Methanol, acetaldehyde, and acetone in the surface waters of the Atlantic Ocean

Beale, Rachael; Dixon, Joanna L.; Arnold, S. R.; Liss, Peter S.; Nightingale, Philip D.

doi:10.1002/jgrc.20322

Cited by 79 publications

(179 citation statements)

References 62 publications

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“…This could be due to elevated microbial acetone oxidation rates in the light (Table 1). Acetone oxidation rates correlate with bacterial production (r = 0.856, P > 0.05), and Beale et al [2013] report a negative relationship between acetone seawater concentrations and bacterial production. Thus, although acetone oxidation rates are low, these relationships suggest that as bacterial production increases, so does the rate of microbial acetone oxidation, leading to a reduction in the in situ concentration of acetone.…”

Section: Discussionmentioning

confidence: 95%

“…[19] Microbial oxidation rates (integrated to 1 m) are compared to air-sea flux estimates from the same cruises [Beale et al, 2013;Beale, 2011] (Table S3). Comparisons suggest that for methanol, microbial oxidation (loss) is of the same order of magnitude as the air-sea flux.…”

Section: Discussionmentioning

confidence: 99%

“…In remote marine air, oceanic sources and sinks of OVOCs are assumed to be significant in controlling air concentrations [Read et al, 2012], although the magnitude and direction of the OVOC air-sea fluxes are a matter of debate [Beale et al, 2013;Carpenter et al, 2004;Heikes et al, 2002;Marandino et al, 2005;Taddei et al, 2009;Williams et al, 2004] largely as a consequence of extremely limited OVOC measurements in oceanic surface waters. Knowledge of OVOC production and loss rates, and an appreciation of the mechanisms involved in our oceans are also lacking.…”

Section: Introductionmentioning

confidence: 99%

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Production of methanol, acetaldehyde, and acetone in the Atlantic Ocean

Dixon

Beale

2013

Geophysical Research Letters

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[1] The biogeochemistry of oxygenated volatile organic compounds (OVOCs) like methanol, acetaldehyde, and acetone in marine waters is poorly understood. We report the first in situ gross production rates for methanol, acetaldehyde, and acetone of 49-103, 25-98, and 2-26 nmol L À1 d À1 over contrasting areas of marine productivity, including oligotrophic gyres and eutrophic upwellings. Photochemical production estimates are mostly negligible for methanol, up to 68% for acetaldehyde and up to 100% of gross production rates for acetone. Microbial surface OVOC oxidation to CO 2 accounts for between 10-50% and 0.5-13% of the methanol and acetone losses, respectively, but largely control acetaldehyde concentrations (49-100%). Biological lifetimes in a coastal upwelling vary between ≤1 day for acetaldehyde, to approximately 7 days for methanol and up to~80 days for acetone. In open oceanic environments, the lifetime of acetaldehyde ranges between 2 and 5 h, compared to 10-26 days for methanol and 5-55 days for acetone.

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Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Production of methanol, acetaldehyde, and acetone in the Atlantic Ocean

Dixon

Beale

2013

Geophysical Research Letters

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“…From in situ seawater concentration measurement and modeled atmospheric distribution over the Atlantic, Beale et al (17) recently calculated a net oceanic emission of 12 Tg·y −1 , but saw evidence for both oceanic production and uptake.…”

Section: ) Millet Et Al (5) Modeled a Gross Deposition Of −101mentioning

confidence: 99%

“…The turnover time of seawater methanol is thus quite short, on the order of a few days (13,14). However, significant oceanic concentrations of methanol have been detected in the range of 50∼400 nM (9,(15)(16)(17), leading to questions about its source.…”

