RIVERINE NITROGEN FIXATION: AN UPDATED SYNTHESIS
Dinitrogen (N2) fixation is a fundamental process that has historically been understudied in riverine ecosystems. In 2008, Marcarelli and colleagues published a synthesis of riverine N2 fixation rates from 22 streams across 9 studies. Over the last fifteen years, the number of publications that report riverine N2 fixation rates has increased with 30+ new studies that help fill this gap in research on stream nitrogen cycling. We present an updated synthesis of N2 fixation rates in streams and rivers with data derived from published literature and public data repositories, including a dataset that was generated by the Aquatic Nitrogen Fixation Research Coordination Network. This synthesis includes over 800 N2 fixation rates across >100 riverine sites. Median fixation rates are approximately 4 g-N m-2 h-1, which is comparable to the median reported in the 2008 paper of 10 g-N m-2 h-1. The updated dataset spans 4 continents and a wide range of environmental conditions, including nitrate concentrations ranging from 0.9 - 3600 g-N L-1. Preliminary results show a negative relationship between nitrate availability and N2 fixation rates, while in 2008 the limited available data did not detect this relationship. For a subset of streams, we compare N2 fixation to denitrification and dissolved inorganic nitrogen uptake rates to evaluate the contribution of N2 fixation to other nitrogen cycle fluxes. This updated synthesis shows how 15 years of additional studies results in a more complete understanding of the ecological significance and environmental conditions affecting N2 fixation in streams.
Primary Presenter: Megan Berberich, Michigan Technological University (berberme@mail.uc.edu)
Authors:
Megan Berberich, Michigan Technological University (meberber@mtu.edu)
Michelle Catherine Kelly, Michigan Technological University (mckelly1@mtu.edu)
Robinson Fulweiler, Boston University (rwf@bu.edu)
Thad Scott, Baylor University (thad_Scott@baylor.edu)
Amy Marcarelli, Michigan Technological University (ammarcar@mtu.edu)
RIVERINE NITROGEN FIXATION: AN UPDATED SYNTHESIS
Category
Scientific Sessions > SS14 - Exploring Nitrogen Fixation Along the Freshwater-Marine Continuum; A Joint ASLO-SFS Endeavor
Description
Time: 01:30 PM
Date: 4/6/2024
Room: Lecture Hall