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General Session 2: Marine & estuarine biogeochemistry |
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Nitrogen reduction pathways in estuarine sediments: Influences of organic carbon and sulfide
Wednesday 11th @ 1110-1130
Conference Hall
Craig Tobias* , University of Connecticut
Patrick Plummer, US Coast Guard Academy
Presenter Email: craig.tobias@uconn.edu
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| Rates of sediment denitrification, anaerobic ammonium oxidation (anammox), and dissimilatory nitrate reduction to ammonium (DNRA) were mapped across the entire Niantic River Estuary, CT, USA, at 100–200m scale resolution. Overall, denitrification accounted for ~ 90% of the nitrogen reduction, followed by DNRA and anammox. However, the relative importance of these reactions to each other was not evenly distributed. A Nitrogen Retention Index (NIRI) was calculated from the rate data as a metric to assess the relative amounts of nitrogen being recycled versus retained following reduction. Controls on NIRI were linked to organic carbon abundance and source, and pore water sulfide. Sulfide proved the single best predictor of NIRI, accounting for 44% of its observed variance in NIRI. We suggest that as a single metric, sulfide may have utility as a proxy for gauging the distribution of denitrification, anammox, and DNRA. |
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