Degradation of 1,1,2,2-tetrachloro ethane and accumulation of vinyl chloride in wetland sediment microcosms and in situ porewater: biogeochemical controls and associations with microbial communities
Degradation of 1,1,2,2-tetrachloro ethane and accumulation of vinyl chloride in wetland sediment microcosms and in situ porewater: biogeochemical controls and associations with microbial communities
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DOI：
10.1016/j.jconhyd.2003.08.010
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发表时间：
2004-05-01
影响因子：
3.6
通讯作者：
Voytek, MA
中科院分区：
文献类型：
--
作者：
Lorah, MM;Voytek, MA
在实验室微生物实验中，采用同步地球化学和遗传分析的方法，对厌氧湿地沉积物中1,1,2,2-四氯乙烷（TeCA）和1,1,2-三氯乙烷（112TCA）的生物降解途径及其相关微生物群落进行了评价。将实验结果与湿地的原位孔隙水数据进行比较，以更好地了解排放到马里兰州阿伯丁试验场淡水潮汐湿地的氯化溶剂羽流中子产物分布的控制因素。两个地点的湿地沉积物构建的微环境中，TeCA的初始降解步骤（同时氢解生成112TCA和二氯消除生成1,2-二氯乙烯（12DCE））差异不大。然而，两个位点的显微观察显示，在随后的112TCA的二氯消除的相对优势上存在实质性差异。在最初含铁还原和随后同时含铁还原和产甲烷的微环境中，112TCA二氯消除的优势更大，导致氯乙烯（VC）产量约为孵育过程中仅产甲烷的微环境的两倍。VC产量高的微生物也表现出明显更快的VC降解。对湿地孔隙水中氧化还原敏感成分TeCA及其厌氧降解产物的现场测量也表明，在同时发生甲烷生成和铁还原的情况下，VC的产生和降解更大。分子指纹图谱表明，细菌种类[以Mn/1消化酶的198碱基对（bp）片段大小为代表]与112TCA二氯消除过程中产生VC有关，而甲烷球菌或甲烷杆菌家族的产甲烷菌（190和307 bp）与12DCE氢解过程中产生VC有关。利用醋酸盐的产甲烷菌似乎参与了VC的生物降解。在观察到VC降解的微环境中，唯一具有乙酰营养化成员的产甲烷菌群Methanosarcinaceae的相对丰度增加了一倍。此外，利用已知的dehalococoides和Desulfuromonas群中脱盐呼吸细菌的特异性引物进行分子分析表明，这些细菌存在于VC产量和降解最高的地点的微环境浆中。生物地球化学控制和参与TeCA降解的微生物群落的确定有助于更好地了解湿地生物降解率和子产物分布的异质性，从而提高制定修复和监测计划的能力。Elsevier B.V.出版
The biodegradation pathways of 1,1,2,2-tetracliloroethane (TeCA) and 1,1,2-trichloroethane (112TCA) and the associated microbial communities in anaerobic wetland sediments were evaluated Using Concurrent geochemical and genetic analyses over time in laboratory rnicrocosm experiments. Experimental results were compared to in situ porewater data in the wetland to better understand the factors controlling daughter product distributions in a chlorinated solvent plume discharging to a freshwater tidal wetland at Aberdeen Proving Ground, Maryland. Microcosms constructed with wetland sediment from two sites showed little difference in the initial degradation steps of TeCA, which included simultaneous hydrogenolysis to 112TCA and dichloroelimination to 1,2-dichloroethene (12DCE). The rnicrocosms from the two sites showed a substantial difference, however, in the relative dominance of subsequent dichloroelimination of 112TCA. A greater dominance of 112TCA dichloroelimination in microcosms constructed with sediment that was initially iron-reducing and subsequently simultaneously iron-reducing and methanogenic caused approximately twice as much vinyl chloride (VC) production as microcosms constructed with sediment that was methanogenic only throughout the incubation. The microcosms with higher VC production also showed substantially more rapid VC degradation. Field measurements of redox-sensitive constituents, TeCA, and its anaerobic degradation products along flowpaths in the wetland porewater also showed greater production and degradation of VC with concurrent methanogenesis and iron reduction.Molecular fingerprinting indicated that bacterial species [represented by a peak at a fragment size of 198 base pairs (bp) by Mn/1 digest] are associated with VC production from 112TCA dichloroelimination, whereas methanogens (190 and 307 bp) from the Methanococcales or Methanobacteriales family are associated with VC production from 12DCE hydrogenolysis. Acetate-utilizing methanogens (acetotrophs) appear to be involved in the biodegradation of VC. The relative abundance of Methanosarcinaceae, the only methanogen group with acetotrophic members, doubled in microcosms in which degradation of VC was observed. In addition, molecular analyses using primers specific for known dehalorespiring bacteria in the Dehalococcoides and Desulfuromonas groups showed the presence of these bacteria in microcosm slurry from the site that showed the highest VC production and degradation. Determination of biogeochemical controls and microbial consortia involved in TeCA degradation is leading to a better understanding of the heterogeneity in biodegradation rates and daughter product distribution in the wetland, improving capabilities for developing remediation and monitoring plans. Published by Elsevier B.V.