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| Titel |
Fine-scale variability in methanol uptake and oxidation: from the microlayer to 1000 m |
| VerfasserIn |
J. L. Dixon, 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 ; 9, no. 8 ; Nr. 9, no. 8 (2012-08-06), S.2961-2972 |
| Datensatznummer |
250007229
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| Publikation (Nr.) |
 copernicus.org/bg-9-2961-2012.pdf |
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| Zusammenfassung |
| The aim of this research was to make the first depth profiles of the
microbial assimilation of methanol carbon and its oxidation to carbon
dioxide and use as an energy source from the microlayer to 1000 m. Some of
the highest reported methanol oxidation rate constants of 0.5–0.6 d−1
were occasionally found in the microlayer and immediately underlying
waters (10 cm depth), albeit these samples also showed the greatest
heterogeneity compared to other depths down to 1000 m. Methanol uptake into
the particulate phase was exceptionally low in microlayer samples,
suggesting that any methanol utilised by microbes in this environment is for
energy generation. The sea surface microlayer and 10 cm depth also showed a
higher proportion of bacteria with a low DNA content, and bacterial leucine
uptake rates in surface microlayer samples were either less than or the
same as those in the underlying 10 cm layer. The average methanol oxidation
and particulate rates were however statistically the same throughout the
depths sampled, although the latter were highly variable in the near-surface
0.25–2 m compared to deeper depths. The statistically significant
relationship demonstrated between uptake of methanol into particles and
bacterial leucine incorporation suggests that many heterotrophic bacteria
could be using methanol carbon for cellular growth. On average, methanol
bacterial growth efficiency (BGEm) in the top 25 m of the water column
is 6% and decreases with depth. Although, for microlayer and 10 cm-depth
samples, BGEm is less than the near-surface 25–217 cm, possibly
reflecting increased environmental UV stress resulting in increased
maintenance costs, i.e. energy required for survival. We conclude that
microbial methanol uptake rates, i.e. loss from seawater, are highly variable,
particularly close to the seawater surface, which could significantly impact
upon seawater concentrations and hence the air–sea flux. |
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