基于GasBench-IRMS的挥发性氯代烃碳氯同位素指纹特征分析

Isotopic Fingerprint Analysis of Carbon and Chlorine of Volatile Chlorinated Hydrocarbons Based on GasBench-IRMS

挥发性氯代烃(VCHs)是一种有毒工业原料。近年来,我国地下水VCHs污染日趋严重,而寻找地下水中VCHs的污染源是其污染防治的难点和关键。为了查明国内VCHs的碳、氯同位素组成特征,为地下水VCHs污染源解析提供二维同位素信息,利用一种单体碳、氯稳定同位素分析新技术,对国内3个厂商生产的4种VCHs试剂(TCE、PCE、DCM、CT)进行了测试,并与国外数据进行了对比。结果显示,国内VCHs试剂的δ13CPDB值在-51.09‰^-24.62‰之间,δ37ClSMOC值在-1.23‰~6.73‰之间。生产原料、生产工艺的差异使得不同厂商生产的VCHs试剂具有不同的碳、氯同位素组成,即"同位素指纹"特征,与单一同位素相比,二维同位素能够更好地表征这种特征,可为地下水中VCHs的来源解析提供更加可靠的依据。

Volatile chlorinated hydrocarbons （VCHs） are toxic industrial raw materials and the groundwa- ter pollution caused by VCHs has become more and more severe in China. Identifying the contamination sources of VCHs in groundwater is difficult and pivotal for groundwater pollution prevention and control- ling. In order to ascertain the characteristics of isotopic composition of VCHs to provide two-dimensional i- sotope information for sources analysis, the technique of stable carbon and chlorine isotopes analysis is ap- plied to test four chlorinated solvents （TCE, PCE, DCM, CT） in this study. The results showed that the isotope ratio for δ^13 C of different VCHs ranged from - 51. 09%o to - 24. 62%0, and from - 1.23%o to 6.73%0 for δ^37C1. The different raw materials and production processes of different manufacturers caused different composition characteristic of carbon and chlorine isotopes of VCHs, namely ＂isotope finger- print＂. Compared with single isotope, two-dimensional isotopes better revealed this characteristic and pro- vided higher reliable evidence for contamination sources analysis of VCHs in groundwater.