铅锌矿污染土壤中颗粒态有机质对重金属的富集作用

Enrichment of Heavy Metals in Particulate Organic Matter in a Lead/Zinc Mining Contaminated Soil

积累在土壤中重金属的生物有效性及其可移动性不仅与重金属浓度有关,更与其存在的形态和载体对重金属的吸持能力有关,因此防治土壤重金属污染的关键是降低土壤重金属的含量和有效性。本文主要研究了取自浙江省绍兴市某铅锌矿污染矿区的污染土壤中铅、锌、铜、镉在不同粒级的颗粒态有机物(POM)的分布。采用物理分馏法把土壤POM按粒级和密度分散。四种重金属在土壤POM中都有显著的富集。重金属在土壤POM中的富集程度随着POM粒级的减小而增加。0.05～0.25mm的POM对重金属的富集起首要作用,Zn、Pb在最大的POM组分中(>1mm)富集浓度是其在最小POM组分中(0.05～0.25mm)的1/4～1/3。四种重金属中,铜在POM中的富集最强烈,最高相对富集系数达到14.67,是Pb的6倍。

Bioavailability and movability of heavy metals accumulated in soil relate to not only the concentrations of heavy metals, but also its forms and soil adsorption characteristics. So the key point of prevention and remediation of the contanaination of heavy metals is to reduce the concentrations and bioavailability of heavy metals. The distribution of heavy metals in different size fractions of particulate organic matter （POM） in polluted soils around a zinc-lead mine in Shaoxing, Zhejing Province was investigated. According to the size and density of POM in soil, physical fractionations were carried out to separate POM. All of the four heavy metals （Lead, Zinc, Copper and Cadmium） were significantly enriched in the POM fractions. Enrichment of heavy metals in POM increased with a decrease in POM size. Most heavy metals were enriched in 0.05-0.25 mm POM. In the finest POM fraction （0.05-0.25 mm）, Zn and Pb concentrations were three to four times as those in 〉1 mm POM. Among four heavy metals, copper was most strongly enriched. The enrichment coefficient of Cu was 14.67, about 6 times of Pb.