垃圾处理园区周边土壤-地下水重金属分布特征

测定并分析生活垃圾综合处理园区周边剖面土壤-地下水中重金属（Cr、Cu、Ni、Pb、Zn、As、Cd和Hg）的含量结果表明，在土壤水的对流、扩散作用下重金属在各点位土壤剖面中均存在明显的纵向迁移现象，同时土壤介质的吸附、拦截等阻滞作用导致重金属主要富集于150~200cm中层土壤中.该区域土壤中重金属虽有积累但尚未超标，垃圾焚烧飞灰沉降导致上游点位土壤中重金属含量高于另外两个距离更近的下游点位；而园区邻近地下水中Zn、Ni含量相对其他远距离点位明显增加，且Zn含量超出了地下水质量标准，推测是由垃圾渗滤液下渗的影响所致.借助高通量测序手段分析发现，不同深度土壤及地下水之间的微生物群落结构存在显著差异（p<0.01），由于还存在其他土壤环境要素的作用，土壤中大部分微生物群落受重金属影响较小，而地下水中微生物群落明显受到垃圾渗滤液中重金属Zn、Ni富集的影响.本研究可为垃圾综合处理园区的土壤-地下水系统污染风险评估奠定基础，为其环境安全管理提供科学指导.

Spatial distribution characteristics of heavy metals in the soil-groundwater system around an integrated waste management facility

The concentrations of heavy metals (Cr, Cu, Ni, Pb, Zn, As, Cd, and Hg) in the soil-groundwater system around an integrated waste management facility were determined. The results showed that an obvious vertical migration of heavy metals was observed with the highest concentration levels found at the depth of 150~200cm, which was attributed to the convection and diffusion of soil water and the adsorption and interception of the soil media. In spite of clues for heavy metals accumulation in the soil, the concentrations of heavy metals were lower than the critical limit of national soil quality standard. In soil samples, the contents of heavy metals at the upstream site were higher than those of the other two closer downstream sites, which was mainly caused by atmospheric deposition. In groundwater samples, the values of Zn and Ni adjacent to the integrated waste management facility were significantly higher that those at other further sites and the content of Zn even exceeded the groundwater quality standard, which was contributed by the infiltration of landfill leachate. Through high-throughput sequencing analysis, significant differences were found between soil and groundwater samples (P<0.01) in terms of microbial community structure:there was no significant correlation between most microbial communities in the soil and heavy metals, while the microbial community in groundwater was closely related with the enrichment of heavy metals Zn and Ni. These results would be helpful to assess and manage the environmental risks of the soil-groundwater system adjacent to the integrated waste management facility.