Analytical Sciences

The Use of Noble Gas Isotopes in Detecting Methane Contamination of Groundwater in Shale Gas Development Areas: An Overview of Technology and Methods

Chunhui CAO,*,** Liwu LI,*,** Li DU,*,** Yuhui WANG,*,**,*** and Jian HE*,**

*Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
**Key Lab of Petroleum Resources, Gansu Province/Key Lab of Petroleum Resources Research, Institute of Geology and Geophysics, CAS, Lanzhou 730000, China
***College of Earth Science, University of the Chinese Academy of Sciences, Beijing 100049, China

Groundwater contamination by stray gas (mainly methane) in areas of shale-gas development has captured publics, political and scientific attention. However, the sources and potential mechanisms of groundwater contamination are still debated. Noble gases can provide useful information on fluid migration for discerning the scale, conditions, and physical mechanisms. In this study, details about analytical technology and theoretical approach of noble gases in tracing groundwater contaminations are presented. In addition, applications of noble-gases isotopes for determining contamination sources and potential pathways are explored and reviewed. Recent developments are discussed and highlighted with focusing on new utilities of noble-gas isotope parameters in evaluating groundwater contamination. Some usages of indicators (⁴He/²⁰Ne, CH₄/³⁶Ar, ⁴He/CH₄, etc.) are discussed through specific research articles. And it is a new trend to make comprehensive use of multiple geochemical parameters to determine the occurrence, source, and process of methane pollution in groundwater.

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