溶解性有机质对冻融作用下污染土壤中重金属Pb的溶出释放规律

摘要

The effect of dissolved organic matter (DOM) on Pb leaching in Pb-contaminated soil treated by freeze-thaw action was investigated with the laboratory simulation experiments.The results showed that physiochemical properties of soil and chemical speciation of Pb were significantly changed by freeze-thaw action; DOM could significantly facilitate Pb leaching in freeze-thaw soil compared with non freeze-thaw soil.The leaching influences of DOM on Pb in Pb-contaminated soil were closely related to the soil type,soil contamination time and contamination degree.The leaching influence of DOM on Pb in brown soil was greater than that of in black soil,and increased with the time and degree of soil contaminated by Pb increasing.The leaching influences of DOM on Pb in Pb-contaminated soil were also closely related to the mass concentration,properties and component of DOM.The leaching amount of Pb was improved by the increase of DOM mass concentration,the lower pH of DOM and the lowmolecular-weight hydrophilic fraction of DOM facilitated the leaching of Pb from in soil.%采用室内模拟实验方法研究了溶解性有机质(DOM)对冻融作用下污染土壤中重金属Pb的溶出规律.结果表明:冻融作用明显改变了土壤基本理化性质和重金属Pb的化学形态；与未冻融土壤相比,DOM明显促进了冻融土壤中Pb的溶出释放.DOM对污染土壤中Pb的溶出释放作用与土壤类型、土壤污染时间和污染程度有关:DOM对棕壤中Pb的溶出释放作用大于对黑土中Pb的溶出释放作用；而且随着土壤Pb污染时间越长和污染程度越重,DOM对土壤中Pb的溶出释放作用越大.DOM对土壤中Pb的溶出释放还与DOM质量浓度、性质和组成密切相关:DOM质量浓度的增加提高了污染土壤中Pb的溶出释放；DOM的低pH和小分子量亲水性组分利于土壤中Pb的溶出释放.