煤矸石酸性水释放对土壤重金属化学行为的影响

Acid Water of Coal Gangue Piles on Chemical Behavior of Heavy Metals in Soil

利用微波消解法和Tessier的5步连续提取法分析测定了韩城燎原矿区高硫煤矸石堆放场不同深度土壤的9种重金属含量和不同赋存形态,并结合重金属分配系数分析了它们的释放迁移能力。结果表明,堆放场土壤重金属As、Cd、Cr、Cu、Ni、Pb、Sn、V、Zn的均值皆超过远离堆放场土壤背景值和中国土壤背景值,其中以As、Cd、Zn为最显著。在不断接受煤矸石堆放场雨水淋溶释放的酸性水入渗条件下,污染土壤中重金属的生物有效性和迁移性为:Cd>Zn>Ni>Sn>Pb>Cu>As>Cr>V。由于受到土壤含水率和有机质的影响,在土壤40—60cm范围内,重金属Cd、Cr、Cu、Ni、Pb、Zn释放迁移能力为最弱。酸性水入渗对As、Cd释放迁移能力影响较小,而对Cd释放迁移能力影响较大。

The total concentrations and geochemical forms of 9heavy metals in soil of Liaoyuan mine area in Hancheng city were studied through the usage of microwave digestion method and Tessier 5step sequential extraction method,and the release and migration characteristics of the 9heavy metals in soil were analyzed based on heavy metal distribution coefficient.The results showed that the average concentrations of As,Cd,Cr,Cu,Ni,Pb,Sn,V and Zn were significantly higher than the heavy metal background values of soils far away from coal gangue plies and national heavy metal background values of soil,especially for As,Cd and Zn.During the infiltration process of acid water under the condition of continued acid water supply,the mobility and bioavailability of heavy metals in polluted soils listed in the order of Cd〉Zn〉Ni〉Sn〉Pb〉Cu〉As〉Cr〉V.Due to the influence of soil moisture and organic matter content,the release and transport capacities of Cd,Cr,Cu,Ni,Pb and Zn were the lowest in the 40—60cm soil layer.The acid water infiltration exerted less significant effect on the release and transport of As and Cd,while showed the strongest effect on the release and migration ability of Cd.