Investigation On Mode Of Action Of Pesticides To Daphnia Magna And HepG2,and Their Comparison

As the population increases,the planted area is continually expanded.In order to ensure the sustainable development of agriculture,increase the yield and improve quality of crops,a number of pesticides are used.However,the safety and environmental pollution problems caused by the irregular use of pesticides are becoming more and more serious.The pesticides have toxic effects not only to target organisms;they may also have certain toxic effects to non-target organisms.Therefore,it is particularly important to evaluate the toxicity and mechanism of pesticides against non-target organisms.In this thesis,the toxicity of pesticides to aquatic organisms(i.e.Daphnia magna)and cells was studied,and the correlation and modes of action were discussed between toxicity values of Daphnia magna and cells for different types of pesticides.The results provide a strong scientific basis for the safety evaluation of pesticides in the aquatic environment.The following conclusions were obtained in this thesis:(1)The acute toxicity data of 25 baseline compounds to Daphnia Magna obtained by experiment was compared with toxicity of 57 agricultural chemicals to Daphnia Magna obtained from literatures.The critical concentrations of these compounds in D.magna were calculated and the toxic modes of action of the compounds on D.magna were studied.The results showed that the critical concentration of baseline compounds in D.magna fluctuated in a small range,and the critical concentration range of pesticides in D.magna was very wide,indicating that most pesticides were reactive compounds for D.magna.In addition,QSAR models of herbicides,insecticides and fungicides for D.magna were developed,respectively.The toxic effects of herbicides on D.magna were related to hydrophobicity and the ionization;the toxic effects of pesticides on D.magna was related to the hydrogen-bonds and van der Waals forces;the toxic effect of fungicides on D.magna was related to the heat of formation and the polar surface area.Indicate there were some differences in the toxicity mode of different pesticides on D.magna.(2)The cytotoxicity data of 15 pesticides to HepG2 obtained by experiment,and the toxicity ratio was used to determine residual toxicity of pesticides.The compounds that above the critical threshold(logTR=1)were the reactive chemicals,below the critical threshold were baseline compounds,and it was found that a part of the herbicide and the bactericide were baseline compounds,and the insecticide were reactive compounds.The pesticides were divided into herbicides,insecticides and fungicides to develop the QSAR models.The toxic effect of herbicides on HepG2 was related to the molecular volume and hydrophobicity.On the other hand,the toxic effect of insecticides on HepG2 was related to hydrophobicity,the highest occupied molecular orbital energy and molecular mass.The toxic effect of the fungicides on HepG2 was related to hydrophobicity and molecular volume.Indicate there were some differences in the toxicity mode of different pesticides on HepG2.(3)The correlation between the acute toxicity to D.magna and the cytotoxicity HepG2 for some typical pesticides was poor.The toxic mechanism of typical pesticides against D.magna and HepG2 was judged by the critical value.The results showed that most of the pesticides had the same toxicity model to HepG2 and D.magna,but some pesticides were different.This indicated that cytotoxicity can be used to predict the toxicity model of D.magna,but the correlation between them is poor,due to the differences in mechanism.