湖南某铅锌矿污染土壤稳定化修复研究

使用海泡石、磷酸二氢钙、钙镁磷肥、氧化钙和氧化镁等土壤改良剂及其组合,对湖南省某铅锌矿冶炼厂附近的重金属污染土壤进行了稳定化修复试验,利用BCR连续提取法进行形态分析,并进行稳定化效果的评价。结果表明,各改良剂组合均能够有效改变土壤中Zn、Cd和Pb的形态分布,弱酸提取态含量的减少率分别为Zn:17.03%~83.13%,Cd:45.03%~99.17%,Pb:54.05%~99.44%,降低重金属的不稳定形态和生物可利用性,稳定化效果显著。改良剂对Zn元素的稳定化效果影响程度为:钙镁磷肥+氧化钙钙镁磷肥+氧化镁钙镁磷肥海泡石+磷酸二氢钙海泡石;对Cd元素的稳定化效果影响程度为:钙镁磷肥+氧化钙钙镁磷肥+氧化镁钙镁磷肥海泡石+磷酸二氢钙海泡石;对Pb元素的稳定化效果影响程度为:海泡石+磷酸二氢钙钙镁磷肥+氧化镁钙镁磷肥+氧化钙钙镁磷肥海泡石。该复合污染土壤中,Zn、Cd、Pb稳定效果最优处理为10%钙镁磷肥+5%氧化钙组合。

Stabilization of soil contaminated by a lead zinc mine in Hunan

In this study, sepiolite, calcium dihydrogen phosphate, calcium magnesium phosphate ( FCMP) , calcium oxide, magnesium oxide and their compositions were used to remediate soils contaminated by a nearby lead-zinc smelter. Stabilization effectiveness was evaluated by modified BCR sequential extraction procedure. The results showed that the amendment composi-tions changed speciations of Zn, Cd and Pb in treated soils. Compared with the control treatment, the reduction rate of acid extractable fraction were 17. 03% ~83. 13% for Zn, 45. 03% ~99. 17% for Cd, and 54. 05% ~99. 44% for Pb, reduced the unstable speciations and bioavailability of heavy metals, achieved obvious stabilization effect. Effects on Zn and Cd stabili-zation of different amendments followed the same order of FCMP+CaO>FCMP+MgO>FCMP>sepiolite+ Ca ( H2 PO4 ) 2 >sepiolite . Effects on Pb stabilization of different amendments followed the order of sepiolite+ Ca ( H2 PO4 ) 2 > FCMP+MgO>FCMP+CaO>FCMP>sepiolite. For the compound pollution of Zn, Cd, and Pb in the studied soil, the optimal stabilization treatment was 10% of FCMP and 5% CaO combination.