Use of chlorofluorocarbons (CCl₃F and CCl₂F₂) as hydrologic tracers and age‐dating tools: The alluvium and terrace system of central Oklahoma

Abstract

The use of Chlorofluorocarbons (CFCs) as an age‐dating tool and tracer in shallow groundwaters has been investigated. New methodology for field sampling and preserving groundwaters containing parts per trillion concentrations of the CFCs, F‐1l and F‐12, is presented. Samples are analyzed by purge‐and‐trap gas chromatography with an electron capture detector. Physical and chemical processes that can alter natural concentrations (air‐water equilibrium) of CFCs were investigated to assess dating uncertainties. CFC model recharge ages appear to be defined within 2 years under optimum conditions. The method was applied to central Oklahoma to demonstrate the usefulness of CFCs as (1) an age‐dating tool of shallow groundwaters, (2) a tracer of sewage effluent in surface and shallow groundwaters, and (3) a tracer of shallow groundwater. Results of dating indicate two primary recharge periods in central Oklahoma over the past 45 years that correspond to the wet periods 1945–1960 and 1967–1975.

Impact of excessive groundwater pumping on rejuvenation processes in the Bandung basin (Indonesia) as determined by hydrogeochemistry and modeling

“…Chlorofluorocarbons (CFCs) are useful tools for tracing and dating groundwater after 1945 (Busenberg and Plummer 1992;Plummer et al 2000Plummer et al , 2001 because the release of CFCs into the atmosphere started after the 1940s (USGS 2010). Therefore, CFCs were employed as a marker for young groundwater; consequently, if the samples possess some dissolved CFCs, it means a fraction of the water had been recharged since 1940.…”

Assessing the applicability of global CFC and SF6 input functions to groundwater dating in the UK

“…Chlorofluorocarbons (CFCs) and sulphur hexafluoride (SF 6 ) are increasingly being used to date recent groundwater components (Busenberg and Plummer, 1992;Cook et al 1996;Oster et al, 1996: Busenberg andPlummer, 2000). Their use in this role depends critically on the input function, i.e.…”

Hydrogeology, ground-water quality, and source of ground water causing water-quality changes in the Davis well field at Memphis, Tennessee

“…Microbial degradation of both CFC-11 and CFC-12 has been documented in anaerobic methanogenic soils and sediments, but no degradation has been observed in aerobic aquifer systems (Lovely and Woodward, 1992). The rate of microbial degradation of CFC's has been shown to decrease with increasing fluorine content (Busenberg and Plummer, 1992); therefore, CFC-11 (CCI 3 F) would be degraded more rapidly than CFC-12 (CC1 2 F 2 ). CFC analyses of samples from well M414 could indicate degradation of CFC-11 and persistence of CFC-12, and data from well M419 could indicate degradation of both CFC's in an anaerobic aquifer.…”

“…Atmospheric concentrations of CFC's have steadily increased since their initial production. CFC concentrations have been measured in the atmosphere since the mid-1970's and, prior to that, concentrations were estimated from production data (Busenberg and Plummer, 1992). These data and the aqueous solubility of CFC's form the basis for the use of CFC's as hydrologic tracers and age-dating tools (Busenberg and Plummer, 1992).…”