期刊
LIMNOLOGY AND OCEANOGRAPHY
卷 54, 期 3, 页码 723-734出版社
AMER SOC LIMNOLOGY OCEANOGRAPHY
DOI: 10.4319/lo.2009.54.3.0723
关键词
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资金
- Danish National Science Research Council [272-05-0268, 27205-0363, 272-06-0504]
- European Union [GOCECT2003505564]
- NERC [NE/F012691/1]
- Japan Society for the Promotion of Science [18710021, 17204046]
- JAMSTEC
- Danish National Research Foundation
- Max Planck Society
- NERC [NE/F012691/1] Funding Source: UKRI
- Grants-in-Aid for Scientific Research [17204046, 18710021] Funding Source: KAKEN
- Natural Environment Research Council [NE/F012691/1] Funding Source: researchfish
On the basis of in situ NO3- microprofiles and chamber incubations complemented by laboratory-based assessments of anammox and denitrification we evaluate the nitrogen turnover of an ocean margin sediment at 1450-m water depth. In situ NO3- profiles horizontally separated by 12 mm reflected highly variable NO3- penetration depths, NO3- consumption rates, and nitrification. On average the turnover time of the pore-water NO3- pool was similar to 0.2 d. Net release of NH4+ during mineralization (0.95 mmol m(-2) d(-1)) sustained a net efflux of ammonia (53%), nitrification (24%), and anammox activity (23%). The sediment had a relatively high in situ net influx of NO3- (1.44 mmol m(-2) d(-1)) that balanced the N-2 production as assessed by onboard tracer experiments. N2 production was attributed to prokaryotic denitrification (59%), anammox (37%), and foraminifera-based denitrification (4%). Anammox thereby represented an important nutrient sink, but the N2 production was dominated by denitrification. Despite the fact that NO3- stored inside foraminifera represented similar to 80% of the total benthic NO3- pool, the slow intracellular NO3- turnover that, on average, sustained foraminifera metabolism for 12-52 d, contributed only to a minor extent to the overall N-2 production. The microbial activity in the surface sediment is a net nutrient sink of similar to 1.1 mmol N m(-2) d(-1), which aligns with many studies performed in coastal and shelf environments. Continental margin areas can act as significant N sinks and play an important role in regional N budgets.
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