Show simple item record

dc.contributor.authorClilverd, Hannah M.
dc.date.accessioned2015-06-15T21:40:49Z
dc.date.available2015-06-15T21:40:49Z
dc.date.issued2007-05
dc.identifier.urihttp://hdl.handle.net/11122/5557
dc.descriptionThesis (M.S.) University of Alaska Fairbanks, 2007en_US
dc.description.abstractThe aquatic-terrestrial interface is an active site of biogeochemical transformation, regulating the flux of nutrients between ecosystems. I addressed the hydrologic controls on nitrogen biogeochemistry in the hyporheic zone of a glacially fed river. I measured hyporheic concentrations of solutes and gases along subsurface flowpaths on two islands. Denitrification was quantified using an in situ [delta]⁻¹⁵NO₃⁻ push-pull technique. Nitrate concentration was consistently greater in river than in hyporheic water. Denitrification ranged from 1.9 - 29.4 mgN kg sediment⁻¹ day⁻¹. Hotspots of methane partial pressure, averaging 50,000 ppmv, were found in densely vegetated areas with low oxygen concentration (<0.5 mgO₂ L⁻¹). Hyporheic flow was an important source of nitrogen to microbes and vegetation, transporting on average 0.41 gNO₃⁻-N m⁻² day⁻¹ through surface sediments. Results suggest that denitrification is a major sink for river nitrate in boreal forest floodplain soils, particularly at the river-sediment interface. The stability of the river hydro graph is a key factor regulating anaerobic metabolism in the hyporheic zone.en_US
dc.description.tableofcontents1. Introduction -- The hyporheic zone -- Biogeochemical transformations along hyporheic flowpaths -- Nitrogen supply in riparian zones -- Hydrology and biogeochemistry of the Tanana River at Bonanza Creek LTER -- Literature cited -- 2. Surface-subsurface hydrologic exchange and nutrient dynamics in the hyporheic zone of the Tanana River in Interior Alaska -- Literature cited -- 2. Surface-subsurface hydrologic exchange and nutrient dynamics in the hyporheic zone of the Tanana River in Interior Alaska -- Abstract -- Introduction -- Methods -- Study site -- Study design -- Sampling and analytical techniques -- In situ denitrification -- Push-pull calculations -- Data analysis -- Analysis of subsurface hydrology and capillary rise -- Long term patterns in climate and river hydrology -- Results -- Climate and river hydrology -- Spatial patterns in hyporheic chemistry -- Subsurface hydrology and nitrogen losses -- Temporal variation in hyporheic chemistry -- Discussion -- Hyporheic zone hydrology and nitrogen transformation -- Subsurface methane and carbon dioxide -- Climate, river hydrology and hyporheic chemistry -- Acknowledgements -- Literature cited -- 3. Conclusions -- Literature cited.en_US
dc.language.isoen_USen_US
dc.titleSurface-subsurface hydrologic exchange and nutrient dynamics in the hyporheic zone of the Tanana Riveren_US
dc.typeThesisen_US
dc.type.degreemsen_US
dc.identifier.departmentDepartment of Biology and Wildlifeen_US
refterms.dateFOA2020-03-05T10:10:19Z


Files in this item

Thumbnail
Name:
Clilverd_H_2007.pdf
Size:
2.395Mb
Format:
PDF

This item appears in the following Collection(s)

  • Biological Sciences
    Includes WIldlife Biology and other Biological Sciences. For Marine Biology see the Marine Sciences collection.

Show simple item record