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| Titel |
The influence of ocean acidification on nitrogen regeneration and nitrous oxide production in the northwest European shelf sea |
| VerfasserIn |
D. R. Clark, I. J. Brown, A. P. Rees, P. J. Somerfield, P. I. Miller |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 11, no. 18 ; Nr. 11, no. 18 (2014-09-18), S.4985-5005 |
| Datensatznummer |
250117598
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| Publikation (Nr.) |
 copernicus.org/bg-11-4985-2014.pdf |
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| Zusammenfassung |
| The assimilation and regeneration of dissolved inorganic nitrogen, and the
concentration of N2O, was investigated at stations located in the NW
European shelf sea during June/July 2011. These observational measurements
within the photic zone demonstrated the simultaneous regeneration and
assimilation of NH4+, NO2− and NO3−.
NH4+ was assimilated at 1.82–49.12 nmol N L−1 h−1 and regenerated at
3.46–14.60 nmol N L−1 h−1; NO2-
was assimilated at 0–2.08 nmol N L−1 h−1
and regenerated at 0.01–1.85 nmol N L−1 h−1; NO3− was assimilated at 0.67–18.75 nmol N L−1 h−1 and regenerated at
0.05–28.97 nmol N L−1 h−1. Observations implied that these processes were closely coupled at the
regional scale and that nitrogen recycling played an important role in sustaining
phytoplankton growth during the summer. The [N2O], measured in water
column profiles, was 10.13 ± 1.11 nmol L−1 and
did not strongly diverge from atmospheric equilibrium indicating that
sampled marine regions were neither a strong source nor sink of N2O to
the atmosphere. Multivariate analysis of data describing water column
biogeochemistry and its links to N-cycling activity failed to explain the
observed variance in rates of N-regeneration and N-assimilation,
possibly due to the limited number of process rate observations. In the
surface waters of five further stations, ocean acidification (OA) bioassay
experiments were conducted to investigate the response of NH4+
oxidising and regenerating organisms to simulated OA conditions, including
the implications for [N2O]. Multivariate analysis was undertaken which
considered the complete bioassay data set of measured variables describing
changes in N-regeneration rate, [N2O] and the biogeochemical
composition of seawater. While anticipating biogeochemical differences
between locations, we aimed to test the hypothesis that the underlying
mechanism through which pelagic N-regeneration responded to simulated OA
conditions was independent of location. Our objective was to develop a
mechanistic understanding of how NH4+ regeneration, NH4+
oxidation and N2O production responded to OA. Results indicated that
N-regeneration process responses to OA treatments were location specific;
no mechanistic understanding of how N-regeneration processes respond to
OA in the surface ocean of the NW European shelf sea could be developed. |
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