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dc.contributor.advisorChairperson, Graduate Committee: Brian L. McGlynn.en
dc.contributor.authorGardner, Kristin Kiaraen
dc.contributor.otherBrian L. McGlynn was a co-author of the article, 'Seasonality in spatial variability and influence of land use/land cover and watershed characteristics on streamwater nitrogen export in a developing watershed in the Rocky Mountain West ' in the journal 'Water resources research' which is contained within this thesis.en
dc.contributor.otherBrian L. McGlynn was a co-author of the article, 'A multi-analysis approach to assess the spatio-temporal patterns of watershed response to localized inputs of nitrogen' in the journal 'Water resources research' which is contained within this thesis.en
dc.contributor.otherBrian L. McGlynn, and Lucy A. Marshall were co-authors of the article, 'Quantifying watershed sensitivity to spatially variable nitrogen loading and the relative importance of nitrogen retention mechanisms' in the journal 'Water resources research' which is contained within this thesis.en
dc.description.abstractAnthropogenic activity has greatly increased watershed export of bioavailable nitrogen. Escalating levels of bioavailable nitrogen can deteriorate aquatic ecosystems by promoting nuisance algae growth, depleting dissolved oxygen levels, altering biotic communities, and expediting eutrophication. Despite these potential detrimental impacts, there is notable lack of understanding of the linkages between anthropogenic nitrogen inputs and the spatial and seasonal heterogeneity of stream network concentrations and watershed nitrogen export. This dissertation research seeks to more accurately define these linkages by investigating the roles of landscape position and spatial distribution of anthropogenic nitrogen inputs on the magnitude and speciation of watershed nitrogen export and retention and how these roles vary seasonally across contrasting landscapes in a 212 km ² mountainous watershed in southwest Montana. Results indicate localized inputs of anthropogenic nitrogen occurring in watershed areas with quick transport times to streams had disproportionate effects on watershed nitrogen export compared to spatially distributed or localized inputs of nitrogen to areas with longer transport times. In lower elevation alluvial streams, these effects varied seasonally and were most evident during the dormant winter season by amplified nitrate peaks, elevated dissolved organic nitrogen:dissolved organic nitrogen (DIN:DON) ratios and lower dissolved organic carbon (DOC):total dissolved nitrogen (DOC:TDN). During the summer growing season, biologic uptake of nitrogen masked anthropogenic influences on watershed nitrogen export; however, endmember mixing analysis of nitrate isotopes revealed significant anthropogenic influence during the growing season, despite low nitrate concentrations and DIN:DON ratios. In contrast, streams draining alpine environments consisting of poorly developed, shallow soils and small riparian areas exhibited yearlong elevated nitrate concentrations compared to other sites, suggesting these areas were highly nitrogen enriched. Watershed modeling revealed the majority of watershed nitrogen retention occurred in the upland environment, most likely from biological uptake or lack of hydrologic connectivity. This work has critical implications for watershed management, which include: 1) developing flexible strategies that address varying landscape characteristics and nitrogen loading patterns across a watershed, 2) avoiding clustering nitrogen loading in areas with quick travel times to surface waters, 3) seasonal monitoring to accurately gauge watershed nitrogen saturation status, and 4) incorporating spatial relationships into streamwater nitrogen models.en
dc.publisherMontana State University - Bozeman, College of Agricultureen
dc.subject.lcshLand useen
dc.subject.lcshBayesian statistical decision theoryen
dc.titleSpatial and seasonal variability of watershed response to anthropogenic nitrogen loading in a mountainous watersheden
dc.rights.holderCopyright 2010 by Kristin Kiara Gardneren
thesis.catalog.ckey1750955en, Graduate Committee: Lucy Marshall; Duncan T. Patten; Wyatt Cross; Rick L. Lawrenceen Resources & Environmental Sciences.en
mus.relation.departmentLand Resources & Environmental Sciences.en_US

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