Université d'Abobo-Adjamé, UFR-SFA, Laboratoire de Physique Fondamentale et Appliquée (LPFA), 02 B.P. 801 Abidjan 02, Cote d'Ivoire.
Chemosphere. 2011 Sep;84(11):1617-29. doi: 10.1016/j.chemosphere.2011.05.016.
The purpose of this paper is to study the redistribution of chemical species (OH, HO(2), H(2)O(2), HNO(3) and H(2)SO(4)) over West Africa, where the cloud cover is ubiquitously present, and where deep convection often develops. In this area, because of these cloud systems, chemical species are redistributed by the ascending and descending flow, or leached if they are soluble. So, we carry out a mesoscale study using the Regional Atmospheric Modelling System (RAMS) coupled to a code of gas and aqueous chemistry (RAMS_Chemistry). It takes into account all processes under mesh. We examine several cases following the period (November and July), with inputs emissions (anthropogenic, biogenic and biomass burning). The radicals OH and HO(2) are an indicator of possibilities for chemical activity. They characterize the oxidizing power of the atmosphere and are very strong oxidants. The acids HNO(3) and H(2)SO(4) are interesting in their transformation into nitrates and sulfates in precipitation. In November, when photochemistry is active during an event of biomass burning, concentrations of chemical species are higher than those of November in the absence of biomass burning. The concentrations of nitric acid double and sulfuric acid increases 70times. In addition, the concentrations are even lower in July if there is a deep convection. Compared to measures of the African Monsoon Multidisciplinary Analysis (AMMA), the results and observations of radicals OH and HO(2) are the same order of magnitude. Emissions from biomass burning increase the concentrations of acid and peroxide, and a deep convection cloud allows the solubility and the washing out of species, reducing their concentration. Rainfalls play a major role in solubility and washing out acids, peroxides and radicals in this region.
本文旨在研究化学物质（OH、HO(2)、H(2)O(2)、HNO(3)和 H(2)SO(4))在广泛存在云层且深对流经常发生的西非的再分布情况。在这个地区，由于这些云系统的存在，化学物质会通过上升和下降气流重新分布，或者如果它们是可溶的，就会被淋洗。因此，我们使用区域大气建模系统（RAMS）与气体和水化学代码（RAMS_Chemistry）进行了中尺度研究。它考虑了网格下的所有过程。我们检查了几个案例，这些案例是在（11 月和 7 月）期间，输入了排放物（人为的、生物的和生物质燃烧的）。自由基 OH 和 HO(2)是化学活性可能性的指标。它们表征了大气的氧化能力，是非常强的氧化剂。酸 HNO(3)和 H(2)SO(4)在转化为硝酸盐和硫酸盐方面很有趣。在 11 月，当光化学在生物质燃烧事件中活跃时，化学物质的浓度高于没有生物质燃烧的 11 月的浓度。硝酸的浓度增加了两倍，硫酸的浓度增加了 70 倍。此外，如果存在深对流，7 月的浓度甚至更低。与非洲季风多学科分析（AMMA）的测量结果相比，自由基 OH 和 HO(2)的结果和观测结果处于同一数量级。生物质燃烧的排放物增加了酸和过氧化物的浓度，深对流云允许物质的溶解度和淋洗，从而降低了它们的浓度。降雨在该地区的酸、过氧化物和自由基的溶解度和淋洗中起着重要作用。
