THE POTENTIAL ROLE OF THE OCEAN IN REGULATING ATMOSPHERIC CH3BR

An increase or decrease in anthropogenic emissions of methyl bromide (CH3Br) will induce a compensating flux of this gas from the ocean to the atmosphere. This, in turn, will tend to lessen the expected change in atmospheric mixing ratio from that calculated in models that incorporate a constant oceanic source. To a first degree, this buffering effect by the ocean is independent of in situ oceanic production and land based sources. The partial lifetime of atmospheric CH3Br with respect to the ocean could reasonably range from 1.3 to 14 y, with a current best estimate of 3.7 y. This yields an effective atmospheric lifetime, which incorporates oceanic losses and thus can be used in simple, mass balance calculations of atmospheric CH3Br, of 1.2 y, with a probable range of 0.7 to 1.8 y.