Time scales in atmospheric chemistry: CH 3 Br, the ocean, and ODPs
- Author(s): Prather, MJ
- et al.
Methyl bromide( CH3Br)s uppliesa bouth alf of the chemicallya ctiveb romine (Bry)in thes tratospheEreff.o rtsto c ontroBl ry-catalyzoezdo ned epletiobny p hasinogu t, for example,a griculturaul seo f CH3Brm ay be thwartedb y a lack of understandinogf how the variedb iogeochemicapl rocesseisn teracta s a coupleds ystem: in additiont o the chemical industry,l argen aturals ourcesc omef rom the ocean;a ndl osseso ccuri n the atmosphereo, cean,a nd soils. A simplifiedo ne-dimensionaslt ratosphere-troposphere-ocean modeflo r (CH3BrB, ry• thatf itsc urrenut nderstandoinfg s ourceasn ds inksis a nalyzeidn termso f naturalm odes. Surfacea nd oceans ourcesh ave effectively different steadys tate lifetimes (1.0 and0 .5 years,r espectively)b, ut the natural-moded ecayt imeso f the system (1.8y earsfo rC H3Bra nd4 .5y earsfo rs tratospheBrircy )d on otd epenodn t hel ocationo f sources.T he cumulativeo zoned epletionr esultingf rom a singlea tmosphericre leaseo f CH3Brin tegrateosv ert hec onsequesnlto wr isea ndf all of Bryi n thel owers tratosphere. Thus, in spiteo f the 1-yearl ifetime of CH3Br,o nly half of the anticipatedo zoner ecovery occurs in the first 7 years.
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