2023 Early Hearing Detection & Intervention Conference
March 5-7, 2023 • Cincinnati, OH
5/20/2019 | 11:15 AM - 11:30 AM | DENITRIFICATION IN A LARGE RIVER NETWORK OF MIXED LAND USE—A STRUCTURAL EQUATION MODELING ANALYSIS | 250 AB
DENITRIFICATION IN A LARGE RIVER NETWORK OF MIXED LAND USE—A STRUCTURAL EQUATION MODELING ANALYSIS
Land-use patterns and instream biogeochemistry processes affect loading rates of nitrogen from tributary rivers to the Great Lakes. Generally, loading rates are reasonably well documented, but land-use patterns and instream conditions that create biogeochemical hot spots for nitrogen processing and loss are less well understood on a broad scale. We evaluated instream nitrogen loss through measures of sediment denitrification and denitrification enzyme assay (DEA) rates at 110 sites distributed throughout the Fox River basin (16,400-km2 watershed) at baseflow conditions in August 2016. We developed a Structural Equation Model (SEM) to describe land use, sediment properties, and water column nitrogen availability that drive instream denitrification and DEA rates at base flow conditions. In August 2017, we resampled 50 of the 110 sites to validate the SEM model under baseflow conditions and in 2018 (May, June, August) we resampled 28 sites to assess the model extension to other flow conditions. Extension of the model to subsequent years and other flow conditions will be presented. The results provide additional information on the suite of factors that likely constrain instream biogeochemical cycling of nitrogen across a large river network
- Nutrients
- Nitrogen
- Non-point Source
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Presenters/Authors
Lynn Bartsch
(), U.S. Geological Survey, lbartsch@usgs.gov;
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Rebecca Kreiling
(), U.S. Geological Survey, rkreiling@usgs.gov;
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Victoria Christensen
(), U.S. Geological Survey, vglen@usgs.gov;
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