Although a large volume of monitoring and computer simulation data exist for global coverage of HF, study of HF in the troposphere is still limited to industry whose primary interest is the safety and risk assessment of HF release because it is a toxic gas. There is very limited information on atmospheric chemistry, emission sources, and the behavior of HF in the environment. We provide a comprehensive review on the atmospheric chemistry of HF, modeling the reactions and transport of HF in the atmosphere, the removal processes in the vertical layer immediately adjacent to the surface (up to approximately 500 m) and recommend research needed to improve our understanding of atmospheric chemistry of HF in the troposphere. The atmospheric chemistry, emissions, and surface boundary layer transport of hydrogen fluoride (HF) are summarized. Although HF is known to be chemically reactive and highly soluble, both factors affect transport and removal in the atmosphere, the chemistry can be ignored when the HF concentration is at a sufficiently low level (e.g., 10 ppmv). At a low concentration, the capability for HF to react in the atmosphere is diminished and therefore the species can be mathematically treated as inert during the transport. At a sufficiently high concentration of HF (e.g., kg/s release rate and thousands of ppm), however, HF can go through a series of rigorous chemical reactions including polymerization, depolymerization, and reaction with water to form molecular complex. As such, the HF species cannot be considered as inert because the reactions could intimately influence the plume’s thermodynamic properties affecting the changes in plume temperature and density. The atmospheric residence time of HF was found to be less than four (4) days, and deposition (i.e., atmosphere to surface transport) is the dominant mechanism that controls the removal of HF and its oligomers from the atmosphere. The literature data on HF dry deposition velocity was relatively high compared to many commonly found atmospheric species such as ozone, sulfur dioxide, nitrogen oxides, etc. The global average of wet deposition velocity of HF was found to be zero based on one literature source. Uptake of HF by rain drops is limited by the acidity of the rain drops, and atmospheric particulate matter contributes negligibly to HF uptake. Finally, given that the reactivity of HF at a high release rate and elevated mole concentration cannot be ignored, it is important to incorporate the reaction chemistry in the near-field dispersion close to the proximity of the release source, and to incorporate the deposition mechanism in the far-field dispersion away from the release source. In other words, a hybrid computational scheme may be needed to address transport and atmospheric chemistry of HF in a range of applications. The model uncertainty will be limited by the precision of boundary layer parameterization and ability to accurately model the atmospheric turbulence.

中文翻译：

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氟化氢的大气化学

尽管存在大量关于 HF 的全球覆盖的监测和计算机模拟数据，但对流层中 HF 的研究仍仅限于主要关注 HF 释放的安全性和风险评估的行业，因为它是一种有毒气体。关于大气化学、排放源和环境中 HF 行为的信息非常有限。我们对 HF 的大气化学进行了全面审查，模拟了 HF 在大气中的反应和传输，紧邻地表（高达约 500 m）的垂直层中的去除过程，并推荐了需要进行的研究以提高我们的理解对流层中 HF 的大气化学。概括了氟化氢 (HF) 的大气化学、排放和表面边界层传输。虽然已知 HF 具有化学反应性和高度溶解性，但这两个因素都会影响大气中的迁移和去除，当 HF 浓度足够低（例如，10 ppmv）时，可以忽略化学反应。在低浓度下，HF 在大气中发生反应的能力会减弱，因此可以在数学上将这些物质在传输过程中视为惰性。然而，在足够高的HF浓度（例如，kg/s释放速率和数千ppm）下，HF可以经历一系列严格的化学反应，包括聚合、解聚和与水反应形成分子复合物。因此，不能将 HF 物质视为惰性物质，因为这些反应会直接影响羽流的热力学特性，从而影响羽流温度和密度的变化。发现 HF 在大气中的停留时间少于四 (4) 天，并且沉积（即大气到表面的传输）是控制从大气中去除 HF 及其低聚物的主要机制。与许多常见的大气物质（如臭氧、二氧化硫、氮氧化物等）相比，HF 干沉降速度的文献数据相对较高。根据一个文献来源，HF 的湿沉降速度的全球平均值为零。雨滴对 HF 的吸收受到雨滴酸度的限制，大气颗粒物对 HF 吸收的贡献可以忽略不计。最后，鉴于 HF 在高释放速率和高摩尔浓度下的反应性不可忽视，重要的是在靠近释放源的近场分散中加入反应化学，并在远离释放源的远场分散中加入沉积机制。换句话说，可能需要一种混合计算方案来解决 HF 在一系列应用中的传输和大气化学问题。模型的不确定性将受到边界层参数化精度和大气湍流准确建模能力的限制。