贵州独山锑矿区土壤-头花蓼系统中重金属的分布特征

Distribution characteristics of heavy metals in soil-Polygonum capitatum system at Dushan antimony deposit,Guizhou Province

通过野外调查采样,分析贵州独山锑矿区土壤6种重金属(Sb、As、Cd、Zn、Pb、Mn)含量及其在头花蓼不同部位的分布特征。结果表明:矿区土壤Sb、As、Cd、Zn、Pb和Mn的平均含量分别为1566.55、23.98、1.21、117.81、34.27和460.98 mg·kg-1,Sb、As、Cd、Zn含量分别为贵州省土壤背景值的699.35、1.20、4.88和1.18倍,且土壤中Sb与As呈显著正相关性(P<0.05),具有同源性。内梅罗综合污染指数法评价表明,矿区土壤重金属污染指数为112.75~1295.22(平均500.37),为重度污染水平。头花蓼在锑矿区污染土壤中具有较强的耐受性,且Sb、Mn在头花蓼各部位的含量分布分别为根>叶>茎>花、叶>花>根>茎,As、Cd、Zn、Pb无明显规律。矿区头花蓼各部位的As、Cd、Pb含量均未超过《中医药-中草药重金属限量》国际标准值,但该矿区头花蓼中的Sb对人体的健康存在一定健康风险。

The contents and distribution characteristics of six heavy metals （Sb, As, Cd, Zn, Pb, Mn） were investigated by sampling soil and different parts of Polygonum capitatum from Dushan antimony deposit in Guizhou. The results showed that the contents of Sb, As, Cd, Zn, Pb and Mn in soil samples were 1566.55, 23.98, 1.21, 117.81, 34.27 and 460.98 mg·kg-1, respectively. The contents of Sb, As, Cd and Zn were 699.35, 1.20, 4.88 and 1.18 times higher than the soil background values in Guizhou, respectively. In addition, the correlation between Sb and As in soil was significant （P〈0.05）, showing a homologous pattern. The evaluation using Nemerow comprehensive index showed that the pollution index of soil heavy metals in this area ranged from 112.75 to 1295.22, with an average of 500.37, indicating the serious pollution. Besides, P. capitatum showed good growth and tolerance in the soils contaminated by antimony mining. The Sb and Mn contents in P. capitatum were in order of root 〉 leaf 〉 stalk 〉 flower and leaf 〉 flower 〉 root 〉 stalk, respectively, but As, Cd, Zn and Pb exhibited no obvious pattern. Although As, Cd, Pb contents in P. capitatum were lower than the maximum limits of heavy metals in natural materials of Traditional Chinese Medicine （ISO 18664）, Sb in Polygonum capitatum may be harmful to human health.