Chlorofluorocarbons

Plummer, L. Niel; Busenberg, Eurybiades

doi:10.1007/978-1-4615-4557-6_15

Cited by 119 publications

(166 citation statements)

References 88 publications

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“…Their use in this role depends critically on the input function, i.e. the atmospheric mixing ratio over time for the individual gases (Plummer and Busenberg, 1999). Observations by the worldwide network of atmospheric monitoring stations (largely based on the five long-term ALE/GAGE/AGAGE collection stations -see http://agage.eas.gatech.edu) indicate that the gases are well-mixed in the atmosphere (Maiss and Brenninkmeier, 1998), and therefore a single input function for each gas should in theory suffice for groundwater investigations in the northern hemisphere (there is a slight lag in the southern hemisphere inputs).…”

Section: Introductionmentioning

confidence: 99%

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

Darling

Gooddy

2007

Science of The Total Environment

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Chlorofluorocarbons (CFCs) and sulphur hexafluoride (SF 6 ) are increasingly being used to date recent groundwater components. While these trace gases are generally well-mixed in the atmosphere, there is evidence that local atmospheric excesses (LAEs) exist in some areas of the world, primarily associated with urbanisation and thereby affecting the interpretation of data derived from groundwater studies. Since the soil acts as a low-pass filter for atmospheric trace gas fluctuations, the possible existence of LAEs in the UK has been investigated by measuring the mixing ratios of CFC-11, CFC-12 and SF 6 in soil gases from sites within the UK's two largest cities (London and Birmingham) and a smaller urban area, Bristol. While there was some evidence of excesses, most of the measured mixing ratios for CFC-12 and SF 6 were less than 10% above the current northern hemisphere atmospheric mixing ratio (NH-AMR) values. CFC-11 was more variable, but usually less than 20% above the NH-AMR value. Surface waters were also investigated as possible short-term archives of trace-gas information but were much less consistent in performance.While the lack of significant current LAEs for SF 6 can justifiably be extrapolated to past decades, different global emission patterns mean that this is much harder to justify for the CFCs. Nevertheless, in the absence of further evidence it is concluded that the use of CFC and SF 6 input functions based on the NH-AMR curves is generally justified for the UK, with the proviso that urban groundwater investigations should not rely on the CFCs as age tracers.

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Section: Introductionmentioning

confidence: 99%

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

Darling

Gooddy

2007

Science of The Total Environment

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“…Sulfur hexafluoride (SF 6 ) is manufactured for use in electrical components but also has natural sources in volcanic fluids and fluid inclusions in rocks (Busenberg and Plummer, 1997). Both dating methods work by comparing concentrations in a water sample with (Plummer and Busenberg, 1999;Busenberg and Plummer, 2000). The analytical methods are extremely sensitive and measure trace concentrations several orders of magnitude lower than reporting levels for other organic-compound methods used in this study.…”

