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CC BY V4.0, Open Access
Journal article
Chemical mixing in the bottom boundary layer of a eutrophic reservoir: The effects of internal seiching on nitrogen dynamics
Limnology and oceanography, Vol.60(5), pp.1642-1655
09/01/2015
Handle:
https://hdl.handle.net/2376/124118
Abstract
In lakes and reservoirs, the bottom boundary layer (BBL) mediates chemical fluxes between sediments and the overlying water column. At the internal shoreline, where the thermocline contacts the lakebed, the motions of internal waves can create fluctuating redox conditions and dynamic physical forcing that may support ecologically important reactions such as denitrification. We characterized physical and chemical dynamics within the internal shoreline of a eutrophic reservoir during the spring and early summer of 2012 (18 May to 18 July). An internal seiche was found to generate quasi-periodic fluctuations (periods about 12-24 h) in BBL stratification, temperature, and redox conditions. To examine possible implications for chemical mixing and microbial processing, differences between vertically offset, simultaneous BBL measurements of velocity, temperature, N-2, and N2O were made over 23 h. Vertical differences in BBL temperature, N-2, and N2O formed and collapsed during the wave cycle, with the largest differences occurring following the arrival of an internal bore. Through much of the wave cycle, chemical differences were explained by physical advection and mixing. However, chemical differences measured after bore arrival were not explained by advection, possibly owing to local production of N-2 and N2O. These results highlight the dynamic physical environment within the internal shoreline, and the potential of this zone to contribute to system wide denitrification and nitrous oxide production.
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Details
- Title
- Chemical mixing in the bottom boundary layer of a eutrophic reservoir: The effects of internal seiching on nitrogen dynamics
- Creators
- Bridget R Deemer - Washington State University VancouverStephen M Henderson - Washington State UniversityJohn A Harrison - Washington State University Vancouver
- Publication Details
- Limnology and oceanography, Vol.60(5), pp.1642-1655
- Academic Unit
- Environment, School of the (CAS); Harrison Research Group: Global Change and Watershed Biochemistry
- Publisher
- WILEY-BLACKWELL
- Number of pages
- 14
- Grant note
- USACE IWR 1045286; 135211; 0903714 / National Science Foundation (NSF)
- Identifiers
- 99900667907901842
- Language
- English
- Resource Type
- Journal article