Acute Toxicity And Oxidation Stress Response Of Etsenia Fetida Under Lead Exposure In Soil

The method by detecting content of chemical component in soil has adopted for along time. Compared with the traditional Analysis means, more and more researcheshas chosen the molecular biomarkers to study soil heavy metal pollution as theenvironment becoming serious in recent years. So, the superoxide dismutase(SOD),catalase(CAT),peroxidase (POD)in Antioxidant enzyme system and themalondia-ldehyde (MDA) produced by Lipid peroxidation were selected as thebiomarkers for earthworm(Eisenia fetida), through the toxicity tests ofLead-contaminated in artificial and natural soil, with the aim to seek the sensitivebiomarkers, to provide Reference for ecological risk assessment and Eco-toxicologicaldiagnosis of soil pollution under lead exposure.Acute toxicity and oxidation stress response of Eisenia fetida under leadexposure in soil was studied based on the test method recommended by OECD. Theresults of acute toxicity test showed that14d LC50was2595.54mg/kg on Eiseniafetida (95%confidence interval:2323.52~2793.41mg/kg) for lead, according tologarithmic concentration-probit line for determination of LC50. The inhibiting rate ofEisenia fetida was significantly increased and had a linear relationship with theincreasing of lead concentrations under higher Pb exposure(2500~3200mg/kg).The sublethal toxicity test results by lead exposure in artificial soil showed that,the superoxide dismutase (SOD) activity in the first, seventh, fourteenth day, theperoxidase (POD) activity in the first, fourteenth day and the content ofmalondial-dehyde(MDA) in the fourteenth day indicated a good dose-responserelationship with the concentrations of lead pollution exposure, while the activity ofCAT dose not indicated a dose-response relationship with Pb concentration. The resultshow that, we could use SOD,CAT and MDA in earthworm (Eisenia fetida) bodiesas sensitive biomarkers to study the toxicity of lead to Eisenia fetida. The sublethal toxicity test results by lead exposure in natural soil showed that,SOD and POD may be exposed to lead in the short-term (14days) to play a leadingrole, CAT relative in a secondary position, but with the exposure time, CAT may inthe long-term exposure to lead role.By Consistency demonstrated by the artificial soil test results and actual soil testresults, we can see that earthworms antioxidant enzymes SOD and POD have a betterindication role than CAT in response to lead contamination in the soil. To some extent,Lipid peroxidation products MDA can be used as biomarker for oxidative stresscaused by Pb. In conclusion, SOD、POD activity and MDA content on Eiseniafetida could be used to evaluate the toxicity effect of lead contaminated soil.Additionally, it can be used for ecological risk assessment and early warningbiomarkers of potential danger of soil.