Thermal groundwaters of the UK: geochemical indications of flow, vulnerability and possible threat to the shallow hydrosphere

Darling, W. George. 2019 Thermal groundwaters of the UK: geochemical indications of flow, vulnerability and possible threat to the shallow hydrosphere. Quarterly Journal of Engineering Geology and Hydrogeology, 52 (4). 557-562. https://doi.org/10.1144/qjegh2018-199

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Official URL: http://dx.doi.org/10.1144/qjegh2018-199

Abstract/Summary

Three types of thermal groundwater are known from the UK: warm springs (≤45°C), mine inflows (≤50°C) and deep basin waters (≤80°C). The warm springs depend on Carboniferous Limestone conveying water to sufficient depth (600–3000 m) to acquire a significantly higher temperature. The springs have residence times of a few thousand years, but also contain ≤5% modern groundwater. Their water quality is little threat to the environment; the main danger to the springs is construction activity near the emergences. Mine inflows significantly >20°C are known only from Cornish granite. High dissolved 4He has been interpreted as indicating long residence of the thermal component, but there is also modern water in the system, leading to uncertainty in the mean age. Unpredictable fracturing could hinder development of this resource, while the seawater-like salinity, combined with the presence of toxic metals, would require treatment or re-injection of the spent water to protect the near-surface environment. Mesozoic sedimentary basin brines reach temperatures >60°C, suitable for district heating. This resource is large and effectively invulnerable. However, these waters are generally more saline than seawater and, while disposal of spent brine could take place into the sea under favourable conditions, re-injection would be necessary for inland sites.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1144/qjegh2018-199
ISSN:	1470-9236
Additional Keywords:	GroundwaterBGS, Groundwater, Groundwater thermometry
Date made live:	28 Aug 2019 12:32 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/524916

Item Type:

Publication - Article

Digital Object Identifier (DOI):

https://doi.org/10.1144/qjegh2018-199

ISSN:

1470-9236

Additional Keywords:

GroundwaterBGS, Groundwater, Groundwater thermometry

Date made live:

28 Aug 2019 12:32 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/524916