Methyl chloride and methyl bromide emissions from baking: an unrecognized anthropogenic source

摘要: Methyl chloride and methyl bromide (CH3Cl CH3Br) are the largest natural sources of chlorine bromine, respectively, to stratosphere, where they contribute ozone depletion. We report anthropogenic production CH3Cl CH3Br during breadbaking, suggest this is an abiotic process involving ester functional groups in pectin lignin structural polymers plant cells. Wide variations baking styles allow only rough estimates flux halides on a global basis. A simple model suggests that emissions from breadbaking likely peaked circa 1990 at approximately 200tonnes per year (about 0.3% industrial production), prior restrictions dough conditioner potassium bromate. In contrast, may be similar magnitude as acknowledged present-day emissions. Because mechanisms involve compounds widely found materials, type halide occur other cooking techniques well.