Abstract:

A large amount of fly ash is accumulated in the ash yard of coal-fired power plants, and the heavy metals contained in fly ash may threaten human health. In order to find out the pollution status and health risks of heavy metal pollution in the soil of the ash yard of coal-fired power plants, an ash yard of a coal-fired power plant in Jilin Province and its surrounding areas was taken as the study area. 20 soil samples were collected to analyze the content of the main heavy metal. The pollution load index method (PLI) and the US EPA health risk assessment model were used to evaluate the pollution level and health risks respectively of heavy metals. The average content of Cr, Ni, Cu, Cd and Pb was higher than the background value of the soil environment, especially the counterpart of Cd is 11 times the background value, and its content was also higher than the “Soil Environmental Quality” (GB 15618—2018), which was obviously enriched in the study area. The analysis results of soil heavy metal content showed that the leakage of ash water and fly ash dispersion were the main ways of heavy metal migration of fly ash in ash yard. The results of pollution load index method showed that the soil at the largest drop difference between the ash yard and its northwest ash dam was moderately polluted, and the soil at other sampling points was slightly polluted. The soil pollution was mainly caused by the leakage of ash water from the ash dam, which was less affected by the prevailing wind. The study area was generally slightly polluted. According to the results of human health risk assessment, oral intake was the main way of exposure to heavy metals, and the non-carcinogenic and carcinogenic risks of children were higher than those of adults. The 7 heavy metal elements had no non-carcinogenic risks to adults and children; Cr, Cd, and As had acceptable carcinogenic risks to adults and children. Among which Cr was the main carcinogen, and necessary treatment measures should be carried out for Cr.

Key words: coal-fired power plant, ash yard, soil, heavy metal, health risk, pollution load index

摘要：

燃煤电厂贮灰场堆积了大量的粉煤灰,而粉煤灰中蕴含的重金属可能会威胁到人类健康。为查明燃煤电厂贮灰场土壤重金属污染状况及对人体健康风险问题,以吉林省某燃煤电厂贮灰场及其周边地区为研究区,采集20个土壤样品进行主要重金属含量的分析。应用污染负荷指数法（PLI）评价研究区重金属污染水平,采用US EPA模型进行贮灰场重金属健康风险评价。研究区土壤Cr、Ni、Cu、Cd、Pb平均含量高于土壤环境背景值,其中Cd的平均含量是背景值的11倍,并且其含量均高于《土壤环境质量标准》（GB 15618—2018）的风险筛选值,Cd在研究区土壤中有明显的富集。土壤重金属含量分析结果显示,灰水渗漏和粉煤灰飞灰飘散是贮灰场粉煤灰重金属迁移的主要方式。土壤重金属变异系数排序为：Ni>Cu>As>Zn>Pb>36%>Cd>Cr>15%,Cd、Cr属于中度变异,贮灰场粉煤灰是其主要污染来源,Ni、Cu、As、Zn、Pb属于高度变异,除了贮灰场影响因素外,人类活动也是其重要来源。污染负荷指数法的评价结果显示,贮灰场及其西北侧灰坝下落差最大处部分土壤处于中度污染,其他采样点土壤处于轻度污染。土壤污染主要源于灰坝处灰水渗漏,受盛行风影响较小,研究区总体处于轻度污染。人体健康风险评价结果显示,经口摄入是重金属暴露风险的主要途径,研究区土壤重金属存在的非致癌和致癌风险,儿童均高于成人,7种重金属元素对成人与儿童不存在非致癌风险;Cr、Cd、As对成人和儿童均存在可接受的致癌风险,其中Cr是主要的致癌因子,应针对Cr开展必要的治理措施。

关键词: 燃煤电厂, 贮灰场, 土壤, 重金属, 健康风险, 污染负荷指数