Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
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Item The role of stream network nutrient uptake kinetics and groundwater exchange in modifying the timing, magnitude, and form of watershed export(Montana State University - Bozeman, College of Agriculture, 2012) Covino, Timothy Patrick; Chairperson, Graduate Committee: Brian L. McGlynn.; Brian L. McGlynn and Rebecca A. McNamara were co-authors of the article, 'Tracer additions for spiraling curve characterization (TASCC): quantifying stream nutrient uptake kinetics from ambient to saturation' in the journal 'Limnology and oceanography: methods' which is contained within this thesis.; Brian McGlynn and Rebecca McNamara were co-authors of the article, 'Land use / land cover and scale influences on in-stream nitrogen uptake kinetics' in the journal 'Journal of geophysical research - biogeosciences' which is contained within this thesis.; Brian McGlynn and John Mallard were co-authors of the article, 'Stream-groundwater exchange and hydrologic turnover at the network scale' in the journal 'Water resources research' which is contained within this thesis.; Brian McGlynn and Michelle Baker were co-authors of the article, 'Separating physical and biological nutrient retention and quantifying uptake kinetics from ambient to saturation in successive mountain stream reaches' in the journal 'Journal of geophysical research - biogeosciences' which is contained within this thesis.In this PhD dissertation research we sought to elucidate stream network biological and physical influences on hydrological and biogeochemical signatures observed along stream networks and at watershed outlets. Our research indicates that stream nutrient uptake and groundwater exchange processes can modify inputs from terrestrial sources and influence the timing and signature of watershed fluxes. We determined that stream nutrient uptake followed Michaelis-Menten kinetics across a broad range of systems and that land use / land cover change can alter stream nutrient uptake magnitudes. Additionally, we found that watershed structure and network geometry exerted strong controls over sourcewater contributions and streamwater compositions along stream networks and at watershed outlets. Combined, this PhD research suggests that uptake kinetics and hydrologic turnover exert strong controls over streamwater composition and sourcewater contributions, and that physical and biological contributions to total nutrient retention and the dynamic and concentration dependent nature of biological uptake combine to control solute and nutrient signatures. We suggest accurate assessment of total retention across stream reaches and stream networks requires quantification of physical retention and the concentration dependent nature of biological uptake, understanding necessary to help mitigate the potentially deleterious influences elevated nutrient export can have on downstream ecosystems.