Anthropogenic Sulfur Perturbations on Biogenic Oxidation: SO2 Additions Impact Gas-Phase OH Oxidation Products of α- and β-Pinene

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• 作者：Beth Friedman ; Patrick Brophy ; William H. Brune ; Delphine K. Farmer
• 刊名：Environmental Science & Technology
• 出版年：2016
• 出版时间：February 2, 2016
• 年：2016
• 卷：50
• 期：3
• 页码：1269-1279
• 全文大小：532K
• ISSN：1520-5851

文摘

In order to probe how anthropogenic pollutants can impact the atmospheric oxidation of biogenic emissions, we investigated how sulfur dioxide (SO₂) perturbations impact the oxidation of two monoterpenes, α-and β-pinene. We used chemical ionization mass spectrometry to examine changes in both individual molecules and gas-phase bulk properties of oxidation products as a function of SO₂ addition. SO₂ perturbations impacted the oxidation systems of α-and β-pinene, leading to an ensemble of products with a lesser degree of oxygenation than unperturbed systems. These changes may be due to shifts in the OH:HO₂ ratio from SO₂ oxidation and/or to SO₃ reacting directly with organic molecules. Van Krevelen diagrams suggest a shift from gas-phase functionalization by alcohol/peroxide groups to functionalization by carboxylic acid or carbonyl groups, consistent with a decreased OH:HO₂ ratio. Increasing relative humidity dampens the impact of the perturbation. This decrease in oxygenation may impact secondary organic aerosol formation in regions dominated by biogenic emissions with nearby SO₂ sources. We observed sulfur-containing organic compounds following SO₂ perturbations of monoterpene oxidation; whether these are the result of photochemistry or an instrumental artifact from ion–molecule clustering remains uncertain. However, our results demonstrate that the two monoterpene isomers produce unique suites of oxidation products.