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.

随着大气相对湿度循环，盐气溶胶以离子盐或离子水溶液的形式存在。过饱和和欠饱和相变通常表现出作为相对湿度函数的滞后行为。相变从固体颗粒突然变为饱和水溶液时的（增加的）RH 是潮解相对湿度（DRH）。干燥水滴在结晶之前保持过饱和溶胶的相对湿度降低，即风化相对湿度 (ERH)。风化可能因成核机制而异，要么通过与种子接触，要么将种子浸入过饱和液滴中。一系列实验室研究的目的是进一步研究代表大气颗粒的气溶胶类型和尺寸的接触风化与浸没风化的比较。单液滴光阱中的气溶胶相变将用于系统地跟踪风化机制。考虑气溶胶颗粒相变的重要性包括对非均质化学过程、光散射以及云形成和降水的影响。对均相（气相）化学和气候的直接影响也仍然不确定。