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Production of nitrogen gas via anammox and denitrification in intact sediment cores along a continental shelf to slope transect in the North Atlantic
Author(s) -
Trimmer Mark,
Nicholls Joanna Claire
Publication year - 2009
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.2009.54.2.0577
Subject(s) - anammox , denitrification , continental shelf , transect , sediment , environmental science , oxygen minimum zone , oceanography , nitrogen , chemistry , geology , denitrifying bacteria , geomorphology , organic chemistry , upwelling
We measured the production of N 2 gas from anammox and denitrification simultaneously in intact sediment cores at six sites along a transect of the continental shelf (50 m) and deeper slope (2000 m) in the North Atlantic. Maximum rates of total N 2 production were measured on the shelf and were largely due to denitrification, with anammox contributing, on average, 33% of this production. On the continental slope, the production of N 2 gas decreased but the proportion due to anammox reached a maximum of 65%. This change in both amount and dominant pathway of N 2 production could be explained largely by the concentration of organic carbon at each site. With increasing carbon the total production of N 2 increased rapidly while the response of anammox was not significant. On the continental slope, total N 2 production fell below 2 µmol N m ‐2 h ‐1 and anammox was strongly related (r = 0.95) to denitrification but the relative magnitude of anammox to denitrification (1.65 : 1) suggested that anammox could not be fuelled by NO 2 ‐ from denitrification alone. On the shelf, however, where total N 2 production was predominantly greater than 2 µmol N m ‐2 h ‐1 , no relationship between anammox and denitrification was found and anammox remained constant at 1.4 µmol N m ‐2 h ‐1 . Despite the constancy and greater availability of NO 3 ‐ and lower temperatures on the continental slope, the significance of anammox to the total production of N 2 appears primarily controlled by the overall rate of N 2 production.