矿物固化剂添加下土壤重金属有效性变化及污染风险评价

The Effective Changes and Pollution Risk Assessment of Heavy Metal under Mineral Curing Agents Addition

采集重金属污染原土为供试土壤,通过施加1%和2.5%的沸石、膨润土、硅藻土、蛭石4种矿物固化剂,研究矿物添加对土壤重金属全量、有效态、生物有效性及形态分级的影响,并评价其污染及生态风险.结果表明:添加矿物固化剂后土壤中Cu、Zn、Pb含量仍在土壤重金属污染管控筛选值范围内,其污染及生态风险均相对较低;矿物固化剂添加后可不同程度地降低土壤重金属有效态及生物有效性,且以硅藻土和蛭石处理效果相对较好;矿物添加后可能通过促进EXCH-Cd向FeMnOX-Cd转化而降低土壤中Cd的生物有效性;整体上,2.5%矿物固化剂下土壤重金属综合污染指数下降更为明显.综上,适量矿物固化剂添加可以降低土壤重金属有效性并控制其污染及生态风险.

Sampling heavy metal contaminated soil as experimental soil,four mineral curing agents(zeolite,bentonite,diatomite and vermiculite)with 1%and 2.5%were separately applied into the soil,the effects of mineral addition on the total quantity,availability,bioavailability and fractionation of heavy metals in soil were studied,and the pollution and ecological risks of heavy metals in soil were furtherly evaluated.The results demonstrated that the contents of Cu,Zn and Pb in soil were still within the scope of the screening value for soil heavy metal pollution control with relatively low pollution and ecological risk after adding mineral curing agents;adding mineral curing agents could reduce the availability and bioavailability of heavy metals in soils in different degrees,and diatomite and vermiculite were relatively effective;meanwhile,mineral addition may reduce the bioavailability of Cd in soil by promoting the transformation of EXCH-Cd to FeMnOX-Cd;overall,more significant decrease of the comprehensive pollution index and cumulative index of heavy metals in soil was found with 2.5%mineral curing agent addition.Thus,adding appropriate mineral curing agent could reduce the availability of heavy metals in soil and control their pollution and ecological risk.