Methyl Bromide and Ozone Depletion

Methyl bromide with an approximate tropospheric concentration of 8 pptv and an atmospheric lifetime of about 0.8 years (Montzka et al., 2011).The bromine from CH3Br is thought to deplete from 40 to 100 times more ozone than chlorine. Methyl bromide is the largest source of Br to the stratosphere. It contributes about 50 % of Br radicals and is believed to be responsible for 15 % of ozone depletion caused by halogen radicals. Another 13 % is caused by CH3Cl and almost 50 % by CFCs.CFC concentrations started to decrease in the mid-90s and the Antarctic ozone hole began to re-cover. However, the currently predicted climate change is expected to lead to an increased emission of methyl halides and by that increase their importance for ozone depletion. Global warming and further uncontrolled eutrophication of the oceans may result in an unknown increase of the emission of volatile organohalogens into the global environment. While aiming for alternates for CH3Br, it is also prime necessity to reduce the natural release of CH3Br such as microbial oxidation of bromide and by chemical methods (30% NH4OH) in combination with VIF(virtually impermeable film)(Xuan et al.,2011).