Şimşir Burcu, Yan Jun, Im Jeongdae, Graves Duane, Löffler Frank E
Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences , Shenyang, Liaoning 110016, China.
Department of Microbiology, University of Massachusetts , Amherst, Massachusetts 01002, United States.
Environ Sci Technol. 2017 May 2;51(9):4821-4830. doi: 10.1021/acs.est.6b05554. Epub 2017 Apr 11.
Contaminant discharge from fractured bedrock formations remains a remediation challenge. We applied an integrated approach to assess the natural attenuation potential of sediment that forms the transition zone between upwelling groundwater from a chlorinated solvent-contaminated fractured bedrock aquifer and the receiving surface water. In situ measurements demonstrated that reductive dechlorination in the sediment attenuated chlorinated compounds before reaching the water column. Microcosms established with creek sediment or in situ incubated Bio-Sep beads degraded C-C chlorinated solvents to less-chlorinated or innocuous products. Quantitative PCR and 16S rRNA gene amplicon sequencing revealed the abundance and spatial distribution of known dechlorinator biomarker genes within the creek sediment and demonstrated that multiple dechlorinator populations degrading chlorinated C-C alkanes and alkenes co-inhabit the sediment. Phylogenetic classification of bacterial and archaeal sequences indicated a relatively uniform distribution over spatial (300 m horizontally) scale, but Dehalococcoides and Dehalobacter were more abundant in deeper sediment, where 5.7 ± 0.4 × 10 and 5.4 ± 0.9 × 10 16S rRNA gene copies per g of sediment, respectively, were measured. The microbiological and hydrogeological characterization demonstrated that microbial processes at the fractured bedrock-sediment interface were crucial for preventing contaminants reaching the water column, emphasizing the relevance of this critical zone environment for contaminant attenuation.
来自裂隙基岩地层的污染物排放仍然是一个修复难题。我们采用了一种综合方法来评估沉积物的自然衰减潜力，该沉积物形成了来自受氯化溶剂污染的裂隙基岩含水层的上升地下水与接受地表水之间的过渡带。现场测量表明，沉积物中的还原脱氯作用在氯化化合物到达水柱之前就使其衰减。用小溪沉积物或现场培养的生物分离珠建立的微观模型将碳-碳氯化溶剂降解为氯化程度较低或无害的产物。定量PCR和16S rRNA基因扩增子测序揭示了小溪沉积物中已知脱氯剂生物标志物基因的丰度和空间分布，并表明多个降解碳-碳氯化烷烃和烯烃的脱氯剂种群共同存在于沉积物中。细菌和古菌序列的系统发育分类表明在空间（水平300米）尺度上分布相对均匀，但脱卤球菌属和脱卤杆菌属在较深沉积物中更为丰富，在那里每克沉积物分别测得5.7±0.4×10和5.4±0.9×10个16S rRNA基因拷贝。微生物学和水文地质学特征表明裂隙基岩-沉积物界面处的微生物过程对于防止污染物到达水柱至关重要，强调了这个关键区域环境对污染物衰减的相关性。
