Photochemical Cycling Between Humic-Like Substances and Simple Dicarbonylic Species in the Atmospheric Aerosol

大气气溶胶中腐殖质类物质和简单二羰基物质之间的光化学循环

• 批准号: 0714329
• 负责人: Michael Hoffmann
• 金额: --
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-07-01 至 2010-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0714329&HistoricalAwards=false
• 关键词: Photochemical; Cycling; Between; Humic; Like

Both the physical state and the chemical transformations of organic matter in atmospheric aerosols remain a complex problem. Atmospheric chemists have often sought the identification and quantitation of discrete low molecular weight (MW) compounds such as hydrocarbons, lipids, fatty acids and other identifiable compound classes. However, a mass balance of these constituents often falls short of the total carbon present in many aerosol phases. Organic aerosol formation by in-situ photochemical oxidation of gas phase trace species, their subsequent condensation and perhaps polymerization on existing airborne particles is a known path for the accretion of organic phases in aerosols and droplets. Colored biogenic polymers are widespread in soils, aquatic and marine environments and compounds similar to these are also increasingly being studied in aerosol systems. Photochemical driven degradation of these ''humic-like'' substances may be another path to the complex organic substances found in atmospheric aerosol systems. Based on initial laboratory studies of the aqueous phase photolysis of pyruvic acid, Caltech investigators seek to further investigate the photocrosslinking of a-dicarbonylic and oxocarboxylic acids in the presence of natural macromolecular mater as indicators of the kinds of photochemical cycling which may be responsible for some of the higher molecular weight organic matter found in atmospheric aerosols.

大气气溶胶中有机物的物理状态和化学转化仍然是一个复杂的问题。大气化学家经常寻求鉴定和定量离散的低分子量（MW）化合物，如碳氢化合物、脂类、脂肪酸和其他可识别的化合物类别。然而，这些成分的质量平衡往往低于许多气溶胶相中存在的总碳量。有机气溶胶的形成是由气相痕量物质的原位光化学氧化，它们随后的冷凝和可能的聚合在现有的空气中粒子上，这是一个已知的气溶胶和液滴中有机相增加的途径。有色生物源性聚合物广泛存在于土壤、水生和海洋环境中，类似的化合物在气溶胶系统中的研究也越来越多。光化学驱动的这些“腐殖质样”物质的降解可能是大气气溶胶系统中发现的复杂有机物质的另一条途径。基于对丙酮酸的水相光解的初步实验室研究，加州理工学院的研究人员寻求进一步研究在天然大分子物质存在的情况下，二羰基酸和氧羧酸的光交联，作为光化学循环的指示物，这可能是大气气溶胶中发现的一些高分子量有机物质的原因。