Halogenation processes of secondary organic aerosol and implications on halogen release mechanisms
Halogenation processes of secondary organic aerosol and implications on halogen release mechanisms
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DOI：
10.5194/acp-12-5787-2012
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发表时间：
2012-07
影响因子：
6.3
通讯作者：
J. Ofner;N. Balzer;J. Buxmann;H. Grothe;P. Schmitt‐Kopplin;U. Platt;C. Zetzsch
中科院分区：
文献类型：
--
作者：
J. Ofner;N. Balzer;J. Buxmann;H. Grothe;P. Schmitt‐Kopplin;U. Platt;C. Zetzsch
抽象的。反应性卤素物质 (RHS)，例如 X·、X 2 和含有 X = 氯和/或溴的 HOX，由各种来源释放，例如光激活海盐气溶胶或从盐田和盐湖。尽管对 RHS 反应进行了许多研究，但 RHS 与二次有机气溶胶 (SOA) 和生物质燃烧产生的有机气溶胶 (BBOA) 反应的潜力却被忽视了。此类反应可构成对流层边界层中气态有机卤素化合物或卤化有机物的来源，并可影响大气气溶胶的物理化学性质。来自 α-蒎烯、儿茶酚和愈创木酚的 SOA 模型用于研究与 RHS 的异质相互作用。在紫外/可见光照射下，颗粒在气溶胶烟雾室中暴露于分子氯和溴，以及从模拟天然卤素源（如盐盘）释放的 RHS。随后，使用各种物理化学和光谱方法对气溶胶进行了详细表征。基本特征与异质卤化相关，从而产生新的官能团（FTIR 光谱）、改变 UV/VIS 吸收、化学成分（超高分辨率质谱 (ICR-FT/MS)）或气溶胶尺寸分布。然而，卤素释放机制也被发现受到有机气溶胶存在的影响。这些相互作用过程、气溶胶化学和物理特性的变化可能会影响例如气溶胶充当云凝结核的能力，其吸附其他低挥发性气体的潜力，或其对辐射强迫和最终地球辐射平衡的贡献。
Abstract. Reactive halogen species (RHS), such as X·, X 2 and HOX containing X = chlorine and/or bromine, are released by various sources like photo-activated sea-salt aerosol or from salt pans, and salt lakes. Despite many studies of RHS reactions, the potential of RHS reacting with secondary organic aerosol (SOA) and organic aerosol derived from biomass-burning (BBOA) has been neglected. Such reactions can constitute sources of gaseous organohalogen compounds or halogenated organic matter in the tropospheric boundary layer and can influence physicochemical properties of atmospheric aerosols. Model SOA from α-pinene, catechol, and guaiacol was used to study heterogeneous interactions with RHS. Particles were exposed to molecular chlorine and bromine in an aerosol smog-chamber in the presence of UV/VIS irradiation and to RHS, released from simulated natural halogen sources like salt pans. Subsequently, the aerosol was characterized in detail using a variety of physicochemical and spectroscopic methods. Fundamental features were correlated with heterogeneous halogenation, which results in new functional groups (FTIR spectroscopy), changes UV/VIS absorption, chemical composition (ultrahigh resolution mass spectroscopy (ICR-FT/MS)), or aerosol size distribution. However, the halogen release mechanisms were also found to be affected by the presence of organic aerosol. Those interaction processes, changing chemical and physical properties of the aerosol are likely to influence e.g. the ability of the aerosol to act as cloud condensation nuclei, its potential to adsorb other gases with low-volatility, or its contribution to radiative forcing and ultimately the Earth's radiation balance.