低源分散式燃煤汞排放对周边土壤的影响

Effect of Mercury Emission from Low-source Coal Combustion on Surrounding Soil

为评估农村低源分散式燃煤汞排放对周边农用土壤造成的影响,对土壤样品中总汞、甲基汞含量及汞形态分布进行测定,评价其污染程度和潜在生态风险。结果表明,研究区土壤中总汞(THg)、甲基汞(MeHg)平均含量分别为(0.37±0.08)mg/kg,(0.67±0.35)μg/kg,超标倍数分别为背景值的1.71、2.03倍,均未超过农用地土壤筛选值。单因子指数法、地累积指数法和潜在生态风险评价结果表明,土壤总汞呈中度及以下污染水平,土壤甲基汞呈重度及以下污染水平,总汞以中度生态风险为主。汞形态分析表明,土壤汞以残渣态和有机结合态为主,具有潜在的环境风险。

In order to assess the impact of mercury emission from rural low-source coal combustion on surrounding agricultural soils, the content and distribution of total mercury, methylmercury and mercury forms in soil samples were determined, and pollution levels and potential ecological risks were evaluated.The results show that the average concentrations of total mercury and methylmercury are(0.37±0.08)mg/kg and(0.67±0.35)μg/kg, respectively, less than the risk screening values for soil contamination of agricultural land, and ratios of the above-standard values are 1.71 and 2.03 times of the background values, respectively.The results of single-factor index, geoaccumulation index and potential ecological risk assessment show that the total mercury in soil is moderate and below, the methylmercury in soil is severe and below, and the main ecological risk of total mercury is moderate.The analysis of mercury speciation indicates that the residue and organic combination forms are the main forms of mercury in soil, which has potential environmental risks.