北京市密云水库上游金矿区土壤重金属含量、来源及污染评价

Contents, Sources and Contamination Assessment of Soil Heavy Metals in Gold Mine Area of Upstream Part of Miyun Reservoir, Beijing, China

运用多变量分析、富集因子及地累积指数法对北京市密云水库上游金矿区土壤重金属的来源、污染评价进行了研究。利用电感耦合等离子体质谱法(ICP-MS)测定土壤中Be、V、Co、Ni、Cu、Cd、Pb的含量,用原子荧光光谱法(AFS)测定As、Hg含量,用X射线衍射(XRD)测定土壤所含矿物质成分。结果表明,除As外各重金属平均含量均高于北京市土壤元素背景值。XRD分析结果显示,土壤的矿物质成分相似,主要包括石英、长石、伊利石、高岭石、蒙脱石、方解石。多变量分析(主成分、聚类、相关性分析)表明,Cu、Cd、Pb和Hg为人为源,主要来源于矿产的开采或运输过程;Be、V、Ni和Co来自混合源,即矿产开采过程和土壤背景;As为自然源,来自于岩石矿物的风化、侵蚀及土壤母质。富集因子法及地累积指数法评价结果表明,Cu、Cd、Pb、Hg污染较严重,受人为活动的显著影响,而Be、V、Co、Ni轻微污染,As无污染。该结果进一步验证了多变量分析的结果。

In this investigation, concentrations of heavy metals（Be, V, Co, Ni, Cu, Cd, Pb） in soils were determined by inductively coupled plasma mass spectrometry（ICP-MS）. Soil As, Hg were measured by atomic fluorescence spectrometry（AFS）. X-ray diffraction（XRD） was used to analyzed the mineral composition of soil. The average concentrations of heavy metals in the soils had exceeded the background values of Beijing soils except As. The minerals were very similar among soils and composed of quartz, feldspar, illite, kaolinite, smectite and calcite. Multivariate analysis （principle component analysis, cluster analysis, and correlation analysis） showed that （1）soil Cu, Cd, Pb and Hg had come mainly from anthropogenic sources via mineral exploitation and transportation activities; （2）Be, V, Ni and Co were associated with a mixed sources through both mineral exploitation and the soil background; and （3）As had derived from the weathering of rock and soil parent materials. Assessments by enrichment factor and geoaccumulation index showed that the soils were seriously polluted by Cu, Cd, Pb, and Hg, which were profoundly influenced by human activities, whereas slightly by Be, V, Co, and Ni. Arsenic had not contaminated the soils yet.