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| Titel |
East Siberian Sea, an Arctic region of very high biogeochemical activity |
| VerfasserIn |
L. G. Anderson, G. Björk, S. Jutterström, I. Pipko, N. Shakhova, I. Semiletov, I. Wåhlström |
| 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 ; 8, no. 6 ; Nr. 8, no. 6 (2011-06-30), S.1745-1754 |
| Datensatznummer |
250005968
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| Publikation (Nr.) |
 copernicus.org/bg-8-1745-2011.pdf |
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| Zusammenfassung |
| Shelf seas are among the most active biogeochemical
marine environments and the East Siberian Sea is a prime example. This sea
is supplied by seawater from both the Atlantic and Pacific Oceans and has a
substantial input of river runoff. All of these waters contribute chemical
constituents, dissolved and particulate, but of different signatures. Sea
ice formation during the winter season and melting in the summer has a major
impact on physical as well as biogeochemical conditions. The internal
circulation and water mass distribution is significantly influenced by the
atmospheric pressure field. The western region is dominated by input of
river runoff from the Laptev Sea and an extensive input of terrestrial
organic matter. The microbial decay of this organic matter produces carbon
dioxide (CO2) that oversaturates all waters from the surface to bottom
relative to atmospheric level, even when primary production, inferred from
low surface water nutrients, has occurred. The eastern surface waters were
under-saturated with respect to CO2 illustrating the dominance of
marine primary production. The drawdown of dissolved inorganic carbon equals
a primary production of ~0.8 ± 2 mol C m−2, which when
multiplied by half the area of the East Siberian Sea, ~500 000 km2, results in an annual primary production of 0.4 (± 1) × 1012 mol C or
~4 (± 10) × 1012 gC. Microbial
decay occurs through much of the water column, but dominates at the sediment
interface where the majority of organic matter ends up, thus more of the
decay products are recycled to the bottom water. High nutrient
concentrations and fugacity of CO2 and low oxygen and pH were observed
in the bottom waters. Another signature of organic matter decomposition,
methane (CH4), was observed in very high but variable concentrations.
This is due to its seabed sources of glacial origin or modern production
from ancient organic matter, becoming available due to sub-sea permafrost
thaw and formation of so-called taliks. The decay of organic matter to
CO2 as well as oxidation of CH4 to CO2 contribute to a
natural ocean acidification making the saturation state of calcium carbonate
low, resulting in under-saturation of all the bottom waters with respect to
aragonite and large areas of under-saturation down to 50 % with respect to
calcite. Hence, conditions for calcifying organisms are very unfavorable. |
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