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| Titel |
Variable C : N : P stoichiometry of dissolved organic matter cycling in the Community Earth System Model |
| VerfasserIn |
R. T. Letscher, J. K. Moore, Y.-C. Teng, F. Primeau |
| 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 ; 12, no. 1 ; Nr. 12, no. 1 (2015-01-12), S.209-221 |
| Datensatznummer |
250117767
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| Publikation (Nr.) |
 copernicus.org/bg-12-209-2015.pdf |
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| Zusammenfassung |
| Dissolved organic matter (DOM) plays an important role in the ocean's
biological carbon pump by providing an advective/mixing pathway for
~ 20% of export production. DOM is known to have a
stoichiometry depleted in nitrogen (N) and phosphorus (P) compared to the
particulate organic matter pool, a fact that is often omitted from
biogeochemical ocean general circulation models. However the variable C : N : P
stoichiometry of DOM becomes important when quantifying carbon export from
the upper ocean and linking the nutrient cycles of N and P with that of
carbon. Here we utilize recent advances in DOM observational data coverage
and offline tracer-modeling techniques to objectively constrain the variable
production and remineralization rates of the DOM C : N : P pools in a simple
biogeochemical-ocean model of DOM cycling. The optimized DOM cycling
parameters are then incorporated within the Biogeochemical Elemental Cycling
(BEC) component of the Community Earth System Model (CESM) and validated against
the compilation of marine DOM observations. The optimized BEC simulation
including variable DOM C : N : P cycling was found to better reproduce the
observed DOM spatial gradients than simulations that used the canonical
Redfield ratio. Global annual average export of dissolved organic C, N, and
P below 100 m was found to be 2.28 Pg C yr−1 (143 Tmol C yr−1,
16.4 Tmol N yr−1, and 1 Tmol P yr−1, respectively, with an average
export C : N : P stoichiometry of 225 : 19 : 1 for the semilabile (degradable) DOM
pool. Dissolved organic carbon (DOC) export contributed ~ 25% of the combined organic
C export to depths greater than 100 m. |
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