Study On Effects Of Earthworm Accumulation Of Heavy Metal In Soil

In recent years, the pollution of soil is rising and soil heavy metal pollution has become the urgent the topic which needs to study. Bioremediation in this kind of pollution play an irreplaceable advantage, it is will become the trend of soil pollution control. Earthworm is the major groups of animals in soil. It can accumulate part of heavy metals in environmental, and plays an important role in ecological system. Earthworm's ability of improving soil structure, moisture and nutrient supply, and improving soil fertility, etc is irreplaceable. Simultaneously the interaction between the soil pollutants and earthworm has also been researched a lot. Therefore, through the field or lab biology toxicological test, it can use the worms to evaluation ecology toxic of soil's chemical pollutants. In this experiment, we inoculate earthworm in heavy metal pollution of soil. Through the activities of earthworm to enrichment and activate heavy metal, it will study the possibility of remediating the heavy metal pollution soil. In a word, it's a more effective, low cost, and more safety way to settle the problem of the heavy metal pollution by earthworm.In this experiment, the soil which we study is from farm, and Eisenia foetida is being chosen for the test earthworm. Through the acute toxicology experiment researching on heavy metal(Cu, Hg, Pb, Zn) to reveals the relationship between the dose of heavy metal and earthworm, and calculate the LC50 and choose the suitable heavy doses which can survive earthworm and do the experiment. Then adding the amount of heavy metal salt to soil simulating contaminated soil to breed earthworm, and investigate the growth of earthworms. Then it takes certain earthworm from the soil every time to dispel, and use the ICP-AES to determine the concentration of heavy metals in earthworms. Through experiments have found that:when the concentration of heavy metals in the soil is 0.5 percentages, it fits the half lethal dose. Earthworm living in soil after 50 days, only in the blank's earthworm weight increased. In the containing heavy metals soil, the earthworm weight increased first then reduced. In the highest concentration of heavy metals soils, a death can be obtained. We can draw a conclusion that the heavy metals have a negative effect on the growth of Eisenia foetida. Along with the increase of concentration of heavy metals in the soil, the enrichment quantity of earthworm is also increasing. With the increase of concentration of time, the enrichment of heavy metal in the earthworm has been changed. The sequence of heavy metal Cu, Hg, Pb, Zn concentration in earthworm:Zn> Cu> Pb> Hg. It is fully showed that earthworms can have good accumulation on heavy metal, and can use the earthworm to treatment the problem of heavy metal pollution.