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Using boreholes as windows into groundwater ecosytems

Sorensen, James P.R.; Maurice, Louise; Edwards, Francois K.; Lapworth, Daniel J.; Read, Daniel S.; Allen, Debbie; Butcher, Andrew S.; Newbold, Lindsay K.; Townsend, Barry R.; Williams, Peter J.. 2013 Using boreholes as windows into groundwater ecosytems. Plos One, 8 (7), e70264. 10.1371/journal.pone.0070264

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Abstract/Summary

Groundwater ecosystems remain poorly understood yet may provide ecosystem services, make a unique contribution to biodiversity and contain useful bio-indicators of water quality. Little is known about ecosystem variability, the distribution of invertebrates within aquifers, or how representative boreholes are of aquifers. We addressed these issues using borehole imaging and single borehole dilution tests to identify three potential aquifer habitats (fractures, fissures or conduits) intercepted by two Chalk boreholes at different depths beneath the surface (34 to 98 m). These habitats were characterised by sampling the invertebrates, microbiology and hydrochemistry using a packer system to isolate them. Samples were taken with progressively increasing pumped volume to assess differences between borehole and aquifer communities. The study provides a new conceptual framework to infer the origin of water, invertebrates and microbes sampled from boreholes. It demonstrates that pumping 5 m3 at 0.4–1.8 l/sec was sufficient to entrain invertebrates from five to tens of metres into the aquifer during these packer tests. Invertebrates and bacteria were more abundant in the boreholes than in the aquifer, with associated water chemistry variations indicating that boreholes act as sites of enhanced biogeochemical cycling. There was some variability in invertebrate abundance and bacterial community structure between habitats, indicating ecological heterogeneity within the aquifer. However, invertebrates were captured in all aquifer samples, and bacterial abundance, major ion chemistry and dissolved oxygen remained similar. Therefore the study demonstrates that in the Chalk, ecosystems comprising bacteria and invertebrates extend from around the water table to 70 m below it. Hydrogeological techniques provide excellent scope for tackling outstanding questions in groundwater ecology, provided an appropriate conceptual hydrogeological understanding is applied.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1371/journal.pone.0070264
CEH Sections: Acreman
Boorman (to September 2014)
ISSN: 1932-6203
Additional Information. Not used in RCUK Gateway to Research.: This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Additional Keywords: GroundwaterBGS, Groundwater, Groundwater ecology
NORA Subject Terms: Hydrology
Related URLs:
Date made live: 09 Aug 2013 10:33 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/502910

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