【摘要】 随着煤炭行业的萧条,废弃煤矿逐渐增加。为有效管理和改善矿区废弃地环境生态系统,采集废弃22年的重庆中梁山马家沟煤矿区内18个表层土壤样品和1个煤矸石样品,以及矿区之外的2个背景土壤样品,分析样品中多环芳烃(USEPA16 PAHs)、正构烷烃(n-alkanes)、汞(Hg)和有机质(OM)含量水平。结果表明,表层土壤中PAHs的平均含量为170. 3 ng/g,低于我国正在运行的煤矿区土壤PAHs含量水平,高于山区背景土壤PAHs含量水平。主成分分析(PCA)结果表明煤燃烧释放和原煤残渣分别贡献78. 3%和17. 6%,是表层土壤中PAHs的主要来源。PAHs与n-alkanes的相关系数r=0. 83(P<0. 01),表明土壤中两者具有类似的输入途径和富集行为。PAHs与Hg之间不存在相关性,表明煤矿长期废弃后,这两种与矿区活动释放有关的污染物的环境归趋有显著差异。PAHs和OM之间也不存在相关性,表明与煤矿相关的有机质来源已经被植物、微生物的分泌物质及其残体的有机质替代,生态环境正逐步恢复。风险评价结果表明PAHs含量水平相对安全。值得注意的是,Hg含量超过农用地土壤污染风险筛选值。因此,政府对矿区旧址的土地利用应当基于多污染参数的叠加结果,避免单一指标的片面性评价与诊断。更多还原

【Abstract】 Abandoned coal mines increase gradually as coal industry depressing. In this study,18 topsoil samples,2 background soil samples and 1 coal gangue sample were collected in the Majiagou coal mine,an abandoned coal mine for 22 years,in Zhongliang Mountain,Chongqing. Concentrations of Polycyclic Aromatic Hydrocarbons( PAHs),n-alkanes,total mercury( Hg),and organic matter( OM) were measured to better understand and manage the environmental ecosystem of this abandoned mining area. The mean concentration of PAHs in the topsoil was 170. 3 ng/g,higher than that of the background soil in this area but lower than those of running coal mines in China. Principal Component Analysis( PCA) results suggested that coal combustion emission and raw coal residue contributed 78. 3% and 17. 6%,respectively. The correlation coefficient between PAHs and n-alkanes was 0. 83( P <0. 01),indicating that they share similar input pathway and enrichment behavior in the topsoil. There was no correlation between PAHs and Hg,indicating that the two pollutants released by the mining activity exhibited significant different environmental fates,while no correlation between PAHs and OM,indicating that OM sources associated with coal mines had been replaced by OM sources of plants,microbial secretions and their residues. The risk assessment results indicated that the risk level of PAHs was relatively safe,but the content of Hg exceeded the soil pollution risk screening value of agricultural land. Therefore,the land utilization of this mining area by local government should be according to the superposition of multiple pollution parameters,avoiding the one-sided evaluation and diagnosis of any single indicator.更多还原