Physicochemical and biological quality of soil in hexavalent chromium-contaminated soils as affected by chemical and microbial remediation

摘要

Chemical and microbial methods are the main remediation technologies for chromium-contaminated soil. These technologies have progressed rapidly in recent years; however, there is still a lack of methods for evaluating the chemical and biological quality of soil after different reme diation technologies have been applied. In this paper, micro bial remediation with indigenous bacteria and chemical re mediation with ferrous sulphate were used for the remedia tion of soils contaminated with Cr(VI) at two levels (80 and 1,276 mg kg~(-1) through a column leaching experiment. After microbial remediation with indigenous bacteria, the average concentration of water-soluble Cr(VI) in the soils was reduced to less than 5.0 mg kg~(-1). Soil quality was evaluated based on 11 soil properties and the fuzzy comprehensive assessment method, including fuzzy mathematics and correlative analysis. The chemical fertility quality index was improved by one grade using microbial remediation with indigenous bacteria, and the biological fertility quality index increased by at least a factor of 6. Chemical remediation with ferrous sulphate, however, resulted in lower levels of available phosphorus, dehydrogenase, catalase and polyphenol oxidase. The re sult showed that microbial remediation with indigenous bacteria was more effective for remedying Cr(VI)-contam-inated soils with high pH value than chemical remediation with ferrous sulphate. In addition, the fuzzy comprehensive evaluation method was proven to be a useful tool for monitor ing the quality change in chromium-contaminated soils.