Journal of Contaminant Hydrology ( IF 3.6 ) Pub Date : 2021-03-05 , DOI: 10.1016/j.jconhyd.2021.103794 Cecilie B Ottosen 1 , Poul L Bjerg 1 , Daniel Hunkeler 2 , Jeremy Zimmermann 2 , Nina Tuxen 3 , Dorte Harrekilde 4 , Lars Bennedsen 5 , Gareth Leonard 6 , Lærke Brabæk 1 , Inge Lise Kristensen 1 , Mette M Broholm 1
Over the last decade, activated carbon amendments have successfully been applied to retain chlorinated ethene subsurface contamination. The concept of this remediation technology is that activated carbon and bioamendments are injected into aquifer systems to enhance biodegradation. While the scientific basis of the technology is established, there is a need for methods to characterise and quantify the biodegradation at field scale. In this study, an integrated approach was applied to assess in situ biodegradation after the establishment of a cross sectional treatment zone in a TCE plume. The amendments were liquid activated carbon, hydrogen release donors and a Dehalococcoides containing culture. The integrated approach included spatial and temporal evaluations on flow and transport, redox conditions, contaminant concentrations, biomarker abundance and compound-specific stable isotopes. This is the first study applying isotopic and microbial techniques to assess field scale biodegradation enhanced by liquid activated carbon and bioamendments. The injection enhanced biodegradation from TCE to primarily cis-DCE. The Dehalococcoides abundances facilitated characterisation of critical zones with insufficient degradation and possible explanations. A conceptual model of isotopic data together with distribution and transport information improved process understanding; the degradation of TCE was insufficient to counteract the contaminant input by inflow into the treatment zone and desorption from the sediment. The integrated approach could be used to document and characterise the in situ degradation, and the isotopic and microbial data provided process understanding that could not have been gathered from conventional monitoring tools. However, quantification of degradation through isotope data was restricted for TCE due to isotope masking effects. The combination of various monitoring tools, applied frequently at high-resolution, with system understanding, was essential for the assessment of biodegradation in the complex, non-stationary system. Furthermore, the investigations revealed prospects for future research, which should focus on monitoring contaminant fate and microbial distribution on the sediment and the activated carbon.
中文翻译:
现场注入活性炭和生物修正物后评估氯化乙烯的降解:同位素和微生物分析的应用
在过去的十年中,活性炭修正剂已成功应用于保留氯化乙烯地下污染。该修复技术的概念是将活性炭和生物修正物注入含水层系统中,以增强生物降解作用。在建立该技术的科学基础的同时,需要一种方法来表征和量化田间规模的生物降解。在这项研究中,在TCE羽流中建立了横截面处理区域后,采用了一种综合方法来评估原位生物降解。修正案包括液态活性炭,氢释放供体和脱卤球菌。包含文化。综合方法包括对流动和运输,氧化还原条件,污染物浓度,生物标志物丰度和化合物特异性稳定同位素的时空评估。这是第一项应用同位素和微生物技术评估液体活性炭和生物修正剂增强的田间规模生物降解的研究。注射增强了从TCE到主要是顺式DCE的生物降解。该Dehalococcoides丰富的区域有助于对关键区域进行表征,而退化程度不足,并可能做出解释。同位素数据的概念模型以及分配和运输信息提高了对过程的了解;TCE的降解不足以抵消流入处理区和沉积物解吸的污染物输入。综合方法可用于现场记录和表征降解以及同位素和微生物数据提供了对过程的了解,而这是无法从常规监测工具中收集到的。但是,由于同位素掩盖效应,TCE限制了通过同位素数据进行降解的定量分析。各种监视工具的结合,经常以高分辨率应用,并具有系统的了解,对于评估复杂的,非平稳的系统中的生物降解至关重要。此外,调查揭示了未来研究的前景,该研究应侧重于监测污染物的命运以及沉积物和活性炭上的微生物分布。