Contribution of the gas-phase reaction between hydroxyl radical and sulfur dioxide to the sulfate aerosol over West Pacific-猫眼课题宝

DOI：

10.5194/acp-2021-788

发表时间：

2021-10

期刊：

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其他

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作者：

Yu‐Wen Chen;Yi-Chun Chen;C. Chou;H. Hung;S. Chang;L. Eirenschmalz;M. Lichtenstern;H. Ziereis;H. Schlager;G. Stratmann;K. Kaiser;J. Schneider;S. Borrmann;F. Obersteiner;Eric Förster;A. Zahn;Wei‐Nai Chen;P. Lin;Shuenn-Chin Chang;M. D. Andrés Hernández;Pao K. Wang;J. Burrows

抽象。硫酸盐是大气气溶胶或细颗粒物的主要成分之一。含有硫酸盐的气溶胶会导致空气质量下降、生态系统受损并影响气候变化。硫酸盐气溶胶可能来源于直接排放到大气中的硫酸盐气溶胶和大气物理化学过程产生的硫酸盐气溶胶。后者是由二氧化硫（SO2）通过氧化在气相反应或在水相中产生的。已经提出了几种SO2氧化的机制，但各种机制的区分和来源的识别仍然具有挑战性。为了满足这一需求，提出并研究了一种估算羟基自由基（OH）与SO2气相反应对硫酸盐气溶胶贡献的新方法。简而言之，我们认为OH反应率的各个微量气体，竞争OH自由基与SO2在对流层中，并估计分数的SO2-OH反应中的总OH反应。通过统计分析SO2-OH反应与大气中硫酸盐浓度的关系，探讨了大气气溶胶中硫酸盐的来源。我们测试这种方法使用的数据，从地面观测和飞机测量期间的影响，大城市的区域到全球尺度的污染物在亚洲（EMeRGe-Asia）在台湾西部和西太平洋地区的运输和转化。我们的研究结果表明，估计的SO2-OH反应性分数与硫酸盐浓度有很好的相关性。SO2-OH反应产生的硫酸盐约占研究区地表和近地表（海拔< 600 m）气溶胶中硫酸盐总量的30%，与其他模式模拟的结果相当。在其假设和局限性内，这种新方法为研究区域和全球SO2-OH反应的重要性提供了一种有价值的方法。

Abstract. Sulfate is among the major components of atmospheric aerosols or fine particulate matters. Aerosols loaded with sulfate result in low air quality, damage to ecosystems, and influences on climate change. Sulfate aerosols could originate from that directly emitted to the atmosphere and that produced by atmospheric physicochemical processes. The latter is generated from sulfur dioxide (SO2) via oxidation either in the gas phase reactions or in the aqueous phase. Several mechanisms of SO2 oxidation have been proposed, but the differentiation of the various mechanisms and identification of the sources remain challenging. To meet this need, a new method to estimate the contribution of the gas-phase reaction between hydroxyl radical (OH) and SO2 to the sulfate aerosol is proposed and investigated. Briefly, we consider the OH-reaction rates of the respective trace gases that compete for OH radicals with SO2 in the troposphere, and estimate the fraction of SO2-OH reaction in the total OH reactivity. Then the relationship between sulfate concentration and the SO2-OH reaction is analyzed statistically to investigate the sources of sulfate in aerosols. We test this method using the data from ground-based observations and aircraft measurements made during the Effect of Megacities on the transport and transformation of pollutants on the Regional to Global scales in Asia (EMeRGe-Asia) over the western Taiwan and West Pacific regions. Our results show that the estimated SO2-OH reactivity fraction is well-correlated with sulfate concentration. The sulfate production from SO2-OH reaction accounts for approximately 30 % of the total sulfate in aerosols collected at the surface and near-surface (altitude < 600 m) in our study area, comparable to the estimates from other model simulations. Within its assumptions and limitations, this new method provides a valuable approach to investigate the significance of SO2-OH reaction regionally and globally.

Contribution of the gas-phase reaction between hydroxyl radical and sulfur dioxide to the sulfate aerosol over West Pacific

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