Atmospheric Bases-Enhanced Iodic Acid Nucleation: Altitude-Dependent Characteristics and Molecular Mechanisms,Environmental Science & Technology

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Atmospheric Bases-Enhanced Iodic Acid Nucleation: Altitude-Dependent Characteristics and Molecular Mechanisms
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2024-09-09 , DOI: 10.1021/acs.est.4c06053
Jing Li ₁ , An Ning ₁ , Ling Liu ₁ , Xiuhui Zhang ₁

Affiliation

Iodic acid (IA), the key driver of marine aerosols, is widely detected within the gas and particle phases in the marine boundary layer (MBL) and even the free troposphere (FT). Although atmospheric bases like dimethylamine (DMA) and ammonia (NH₃) can enhance IA particles formation, their different efficiencies and spatial distributions make the dominant base-stabilization mechanisms of forming IA particles unclear. Herein, we investigated the IA–DMA–NH₃ nucleation system through quantum chemical calculations at the DLPNO–CCSD(T)/aug-cc-pVTZ(-PP)//ωB97X-D/6-311++G(3df,3pd) + aug-cc-pVTZ-PP level of theory and cluster dynamics simulations. We provide molecular-level evidence that DMA and NH₃ can jointly stabilize the IA clusters. The formation rates of IA clusters initially decline before rising from the MBL to the FT, owing to variations in mechanism. In the MBL, IA–DMA nucleation predominates, while the contribution of IA–DMA–NH₃ synergistic nucleation cannot be overlooked in polar and NH₃-polluted regions. In the lower FT, IA–DMA–NH₃ nucleation prevails, whereas in the upper FT, IA–NH₃ nucleation dominates. The efficiency of IA–DMA–NH₃ nucleation is comparable to that of IA-iodous acid nucleation in the MBL and sulfuric acid-NH₃ nucleation in the FT. Hence, the IA–DMA–NH₃ mechanism holds promise for revealing the missing sources of tropospheric IA particles.

中文翻译：

大气碱增强碘酸成核：海拔依赖性特征和分子机制

碘酸 (IA) 是海洋气溶胶的关键驱动因素，在海洋边界层 (MBL) 甚至自由对流层 (FT) 的气相和颗粒相中广泛检测到。尽管二甲胺 (DMA) 和氨 (NH ₃ ) 等大气碱可以增强 IA 颗粒的形成，但它们不同的效率和空间分布使得形成 IA 颗粒的主要碱稳定机制尚不清楚。在此，我们通过量子化学计算在DLPNO–CCSD(T)/aug-cc-pVTZ(-PP)//ωB97X-D/ _6-311 ++G(3df, 3pd) + aug-cc-pVTZ-PP 理论和簇动力学模拟水平。我们提供了分子水平的证据表明 DMA 和 NH ₃可以共同稳定 IA 簇。由于机制的变化，IA簇的形成率最初下降，然后从MBL上升到FT。在MBL中，IA-DMA成核占主导地位，而IA-DMA-NH ₃协同成核的贡献在极性和NH ₃污染区域中不可忽视。在较低的 FT 中，IA-DMA-NH ₃成核占主导地位，而在较高的 FT 中，IA-NH ₃成核占主导地位。 IA-DMA-NH ₃成核的效率与MBL 中IA-碘酸成核和FT 中硫酸-NH ₃成核的效率相当。因此，IA-DMA-NH ₃机制有望揭示对流层 IA 粒子的缺失来源。

更新日期：2024-09-09

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