Atmospheric sulfate aerosols have important impacts on air quality, climate, and human and ecosystem health. However, current air-quality models generally underestimate the rate of conversion of sulfur dioxide (SO2) to sulfate during severe haze pollution events, indicating that our understanding of sulfate formation chemistry is incomplete. This may arise because the air-quality models rely upon kinetics studies of SO2 oxidation conducted in dilute aqueous solutions, and not at the high solute strengths of atmospheric aerosol particles. Here, we utilize an aerosol flow reactor to perform direct investigation on the kinetics of aqueous oxidation of dissolved SO2 by hydrogen peroxide (H2O2) using pH-buffered, submicrometer, deliquesced aerosol particles at relative humidity of 73 to 90%. We find that the high solute strength of the aerosol particles significantly enhances the sulfate formation rate for the H2O2 oxidation pathway compared to the dilute solution. By taking these effects into account, our results indicate that the oxidation of SO2 by H2O2 in the liquid water present in atmospheric aerosol particles can contribute to the missing sulfate source during severe haze episodes.

中文翻译：

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潮解气溶胶颗粒中的过氧化氢快速氧化二氧化硫。


大气硫酸盐气溶胶对空气质量、气候以及人类和生态系统健康具有重要影响。然而，当前的空气质量模型普遍低估了严重雾霾污染事件期间二氧化硫（SO2）转化为硫酸盐的速率，这表明我们对硫酸盐形成化学的理解并不完整。这可能是因为空气质量模型依赖于在稀水溶液中进行的二氧化硫氧化动力学研究，而不是在大气气溶胶颗粒的高溶质强度下进行的。在这里，我们利用气溶胶流反应器，使用 pH 缓冲的亚微米潮解气溶胶颗粒，在相对湿度为 73% 至 90% 的情况下，对过氧化氢 (H2O2) 水氧化溶解 SO2 的动力学进行直接研究。我们发现，与稀溶液相比，气溶胶颗粒的高溶质强度显着提高了 H2O2 氧化途径的硫酸盐形成速率。考虑到这些影响，我们的结果表明，大气气溶胶颗粒中存在的液态水中的 SO2 被 H2O2 氧化可能导致严重雾霾天气期间硫酸盐来源的缺失。