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| Titel |
Link or sink: a modelling interpretation of the open Baltic biogeochemistry |
| VerfasserIn |
M. Vichi, P. Ruardij, J. W. Baretta |
| 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 ; 1, no. 1 ; Nr. 1, no. 1 (2004-11-04), S.79-100 |
| Datensatznummer |
250000073
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| Publikation (Nr.) |
 copernicus.org/bg-1-79-2004.pdf |
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| Zusammenfassung |
| A 1-D model system, consisting of the 1-D version of the Princeton
Ocean Model (POM) coupled with the European Regional Seas Ecosystem
Model (ERSEM) has been applied to a sub-basin of the Baltic Proper,
the Bornholm basin. The model has been forced with 3h meteorological
data for the period 1979-1990, producing a 12-year hindcast validated
with datasets from the Baltic Environmental Database for the same
period. The model results demonstrate the model to hindcast the time-evolution
of the physical structure very well, confirming the view of the open
Baltic water column as a three layer system of surface, intermediate
and bottom waters. Comparative analyses of modelled hydrochemical
components with respect to the independent data have shown that the
long-term system behaviour of the model is within the observed ranges.
Also primary production processes, deduced from oxygen (over)saturation
are hindcast correctly over the entire period and the annual net primary
production is within the observed range. The largest mismatch with
observations is found in simulating the biogeochemistry of the Baltic
intermediate waters. Modifications in the structure of the model (addition
of fast-sinking detritus and polysaccharide dynamics) have shown that
the nutrient dynamics are linked to the quality and dimensions of
the organic matter produced in the euphotic zone, highlighting the
importance of the residence time of the organic matter within the
microbial foodweb in the intermediate waters. Experiments with different
scenarios of riverine nutrient loads, assessed in the limits of a
1-D setup, have shown that the external input of organic matter makes
the open Baltic model more heterotrophic. The characteristics of the
inputs also drive the dynamics of nitrogen in the bottom layers leading
either to nitrate accumulation (when the external sources are inorganic),
or to coupled nitrification-denitrification (under strong organic
inputs). The model indicates the permanent stratification to be the
main feature of the system as regulator of carbon and nutrient budgets.
The model predicts that most of the carbon produced in the euphotic
zone is also consumed in the water column and this enhances the importance
of heterotrophic benthic processes as final closure of carbon and
nutrient cycles in the open Baltic. |
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