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

Abstract

Groundwater contamination by stray gas (mainly methane) in areas of shale gas development has captured the publics', political and scientific attention. However, sources and potential mechanisms of groundwater contamination are still debated. Noble gases can provide useful information on fluid migration for discerning 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 focusing on new utilities of noble gas isotope parameters in evaluating groundwater contamination. Some usages of indicators (4 He/ 20 Ne, CH 4 / 36 Ar, 4 He/CH 4 , 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.