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Hydrogeological borehole investigations of groundwater ecology in the English Chalk

Maurice, Louise; Sorensen, James; Newbold, Lindsay; Read, Daniel; Allen, Debbie; Edwards, Francois; Bloomfield, John. 2012 Hydrogeological borehole investigations of groundwater ecology in the English Chalk. [Lecture] In: 21st International Conference on Subterranean Biology, Kosice, Slovakia, 2-7 Sep 2012. (Unpublished)

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Abstract/Summary

Estimating the numbers of stygobiotic invertebrates in aquifers, and understanding their distribution within boreholes and how this relates to their distribution within aquifers is important for understanding their environmental and habitat requirements, as well as the ecosystem services they might provide (e.g. their role in biogeochemical cycling and their potential as water quality indicators). Single borehole dilution tracer tests and borehole imaging were used to identify the location of major flowing fissures intercepted in two boreholes of approximately 100 m depth in the English Chalk. To investigate variability in invertebrate faunal communities and numbers with depth, 3 flowing fissures were selected in each borehole – one near the water table, one near the bottom of the borehole and one in the middle. A double packer system was used to isolate each of these fissures, enabling them to be directly sampled. At each interval, invertebrates were collected from 5000 litres of pumped water. Previous net hauling from above the bottom of boreholes and borehole CCTV images indicated that stygobiotic invertebrates live in the water column (particularly on the borehole walls) at substantial depths above the bottom. Fauna from the isolated packer intervals therefore comprise both animals living in the borehole water column within the isolated interval and those living within the water pumped from the aquifer. The 5000 litres of pumped water was divided into 13 samples in which fauna were collected separately to investigate how numbers and types of invertebrates relate to the amount of water that has already been pumped from the interval. In each interval, water chemistry and microbiological samples were collected at the beginning, middle, and end of pumping. Results indicate that different intervals contain different numbers and types of fauna, and have different microbial populations, and provide new information on the ecology of Chalk groundwaters.

Item Type: Publication - Conference Item (Lecture)
Programmes: BGS Programmes 2010 > Groundwater Science
CEH Topics & Objectives 2009 onwards > Water > WA Topic 2 - Ecohydrological Processes > WA - 2.4 - Quantify the importance of food web structure and trophic interactions ...
CEH Sections: Acreman
Additional Keywords: GroundwaterBGS, Groundwater, Groundwater ecology
Related URLs:
Date made live: 01 Oct 2012 12:39
URI: http://nora.nerc.ac.uk/id/eprint/19772

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