GREEN PLANTS - A TERRESTRIAL SINK FOR ATMOSPHERIC CH3BR

Methyl bromide is reactively removed from air by the foliage of all 9 herbaceous, 18 deciduous, and 12 coniferous plants we have tested: in a process that appears enzymatic. Excised plant leaves yielded removal rates directly proportional to leaf surface area and first-order in C H3Br concentration from 10 ppmv to 500 pptv, the current limit of our experimental technique. Observed rate constants for different plants v ary within a factor of about 100 with a lower value of 1x10(-3) hr(-1) cm(-2) in systems where the rate is not diffusion limited. This sink f or atmospheric CH3Br could be significant in calculations of the globa l methyl bromide budget.