The Toxic Effects Of Difenoconazole And Cd Combined Pollution On Earthworms

Difenoconazole,a triazole systemic fungicide,destroys the structure and function of cell membranes by inhibiting the synthesis of ergosterol in cells,which ultimately leads to the death of pathogenic bacteria,thereby achieving the purpose of sterilization.At present,it is applied to the control of fungal diseases in 46 kinds of crops such as rice,wheat,and corn.It is the most widely used triazole fungicide in China.The triazole compounds have the characteristics of lipophilicity,low biodegradability and easy transfer in the environment,so that they can exist in the soil and water environment for a long time,and have certain toxic effects on soil and water organisms.Cadmium(Cd)is a highly toxic heavy metal.The Bulletin of the National Survey of Soil Pollution pointed out that China's soil had a cadmium point exceeding standard rate of 7.0%,ranking first among pollutants exceeding the standard rate.Cadmium has large biological activity and is difficult to be transformed and degraded.It is easy to accumulate through the food chain,and it will affect animal and plant metabolism,tissues and organs,immune,nervous and reproductive systems.In this study,Eisenia fetida was used as the research object.The artificial soil method was used to study the ecotoxicological effects of difenoconazole and cadmium on earthworms.The test selected 0,0.5,1.0,2.5,5.0 mg·kg-1 of difenoconazole for a single test,and 5 mg·kg-1 of cadmium and the above concentration of difenoconazole were used for a composite test.Sampling measurement index on day 7,14,21,28.By studying the activities of superoxide dismutase,catalase,peroxidase,glutathione thiotransferase,and changes in malondialdehyde and reactive oxygen content of earthworms,the analysis of difenoconazole and cadmium The effect on the ecotoxicological effects of earthworms,with a view to providing a basis for early warning of soil composite pollution and ecological risk assessment and judgment.The main test results are as follows:(1)In the case of difenoconazole single exposure,different treatment concentrations had a toxic effect on earthworms,which changed the activity of antioxidant enzymes in the body.With the extension of the exposure time,the activities of SOD,CAT,and POD in the earthworm showed a trend of first increase and then decrease,while the activity of GST also showed a tendency of inhibition-activation-recovery,indicating that the antioxidant enzyme system and GST cooperated to eliminate There was excessive ROS in the earthworm,and the MDA and ROS contents gradually recovered to the control level in the later stage.(2)The changes in the antioxidant enzyme system,GST activity,ROS and MDA content of earthworms during the combined exposure with difenoconazole and cadmium were similar to those of the single exposure with difenoconazole.However,the activities of SOD and GST are lower and the degree of inhibition is higher than that of single exposure.At the same time,the content of ROS and MDA increased significantly compared with the single exposure,indicating that the type of interaction between anisole and cadmium combined pollution was synergistic,and the combined pollution enhanced the toxic effect on earthworms.