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| Titel |
Rapid biological oxidation of methanol in the tropical Atlantic: significance as a microbial carbon source |
| VerfasserIn |
J. L. Dixon, R. Beale, P. D. Nightingale |
| 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. 9 ; Nr. 8, no. 9 (2011-09-23), S.2707-2716 |
| Datensatznummer |
250006130
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| Publikation (Nr.) |
 copernicus.org/bg-8-2707-2011.pdf |
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| Zusammenfassung |
| Methanol is the second most abundant organic gas in the atmosphere
after methane, and is ubiquitous in the troposphere. It plays a significant
role in atmospheric oxidant chemistry and is biogeochemically active. Large
uncertainties exist about whether the oceans are a source or sink of
methanol to the atmosphere. Even less is understood about what reactions in
seawater determine its concentration, and hence flux across the sea surface
interface. We report here concentrations of methanol between 151–296 nM in
parts of the oligotrophic North Atlantic, with corresponding microbial
uptake rates between 2–146 nM d−1, suggesting turnover times
as low as 1 day (1–25 days) in surface waters of the oligotrophic tropical
North East Atlantic. Methanol is mainly (≥97%) used by microbes for
obtaining energy in oligotrophic regions, which contrasts with shelf and
coastal areas where between 20–50% can be used for cell growth.
Comparisons of microbial methanol oxidation rates with parallel
determinations of bacterial leucine uptake suggest that methanol contributes
on average 13% to bacterial carbon demand in the central northern
Atlantic gyre (maximum of 54%). In addition, the contribution that
methanol makes to bacterial carbon demand varies as a power function of
chlorophyll a concentrations; suggesting for concentrations <0.2 μg l−1
that methanol can make a significant contribution to
bacterial carbon demand. However, our low air to sea methanol flux estimates
of 7.2–13 μmol m−2 d−1 suggest that the
atmosphere is not a major methanol source. We conclude that there must be a
major, as yet unidentified, in situ oceanic methanol source in these
latitudes which we suggest is sunlight driven decomposition of organic
matter. |
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