Inhibited Effects of Different Application Levels of Biochar on the Cadmium Absorption in Mung Bean Plants
To investigate the effects of biochar with different application levels on cadmium(Cd)accumulation in mung bean at different growth stages,the pot experiment is undertaken in the Cd-contaminated dryland soil in this study.The chicken manure biochar with three application levels(0,2.5%and 5%,w/w)is added into the soils as the remediation materials.Six mung bean seedlings arere planted in each pot.The growth cycles of mung bean are 70 d.The effects of biochar application levels on soil pH,soil Cd chemical speciation and Cd absorption of mung bean at the pod bearing and harvesting stages are studied.Results show that biochar addition significantly reduces the Cd accumulation in mung bean plants.And the response of Cd uptake by above and below-ground parts of plants to biochar application levels are different.During the pod bearing stage,biochar with different application levels significantly decreases the Cd concentration in the mung bean roots.The 2.5%biochar addition exhibits the most significant effect on the inhibition of Cd accumulation in the mung bean stems,while the 5.0%biochar addition produces the most significant effect on the inhibition of Cd accumulation in the mung bean leaves.During the harvesting stage,the Cd concentrations in the aboveground parts(leaves and stems)of mung bean plants are significantly lower in the treatment with 2.5%biochar addition than that with 5.0%biochar addition.The Cd concentration of mung bean roots is significantly lower in the treatment with 5.0%biochar than that with 2.5%biochar addition.In addition,biochar alters the chemical speciation of soil Cd and reduces the relative proportion of the acid-soluble Cd.That is,at the pod bearing and harvesting stages,the lowest relative proportion of acid-soluble Cd is observed in the soil with 5.0%biochar addition.However,the 2.5%biochar addition significantly reduces the relative proportion of acid-soluble Cd between different growth stages in the same treatment,and the reduction percentage is over 26.68%.Therefore,the application levels of biochar,plant growth stage,and plant tissue utilization should be taken into account when evaluating the remediation of heavy metal contaminated soils.The study will provide a reference for the remediation of heavy metal polluted soil and safe utilization in agricultural dryland.
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万方数据
维普
