底泥铬污染的纳米铁粉修复及其土壤酶活性动态

Remediation of Cr( Ⅵ )-contaminated sediments using nanoscale iron and dynamics of soil enzyme activity

采用纳米铁粉修复Cr(Ⅵ)不同程度污染底泥,通过测定底泥中4种土壤酶活性,分析纳米铁粉修复对Cr(Ⅵ)污染底泥土壤酶活性的恢复情况。结果表明,纳米铁粉修复对底泥Cr(Ⅵ)有很好的去除效果,添加底泥干质量1%的纳米铁粉在16d内对底泥30～100mg·kg-1的Cr(Ⅵ)的去除率均高于99.7%。Cr(Ⅵ)污染显著降低了底泥多酚氧化酶、过氧化氢酶、蛋白酶和脲酶的活性。其中多酚氧化酶对Cr(Ⅵ)污染有很好的线性响应,可用于0～100mg·kg-1底泥Cr(Ⅵ)污染评价。经过16d的纳米铁粉修复,Cr(Ⅵ)污染底泥的脲酶活性恢复至未污染对照水平,过氧化氢酶活性的恢复效果不明显,多酚氧化酶和蛋白酶活性有待进一步恢复。

A series of laboratory experiments were performed to elucidate the removal of hexavalent chromium in the sediments using nanoscale iron. The activities of polyphenol oxidase, calatase, protease and urease were measured to assess the restoration of soil enzymes after the remediation. The results showed that nanoscale iron had excellent ability to remove hexavalent chromium from contaminated sediments. After 16 days remediation using nanoscale iron, the removal rate of hexavalent chromium were all higher than 99.7% at different concentration of hexavalent chromium from 30 - 100 mg·kg^-1. Hexavalent chromium was found to inhibit the activities of polyphenol oxidase, calatase, protease and urease significantly. There was a significant negative correlation between polyphenol oxidase and hexavalent chromium concentration, so it was presumed to use polyphenol oxidase activity as primary biochemical index to evaluate hexavalent chromium pollution. The activity of urease was restored to the control level after 16 days remediation using nanoscale iron, while the remediation had no obvious effect on the activity of calatase. Yet it was depressed that the activity of polyphenol oxidase and protease were not restored to the control level in the course of experiments, so the further research was still needed.