Study On Soil Labile Cadmium Response Of Eisenia Foetida Antioxidant System

The situation of heavy metals pollution of soil in China is becoming more and more serious,the heavy metal cadmium?Cd?elements have strong ability of migration in the soil,not only brings the toxic effect to soil organisms,it is easy to accumulate in plants,and then through the food chain causing harm to human health.The potential toxic effects of traditional soil quality evaluation method of total concentration of heavy metal pollutants are often not based on a true reflection of pollutants,so this research adopts indoor simulation experiment to Eisenia fetida as the research object,select the red soil as tested soil,artificial investment design 8 concentration gradient of cadmium(0,3,6,12,24,48,72,96mg·kg^-1).We using CaCl₂ extraction,HAc extraction,rye seedling method to determining the soil labile cadmium.And we dected the earthworm's antioxidant system:metallothionein?Metallothionein,MT?,catalase?Catalase.CAT?,glutathione S-transferase?Glutathione S-transferases GST?,glutathione peroxidase?Glutathione peroxidase GPX?,superoxide dismutase?Superoxide D Ismutase,SOD?in response to soil heavy metals under cadmium stress,and to explore the correlation between bioavailable cadmium and pure earthworm toxicity.The main results are summarized as follows:?1?With the increasing of soil Cd concentration,the concentration of Cd was significantly higher than that of control group?P<0.05?.In addition to the treatment of cadmium3mg·kg^-1,the other treatments were significantly higher?P<0.01?than the control group.There was a significant positive correlation between the concentration of cadmium in soil and the content of cadmium in soil under the condition of P<0.01(0-96mg·kg^-1).?2?With the increase of soil Cd concentration,the accumulation of metallothionein in earthworms increased,and was significantly higher than that in the control group.There was a significant positive correlation between the content of metallothionein and the content of cadmium in soil.The SOD activity of earthworms showed a decreased trend of the inverted U type,and the soil Cd concentration was 24 mg·kg^-1 when its activity was significantly increased,Cd concentration in soil was 96 mg·kg^-1 the viability decreased significantly,which accord with the hormesis effect model;The CAT activity of earthworms was significantly higher than that of the control group at the Cd concentration of 6 mg·kg^-1,12 mg·kg^-1,24 mg·kg^-1;earthworm GST activity showed an increase with the Cd concentration in soil increased,and soil Cd concentration was 24 mg·kg^-1 when the activity began to increase;earthworm GPX activity in the concentration gradient did not change significantly.?3?In this study,we use CaCl₂ extraction Cd,HAc extraction Cd,rye seedling accumulate Cd determine soil labile cadmium content and found that they all showed a significant positive correlation with the cadmium bioaccumulate by earthworms,the metallothionein content,the GST activity and the SOD activity.Based on the above research results,this paper reveals the E.fetida enrichment of cadmium and its metallothioneine and soil cadmium pollution concentration has a good correlation,metallothionein is available for cadmium pollution ecological risk diagnosis of sensitive and stable biomarkers,and the calcium chloride extraction method,extraction,determination of acetic acid leaching of soil rye seedling method available cadmium content is expected to replace the total soil Cd concentration as E.fetida actual exposure concentration.