典型矿冶周边地区土壤重金属污染及有效性含量

Contamination and availabile contents of heavy metals in soils in the typical mining and smelting circumjacent districts

对湖南长沙、株洲、衡阳、郴州等地区的典型矿冶污染土壤进行了采样分析与有效性含量提取,结果表明,土壤中重金属污染严重,矿区土壤主要污染元素为Pb、Zn、As、Cr、Cu,而冶炼业周边污染土壤中主要是Zn、Pb、Cr、As、Cu、Cd,其污染程度均远远高于国家环境质量二级标准;Pb、Cd和Zn污染主要来源于采矿、冶炼活动而As污染可能还与农业生产有关。不同浸提液对土壤中Pb、Zn、Cd、As、Cu有效性质量分数的提取能力(设其符号为u)依次为u(NH4NO3)>u(HCl)>u(CaCl2);而对有效性Cr,HCl提取量为最高;盐基离子,尤其是NH4、NO3效应和酸效应(H+)大大促+-进了土壤中重金属离子的环境危害行为。

In this study, the contamination and availability of heavy metals in soils from four typical mining and smelting circumjacent districts i.e. Changsha, Zhuzhou, Hengyang and Chenzhou in Hunan province were investigated. The results showed that the soils in the mining districts were seriously contaminated mainly by Pb, Zn, As, Cr, and Cu and in the smelting districts mainly by Zn, Pb, Cr, As, Cu and Cd. The contamination degree of metals was farther beyond the national standard Ⅱ of soil environmental quality. High contents of lead, cadmium and zinc were mainly the result of the mining and smelting activities, and high content of arsenic may also be due to the agricultural activities. The extracting ability of different extracting solutions for lead, zinc, cadmium, arsenic and copper was 1.0 mol?L-1 NH4NO3>0.1 mol?L-1 HCl>0.1 mol?L-1 CaCl2, while HCl had the highest extracting ability for chromium. According to the results, the environmental jeopardizes of metals were aggravated significantly by the effects of salt ions (ammonium and nitrate) and acidification (H+).