" From McCulloch (1992).

" From McCulloch (1992).

Table 12.6 shows one estimate of the emissions of Halon-121f and Halon-1301 into the atmosphere from 1963 to 1990 (McCulloch, 1992). Table 12.7 gives the 1995 WMO estimate of the methyl bromide sources, both natural and anthropogenic (which are about equal in magnitude). Despite the fact that compounds such as methyl bromide and chlorobromomethane can be removed by reaction with OH in the troposphere (e.g., Orkin et al., 1997), whereas the halons cannot, the emissions of methyl bromide in particular are of a sufficient magnitude that some CH3Br does reach the stratosphere. One set of measurements of the vertical profiles of CH3Br, CH2Br2, Halon-f211, and Halon-1301 suggests that CH3Br is responsible for ~ 55-70% of the bromine carried into the stratosphere by these compounds (Kourtidis et al., f 998).

Methyl bromide is used as a fumigant for soils (the agricultural use shown in Table f2.7) and shipments of fruits and vegetables as well as for buildings for termite control (shown as "structural purposes" in Table 12.7). Large amounts are released during biomass burning (e.g., see Mano and Andreae, 1994; Cicerone, 1994)

TABLE 12.7 Estimated Annual Emissions of CH3Bru
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