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Download StatisticsBrekenfeld, Nicolai Salomon (2021). Hydrology and nutrient spiralling at the forest groundwater – surface-water interface. University of Birmingham. Ph.D.
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Brekenfeld2021PhD.pdf
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Abstract
Controls of stream and streambed metabolism were investigated at the reach and bedform-scale and methods to facilitate further understanding of these controls developed. Porewater concentrations of conservative and metabolically reactive (DOC, DIC, CH4) solutes along bedforms indicated that groundwater – surface-water mixing explained the majority of the spatial pattern of the reactive solutes. Therefore, our conceptual understanding of bedform-induced hyporheic exchange flow might need to be re-assessed. Hyporheic metabolism was only detected at a few locations with long porewater travel times. In addition, a small, low-cost conductance sensor was developed to measure high-resolution (temporal and spatial) porewater tracer breakthrough curves (BTC), without risking the induction of hyporheic flow. Based on the tracer BTCs, travel times during a storm event showed complex and hysteretic-like behaviour with discharge. During baseflow conditions, partly bedform-independent patterns of hyporheic travel times were observed, suggesting that small-scale streambed irregularities might be important. On a reach-scale, resazurin injections were conducted under contrasting discharge conditions along four consecutive reaches, with alternating flat and steep channel slopes. Metabolic transformation rates increased with discharge, but channel slope did not have a significant effect. Finally, a turbidity correction method for in situ fluorometers was developed, allowing their application during resazurin injections under variable discharge conditions.
| Type of Work: | Thesis (Doctorates > Ph.D.) | |||||||||
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| Award Type: | Doctorates > Ph.D. | |||||||||
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| Licence: | All rights reserved | |||||||||
| College/Faculty: | Colleges (2008 onwards) > College of Life & Environmental Sciences | |||||||||
| School or Department: | School of Geography, Earth and Environmental Sciences | |||||||||
| Funders: | Natural Environment Research Council | |||||||||
| Subjects: | G Geography. Anthropology. Recreation > GB Physical geography G Geography. Anthropology. Recreation > GE Environmental Sciences |
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| URI: | http://etheses.bham.ac.uk/id/eprint/11395 |
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