多污染源作用下填埋场地下水微生物群落分析

为给填埋场地下水污染评价和自然衰减修复提供理论支撑，以四川省红层区某典型生活垃圾填埋场为例，采集了11组具有代表性的地下水水样，通过水化学分析和微生物16S rRNA基因测序，分析了红层区生活垃圾填埋场与其周围农业、生活污染源共同作用下，地下水中微生物的群落结构特征，以及不同污染源对微生物群落结构的影响.地下水水质评价结果表明，调查区地下水水质尚未超标；但相对于背景井，地下水已普遍受到不同污染源的影响，其中垃圾填埋场渗滤液扩散区地下水中（RDPD）的主要污染物为NO₃^-（Pi （背）=7.320）和Cl^-（Pi （背）=7.136）；农业区中（RDAS）的主要污染物为NO₃^-（Pi （背）=15.185）；农业生活混合区中（RDHP）的主要污染物为NO₃^-（Pi （背）=25.040）和SO₄^2-（Pi （背）=8.259）.微生物群落结构分析结果显示，Proteobacteria （43.6%~84.1%）为该研究区域地下水中的优势菌门.Bradyrhizobium和毛单胞菌科（Comamonadaceae）内一个未划分的属为农业区地下水中的优势菌属，甲基珠菌科（Methylococcaceae）内一个未划分的属、毛单胞菌科（Comamonadaceae）内一个未划分的属和sulfuritalea为农业生活混合区地下水中的优势菌，垃圾填埋场渗滤液扩散区无明显的优势菌属，但其群落丰度明显高于其他3组.受不同污染源的综合影响，不同区域地下水中的微生物群落结构复杂，RDPD、RDHP、RDAS地下水中的微生物群落结构组成与背景监测井（RDBJ）中的无显著差异，其中RDPD和RDHP地下水中的微生物群落结构组成较为相似.环境因子对水样品微生物群落影响程度依次为SO₄^2->Cl^-> NH₄⁺-N>NO₃^--N>ORP>pH值，因此，调查区生活垃圾填埋场地下水中的微生物群落结构主要受生活污染源和填埋场污染源的影响，其次为农业污染源，最后是自然因素的影响.

Impacts of different pollution sources on the microbial community in groundwater at municipal solid waste landfill sites

To better understand impacts of different pollution sources including agricultural, domestic, and landfill sources on the microbial community in the groundwater at municipal solid waste landfill sites in red beds area of Sichuan province, water quality and 16S rRNA sequencing analyses of 11groundwater samples were conducted. Groundwater quality analysis result showed that comparing to the background monitoring well (RDBJ), groundwater quality of the investigated area did not exceed the limitation (GB/T 14848-2017), however, they were affected by pollution sources in the vicinity. The major pollutants in the groundwater of landfill diffusion area (RDPD), agricultural area (RDAS), agricultural-domestic area (RDHP) were NO₃^-(P_bi=7.320) and Cl^-(P_bi=7.136), NO₃^-(P_bi=15.185), NO₃^-(P_bi=25.040)and SO₄^2-(P_bi=8.259), respectively. Microbial community diversity analysis results showed that Proteobacteria (43.6%~84.1%) was the dominant phylum, whereas Bradyrhizobium and an unclassified genus of Comanonadaceae were the dominant genera in RDAS groundwater. In RDHP groundwater, an unclassified genus of Methyococcaceae, an unclassified genus of Comamonadaceae and Sulfuritalea were the dominant genera. There was no dominant genus in RDPD groundwater, but the microbial abundancy was higher compared to the ones of the other 3groundwater types. There was no significant difference in the microbial community structures of RDPD, RDHP and RDAS. Moreover, the microbial community structures of RDPD and RDHP were similar. The impacts of environmental factors on groundwater microbial community were SO₄^2- > Cl^- > NH₄⁺-N > NO₃^--N > ORP > pH. Our results indicate that microbial community was mainly affected by the domestic and landfill pollution sources, followed by the agricultural pollution resource, and the natural factors seem to be minor factors. The results will provide a guidance for the environmental assessment and the natural attenuation remediation of groundwater contamination near the landfill sites.