多元重金属与土相互作用及络合剂促解吸机制研究

重金属复合污染是土体遭受污染的一种典型情况，近年来，土体重金属污染事件的频繁发生引起了社会各界的高度重视。本项目以此为背景，通过一系列室内试验，开展典型重金属Cu(II)、Zn(II)、Cd(II)、Pb(II)组成的多元体系中重金属与粉土和粘土相互作用的研究，结合XRD（X光衍射光谱）和FT-IR（傅里叶红外光谱）等光谱分析法揭示多元体系重金属之间的竞争特性及复合重金属与土体的结合机理；采用NTA(氨基三乙酸)、EDTA(乙二胺四乙酸)、柠檬酸三种络合剂作为解吸助剂，研究复合重金属污染土中重金属的释放特性及影响因素，寻求与土类匹配的合适的污染土体修复助剂，揭示络合剂促重金属解吸的内在机制，并获取络合剂作用下单一及多元溶质运移的参数，预测复合重金属在土体中的迁移及归宿。研究成果有望为重金属复合污染土体的风险评估及污染土体的淋洗修复提供可靠的理论依据。

Combined contamination of heavy metals is the main type of soil contamination, and increasingly frequent incidents of soil contamination stemming from heavy metals have aroused broad attention in recent years. Based on this situation, a series of laboratory experiments will be performed to study the behavior between heavy metals in multi systems composed by typical heavy metals (i.e., Cu(II), Zn(II), Cd(II) and Pb(II)) and clay or silt, and competitive sorption mechanism and behavior will be revealed by means of X-ray diffraction spectra (XRD) and Fourier transform infrared spectroscopy (FT-IR). Releasing behavior and influencing factors of multi-metals in combined heavy metal contaminated soil will be studied using chelating agents (i.e., nitrilotriacetic acid trisodium salt monohydrate (NTA), ethylenediamine tetraacetic acid disodium salt (EDTA) and citric acid). Appropriate remediation assistants will be found to match different types of soil, inner mechanism of chelating agents assisting heavy metal release will be studied, and multi solute transport parameters taking account of the effect of chelating agents will be obtained to estimate the migration and fate of multi metal in contaminated soil. The results can be served as reliable theory basis for risk assessment and flushing remediation of soil contaminated by combined heavy metals.