Ozone destruction and bromine photochemistry at ground level in the Arctic spring
Ozone destruction and bromine photochemistry at ground level in the Arctic spring
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DOI：
10.1038/343622a0
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发表时间：
1990-02
期刊：
影响因子：
64.8
通讯作者：
B. Finlayson‐Pitts;F. E. Livingston;H. Berko
中科院分区：
文献类型：
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作者：
B. Finlayson‐Pitts;F. E. Livingston;H. Berko
最近在加拿大Alert(82.5°N，62.3°W)春季进行的北极实地研究表明，地面臭氧浓度从百万分之30-40pp.几乎是每分钟0分。在几个小时到几天的时间内(图2)。1)1，2.同时，收集在纤维素过滤器上的溴的浓度急剧增加，其中50%或更多的溴可归因于HBr1，3等气体化合物。表面臭氧的急剧变化和可过滤溴的增加似乎是由于极地冰盖外逆温层以下的空气平流；在这一空气团中，表面臭氧已被消耗，与溴化合物有关的光化学反应形成了可过滤的溴1。我们报道了实验室实验和计算机动力学模型研究，表明具有光化学活性的溴化合物可能是硝基溴(BrNO2)，它是由N2O5与海盐颗粒中发现的NaBr4反应生成的。BrNO2在日出时会迅速光解，形成破坏臭氧的溴原子。我们提出了关键的现场实验来验证这一假说。
RECENT Arctic field studies in the spring at Alert, Canada (82.5° N, 62.3° W), show that ground-level ozone concentrations fell from 30–40 parts per 109(p.p.b.) to almost 0 p.p.b. in a period of time ranging from a few hours to a few days (Fig. I)1,2. Simultaneously, the concentration of brominated species collected on cellulose filters increases dramatically, with 50% or more of this bromine attributed to gaseous compounds such as HBr1,3. The dramatic change in surface ozone and increase in filterable bromine seem to be due to advection of air below the inversion layer off the polar ice cap; in this air mass, surface ozone has been depleted and filterable bromine formed from photochemical reactions involving bromine compounds1. Here we report laboratory experiments and computer kinetic modelling studies which indicate that the photochemically active bromine compound may be nitryl bromide (BrNO2), formed in the reaction4 of N2O5with NaBr found in sea-salt particles. BrNO2will photolyse rapidly at sunrise, forming ozone-destroying bromine atoms. We propose key field experiments to test this hypothesis.