土壤中重金属[S,S]-乙二胺二琥珀酸浸提及其对重金属形态分布的影响

EXTRACTION OF HEAVY METALS USING [S,S]-EDDS AND ITS EFFECTS ON METALS’FRACTIONS

采用螯合剂[S,S]-乙二胺二琥珀酸([S,S]-EDDS)对废弃矿区附近的农田土壤进行浸提,分析浸提前后残留土壤样品中重金属的形态.结果表明,[S,S]-EDDS对重金属元素的提取率在不同土壤之间有较大差异,对Cu的浸提率为13.4%—13.8%,对Pb的浸提率为2.28%—16.3%,对Zn的浸提率为2.73%—11.3%.[S,S]-EDDS在提取重金属的同时也造成了Fe和Mn的明显溶出,其中Fe的溶出率为0.090%—0.291%,Mn的溶出率为2.53%—6.31%,均远高于对照组.[S,S]-EDDS浸提后酸溶/可交换态金属含量的变化倚赖于金属种类.对于Cu和Zn,经[S,S]-EDDS浸提之后,其酸溶/可交换态含量远低于对照组;但对于Pb,经[S,S]-EDDS浸提之后,酸溶/可交换态含量略高于对照组.[S,S]-EDDS对Cu和Zn四种形态均有浸提作用,且对残渣态的影响小于其它形态.[S,S]-EDDS浸提导致土样中Cu和Zn残渣态比例上升,其它形态比例的变化则依赖于金属的种类以及土壤性质.

Heavy metals and selected mineral elements in two agricultural soils from disused copper and lead-zinc mining area were extracted by [ S, S ]-EDDS. After extraction, the heavy metals in different phases were analyzed by modified BCR sequential extraction procedure. The extraction efficiency was 13.4%-13.8% for Cu, and 2. 28%-16. 3% for Pb, and 2. 73%-11.3% for Zn, respectively. Fe and Mn were also dissolved obviously during the extraction process, and about 0. 090%-0. 291% of total Fe and 2.53%-6.31% of total Mn were extracted. Exchangeable/acid-extractable fractions for Cu and Zn in the two soil samples treated by [ S, S ]-EDDS were much less than that of the control, but exchangeable/acid-extractable fractions for Pb were slightly higher than that of the control. Cu and Zn in exchangeable/acid-extractable fractions, reducible fractions, oxidizable fractions and residual fractions could all be extracted by [ S, S ] -EDDS, but the metal extraction efficiency for the residual metal fractions was the lowest. The residual metal fraction of Cu and Zn increased due to the extraction of [ S, S ] -EDDS, the variation of the other fractions was depended on the properties of the metals and soils.