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dc.contributor.authorButler, James H.  Concept link
dc.contributor.authorYvon-Lewis, Shari  Concept link
dc.contributor.authorLobert, Jurgen M.  Concept link
dc.contributor.authorKing, Daniel B.  Concept link
dc.contributor.authorMontzka, Stephen  Concept link
dc.contributor.authorBullister, John L.  Concept link
dc.contributor.authorKoropalov, Valentin  Concept link
dc.contributor.authorElkins, James W.  Concept link
dc.contributor.authorHall, Bradley D.  Concept link
dc.contributor.authorHu, Lei  Concept link
dc.contributor.authorLiu, Yina  Concept link
dc.identifier.citationAtmospheric Chemistry and Physics 16 (2016): 10899-10910en_US
dc.description© The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Atmospheric Chemistry and Physics 16 (2016): 10899-10910, doi:10.5194/acp-16-10899-2016.en_US
dc.description.abstractExtensive undersaturations of carbon tetrachloride (CCl4) in Pacific, Atlantic, and Southern Ocean surface waters indicate that atmospheric CCl4 is consumed in large amounts by the ocean. Observations made on 16 research cruises between 1987 and 2010, ranging in latitude from 60° N to 77° S, show that negative saturations extend over most of the surface ocean. Corrected for physical effects associated with radiative heat flux, mixing, and air injection, these anomalies were commonly on the order of −5 to −10 %, with no clear relationship to temperature, productivity, or other gross surface water characteristics other than being more negative in association with upwelling. The atmospheric flux required to sustain these undersaturations is 12.4 (9.4–15.4) Gg yr−1, a loss rate implying a partial atmospheric lifetime with respect to the oceanic loss of 183 (147–241) yr and that  ∼  18 (14–22)  % of atmospheric CCl4 is lost to the ocean. Although CCl4 hydrolyzes in seawater, published hydrolysis rates for this gas are too slow to support such large undersaturations, given our current understanding of air–sea gas exchange rates. The even larger undersaturations in intermediate depth waters associated with reduced oxygen levels, observed in this study and by other investigators, strongly suggest that CCl4 is ubiquitously consumed at mid-depth, presumably by microbiota. Although this subsurface sink creates a gradient that drives a downward flux of CCl4, the gradient alone is not sufficient to explain the observed surface undersaturations. Since known chemical losses are likewise insufficient to sustain the observed undersaturations, this suggests a possible biological sink for CCl4 in surface or near-surface waters of the ocean. The total atmospheric lifetime for CCl4, based on these results and the most recent studies of soil uptake and loss in the stratosphere is now 32 (26–43) yr.en_US
dc.description.sponsorshipThis research could not have been done without the support of our various institutions and the programs through which they support science, including funds at various times from NASA’s Upper Atmosphere Research Program, the US Department of Energy, NOAA’s Climate Program Office, the Atmospheric and Geosciences sections of the National Science Foundation, and the National Research Council of the US National Academies of Science.en_US
dc.publisherCopernicus Publications on behalf of the European Geosciences Unionen_US
dc.rightsAttribution 3.0 Unported
dc.titleA comprehensive estimate for loss of atmospheric carbon tetrachloride (CCl4) to the oceanen_US

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Attribution 3.0 Unported
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