Use and application of CFC-11, CFC-12, CFC-113 and SF6 as environmental tracers of groundwater residence time : a review
Chambers, L.A. and Gooddy, D.C. and Binley, A.M. (2019) Use and application of CFC-11, CFC-12, CFC-113 and SF6 as environmental tracers of groundwater residence time : a review. Geoscience Frontiers, 10 (5). pp. 1643-1652. ISSN 1674-9871 (https://doi.org/10.1016/j.gsf.2018.02.017)
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Abstract
Groundwater residence time is a fundamental property of groundwater to understand important hydrogeological issues, such as deriving sustainable abstraction volumes, or, the evolution of groundwater quality. The anthropogenic trace gases chlorofluorocarbons (CFC-11, CFC-12 and CFC-113) and sulphur hexafluoride (SF6) are ideal in this regard because they have been released globally at known rates and become dissolved in groundwater following Henry's Law, integrating over large spatial (global) and temporal (decades) scales. The CFCs and SF6 are able to date groundwater up to ∼100 years old with the caveat of certain simplifying assumptions. However, the inversion of environmental tracer concentrations (CFCs and SF6) to derive groundwater age rests on the accurate determination of groundwater recharge parameters, namely temperature, elevation, salinity and excess air, in addition to resolving the potential for contamination, degradation and unsaturated zone effects. This review explores the fundamentals of CFC-11, CFC-12, CFC-113 and SF6 as environmental tracers of groundwater age and recommends complementary techniques throughout. Once this relatively simple and inexpensive technique has been used to determine initial concentrations at the recharge zone, setting the groundwater dating ‘clock’ to zero, this review then explores the meaning of groundwater ‘age’ in relation to measured environmental tracer concentrations. It is shown that the CFCs and SF6 may be applied to a wide-range of hydrogeological problems and suggests that environmental tracers are particularly powerful tools when integrated with numerical flow and transport models.
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Item type: Article ID code: 67904 Dates: DateEvent30 September 2019Published3 April 2018Published Online10 February 2018AcceptedSubjects: Technology > Engineering (General). Civil engineering (General) Department: Faculty of Engineering > Civil and Environmental Engineering Depositing user: Pure Administrator Date deposited: 16 May 2019 15:03 Last modified: 17 Sep 2024 06:33 Related URLs: URI: https://strathprints.strath.ac.uk/id/eprint/67904