Identifying trends in groundwater quality using residence time indicators: an example from the Permian aquifer of Dumfries, Scotland

MacDonald, Alan; Darling, W.G.; Ball, Derek; Oster, H.

doi:10.1007/s10040-003-0275-3

Cited by 50 publications

(33 citation statements)

References 17 publications

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“…While the reasons for this remain speculative, it is consistent with the observation that CFC-11 is usually the least consistent of the three in groundwater studies (e.g. Dunkle et al, 1993;MacDonald et al, 2003). Consideration of prevailing wind direction and industrial history leads to the empirical prediction that LAEs should be developed least in Bristol and most in Birmingham.…”

Section: General Observationssupporting

confidence: 77%

“…Nevertheless, in the absence of evidence to the contrary, it is proposed here that the default position for the wider UK should be the use of the NH-AMR curves for the CFCs also. This approach has for example been tested with some success in rural areas of England and Scotland (MacDonald et al, 2003). This is not to say that contamination never occurs in rural groundwaters, but it can often be traced to subsurface point sources such as landfills or factories, or to interaction with surface waters.…”

Section: Implications For Non-urban Groundwater Studiesmentioning

confidence: 99%

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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: General Observationssupporting

confidence: 77%

Section: Implications For Non-urban Groundwater Studiesmentioning

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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“…Previous studies have made comparisons between groundwater age and nitrate concentrations (Johnston et al, 1998;MacDonald et al, 2003) and found reasonable linear correlations. Figure 10 shows a cross plot of nitrate-nitrogen against the date of application, that is, the date has been corrected for transit through the unsaturated zone based on the model of Cook and Solomon (1995) (see Figure 4), although as previously stated this transit time is roughly the same as for any conservative solute transport through the unsaturated zone.…”

Section: Discussionmentioning

confidence: 75%

“…Cook et al, 1995;Johnston et al, 1998;Plummer et al, 2001;Rademacher et al, 2003) and in Europe (Oster et al, 1996;Bauer et al, 2001;MacDonald et al, 2003;Bockgård et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Using chlorofluorocarbons (CFCs) and sulphur hexafluoride (SF6) to characterise groundwater movement and residence time in a lowland Chalk catchment

Gooddy

Darling

Abesser

et al. 2006

Journal of Hydrology

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123

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Chlorofluorocarbons (CFCs) and sulphur hexafluoride (SF 6 ) provide a technique for dating groundwater up to 50 years old. When used together, CFCs and SF 6 can help to resolve the extent to which groundwater mixing occurs, and therefore provide indicators of the likely groundwater flow mechanisms. Modelling shows that diffusive retardation of these tracers is likely to be low owing to the high moisture content of the chalk unsaturated zone. Data collected from groundwater and surface water from a lowland Chalk catchment in southern England suggest that groundwater movement can be divided into three regimes: on the interfluves of the catchment, 'piston' flow dominates with a bulk groundwater age of several decades; at the valley bottom, there is mixing between shallow groundwater and stream water; and in an intermediate zone between the top and the bottom of the valley there is approximately 3:1 mixing between new and pre-tracer groundwaters. A conceptual model of groundwater movement has been developed to describe the catchment processes. Surface water-groundwater interactions are found to take place down to depths in excess of 10 metres bgl.The nitrate found at the greatest depth are thought to originate from the mid 1950s.

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“…Residence times have been determined using a range of indicators such as Kr, Cl or C radio-isotopes (Edmunds and Smedley, 2000;Shand et al, 2007) or chlorofluorocarbons (CFCs) or SF6 MacDonald et al, 2003).…”

Section: Persistence In the Groundwater Environmentmentioning

confidence: 99%

Transformation Products of Emerging Organic Compounds as Future Groundwater and Drinking Water Contaminants

Stuart¹,

Lapworth²

2014

Transformation Products of Emerging Contaminants in the Environment

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Identifying trends in groundwater quality using residence time indicators: an example from the Permian aquifer of Dumfries, Scotland

Cited by 50 publications

References 17 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

Using chlorofluorocarbons (CFCs) and sulphur hexafluoride (SF6) to characterise groundwater movement and residence time in a lowland Chalk catchment

Transformation Products of Emerging Organic Compounds as Future Groundwater and Drinking Water Contaminants

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