2022 Early Hearing Detection & Intervention Virtual Conference

March 13 - 15, 2022

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6/05/2017  |   3:30 PM - 3:45 PM   |  PARTITIONING THE ROLE OF BIOLOGY AND SEASONALITY IN DIEL SOLUTE SIGNALS FROM TWO RIVER NETWORKS OF CONTRASTING LAND USE   |  306A

PARTITIONING THE ROLE OF BIOLOGY AND SEASONALITY IN DIEL SOLUTE SIGNALS FROM TWO RIVER NETWORKS OF CONTRASTING LAND USE

Quantifying the relative role of nitrogen (N) uptake processes at the stream network scale is challenging, but empirical data are needed to refine models of N transport and retention in lotic ecosystems. Recently, open-channel methods have facilitated measurements of reach-scale metabolism and denitrification, allowing for partitioning of biological N removal into assimilatory vs. dissimilatory processes. We compared diel signals of dissolved solutes and gasses across seasons in a tributary and mainstem reach in two watersheds of contrasting land use: the Manistee (MI; 83% forested) and Tippecanoe (IN; 82% agricultural). We estimated metabolism and assimilatory N uptake using continuous measurements of dissolved oxygen and NO3-N. During these 36-hour sampling campaigns, we collected dissolved N2 samples to estimate reach-scale denitrification using membrane-inlet mass spectrometry. In summer, assimilatory uptake dominated NO3-N removal in the agricultural Tippecanoe during peak macrophyte growth, while denitrification drove NO3-N removal in the forested Manistee. After macrophyte senescence, denitrification controlled NO3-N removal in the Tippecanoe. Diel measurements of dissolved gasses and solutes in these two contrasting systems strengthen the temporal, spatial, and seasonal context of N dynamics in stream networks.

  • C27 Landuse and Non-Point source Impacts
  • C06 Large River Ecology
  • C10 Biogeochemistry

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Presenters/Authors

Martha M. Dee (), University of Notre Dame, mdee@nd.edu;


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Jennifer L. Tank (), University of Notre Dame, tank.1@nd.edu;


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Timothy Hoellein (), Loyola University Chicago, thoellein@luc.edu;


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Alexander Reisinger (), Cary Institute of Ecosystem Studies, reisingera@caryinstitute.org;


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Alessandra Marzadri (), Center for Ecohydraulics Research, University of Idaho , marzadri@ing.unitn.it;


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