Section: Introductionmentioning

confidence: 99%

Atmospheric deposition of methanol over the Atlantic Ocean

Yang

Nightingale

Beale

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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In the troposphere, methanol (CH 3 OH) is present ubiquitously and second in abundance among organic gases after methane. In the surface ocean, methanol represents a supply of energy and carbon for marine microbes. Here we report direct measurements of airsea methanol transfer along a ∼10,000-km north-south transect of the Atlantic. The flux of methanol was consistently from the atmosphere to the ocean. Constrained by the aerodynamic limit and measured rate of air-sea sensible heat exchange, methanol transfer resembles a one-way depositional process, which suggests dissolved methanol concentrations near the water surface that are lower than what were measured at ∼5 m depth, for reasons currently unknown. We estimate the global oceanic uptake of methanol and examine the lifetimes of this compound in the lower atmosphere and upper ocean with respect to gas exchange. We also constrain the molecular diffusional resistance above the ocean surface-an important term for improving air-sea gas exchange models.trace gas cycling | air-sea exchange | eddy covariance | environmental chemistry | marine micrometeorology Background Atmospheric methanol affects tropospheric oxidative capacity and air pollution by participating in the cycling of ozone and the hydroxyl radical (OH). Methanol is primarily released to air from terrestrial plants (during growth and decay); other identified sources include industrial emissions, biomass and biofuel burning, and atmospheric production (1-5). Methanol reacts with OH in the troposphere with a photochemical lifetime of ∼10 d, leading to formaldehyde (6) and carbon monoxide (7), among other products. Observations suggest that methanol can be further removed from air via deposition to land (8) and to the sea surface (9, 10). In the upper ocean, methanol supports the growth of methylotrophic bacteria (11) and has recently been found to be consumed by SAR11 alphaprotoeobacteria, the most abundant marine heterotrophs (12). The turnover time of seawater methanol is thus quite short, on the order of a few days (13,14). However, significant oceanic concentrations of methanol have been detected in the range of 50∼400 nM (9, 15-17), leading to questions about its source.To understand the global cycling of methanol, it is imperative to quantify its transport between the ocean and the atmosphere. (17) recently calculated a net oceanic emission of 12 Tg·y −1 , but saw evidence for both oceanic production and uptake.

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Air‐sea exchange of methanol and acetone during HiWinGS: Estimation of air phase, water phase gas transfer velocities

Yang

Blomquist

2014

JGR Oceans

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The air-sea fluxes of methanol and acetone were measured concurrently using a protontransfer-reaction mass spectrometer (PTR-MS) with the eddy covariance (EC) technique during the High Wind Gas Exchange Study (HiWinGS) in 2013. The seawater concentrations of these compounds were also measured twice daily with the same PTR-MS coupled to a membrane inlet. Dissolved concentrations near the surface ranged from 7 to 28 nM for methanol and from 3 to 9 nM for acetone. Both gases were consistently transported from the atmosphere to the ocean as a result of their low sea surface saturations. The largest influxes were observed in regions of high atmospheric concentrations and strong winds (up to 25 m s 21 ). Comparison of the total air-sea transfer velocity of these two gases (K a ), along with the in situ sensible heat transfer rate, allows us to constrain the individual gas transfer velocity in the air phase (k a ) and water phase (k w ). Among existing parameterizations, the scaling of k a from the COARE model is the most consistent with our observations. The k w we estimated is comparable to the tangential (shear driven) transfer velocity previously determined from measurements of dimethyl sulfide. Lastly, we estimate the wet deposition of methanol and acetone in our study region and evaluate the lifetimes of these compounds in the surface ocean and lower atmosphere with respect to total (dry plus wet) atmospheric deposition.

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Methanol, acetaldehyde, and acetone in the surface waters of the Atlantic Ocean

Cited by 79 publications

References 62 publications

Production of methanol, acetaldehyde, and acetone in the Atlantic Ocean

Production of methanol, acetaldehyde, and acetone in the Atlantic Ocean

Atmospheric deposition of methanol over the Atlantic Ocean

Air‐sea exchange of methanol and acetone during HiWinGS: Estimation of air phase, water phase gas transfer velocities

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