Open AccessRapid biological oxidation of methanol in the tropical Atlantic: significance as a microbial carbon source
Author(s) -
Joanna L. Dixon,
Rachael Beale,
Philip D. Nightingale
Publication year - 2011
Publication title -
biogeosciences discussions
Language(s) - English
Resource type - Journals
ISSN - 1810-6277
DOI - 10.5194/bgd-8-3899-2011
Subject(s) - methanol , ocean gyre , atmosphere (unit) , environmental chemistry , seawater , flux (metallurgy) , methane , troposphere , carbon fibers , environmental science , organic matter , sink (geography) , dissolved organic carbon , oceanography , atmospheric sciences , chemistry , subtropics , geology , ecology , meteorology , biology , organic chemistry , materials science , physics , cartography , composite number , geography , composite material
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 up to 300 nM, with corresponding microbial uptake rates between 2–146 nM d−1, suggesting turnover times as low as 1 day in surface waters of the oligotrophic tropical North East Atlantic. Comparisons 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%). 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 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