北京市水源涵养区上游万庄金矿田土壤重金属空间分布、形态特征及污染评价

对北京市水源涵养地平谷金矿及尾矿库土壤重金属(As、Cd、Cu、Pb、Cr、Ni、Zn和Hg)的空间分布特征、形态特征及污染现状进行研究与评价。空间分布图显示,As、Cd、Cu、Pb和Zn显示出基本相同的分布情况,污染相对较严重的区域大部分分布在金矿区及周边,受到人为活动的显著影响;Cr和Ni的空间分布特征表明污染严重的区域为尾矿库矿区周边。采用改进的BCR法提取土壤中重金属形态,采用ICP-OES测定。结果表明,Cd可交换态及易还原态占总量的20%~30%,Zn、Pb的易还原态含量较高,为潜在污染源。利用统计学分析,Pb、As、Hg、Zn、Cd可能来源于矿山的开采、金属冶炼等人为活动。地累积指数评价结果表明,研究区域土壤中8种重金属的含量,除Hg外基本均处于污染状态,其中:Ni、Cr、Hg都处于轻度污染或未污染程度;Cu个别采样点处于偏中度与中度污染水平;Pb、As、Cd环境生态污染较严重,个别采样点达到重度污染水平。

Spatial Distribution, Fractionation and Pollution Assessment of Heavy Metals in Wanzhuang Gold Mining Field in Upstream Part of Water Conservation Area of Beijing, China

The objective of this study was to investigate the spatial distribution, fractionation and contamination degree of heavy metals in soils of gold mine and tailings of Pinggu in Beijing. The spatial distributions of As, Cd, Cu, Pb, and Zn were basically the same. Their pollution was more serious in the gold mining and surrounding area, which was obviously affected by human activities. However, the spatial distribution of Cr and Ni showed that the most polluted area was the tailings. Exchange and reducible fractions of Cd accounted for about 20%~30% of the total Cd, respectively. Zinc and Pb were dominated by reducible fraction, which is potential pollution source. Pb, As, Hg, Zn, and Cd came mainly from mine mining, metal smelting and other human activities. The geo-accumulation index showed that the studied areas were seriously polluted by Pb, As and Cd, but slightly by Ni and Cr. The soils had not been contaminated by Hg. Some sample points showed mild and moderate Cu pollution.