Laboratory Studies of Contact Efflorescence

接触风化的实验室研究

• 批准号: 1506691
• 负责人: Margaret Tolbert
• 金额: $ 43.84万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-15 至 2019-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1506691&HistoricalAwards=false
• 关键词: Laboratory; Studies; Contact; Efflorescence

As atmospheric relative humidity cycles, saline aerosols exist either as ionic salts, or as aqueous ionic solution. Supersaturated and undersaturated phase change typically demonstrate hysteresis behavior as a function of relative humidity. The (increasing) RH at which the phase transition abruptly changes from solid particle to a saturated aqueous solution is the deliquescence relative humidity (DRH). The decreasing RH that drying aqueous droplets remain as supersaturated sols until crystallization, is the efflorescence relative humidity (ERH). Efflorescence may differ based on the nucleation mechanism, either by contact with a seed, or immersion of that seed into the supersaturated droplet. The objective of a series of laboratory investigations is to further study contact efflorescence compared to immersion efflorescence on aerosol types and sizes representative of atmospheric particles. Aerosol phase changes in a single droplet optical trap will be used to systematically follow efflorescence mechanisms. The importance of accounting for aerosol particle phase changes includes effects on heterogeneous chemical processes, light scattering, and cloud formation and precipitation. Direct effects on homogeneous (gas phase) chemistry and climate also remain uncertain.

随着大气相对湿度的循环，盐气溶胶要么以离子盐的形式存在，要么以水离子溶液的形式存在。作为相对湿度的函数，过饱和和不饱和相变通常表现出滞后行为。从固体颗粒到饱和水溶液相变的(增加)相对湿度是潮解相对湿度(DRH)。干燥水滴在结晶前以过饱和胶体形式存在的递减相对湿度是风化相对湿度。根据成核机制的不同，开花可能不同，要么是通过接触种子，要么是通过将种子浸入过饱和的液滴中。一系列实验室调查的目的是进一步研究接触风化和浸泡风化对代表大气颗粒物的气溶胶类型和大小的影响。单液滴光学陷阱中的气溶胶相变将被用来系统地跟踪风化机理。考虑气溶胶颗粒相变的重要性包括对非均相化学过程、光散射以及云的形成和降水的影响。对均相(气相)化学和气候的直接影响也仍然不确定。