2023 Early Hearing Detection & Intervention Conference
March 5-7, 2023 • Cincinnati, OH
5/26/2021 | 8:30 AM - 10:30 AM | DISSOLVED N2:AR RATIOS DESCRIBE THE BALANCE BETWEEN DENITRIFICATION AND N FIXATION ACROSS A NITROGEN:PHOSPHORUS GRADIENT IN EXPERIMENTAL POND SYSTEMS | Virtual Platform
DISSOLVED N2:AR RATIOS DESCRIBE THE BALANCE BETWEEN DENITRIFICATION AND N FIXATION ACROSS A NITROGEN:PHOSPHORUS GRADIENT IN EXPERIMENTAL POND SYSTEMS
Quantifying net N2 flux, the balance between denitrification and nitrogen (N) fixation, may help solve the decades-long debate about the significance of N limitation in pond, lake, and reservoir ecosystems. We hypothesized that the stoichiometric imbalance between nitrogen and phosphorus (P) inputs into hypereutrophic experimental ponds would yield under- or over-saturated N2 gas concentrations and net zero N2 flux at the Redfield Ratio. We tested this concept by measuring diel N2:Ar patterns in twelve experimental pond mesocosms representing a N:P gradient ranging from ~2 to 110 (by atoms). Patterns in N2:Ar ratios across mesocosms varied over the diel cycle with minimum values occurring in late afternoon and maximum values occurring before or during sunrise hours. Overall, mesocosms with the lowest N:P ratios had N2:Ar values consistently below equilibrium, mesocosms with N:P ratios near Redfield ratios overlapped with equilibrium values, and mesocosms with high N:P ratios had N2:Ar values consistently above equilibrium. Our results confirm that water column N2:Ar values show promise for evaluating the direction of N fluxes within lakes and may help researchers determine the role of N fixation and denitrification in balancing stoichiometry of lakes across broad scales.
- Nutrient cycling
- Microbial ecology
- Stoichiometry
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Presenters/Authors
Jason M. Taylor
(), USDA, Agricultural Research Service, National Sedimentation Lab, jason.taylor@ars.usda.gov;
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Thad Scott
(), Baylor University, Thad_Scott@baylor.edu ;
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Patrick Kelly
(), Rhodes College, kellyp@rhodes.edu;
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Isabelle Andersen
(), Baylor University, isabelle_andesen1@baylor.edu;
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