Assessing chlorinated ethene degradation in a large scale contaminant plume by dual carbon-chlorine isotope analysis and quantitative PCR
Assessing chlorinated ethene degradation in a large scale contaminant plume by dual carbon-chlorine isotope analysis and quantitative PCR
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DOI：
10.1016/j.jconhyd.2010.09.009
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发表时间：
2011-01-25
影响因子：
3.6
通讯作者：
Bjerg, Poul L.
中科院分区：
文献类型：
--
作者：
Hunkeler, Daniel;Abe, Yumiko;Bjerg, Poul L.
采用新的方法，包括化合物特异性碳和氯同位素分析以及针对Dehaloccocoides sp.和vcrA基因的定量实时聚合酶链反应（qPCR）方法，研究了丹麦沙质含水层中源自四氯乙烯（PCE）源的大量污染物羽流中氯化乙烯的命运。根据SO(4)（2-）中溶解的氧化还原敏感化合物和硫同位素的浓度，对氧化还原条件进行了表征。在源区下降的前400 m，烟柱被限制在含水层的上部20 m。由于地下水流向分散，垂直方向进一步变宽，深度可达50 m。随着烟羽向下倾斜并远离源头，O(2)和NO(3)（-）下降到检测水平以下，而溶解的Fe（2+）和SO(4)（2-）增加到检测水平以上，这可能是由于黄铁矿氧化引起的，这一点得到了SOY贫硫同位素特征的证实。在同一区域，PCE和三氯乙烯（TCE）消失，顺式1,2-二氯乙烯（cDCE）成为主要的氯化乙烯。cDCE的形成和稳定碳同位素数据表明，PCE和TCE可能是通过还原脱氯而不是黄铁矿的非生物还原转化的。TCE和cDCE表现出典型的还原性脱氯的碳同位素趋势，在子产物中（13）C的初始耗尽，然后随着降解的进行（13）C的富集。在源下梯度1000 m处，cDCE是主要的氯化乙烯，并已达到源δ (13)C值，证实cDCE不受非生物或生物降解的影响。进一步下降（高达1900米），cDCE在（13）C中富集高达8%，表明其进一步转化，而氯乙烯（VC）浓度仍然很低(
The fate of chlorinated ethenes in a large contaminant plume originating from a tetrachloroethene (PCE) source in a sandy aquifer in Denmark was investigated using novel methods including compound-specific carbon and chlorine isotope analysis and quantitative real-time polymerase chain reaction (qPCR) methods targeting Dehaloccocoides sp. and vcrA genes. Redox conditions were characterized as well based on concentrations of dissolved redox sensitive compounds and sulfur isotopes in SO(4)(2-).In the first 400 m downgradient of the source, the plume was confined to the upper 20 m of the aquifer. Further downgradient it widened in vertical direction due to diverging groundwater flow reaching a depth of up to 50 m. As the plume dipped downward and moved away from the source, O(2) and NO(3)(-) decreased to below detection levels, while dissolved Fe(2+) and SO(4)(2-) increased above detectable concentrations, likely due to pyrite oxidation as confirmed by the depleted sulfur isotope signature of SOY. In the same zone, PCE and trichloroethene (TCE) disappeared and cis-1,2-dichloroethene (cDCE) became the dominant chlorinated ethene. PCE and TCE were likely transformed by reductive dechlorination rather than abiotic reduction by pyrite as indicated by the formation of cDCE and stable carbon isotope data. TCE and cDCE showed carbon isotope trends typical for reductive dechlorination with an initial depletion of (13)C in the daughter products followed by an enrichment of (13)C as degradation proceeded. At 1000 m downgradient of the source, cDCE was the dominant chlorinated ethene and had reached the source delta(13)C value confirming that cDCE was not affected by abiotic or biotic degradation.Further downgradient (up to 1900 m), cDCE became enriched in (13)C by up to 8% demonstrating its further transformation while vinylchloride (VC) concentrations remained low (