Lacroix Elsa, Brovelli Alessandro, Barry D A, Holliger Christof
Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Ecological Engineering Laboratory, Lausanne, Switzerland Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Enginerring (ENAC), Laboratory for Environmental Biotechnology, Lausanne, Switzerland.
Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Ecological Engineering Laboratory, Lausanne, Switzerland.
Appl Environ Microbiol. 2014 Jul;80(13):3858-67. doi: 10.1128/AEM.00493-14. Epub 2014 Apr 18.
In chloroethene-contaminated sites undergoing in situ bioremediation, groundwater acidification is a frequent problem in the source zone, and buffering strategies have to be implemented to maintain the pH in the neutral range. An alternative to conventional soluble buffers is silicate mineral particles as a long-term source of alkalinity. In previous studies, the buffering potentials of these minerals have been evaluated based on abiotic dissolution tests and geochemical modeling. In the present study, the buffering potentials of four silicate minerals (andradite, diopside, fayalite, and forsterite) were tested in batch cultures amended with tetrachloroethene (PCE) and inoculated with different organohalide-respiring consortia. Another objective of this study was to determine the influence of pH on the different steps of PCE dechlorination. The consortia showed significant differences in sensitivities toward acidic pH for the different dechlorination steps. Molecular analysis indicated that Dehalococcoides spp. that were present in all consortia were the most pH-sensitive organohalide-respiring guild members compared to Sulfurospirillum spp. and Dehalobacter spp. In batch cultures with silicate mineral particles as pH-buffering agents, all four minerals tested were able to maintain the pH in the appropriate range for reductive dechlorination of chloroethenes. However, complete dechlorination to ethene was observed only with forsterite, diopside, and fayalite. Dissolution of andradite increased the redox potential and did not allow dechlorination. With forsterite, diopside, and fayalite, dechlorination to ethene was observed but at much lower rates for the last two dechlorination steps than with the positive control. This indicated an inhibition effect of silicate minerals and/or their dissolution products on reductive dechlorination of cis-dichloroethene and vinyl chloride. Hence, despite the proven pH-buffering potential of silicate minerals, compatibility with the bacterial community involved in in situ bioremediation has to be carefully evaluated prior to their use for pH control at a specific site.
在进行原位生物修复的氯乙烯污染场地中，地下水酸化是源区常见的问题，必须实施缓冲策略以将pH维持在中性范围内。作为传统可溶性缓冲剂的替代品，硅酸盐矿物颗粒可作为长期的碱度来源。在先前的研究中，已基于非生物溶解试验和地球化学模型评估了这些矿物的缓冲潜力。在本研究中，在添加了四氯乙烯（PCE）并接种了不同有机卤化物呼吸菌群的分批培养物中测试了四种硅酸盐矿物（钙铁榴石、透辉石、铁橄榄石和镁橄榄石）的缓冲潜力。本研究的另一个目的是确定pH对PCE脱氯不同步骤的影响。这些菌群在不同脱氯步骤对酸性pH的敏感性上表现出显著差异。分子分析表明，与硫还原螺旋菌属和脱卤杆菌属相比，所有菌群中存在的脱卤球菌属是对pH最敏感的有机卤化物呼吸菌群成员。在以硅酸盐矿物颗粒作为pH缓冲剂的分批培养物中，所测试的所有四种矿物都能够将pH维持在氯乙烯还原脱氯的适当范围内。然而，仅在镁橄榄石、透辉石和铁橄榄石存在时观察到完全脱氯生成乙烯。钙铁榴石的溶解增加了氧化还原电位，不允许脱氯。对于镁橄榄石、透辉石和铁橄榄石，观察到了脱氯生成乙烯的现象，但最后两个脱氯步骤的速率比阳性对照低得多。这表明硅酸盐矿物和/或其溶解产物对顺式二氯乙烯和氯乙烯的还原脱氯有抑制作用。因此，尽管硅酸盐矿物已被证明具有pH缓冲潜力，但在将其用于特定场地的pH控制之前，必须仔细评估其与原位生物修复中涉及的细菌群落的兼容性。
