基于高密度采样的县域尺度土壤重金属污染特征及源解析——以山东省昌乐县为例

Pollution characteristics and source analysis of soil heavy metals at county scale based on high density sampling:a case study of Changle county,Shandong province

为研究区域大尺度土壤重金属污染特征及来源,以山东省昌乐县为研究区域,通过网格化采样和分析测试,获得了5818件表层土壤样品的Cu、Pb、Zn、Ni、Cr、V、Mn、As、Co、Cd、Hg等11种重金属元素含量。进行了潜在生态风险评价,采用差异性分析、主成分分析、绝对主成分-多元线性回归分析、地统计分析等方法,定性、定量解析了来源。结果表明,研究区属土壤重金属高背景区,但总体污染风险低。潜在生态风险污染程度以中度为主,Hg、Cd对综合潜在生态危害的贡献最高,贡献率分别为47.94%和28.28%。解析结果显示,Co、Ni、Cr、V、Mn、Cu主要来自基性岩体控制的成土母岩风化的自然源;Pb、Zn主要来自交通和矿致异常的综合源;As、Cd主要来自碳酸盐岩和砂页岩成土母岩影响的自然源;Hg主要来自人类活动影响的人为源;Pb、V、Cd有30%以上的贡献来自未知源。以上污染源和未知源的平均贡献率分别为45.18%、16.19%、13.78%、5.95%、18.90%。自然源是研究区土壤重金属的主要来源,综合源和人为源对Pb、Zn、Hg的贡献最大,可能造成叠加污染。通过本文的分析研究可进一步筛选污染风险较大区域,在小尺度范围内开展重金属来源识别,尤其是未知源识别,为土壤重金属污染防控提供依据。

To study the pollution characteristics and sources of soil heavy metals in regional large-scale.The Changle County of Shandong Province was taken as the research area.The contents of 11 heavy metal elements,including Cu,Pb,Zn,Ni,Cr,V,Mn,As,Co,Cd,and Hg,were obtained from 5818 surface soil samples through grid sampling and analysis testing.The potential ecological risk was evaluated.The sources were analyzed qualitatively and quantitatively using methods such as difference analysis,principal component analysis,absolute principal component score-multiple linear regression analysis,and geostatistical analysis.The results showed that the study area belongs to the high background area of soil heavy metals content,but the overall pollution risk was low.The pollution degree of potential ecological risk was mainly moderate,with Hg and Cd making the highest contribution to the comprehensive potential ecological hazard,with contribution rates of 47.94%and 28.28%,respectively.The analytical results showed that Co,Ni,Cr,V,Mn,and Cu were mainly derived from the natural sources of soil parent rock weathering controlled by the basic rock mass.Pb and Zn were mainly derived from comprehensive sources of traffic and mine-induced anomalies.As and Cd mainly come from natural sources influenced by carbonate rocks and sand shale parent rocks.Hg was mainly derived from anthropogenic sources affected by human activities.More than 30%of Pb,V,and Cd contributions were derived from unknown sources.The average contribution rates of the above pollution sources and unknown sources were 45.18%,16.19%,13.78%,5.95%,and 18.90%,respectively.Natural sources were the main sources of soil heavy metals in the study area,and comprehensive and anthropogenic sources contributed the most to Pb,Zn,and Hg,which may cause superimposed pollution.Through the analysis and research in this article,areas with high pollution risks can be further screened,and heavy metal sources can be identified on a small scale,especially unknown sources,providing a basis for soil heavy metals pollution prevention and control.