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| Titel |
Interannual sedimentary effluxes of alkalinity in the southern North Sea: Model results compared with summer observations. |
| VerfasserIn |
Johannes Paetsch, Wilfried Kuehn, Katharina Six |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250124558
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| Publikation (Nr.) |
 EGU/EGU2016-4010.pdf |
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| Zusammenfassung |
| Alkalinity generation in the sediment of the southern North Sea is the focus of
several recent studies. One motivation for these efforts is the potentially enhanced
buffering capacity of anthropogenic CO2 invasion into the corresponding pelagic
system.
An adaptation of a global multilayer sediment model (Heinze et al., 1999) in combination
with a pelagic ecosystem model for shelf sea dynamics was used to study the benthic
reactions on very different annual cycles (2001 – 2009) including the River Elbe summer
flooding in 2002. The focus of this study is the efflux of alkalinity, their different contributors
(aerobic respiration, denitrification, net sulfate reduction, calcite dissolution, nitrification) and
their seasonal and interannual cycles.
Similar to the observations covering the southern North Sea (Brenner et al., 2015) the
model results show large horizontal gradients from the near-shore high productive
areas with benthic remineralization up to Rmin = 10.6 mol C m−2 yr−1 and TA
generation RTA = 2 mol C m−2 yr−1 to off-shore moderate productive areas with
mean Rmin = 2.5 mol C m−2 yr−1 and mean TA generation RTA = 0.4 mol C m−2
yr−1.
Beside calcite dissolution, aerobic respiration (producing ammonium) and denitrification
are the largest contributors to alkalinity generation. Nitrification is reducing alkalinity in the
sediment.
Due to low regenerated primary production in summer, the year 2001 exhibits the
lowest input of particulate organic matter into the sediment (POCexp=2.3 mol C m−2
yr−1), while the year 2003 exhibits the highest export production (POCexp=2.6 mol
C m−2 yr−1). The biogeochemical reactions and the effluxes from the sediment
follow these pelagic amplitudes with a time lag of about one year with damped
amplitudes.
References
Brenner, H., Braeckman, U., Le Guitton, M., Meysman, F.J.R., 2015. The impact of
sedimentary alkalinity release on the water column CO2 system in the North Sea.
Biogeosiences Discussion, 12(15): 12395-12453.
Heinze, C., Maier-Reimer, E., Winguth, A.M.E, Archer, D., 1999: A global oceanic
sediment model for long-term climate studies. Glob. Biogeochem. Cycles, 13(1): 221-250. |
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