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Discriminating between Biological and hydrological Controls of hyporheic denitrification across a land use gradient in nine Western Wyoming streams

by Myers, Andrew Kenneth

Abstract (Summary)
I studied nine streams near Grand Teton National Park, Wyoming, covering a land use gradient (urban, agricultural, and forested) to assess influences of land use on denitrification rates and hyporheic exchange. I hypothesized denitrification in the hyporheic zone is governed by availability of chemical substrates and hydrologic transport. I tested this hypothesis by coupling measurements of denitrification potentials in hyporheic sediments with a 2-storage zone solute transport model. Denitrification potentials were lowest on average in hyporheic sediments from forested streams and highest from agricultural streams. Modeling results suggest, on average, agricultural sites are transport-limited by having the slowest exchange rate with hyporheic zone and longest transport before entering storage. Land use influences the capacity for hyporheic denitrification in two ways 1) agricultural and urban practices supply substrates that build the microbial potential for denitrification and 2) agricultural and urban activities alter channel form and substrates, limiting hyporheic exchange.
Bibliographical Information:

Advisor:

School:Utah State University

School Location:USA - Utah

Source Type:Master's Thesis

Keywords:transient storage linx hyporheic zone solute transport model denitrification land use

ISBN:

Date of Publication:05/01/2008

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