地质高背景区铅锌矿废弃地土壤重金属污染评价

调查研究了某废弃铅锌矿区周边农田土壤中重金属Hg、As、Cd、Cr、Pb、Cu、Zn的污染状况,并结合单因素指数法、地累积指数法、污染指数负荷法、灰色聚类法及聚类热图分析对重金属污染程度和空间分布状况进行评价,采用相关性分析和主成分分析识别污染途径。结果表明,研究区Cd、Zn、Hg、Pb、Cu和As含量均超过贵州省土壤背景值。Cd的外源污染最严重,Zn、Pb、Hg次之。重金属污染程度与河流以及距矿区距离呈正相关。主要污染因子为Cd,次要污染因子为Hg和Zn,各采样点均处于严重污染。研究区重金属来源可分为4类,Cu、Cd、Zn属工业源污染,主要为矿山开采;As、Hg污染与工业源和农业源有关;Cr、Pb含量受交通源与工业源以及自然源多方面影响。

Evaluation of Heavy Metal Pollution in Soil of Lead-Zinc Mine Wasteland with Geological High Background

Pollution status of Hg, As, Cd, Cr, Pb, Cu and Zn in farmland soil around an abandoned lead-zinc mining area was investigated. Degree of heavy metal pollution and spatial distribution were evaluated with combination of single factor index method, ground accumulation index method, pollution index load method, grey clustering method and clustering heat map analysis. Pollution pathway was identified by correlation analysis and principal component analysis. The results show that concentrations of Cd, Zn, Hg, Pb, Cu and As in soils of investigated area all exceed the background value of Guizhou Province. The soils are heavily polluted with Cd, moderately polluted with Zn, Pb and Hg. Degree of pollution positively correlates with distance to river and mine. The main pollution factor is Cd, the secondary pollution factors are Hg and Zn, and all sampling points are in serious pollution. The sources of heavy metals in study area are divided into four categories. Cu, Cd and Zn are industrial sources of pollution, mainly from mining. As and Hg pollution are related to industrial and agricultural sources while content of Cr and Pb is affected by many sources of transportation and industrial sources as well as natural sources.