含磷材料及生物炭对复合重金属污染土壤修复效果与修复机理

选取含磷材料（胛）、牛粪生物炭（DM）和水稻秸秆生物炭（Rs）实施Pb、Zn、Cd复合污染土壤化学稳定修复，进而评价修复效果，并分析影响因素；借助BCR连续提取法和x射线衍射光谱（XRD）探讨可能存在的修复机理。经过56d的化学稳定修复，修复材料均能显著降低TCLP提取态Pb、zn、cd，修复效果均为：Pb〉Zn〉Cd。三种修复材料对Pb、cd的修复效果为Er〉DM〉RS，对zn的修复效果基本相同。胛处理使土壤TCLP提取态的Pb、zn、cd分别降低了77．6％、31．5％、27．9％；DM处理使TCLP提取态的Pb、zn、cd分别降低了56．0％、26．1％、10．O％；RS处理使TCLP提取态的Pb、zn、cd分别降低了35．8％，25．0％和4．4％。三种修复材料均可促进Pb、cd从不稳定态向稳定状态转化。胛对Ph的固定机理主要是溶解一沉淀，XRD证明有Ca2Pb8（PO4）6（OH）2和Pb10（PO4）6（OH）2沉淀生成；DM固定Pb包括沉淀、吸附、离子交换等，XRD证明有Ca2Pb8（PO4）6（OH）2生成；Rs固定Pb主要为吸附、离子交换。研究结果表明，含磷材料和牛粪生物炭可作为理想的土壤Pb、zn、cd的修复材料。

Immobilization and Its Mechanisms of Heavy Metal Contaminated Soils by Phosphate-containing Amendment and Biochar

s： Biochar has been used to remediate soils contaminated by heavy metals. In this study we compared the immobilization of Pb, Zn and Cd in soils by phosphorus-containing material（PT）, dairy manure-derived biochar（DM） and rice straw-derived biochar（RS）. Factors influencing the immobilization and underlying mechanisms were explored. Applications of three amendments dramatically decreased leacha- bility of Pb, Zn and Cd after 56 days of incubation, with order Of Pb 〉 Zn 〉 Cd. Of three amendments, PT was the most effective in retaining Pb, and Cd, followed by DM and RS, but they did not show difference in Zn immobilization. Compared with CK, percent reduction of Pb, Zn, and Cd concentrations in TCLP extraction was 77.6%, 31.5%, and 27.9% for PT treatment, 56.0%, 26.1% and 10.0% for DM treatment, and 35.8%, 25.0%, and 4.4% for RS treatment, respectively. These amendments could transform Pb and Cd from soluble to stable forms. The pre- cipitation would contribute to Pb immobilization by PT amendment, as presence of Ca2Pbs （PO4）6（OH）： and Pbz0 （P04）6 （OH）2 was evi- denced by XRD analysis. The Pb immobilization by DM biochar was resulted from precipitation, adsorption and cation exchange, with Ca2Pbs（PO4）6（OH）2 presence as shown by XRD. However, RS biochar stabilized heavy metals only via adsorption and cation exchange. In conclusion, phosphate amendment and dairy manure-derived biochar could effectively immobilize Ph, Zn, and Cd in soil.