| In China,the abuse of herbicides on farmland has caused serious damage to the soil ecosystem.In addition,due to the development of the mining industry,heavy metal pollution is also a serious environmental problem faced by some farmland soils in China,but it lacks systematic research methods.In this study,the earthworm-soil-maize system was used as the research object to investigate the effects of herbicide and cadmium single and compound treatment on animal behavior in the system,and to physicochemical properties and crop growth mediated by changes in animal behavior.(1)The acetochlor treatment experiment showed that acetochlor affected the physiology of earthworms.As the acetochlor concentration increased,the activity of superoxide dismutase(SOD)in the earthworms gradually decreased,while the malondialdehyde(MDA)concentration decreased.Therefore,in order to circumvent the hazard,the behavior of earthworms has changed,with a tendency to spread from the surface(0-10cm)to the deep(10-30cm),and this phenomenon becomes more and more obvious as the processing time increases.The 50 mg/kg treatment group decreased from 88.41% to 15%,and the 100 mg/kg treatment group decreased from 83.23% to 0%.At the end of the experiment,soil organic matter,available phosphorus,and root SOD activity did not change significantly,whereas soil alkalized nitrogen,root MDA,plant biomass,and plant height showed significant differences at the end of the experiment.(2)The cadmium treatment experiment showed that the increase of cadmium concentration gradually reduced the SOD activity in the earthworm,and in the high concentration treatment it was significantly higher than the control at the end of the experiment,but the MDA content increased with the increase of the treatment time.Physiological changes also indicate that they have been poisoned.The percentage of earthworms in deep soil increases with increasing treatment concentration and treatment time,reaching a significant level by the end of the experiment.After 50 days of treatment,the 30 mg/kg treatment group decreased from 88.54% to 3.63%,and the 10mg/kg treatment group decreased from 91.11% to 6.06%.In addition,some soil physicochemical indexes and maize physiology indexes also changed with the change of treatment concentration and time.Among them,soil available phosphorus,SOD and MDA did not change significantly,and soil alkaline N and organic matter content increased with treatment concentration increase.On the contrary,at the end of the experiment,the number of roots,biomass,and plant height decreased significantly as the treatment concentration increased.(3)The combined experiments of cadmium and acetochlor showed that the effect of both on earthworms is an antagonistic effect.Specifically,the content of MDA and SOD in the earthworms were significantly increased under the treatment of high concentrations of acetochlor or cadmium,but when the two are combined,the increase range was lower than the amplitude of the changes between the two.After treatment for 50 days,the surface distribution percentages were: 53.09%,23.93%,47.09%,and 36.17%.The responses of biomass,plant height,and root number were slightly different from the changes on earthworms' behavior,physiological response,and soil parameters.At the end of the experiment,the three indicators were the lowest among the interactions,indicating that the two pollutants acted together.Acetochlor and cadmium can also influence the growth of maize by mediating the behavior of soil animals.Therefore,it is indispensable to analyze the ecological consequences of these two kinds of environmental pollution from the perspective of system,which can provide reference for the correct definition of the ecological risks of other pollutants in the future. |
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