Acute Toxicity And Oxidative Stress Of Atrazine On Eisenia Fetida In Different Soils

As a triazine herbicide,atrazine has been widely used in the world due to its low cost and good weeding effect.But with strong stability,atrazine has caused environmental pollution,especially soil pollution.There are many researches about toxicities of atrazine on earthworms in the artificial soil,but the artificial soil and natural soils are different in physical and chemical properties.So it is not completely objective to use the toxicity of atrazine on earthworms in artificial soil to represent its toxicity of in real soil environment.In order to evaluate ecological risk of atrazine in real soil environment,the acute and chronic toxicities of atrazine on Eisenia fetida were studied in three typical natural soils(black soil,fluvo-aquic soil and red soil).Acute toxicity of atrazine was determined by filter paper test and soil test.In the chronic toxicity study,the concentration of atrazine was set as 0,0.01,0.10,1.00 mg/kg,and in the 14 th,28th,42 nd,56th and 70 th days,the content of reactive oxygen species(ROS),the activities of antioxidant enzyme system(superoxide dismutase,catalase activity,peroxidase)and detoxifying enzymes(glutathione transferase),the level of lipid peroxidation(malondialdehyde)and DNA damage(8-hydroxy deoxyguanosine)in Eisenia fetida were determined.Through the above research,combined with the physical and chemical properties of soil,the toxicity differences of atrazine in different soils were obtained.This research provided data support for the toxicity of atrazine to soil ecosystems in the future.The following results have been obtained:(1)The acute toxicities 14d-LD50 of atrazine in artificial soil,black soil,fluvo-aquic soil and red soil was 240.3,250.0,41.26 and 15.54 mg/kg,respectively.The acute toxicity order in different soils was: red soil > fluvo-aquic soil > artificial soil > black soil.(2)By calculating the integrated biomarker response index(IBR),it was found that the chronic toxicity order of atrazine was: red soil > fluvo-aquic soil > black soil,which was consistent with the acute toxicity.The correlation analysis with soil physical and chemical properties showed that the higher the five indexes of sand,organic matter,cation exchange capacity,organic carbon and available nitrogen in soils are,the lower the toxicity of atrazine in the soil is.(3)After atrazine poisoning,ROS content in almost all treatment groups was significantly increased,and the higher atrazine concentration was,the higher ROS content was.Both antioxidant enzyme and detoxification enzyme were affected more or less and their activities were changed,which indicated that atrazine had caused oxidative stress effects on Eisenia fetida in the three natural soils,and the normal metabolism was broken down.(4)The MDA content and 8-OHd G content in the medium and high concentration groups were significantly higher than the control,indicating that atrazine at medium and high concentrations could cause lipid peroxidation damage and DNA damage in the three soils.