Effect of oceanic uptake on atmospheric lifetimes of selected trace gases

Abstract

[1] We have calculated from a 2°Â 2°grid of oceanic properties the contribution of oceanic loss to the overall lifetimes of a number of anthropogenic and naturally produced trace gases involved in global warming and stratospheric ozone depletion. The model, originally developed for atmospheric methyl bromide, can be used for any well-mixed trace gas where the seawater degradation rate constants and solubilities are known. Of the gases tested, it is clear that known oceanic chemical degradation processes alone are not significant sinks for most HFCs and HCFCs. Chemical degradation in the oceans is a substantial sink for COS (28%) and COCl 2 (8%) and a minor sink for CH 3 Cl (<2%) and CH 3 I (2.5%), and it should be considered when determining atmospheric lifetimes and sink strengths for these gases. Biological degradation processes are likely to increase the oceanic uptake rates of many gases.

20th century trends and budget implications of chloroform and related tri-and dihalomethanes inferred from firn air

“…The model contains 18 equal area latitudinal bands and 6 vertical layers, each of 2.5 km. The ocean component of the 2-D model was removed as the lifetime of CHCl 3 with respect to loss to the ocean has been reported to be insignificant (Kindler et al, 1995;Yvon-Lewis and Butler, 2002) relative to the ∼0.41 year lifetime resulting from the reaction with OH (Ko et al, 2003). Other sink terms including dry deposition and loss to soils were also removed as the reaction with OH was considered to be the dominant loss D. R. Worton et al: Trends and budgets of chloroform and related halomethanes from firn air 2849 process .…”

Carbonyl sulfide in air extracted from a South Pole ice core: a 2000 year record

“…The sources of tropospheric COS include direct terrestrial and oceanic emissions of COS and production in the atmosphere from the oxidation of carbon disulfide (CS 2 ) and dimethyl sulfide (DMS) (Barnes et al, 1994;Chin, 1991;Patroescu et al, 1999). The oceans are both a source and sink of atmospheric COS, with strong latitudinal and seasonal dependence, and a net air/sea flux that is a strong source to the atmosphere (Kettle et al, 2001;Ulshöfer et al, 1995;Weiss et al, 1995;Yvon-Lewis and Published by Copernicus Publications on behalf of the European Geosciences Union.…”

“…Aydin et al: Carbonyl sulfide in air extracted from a South Pole ice core Butler, 2001). Terrestrial sources include anthropogenic emissions of COS and CS 2 , and to a lesser extent biomass burning, emissions from wetlands and volcanism, and oxidation of CS 2 released from anoxic soils (Belviso et al, 1986;Bingemer et al, 1990;Nguyen et al, 1995).…”

Experimental determination of Henry's law constants of difluoromethane (HFC-32) and the salting-out effects in aqueous salt solutions relevant to seawater

“…Other processes, such as dissolution in seawater, are not considered to contribute significantly to the atmospheric removal of CH 2 F 2 . Yvon- Lewis and Butler (2002) estimated partial atmospheric lifetimes of some HCFCs and HFCs with respect to irreversible dissolution in seawater by using physicochemical properties such as solubility and aqueous reaction rates, as well as meteorological data such as temperature and wind speed over the ocean in grids. Their estimates indicated that dissolution in seawater is not a significant sink of the HCFCs and HFCs that were evaluated in the study.…”