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| Titel |
Marine sources of bromoform in the global open ocean – global patterns and emissions |
| VerfasserIn |
I. Stemmler, 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 ; 12, no. 6 ; Nr. 12, no. 6 (2015-03-25), S.1967-1981 |
| Datensatznummer |
250117881
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| Publikation (Nr.) |
 copernicus.org/bg-12-1967-2015.pdf |
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| Zusammenfassung |
| Bromoform (CHBr3) is one important precursor of atmospheric
reactive bromine species that are involved in ozone depletion in the
troposphere and stratosphere. In the open ocean bromoform production
is linked to phytoplankton that contains the enzyme
bromoperoxidase. Coastal sources of bromoform are higher than open
ocean sources. However, open ocean emissions are important because
the transfer of tracers into higher altitude in the air, i.e. into
the ozone layer, strongly depends on the location of emissions. For
example, emissions in the tropics are more rapidly transported into
the upper atmosphere than emissions from higher latitudes. Global
spatio-temporal features of bromoform emissions are poorly
constrained. Here, a global three-dimensional ocean biogeochemistry
model (MPIOM-HAMOCC) is used to simulate bromoform cycling in the
ocean and emissions into the atmosphere using recently published
data of global atmospheric concentrations (Ziska et al., 2013)
as upper boundary conditions. Our simulated surface
concentrations of CHBr3 match the observations
well. Simulated global annual emissions based on monthly mean model
output are lower than previous estimates, including the estimate by
Ziska et al. (2013), because the gas exchange reverses when
less bromoform is produced in non-blooming seasons. This is the case
for higher latitudes, i.e. the polar regions and northern North
Atlantic. Further model experiments show that future model studies
may need to distinguish different bromoform-producing phytoplankton
species and reveal that the transport of CHBr3 from the
coast considerably alters open ocean bromoform concentrations, in
particular in the northern sub-polar and polar regions. |
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