Effects Of Organic Matter And Earthworm On Heavy Metal Accumulation In Amaranthus Hypochondriacus L

Remediation of heavy metal contaminated soil is a study focus in environmental science field, phytoremediation is a wide-concerned method due to its cost-effective, environmental friendly and permanence. In this study, 2 months pot experiments with Amaranthus hypochondriacus L as the phytoremediation plant, straw and two different ecotypes of earthworms(Eisenia fetida and Amynthas robustus) as the potential factors of ameliorating the phytoremediation efficiency were conducted to investigate their effects on acid heavy metal contaminated soil which was typical mineral polluted soil in South China. The objectives of this study were(1) to reveal whether the earthworms and straw can enhance the phytoremediation efficiency, and whether the “straw+ earthworms + Amaranthus” system can reduce the heavy metal content in soil;(2) to evaluate the influences of straw and earthworms on soil properties and plant physiological properties, and the mechanisms of both above working on the phytoremediation efficiency.The mains results are as follow:(1) The highest plant biomass was found under the “Straw + Eisenia fetida” treatment,which results in its migration volume of Cu ? Zn ? Pb and Cd was increased significantly by 325%, 299%, 156% and 248% respectively, and reducing 16% of Cd content in soil while compared to the control treatment.(2) Straw promote the plant growth by improving soil's physical and chemical properties, which shows as reducing the soil bulk density, and increasing the soil organic carbon, total nitrogen and CEC. Straw can also activate soil Cu and Cd by increasing dissolve organic carbon(DOC) content in soil.(3) Earthworms' survivability and tolerability in contaminated soils was differed by their species, the survival rate of Eisenia fetida was more than 60% higher that of Amynthas robustus. Occluding earthworms can enhance the plant biosmass, but fail to activate the heavy metal in soil as the assumption which results in increasing the heavy metal accumulation in plant. Only under the co-operation with straw,earthworms can realize the remediation effect.Adding organic matter and occluding earthworms simultaneously can improve the heavy metal accumulation in plant significantly and reduce the heavy metal content in soil by increasing the plant biomass markedly. Occluding Eisenia fetida rather than Amynthas robustus is a better choice in assisting phytoremediation. “Straw-Eisenia fetida-Amaranthus” system is an effective and environmental friendly remediation method of Cd contaminated soil.