The remarkable effect of FeSO₄ seed aerosols on secondary organic aerosol formation from photooxidation of 伪-pinene/NO_x and toluene/NO_x

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• 作者：Biwu Chu^a ; Jiming Hao^a ; ^{hjm-den@tsinghua.edu.cn} ; Hideto Takekawa^b ; Junhua Li^a ; Kun Wang^a ; Jingkun Jiang^a
• 关键词：Ferrous/Ferric sulfate seed aerosols ; 伪-Pinene photooxidation ; Toluene photooxidation ; Secondary organic aerosol ; Suppression effect
• 刊名：Atmospheric Environment
• 出版年：2012
• 期刊代码：11_13522310
• 类别：env
• 出版时间：August, 2012
• 卷：55
• 期：Complete
• 页码：26-34
• 文件大小：1022 K

摘要

To investigate the effects of Fe(II) and Fe(III) ions on secondary organic aerosol (SOA) formation, we conducted a series of photooxidation experiments with 伪-pinene and toluene in the presence of nitric oxides (NO_x) with/without FeSO₄ or Fe₂(SO₄)₃ seed aerosols. The FeSO₄ seed aerosols suppressed SOA formation, while Fe₂(SO₄)₃ seed aerosols did not display a noticeable effect on SOA formation. We did not observe effects of FeSO₄ and Fe₂(SO₄)₃ seed aerosols on gas phase compounds, including ozone, NO_x, and hydrocarbons (HCs). The negative effect of Fe(II)-containing seed aerosols on SOA formation due to the reduction of condensable compounds (CCs) generated from hydrocarbon oxidation is discussed. The mean molecular weight of CCs reduced by Fe(II) is tentatively estimated to be larger than 300, indicating a possibility that many of the CCs reduced by Fe(II) are oligomers. Reduction of oligomer precursors may interrupt the oligomerization of other aldehyde products. If Fe(II) regeneration from photoreduction of Fe(III) is considered, the estimated mean molecular weight of the CCs reduced would be smaller. However, the negligible effect of Fe(III)-containing seed aerosols on SOA formation indicates that Fe(III) photoreduction is negligible in our experiments.