This thesis examines the spatial and temporal controls on groundwater chemistry in a fractured granitic environment. The research was conducted at the Grimsel Test Site, Switzerland (GTS), where draining and refilling of a nearby surface water reservoir induced microseismicity In the surrounding rocks. The GTS is a network of closely monitored tunnels and boreholes approx 300-500m below ground surface.Characterisation of background geochemical conditions over a two-year period consisted of a time series of physiochemical, major and minor dissolved ion chemistry, stable isotope analysis and dissolved organics, for boreholes spanning the length of the GTS. Results show poor fracture connectivity; physiochemical and dissolved ion chemistry are dominated by water-rock reactions between infiltrating meteoric waters and spatially varying host rock lithology.A new technique is developed that compares the differing signatures of dissolved organic compounds (2D-gas chromatographs) found within surface soils, river sediments and the lake, to those found in groundwater samples from the GTS. Results show that organic signatures are well-preserved and that different groundwater samples can be traced to different surface infiltration sites. This organic fingerprinting technique has the potential to be a powerful new tool for determining groundwater origins. Analysing the groundwater data over time, identified no changes to major or minor ion chemistry, but repeated drops in groundwater pH (1-3 units) were observed during periods of reservoir drainage.These drops were concurrent with nearby shallow (
| Date of Award | 2 Jun 2020 |
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| Original language | English |
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| Awarding Institution | - University Of Strathclyde
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| Sponsors | EPSRC (Engineering and Physical Sciences Research Council) |
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| Supervisor | Richard Lord (Supervisor) & Zoe Shipton (Supervisor) |
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