McCauley S E, Goldstein A H, DePaolo D J
Department of Environmental Science, Policy, and Management (MC 3110), University of California, Berkeley, CA 94720, USA.
Proc Natl Acad Sci U S A. 1999 Aug 31;96(18):10006-9. doi: 10.1073/pnas.96.18.10006.
The atmospheric budget of methyl bromide (CH(3)Br), an ozone-depleting gas, is highly uncertain, because it has complex sources and sinks. Although oceans, biomass burning, and industrial production are identified as the major sources, the fraction of CH(3)Br that is contributed by each source is not well known. A mass-balance approach that exploits differences in the carbon isotopic signature (delta(13)C) of CH(3)Br sources and sinks may provide a means of reducing uncertainties in the atmospheric budget. This approach depends on the distinctiveness of industrially produced methyl bromide. Our delta(13)C measurements of industrial CH(3)Br from the three largest manufacturers worldwide yield a weighted average of -54.4 per thousand relative to the Peedee Belemnite standard. This result suggests that industrial CH(3)Br is isotopically distinct and that the carbon isotopic composition of atmospheric CH(3)Br may indicate what fraction of atmospheric CH(3)Br is anthropogenic.
甲基溴（CH₃Br）是一种消耗臭氧层的气体，其大气收支情况高度不确定，因为它具有复杂的源和汇。虽然海洋、生物质燃烧和工业生产被确定为主要来源，但每个来源对甲基溴的贡献比例尚不清楚。利用甲基溴源和汇的碳同位素特征（δ¹³C）差异的质量平衡方法，可能为减少大气收支的不确定性提供一种手段。这种方法依赖于工业生产的甲基溴的独特性。我们对全球三大制造商生产的工业甲基溴进行的δ¹³C测量结果显示，相对于皮迪菊石标准，加权平均值为每千分-54.4。这一结果表明，工业甲基溴在同位素上具有独特性，大气中甲基溴的碳同位素组成可能表明大气中甲基溴的人为来源比例。
