Effect Of Heavy Metals And Pesticides Combined Pollution On The Elsenia Foetida Earthworm In Soils

Recently, soil heavy metal and pesticide contamination becomes more and more serious in certain areas in China. Adverse effect caused by heavy metals and pesticide in contaminated soils has been a wide concern for many years. In this study, a bioassay experiment with the earthworm (Eisenia Foetida) was conducted to investigate the toxicity effects of single and compound application of heavy metal and pesticide contamination in soil in earthworms.The experiments include that: (1) the effects of single and compound application of Cu and Pb in soil on protein content and surperoxide dismutase (SOD) activity and acetylcholinesterase(AChE) activity in earthworms. (2) the effects of single and compound application of Cu and Carbofuran in soil on protein content and surperoxide dismutase (SOD) activity and acetylcholinesterase(AChE) activity in earthworms.(3) Based on the statistical analysis for the measurements, we will find the referent of effect of pesticides on biology. The results of this study will be helpful for a bio-diagnosis and risk assessment of heavy metal and pesticide contaminated soils.1. Different changes in protein content and SOD activity and AChE activity in the tested earthworms were observed for single application of Cu or Pb. When Cu only was applied to the soil, protein content in earthworms slightly went up and SOD activity and AChE activity slightly decreased with increases in the concentrations of applied Cu. Meanwhile, protein content in the earthworms decreased with expose time,but the tendency of SOD activity and AChE activity were not consistent.2. When Pb only was applied to the soil, protein content in the tested earthworms were decreased firstly and then increased , and SOD activity slightly went up with increases in the concentrations of applied Pb,but AChE activity was complex. With the exposure time, protein content decreased but no obvious effects of Pb on SOD activity and AChE activity was observed in this study.3. When soil was treated with multiple concentrations of Cu and a fixed concentration of Pb, with the extended exposure time, the change of protein content and SOD activity and AChE activity in the earthworm is different. When 200 mg / kgCu namely low concentration of Cu combined with Pb, protein content decreased and AChE activity increased with the exposure time; When 600 mg / kgCu namely middle concentration of Cu combined with Pb, protein content increased and AChE activity were decreased firstly and then increased with the exposure time; When 1000 mg / kgCu namely high concentration of Cu combined with Pb, protein content was complex and AChE activity slightly increased with the exposure time.Comparing to the Pb only treatment, application of Cu increased SOD activity in the earthworm.The result indicates: compound effect of Cu and Pb in the soil was closely related to the combinations of the expose time and the applied metal doses. Difference in exposure time, combination of Cu and Pb concentrations led to different effects on protein content and SOD activity and AChE activity in the earthworms. When comparing to the Pb only treatment, application of Cu increased SOD activity and AChE activity in the earthworm, which indicated that compound treatment of Cu and Pb had enhanced environmental threat to the tested earthworms.4. When Carbofuran only was applied to the soil, with increases in the concentrations of applied Carbofuran, protein content in earthworms slightly went up and SOD activity increased in the 3d and decreased in the 7d and 14d. The AChE activities of earthworms were significantly restrained by Carbofuran and decreased with the concentrations. Meanwhile, the protein content in earthworms decreased according to the order of 14d, 3d, 7d, and the tendency of SOD activity and AChE activity were not consistent with the exposure time.5. When binary-combined pollution of 200ppm Carbofuran and Cu, the protein content and AChE activity in earthworms went up and SOD activity slightly increased with increases in the concentrations of applied Cu; When binary-combined pollution of Carbofuran and 600mg/kg Cu, the change of protein content was not obvious, and SOD activity in earthworms slightly decreased and AChE activity decreased with the exposure time.At the same time, the protein content in the earthworms decreased and the SOD activity and AChE activity went up with expose time.The result means that Carbofuran's toxicity ia the main toxicity in the conbined pollution of Carbofuran and Cu.