An interhemispheric comparison of the concentrations of bromine compounds in the atmosphere
An interhemispheric comparison of the concentrations of bromine compounds in the atmosphere
复制标题
大气中溴化合物浓度的半球间比较
作者：
S. Penkett;B. Jones;M. Rycroft;D. Simmons
至少有7种有机溴化合物在大气1、2(CH3Br2、CH2Br2、CHBr3、CH2BrCl、CF3Br2、CF2BrCl和C2H4Br2)中得到了肯定的鉴定，在沿海海水样品中还观察到了其他有机溴化合物(C2H5Br1、C3H7Br1和CHBr2Cl2)(S.A.P.和R.A.Rasmussen，未发表的数据)。溴化合物的大气化学对平流层有相当大的影响，在平流层中，溴是比氯更有效的催化剂，可以消除臭氧3，4。几种溴化合物还在元素通过对流层的地球化学循环中发挥重要作用5。本文给出了在大纬度范围内(40°N到75°S)四种溴化合物(CF3Br、CH3Br2、CH2Br2和CHBr3)的测量结果。这些数据表明，大气中溴的主要来源可能是溴仿(CHBr3)，它可能是从海洋中排放出来的，由于光解而寿命较短。我们的数据还表明，甲基溴(CH3Br)的主要排放，因此进入平流层的大多数溴，将是人为的。
At least seven organic bromine compounds have been positively identified in the atmosphere1,2 (CH3Br, CH2Br2, CHBr3, CH2BrCl, CF3Br, CF2BrCl and C2H4Br2) and others have been observed in coastal seawater samples (C2H5Br, C3H7Br and CHBr2Cl) (S. A. P. and R. A. Rasmussen, unpublished data). The atmospheric chemistry of bromine compounds has considerable consequence in the stratosphere, where bromine acts as a more efficient catalyst than chlorine in removing ozone3,4. Several bromine compounds also fulfil an important role in the geochemical cycling of the element through the troposphere5. Here we present measurements of four bromine compounds (CF3Br, CH3Br, CH2Br2 and CHBr3) over a large latitudinal range (40° N to 75° S). These data suggest that the major source of bromine in the atmosphere could be bromoform (CHBr3), probably emitted from the ocean and with a short lifetime due to photolysis. Our data also suggest that the major emission of methyl bromide (CH3Br), and hence most bromine entering the stratosphere, will be anthropogenic.