What caused extreme ozone concentrations over Cotonou in December 2005
What caused extreme ozone concentrations over Cotonou in December 2005
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2005 年 12 月科托努上空臭氧浓度极高的原因是什么
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
B. Cros
中科院分区：
文献类型：
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作者：
A. Minga;V. Thouret;M. Saunois;C. Delon;D. Serça;C. Mari;B. Sauvage;A. Mariscal;M. Leriche;B. Cros
摘要。本文报道了非洲极端臭氧测量的第一个记录。作为AMMA项目的一部分，12月20日在科托努上空记录的臭氧垂直剖面图显示，1公里高度的臭氧浓度异常高，高达295 ppb。Flexpart模型的后羽显示，当天在科托努上空1公里处采样的气团来自科托努东北部的燃烧区，并经过受城市污染严重影响的尼日利亚拉各斯。我们使用主机制盒模型来模拟烟羽在其移动过程中的化学成分。我们发现，无论是臭氧前体的生物质燃烧排放，还是拉各斯的额外城市排放，都不足以模拟超过120-150 ppb的臭氧。要在几小时内达到近300 ppb的臭氧浓度，唯一的方法是向空气中注入大量的活性挥发性有机化合物，就像在石化区附近记录的那样。灵敏度测试表明，250 - 600 ppb的挥发性有机化合物与35-80 ppb的氮氧化物相结合，使臭氧浓度高于250 ppb。尼日利亚是非洲第一个拥有天然气开采和石化工业的国家，拉各斯附近经常发生石化爆炸。该地区石化爆炸的假设是最有可能的情况，这可以解释在拉各斯下风的科托努测量到的295 ppb臭氧最大值。
Abstract. This paper reports the first record of extreme ozone measurements in Africa. As part of the AMMA program, the ozone vertical profile recorded on 20 December over Cotonou presents exceptionally high ozone concentrations with up to 295 ppb at 1 km altitude. Retroplumes from the Flexpart model show that the air masses sampled at 1 km over Cotonou on this day came from the burning area situated north-east of Cotonou and passed over Lagos, Nigeria, which is highly impacted by urban pollution. We used the Master Mechanism box model to simulate the chemical composition of the plume during its transit. We find that neither the biomass burning emissions of ozone precursors nor additional urban emissions from Lagos are high enough to simulate more than 120–150 ppb of ozone. The only way to reach almost 300 ppb of ozone within a few hours is to feed the air mass with large amounts of reactive VOCs as those recorded in the vicinity of petrochemical area. Sensitivity tests show that 250–600 ppb of VOCs combined with 35–80 ppb of NOx allow the ozone concentrations to be higher than 250 ppb. Nigeria is the first African country with gas extraction and petrochemical industries, and petrochemical explosions frequently happen in the vicinity of Lagos. The hypothesis of a petrochemical explosion in this area is the most likely scenario which could explain the 295 ppb ozone maximum measured over Cotonou, downwind of Lagos.