.The results demonstrated that Pendimethalin dissipated rapidly in rice plants,field water and soil under the natural ecological environment and the rate of slaking in line with the first-order kinetics equation.The half-life period of Pendimethalin in puddy plant were1.61d-3.81d;the half-life period of Pendimethalin in soil were3.51d-4.41d;the half-life period of Pendimethalin in water were6.30d-9.86d.(3)The test of the rice transplanting under different natural environment in Changsha, Changchun and Guiyang in2012and2013,studied that the recommended dose use16%Pendimethalin WP144g/ha and high-dose use16%Pendimethalin WP216g/ha watered75L/ha diluted spray pesticide on rice and field one time.Determination of Pendimethalin residues in harvest rice and other samples,results show that the Pendimethalin were not detected in harvest rice and other samples.(4)Pendimethalin acute toxicity test showed that Pendimethalin’s medial lethal concentration(LC50) of Danio rerio at24h,48h and96h were10.142mg/L.9.327mg/L and8.158mg/L.Pendimethalin’s safe concentration(SC) of Danio rerio is2.367mg/L as per the formula calculation,which is a medium-toxicity pesticide.The Danio rerio’s behavior was observed and divided into four categories during the test process:normal static,abnormal static,normal movement and abnormal movement.And detailed records of the behavioral characteristics of Danio rerio appeared in the acute toxicity tests and subacute toxicity tests.(5)This paper studied the toxicological effects of Pendimethalin on Eisenia foetida.In the filter paper test method,Pendimethalin’s medial lethal concentration(LC50) of Eisenia foetida at24h and48h were843.420mg/L,607.755mg/L.Pendimethalin’s safe concentration(SC) of Eisenia foetida was94.666mg/L.Pendimethalin is a low-toxicity pesticide.In the artificial soil method,Pendimethalin’s medial lethal concentration(LC50) of Eisenia foetida at7d and14d were3140.843mg/L,2534.791mg/L.In avoidance response test(concentration of Pendimethalin in soil:100mg/kg,250mg/kg,400mg/kg,500mg/kg),the avoidance rate of Eisenia foetida were:9.4%,48.3%,72.5%,86.8%,when the avoidance rate reached up to86.8%,poisoning death phenomenon was still not occurred,indicating that Pendimethalin is a low-toxicity pesticides on Eisenia foetida,and Eisenia foetida have high sensitivity to soil pollution,normally when the soil contaminants reached up to the1/5-1/25semi-lethal concentration of Eisenia foetida,it will exhibit escape behavior. |
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