Document Type

Article

Department/Program

Virginia Institute of Marine Science

Publication Date

2013

Journal

Oceanography

Volume

26

Issue

3

First Page

124

Last Page

131

Abstract

Until recently, it was believed that biological assimilation and gaseous nitrogen (N) loss through denitrification were the two major fates of nitrate entering or produced within most coastal ecosystems. Denitrification is often viewed as an important ecosystem service that removes reactive N from the ecosystem. However, there is a competing nitrate reduction process, dissimilatory nitrate reduction to ammonium (DNRA), that conserves N within the ecosystem. The recent application of nitrogen stable isotopes as tracers has generated growing evidence that DNRA is a major nitrogen pathway that cannot be ignored. Measurements comparing the importance of denitrification vs. DNRA in 55 coastal sites found that DNRA accounted for more than 30% of the nitrate reduction at 26 sites. DNRA was the dominant pathway at more than one-third of the sites. Understanding what controls the relative importance of denitrification and DNRA, and how the balance changes with increased nitrogen loading, is of critical importance for predicting eutrophication trajectories. Recent improvements in methods for assessing rates of DNRA have helped refine our understanding of the rates and controls of this process, but accurate measurements in vegetated sediment still remain a challenge.

DOI

10.5670/oceanog.2013.54

Keywords

C Nitrite Reductase; Benthic Metabolism; Mangrove Sediments; Inorganic Nitrogen; Terminos Lagoon; Fringing Marsh; Denitrification; Dynamics; Shallow; Estuary

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