氯化铁和硫酸铁对酸性土壤中有效态镉和铅污染的修复作用

Remediation of available Cd and Pb contamination in acidic soil by ferric chloride and ferric sulfate

采用浸泡实验法研究了氯化铁和硫酸铁对酸性土壤中有效态镉和铅污染的修复效果,结果表明,氯化铁和硫酸铁均能有效去除土壤有效态镉和铅污染,Fe(Ⅲ)用量为50~100 mmol/kg时,有效态Cd和Pb的去除效果可达70%~96%。氯化铁和硫酸铁能去除土壤中的水溶态、碳酸盐结合态、腐殖酸结合态、铁锰氧化物结合态和强有机结合态Cd和Pb及交换态Cd。氯化铁和硫酸铁对Cd均既有洗脱修复作用又有固定修复作用,且洗脱修复作用的贡献稍大;氯化铁用量较小时(50 mmol/kg)对Pb既有固定修复又有洗脱修复作用,固定修复作用稍大;用量较大时(100 mmol/kg),对Pb只有洗脱修复作用。硫酸铁对Pb的修复作用则以固定修复作用为主,洗脱修复作用很小。

Remediation effects of ferric chloride and ferric sulfate on available Cd and Pb contamination in the acidic soil were studied by soaking experiments. The results show that ferric chloride and ferric sulfate could efficiently remove the available Cd and Pb from the acidic soil. Under 50 ~ 100 mmol / kg dosages of Fe( Ⅲ),the remediation efficiencies of available Cd and Pb reached to 70% ~ 96%. Water-soluble forms,carbonate-combined forms,humic acid-combined forms,iron-manganese oxides-combined forms,and strong organic-combined forms of Cd and Pb,and exchangeable-Cd could be removed by ferric sulfate and ferric chloride. Ferric chloride and ferric sulfate could play both roles of washing remediation and immobilization remediation to Cd,and the contribution of washing remediation was larger. Under smaller dosages( ≤50 mmol / kg) of ferric chloride,both washing remediation and immobilization remediation to Pb were effective,but it was only washing remediation to Pb under larger dosages( ≥100 mmol / kg). Immobilization remediation accounted for an absolute proportion in Pb remediation by ferric sulfate.