A technique for carbon and chlorine isotope analyses of chlorinated aliphatic hydrocarbons in groundwater
A technique for carbon and chlorine isotope analyses of chlorinated aliphatic hydrocarbons in groundwater
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DOI：
10.1007/s12583-013-0328-z
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发表时间：
2013-04
影响因子：
3.3
通讯作者：
Y. Gan;Tingting Yu;Ai-guo Zhou;Yunde Liu;Cun-fu Liu
中科院分区：
文献类型：
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作者：
Y. Gan;Tingting Yu;Ai-guo Zhou;Yunde Liu;Cun-fu Liu
氯化脂肪烃（CAHs）是地下水中的重要污染物，其碳和氯同位素组成稳定。以前发表的方法分析灵敏度低，或者对低浓度CAHs的天然样品不理想。本方法可同时对溶解CAHs的微摩尔浓度进行碳、氯同位素分析。它是通过提取并将CAHs转化为二氧化碳和氯甲烷（CH3Cl）来实现的。特别地，GasBench II采用连续流动界面萃取CH3Cl，用于在线氯同位素分析。因此，通过消除离线制备和分离CH3Cl的过程，大大提高了同位素分析的效率。样品尺寸要求降低到约11 μmol氯。TCE溶剂和水样的δ13C和δ37Cl的标准差分别优于0.30‰和0.20‰（1σ）。碳氯同位素分析可以作为研究地下水中有机污染物来源及其在含水层中的行为的重要工具。该方法原则上适用于生产厂家的产品，也适用于污染场地的样品，将在我们的实地研究中进行验证。
Chlorinated aliphatic hydrocarbons (CAHs), significant contaminants in groundwater, can be characterized by stable isotopic compositions of carbon and chlorine. Previously published methods were of low analytical sensitivity or not ideal for natural samples with low concentrations of CAHs. This method is reported here to carry out simultaneously carbon and chlorine isotope analyses for micromolar concentrations of dissolved CAHs. It was executed by extracting and converting CAHs to carbon dioxide and methyl chloride (CH3Cl). Specially, a continuous-flow interface GasBench II was used to extract CH3Cl for online chlorine isotope analysis. As a result, it greatly enhances the efficiency for isotope analysis by eliminating procedures for offline CH3Cl preparation and separation. Sample size requirement was reduced to approximately 11 μmol chlorine. The standard deviation of δ13C and δ37Cl for both TCE solvents and water samples was better than 0.30‰ and 0.20‰ (1σ), respectively. Carbon and chlorine isotope analyses can be used as an important tool to study the sources of organic contaminants in groundwater and their behaviors in the aquifers. The method is applicable to manufacturers’ products as well as a sample from a polluted site in principle, which will be validated in our field studies.