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| Titel |
Modelling the vertical distribution of bromoform in the upper water column of the tropical Atlantic Ocean |
| VerfasserIn |
I. Hense, B. Quack |
| 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 ; 6, no. 4 ; Nr. 6, no. 4 (2009-04-07), S.535-544 |
| Datensatznummer |
250003637
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| Publikation (Nr.) |
 copernicus.org/bg-6-535-2009.pdf |
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| Zusammenfassung |
| The relative importance of potential source and sink terms for bromoform
(CHBr3) in the tropical Atlantic Ocean is investigated with a coupled
physical-biogeochemical water column model. Bromoform production is either
assumed to be linked to primary production or to phytoplankton losses;
bromoform decay is treated as light dependent (photolysis), and in addition
either vertically uniform, proportional to remineralisation or to
nitrification. All experiments lead to the observed subsurface maximum of
bromoform, corresponding to the subsurface phytoplankton biomass maximum. In
the surface mixed layer, the concentration is set by entrainment from below,
photolysis in the upper few meters and the outgassing to the atmosphere. The
assumed bromoform production mechanism has only minor effects on the solution,
but the various loss terms lead to significantly different bromoform
concentrations below 200 m depth. The best agreement with observations is
obtained when the bromoform decay is coupled to nitrification (parameterised
by an inverse proportionality to the light field). Our model results reveal
a pronounced seasonal cycle of bromoform outgassing, with a minimum in summer
and a maximum in early winter, when the deepening surface mixed layer reaches
down into the bromoform production layer. |
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