地块尺度农田重金属污染程度与来源分析

Pollution levels and sources of heavy metals in plot-scale farmland soil

为查明受污染农田的污染范围、污染程度,采取有效阻控手段,避免危害产生或扩大,在安徽省南部某县采集了不同深度的土壤、地表水、底泥以及地下水样品,测定不同环境样品中重金属含量和其他特征参数,分析不同环境样品的污染程度,并通过同源性分析、聚类分析、空间变异分析等方法解析污染物的主要来源,分析农田土壤的污染程度和范围。结果表明:调查区域部分农用地和林地土壤样品中镉、镍、铬、铜、铅和锌的含量超过其pH范围对应的风险筛选值,农用地和林地土壤样品中总镉超标率分别为16.9%和6.0%,总镍超标率分别为72.9%和88.0%,总铬超标率分别为62.7%和68.0%,总锌超标率分别为5.1%和6.0%;部分底泥样品中镍含量超过相应的风险筛选值限值,超标率为80%;地表水和地下水样品均符合相应水质标准要求。调查范围内林地和农用地土壤中重金属铜、锌、铬、镍、铅、镉之间存在同源性,来自同一母体。

To identify the scope and degree of pollution in contaminated farmland areas and implement effective control measures to prevent harm or further spread,soil samples at various depths,surface water,sediment,and groundwater samples were collected in the southern county of Anhui Province.The heavy metal contents and other characteristic parameters in different environmental samples were measured to analyze the pollution levels.The main pollutant sources were analyzed by homology analysis,clustering analysis,spatial variability analysis,etc.The results indicated that the Cd,Ni,Cr,Cu,Pb,and Zn contents in some soil samples of farmland and forest land in the survey area exceeded the risk screening values corresponding to their pH range.The total Cd exceedance rates in farmland and forest land soil samples was 16.9%and 6.0%,respectively,while the total Ni exceedance rates were 72.9%and 88.0%.The total Cr exceedance rates were 62.7%and 68.0%,and the total Zn exceedance rates were 5.1%and 6.0%.The Ni content in some sediment samples exceeded the corresponding risk screening value limit,with an exceeding rate of 80%.The surface water and groundwater samples met the corresponding water quality standards.There was homology among Cu,Zn,Cr,Ni,Pb and Cd in soil samples of forest land and farmland within the survey area,indicating a common source.