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Denitrification pathways and rates in the sandy sediments of the Georgia continental shelf, USA

Authors
  • Vance-Harris, Cynthia1
  • Ingall, Ellery1
  • 1 Georgia Institute of Technology, School of Earth and Atmospheric Sciences, Atlanta, 30332, Georgia , Atlanta
Type
Published Article
Journal
Geochemical Transactions
Publisher
Springer International Publishing
Publication Date
Feb 02, 2005
Volume
6
Issue
1
Identifiers
DOI: 10.1186/1467-4866-6-12
Source
Springer Nature
Keywords
License
Yellow

Abstract

Denitrification in continental shelf sediments has been estimated to be a significant sink of oceanic fixed nitrogen (N). The significance and mechanisms of denitrification in organic-poor sands, which comprise 70% of continental shelf sediments, are not well known. Core incubations and isotope tracer techniques were employed to determine processes and rates of denitrification in the coarse-grained, sandy sediments of the Georgia continental shelf. In these sediments, heterotrophic denitrification was the dominant process for fixed N removal. Processes such as coupled nitrification-denitrification, anammox (anaerobic ammonium oxidation), and oxygen-limited autotrophic nitrification-denitrification were not evident over the 24 and 48 h time scale of the incubation experiments. Heterotrophic denitrification processes produce 22.8–34.1 μmole N m-2 d-1 of N2 in these coarse-grained sediments. These denitrification rates are approximately two orders of magnitude lower than rates determined in fine-grained shelf sediments. These lower rates may help reconcile unbalanced marine N budgets which calculate global N losses exceeding N inputs.

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