Section: Sampling and Analytical Methodsmentioning

confidence: 99%

Ground-Water Quality and its Relation to Land Use on Oahu, Hawaii, 2000-01

Hunt¹

2003

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Distribution of volatile organic compound mixtures in ground water.Front cover: Island of Oahu as seen by Landsat satellite (cloud-free mosaic by the Pacific Disaster Center) and showing distribution of volatile organic compound mixtures in sampled public-supply and monitoring wells, as seen in figure number 32. Ground-Water Quality and its Relation to Land FOREWORDThe U.S. Geological Survey (USGS) is committed to providing the Nation with accurate and timely scientific information that helps enhance and protect the overall quality of life and that facilitates effective management of water, biological, energy, and mineral resources (http://www.usgs.gov/). Information on the quality of the Nation's water resources is critical to assuring the long-term availability of water that is safe for drinking and recreation and suitable for industry, irrigation, and habitat for fish and wildlife. Population growth and increasing demands for multiple water uses make water availability, now measured in terms of quantity and quality, even more essential to the long-term sustainability of our communities and ecosystems.The USGS implemented the National Water-Quality Assessment (NAWQA) Program in 1991 to support national, regional, and local information needs and decisions related to water-quality management and policy (http://water.usgs.gov/ nawqa). Shaped by and coordinated with ongoing efforts of other Federal, State, and local agencies, the NAWQA Program is designed to answer: What is the condition of our Nation's streams and ground water? How are the conditions changing over time? How do natural features and human activities affect the quality of streams and ground water, and where are those effects most pronounced? By combining information on water chemistry, physical characteristics, stream habitat, and aquatic life, the NAWQA Program aims to provide science-based insights for current and emerging water issues and priorities.From 1991-2001, the NAWQA Program completed interdisciplinary assessments in 51 of the Nation's major river basins and aquifer systems, referred to as Study Units (http://water.usgs.gov/nawqa/studyu.html). Baseline conditions were established for comparison to future assessments, and long-term monitoring was initiated in many of the basins. During the next decade, 42 of the 51 Study Units will be reassessed so that 10 years of comparable monitoring data will be available to determine trends at many of the Nation's streams and aquifers. The next 10 years of study also will fill in critical gaps in characterizing water-quality conditions, enhance understanding of factors that affect water quality, and establish links between sources of contaminants, the transport of those contaminants through the hydrologic system, and the potential effects of contaminants on humans and aquatic ecosystems.The USGS aims to disseminate credible, timely, and relevant science information to inform practical and effective waterresource management and strategies that protect and restore water quality. We hope this NAWQA publ...

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“…The use of the chlorofluorocarbons CFC-11 (CCl 3 F), CFC-12 (CCl 2 F 2 ) and CFC-113 (C 2 Cl 3 F 3 ) and sulphur hexafluoride (SF 6 ) as age tracers is based on the known rise of their concentrations in the atmosphere over the past half-century, the observation that they are well-mixed in the atmosphere, and the assumption that they dissolve in water according to their Henry's Law solubilities at the recharge temperature (Plummer and Busenberg 1999).…”

Section: Trace Gasesmentioning

confidence: 99%

Using environmental tracers to assess the extent of river–groundwater interaction in a quarried area of the English Chalk

Darling

Gooddy

Riches

et al. 2010

Applied Geochemistry

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The Swanscombe area of Kent, SE England represents a typical example of a heavily quarried Chalk area currently undergoing re-development. Because the Chalk is also an important aquifer, a good understanding of groundwater movement is required if environmental impacts are to be minimised and the water resource maximised. In particular, the nature of the relationship between the River Darent and groundwater in the Swanscombe Chalk Block requires better characterisation. Here, 'environmental tracers' in the form of ambient concentrations of stable isotopes, CFCs (chlorofluorocarbons), SF 6 (sulphur hexafluoride) and tritium ( 3 H) are used to investigate this and other aspects of groundwater movement in the vicinity of the quarries. Stable isotopic contrasts indicate little evidence for widespread river infiltration to the regional Chalk aquifer, although stable isotope and tritium data suggest that 20-35% of the abstraction by river-valley public water supply boreholes may be derived from the river. The CFCs, while present at above-modern concentrations in almost all groundwaters, can be used as tracers, indicating basically S-N flowpaths in the area south of the quarries, though sub-karstic conduits associated with areas of Palaeogene cover add a level of uncertainty at the local scale. Simple piston flow residence times based on SF 6 range from 1 to 17 years, but the data are probably better interpreted in terms of mixing between varying amounts of modern recharge derived from the south and deeper stored groundwater. The information gained from environmental tracers can therefore contribute to effective resource management.

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Chlorofluorocarbons

Cited by 119 publications

References 88 publications

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

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

Ground-Water Quality and its Relation to Land Use on Oahu, Hawaii, 2000-01

Using environmental tracers to assess the extent of river–groundwater interaction in a quarried area of the English Chalk

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