Environmental Sciences Section, Bose Institute, P 1/12 CIT Scheme VII-M, Kolkata, 700054, India.
Department of Physics, Bose Institute, 93/1, A.P.C Road, Kolkata, 700009, India.
Sci Rep. 2018 Jan 9;8(1):129. doi: 10.1038/s41598-017-18292-z.
Substantial impacts on climate have been documented for soot‒sulfuric acid (HSO) interactions in terms of optical and hygroscopic properties of soot aerosols. However, the influence of HSO on heterogeneous chemistry on soot remains unexplored. Additionally, oxidation rate coefficients for polycyclic aromatic hydrocarbons intrinsic to the atmospheric particles evaluated in laboratory experiments seem to overestimate their degradation in ambient atmosphere, possibly due to matrix effects which are hitherto not mimicked in laboratory experiments. For the first time, our kinetics study reports significant influence of HSO coating on heterogeneous ozonation of benzo(a)pyrene (BaP) deposited on model soot, representative to atmospheric particles. The approximate specific surface area of model soot (5 mg) was estimated as a measure of the availability of surface molecules to a typical gaseous atmospheric oxidant. Heterogeneous bimolecular reaction kinetics and Raman spectroscopy studies suggested plausible reasons for decreased BaP ozonation rate in presence of HSO: 1. decreased partitioning of O on soot surface and 2. shielding of BaP molecules to gaseous O by acid-BaP reaction or O oxidation products.
已有大量文献记录了黑碳-硫酸（HSO）相互作用对黑碳气溶胶光学和吸湿性的重大影响。然而，HSO 对黑碳非均相化学反应的影响仍未得到探索。此外，在实验室实验中评估的大气颗粒中固有的多环芳烃的氧化速率系数似乎高估了它们在环境大气中的降解，这可能是由于迄今为止实验室实验中未模拟的基质效应。我们的动力学研究首次报道了 HSO 涂层对模型黑碳上沉积的苯并（a）芘（BaP）的非均相臭氧化的显著影响，该模型黑碳代表了大气颗粒。模型黑碳（5 毫克）的近似比表面积被估计为表面分子对典型气态大气氧化剂的可用性的度量。非均相双分子反应动力学和拉曼光谱研究为 BaP 在 HSO 存在下臭氧化速率降低提出了合理的原因：1. 黑碳表面上 O 的分配减少和 2. 酸-BaP 反应或 O 氧化产物对 BaP 分子的屏蔽。
