Enhanced ozone loss by active inorganic bromine chemistry in the tropical troposphere
Enhanced ozone loss by active inorganic bromine chemistry in the tropical troposphere
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DOI：
10.1016/j.atmosenv.2017.02.003
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发表时间：
2017-04-01
影响因子：
5
通讯作者：
Percival, Carl J.
中科院分区：
文献类型：
--
作者：
Le Breton, Michael;Bannan, Thomas J.;Percival, Carl J.
溴化学，特别是在热带地区，被认为在对流层臭氧损失中发挥了重要作用，尽管缺乏对活性溴物种的测量阻碍了对其影响的定量了解。Wang等人（2015年）最近对一氧化溴（BrO）的建模和测量显示，目前的模型低于太平洋上空BrO浓度的预测值，并暗示BrO来源缺失。在这里，我们提出了第一个同时飞机测量大气一氧化溴，BrO（一个自由基，沿着原子溴催化破坏臭氧）和无机溴前体化合物HOBr，BrCl和Br-2在西太平洋从0.5至7公里。这四种物质在整个对流层中存在0.17-1.64 pptv的BrO和3.6-8 pptv的总无机Br，导致臭氧总损失的10-20%，并证实了溴化学在热带对流层中的重要性;由于卤素化学，臭氧水平下降了6 ppb。观测结果与全球化学传输模型进行了比较，发现所观察到的高水平的溴，溴氯化物和HOBr可以调和的积极多相氧化的卤化物（溴和氯-）HOBr和臭氧在云滴和气溶胶。测量结果表明，99%的瞬时游离溴在对流层高达8公里起源于无机卤素光解，而不是从光解的有机溴物种。(C)2017由Elsevier Ltd.出版
Bromine chemistry, particularly in the tropics, has been suggested to play an important role in tropospheric ozone loss although a lack of measurements of active bromine species impedes a quantitative understanding of its impacts. Recent modelling and measurements of bromine monoxide (BrO) by Wang et al. (2015) have shown current models under predict BrO concentrations over the Pacific Ocean and allude to a missing source of BrO. Here, we present the first simultaneous aircraft measurements of atmospheric bromine monoxide, BrO (a radical that along with atomic Br catalytically destroys ozone) and the inorganic Br precursor compounds HOBr, BrCI and Br-2 over the Western Pacific Ocean from 0.5 to 7 km. The presence of 0.17-1.64 pptv BrO and 3.6-8 pptv total inorganic Br from these four species throughout the troposphere causes 10-20% of total ozone loss, and confirms the importance of bromine chemistry in the tropical troposphere; contributing to a 6 ppb decrease in ozone levels due to halogen chemistry. Observations are compared with a global chemical transport model and find that the observed high levels of BrO, BrCI and HOBr can be reconciled by active multiphase oxidation of halide (Br and Cl-) by HOBr and ozone in cloud droplets and aerosols. Measurements indicate that 99% of the instantaneous free Br in the troposphere up to 8 km originates from inorganic halogen photolysis rather than from photolysis of organobromine species. (C) 2017 Published by Elsevier Ltd.