燃煤电厂重金属排放与周边土壤中重金属污染特征及健康风险

Heavy Metal Emissions from Coal-fired Power Plants and Heavy Metal Pollution Characteristics and Health Risks in Surrounding Soils

为揭示燃煤电厂烟气中重金属排放对周边土壤环境的影响.以石家庄地区6座燃煤电厂为研究对象,测定了燃煤电厂烟囱入口烟气中As、Cd、Cr、Cu、Pb、Hg和Ni这7种重金属元素,同时对电厂周边土壤中重金属含量进行了测试分析,并对其进行了源解析和健康风险评价.结果表明,各燃煤电厂烟气经过一系列烟气污染物控制措施净化后,烟气中不同重金属元素的排放量范围为0.11~6.32 mg·(MW·h)^(-1),Cu、Cr和Ni是主要排放污染物.各电厂向大气环境中排放的7种重金属元素总量在33.56~275.71 kg·a^(-1)之间.燃煤电厂周边表层土壤中Cr、Cu、Pb、Hg和Ni这5种重金属元素含量平均值均高于河北土壤背景值,且超出背景值1.16~2.32倍.电厂周边土壤中重金属含量与烟气中重金属排放量具有一定相关性.不同风向上土壤中重金属含量随距电厂距离的增大,呈现出先增大后逐渐减小趋势.源解析表明煤炭燃烧排放对电厂周边土壤重金属的贡献率最大,达到41.4%,其次为工业排放,占比为23.6%,交通运输排放占比为19.6%.总而言之,人为活动对土壤重金属富集起主导作用,约占84.6%.健康风险评估显示电厂周边土壤中重金属元素的健康风险整体处于可接受范围内.

The aim of this study was to reveal the influence of heavy metal emissions from the flue gas of coal-fired power plants on the surrounding soil environment.Seven heavy metals,including As,Cd,Cr,Cu,Pb,Hg,and Ni,were detected in the flue gas of six coal-fired power plants in Shijiazhuang,and the heavy metals in the soil surrounding the power plants were analyzed.The source analysis and health risk assessment of the heavy metals were carried out.The results showed that after a series of flue gas pollutant control measures,the emission concentrations of different heavy metals in the flue gas of the coal-fired power plants ranged from 0.11 to 6.32 mg·(MW·h)^(-1),and Cu,Cr,and Ni were the main pollutants.The total amount of the seven heavy metal elements discharged into the atmosphere by each power plant was 33.56-275.71 kg·a^(-1).The average contents of Cr,Cu,Pb,Hg,and Ni in the surface soil surrounding the coal-fired power plant were higher than the background values of Hebei soil,and the contents were 1.16-2.32 times higher than the background values.The heavy metal content in the soil around the power plants was proportional to the heavy metal emissions in the flue gas.The heavy metal content in the soil under different wind directions first increased and then decreased gradually with the increase in distance from the power plants.Source analysis showed that coal combustion emissions contributed the most to heavy metals in soil around the power plants(41.4%),followed by industrial emissions(23.6%)and transportation emissions(19.6%).Altogether,human activities played a leading role in soil heavy metal enrichment,accounting for 84.6%.The health risk assessment showed that the overall health risk of metal elements in the soil surrounding the power plant was within acceptable limits.