填埋场内重金属总量及其形态分布对迁移性的影响

以杭州市天子岭填埋场为例，对不同深度填埋层中的重金属总量、重金属迁移率和重金属形态分布进行了研究．结果表明，尽管填埋层中的重金属总量是土壤背景值的数十倍，超出土壤环境质量标准，但是重金属的迁移率却很低．另外，重金属迁移率与可交换态含量相关；Cd，Cu，Pb，Cr，Ni和Zn在填埋层中均以残渣态为主，填埋场中重金属都得到了有效固定，迁移性很差；各元素的易还原态与难还原态是重金属除残渣态之外主要的结合态(除Cr)，铁锰氧化物循环是控制填埋场中重金属转化行为的主要机制之一；Cu的酸可溶态与易还原态具有较好的相关性，说明cu这两种形态的转化行为相似．

EFFECT OF THE TOTAL AMOUNT AND SPECIATION OF HEAVY METALS ON ITS MOBILITY IN MUNICIPAL SOLID WASTE LANDFILL

In the study, totalamount, releasingrate and chemical speciation of heavy metals were analyzed to study the migration of heavy metals in a sanitarylandfill - Hangzhou Tianziling landfill.The results showed that the total amounts of heavy metals in landfill layer exceeded soil background values anddid not comply with the national environmental quality standard of China for soils. But the migration ratesof heavy metals in thelandfillwere relativelylow. Chemical speciation analysis of heavy metals indicated that (1) migration rate of heavy metals was positively related to exchangeable fraction; (2) Cd, Cu, Pb, Cr, Ni and Znin landfill were mainly in residual fraction and almost immobile; (3) there were also minor amounts of Cd, Cu, Pb, Ni andZnin easily and moderatelyreducible fractions, and the cycle of Fe/Mn oxides seemed to control the conversionof heavy metals in landfill layer; and (4) good correlation was found between acid soluble fraction and easily reducible fraction of Cu, which indicated that conversion behavior of the two fractions of Cu was similar.