Atmospheric aerosol chemistry

Cocker D.R. Ill, R.C. Flagan, J.H. Seinfeld State-of-the-art chamber facility for studying atmospheric aerosol chemistry. Envir. Sci. Technol. 35 (2001) 2594-2601. 

Meszaros, E. (1999) Fundamentals of atmospheric aerosol chemistry. Akademiai Kiad6, Budapest, 308 pp. 

The essential elements of urban aerosol chemistry are shown in Figure 2, in which we have represented the chemistry in terms of the conversion of SO2, NO and hydrocarbons to particulate sulfate, nitrate, and organics, respectively. Table VII summarizes the key unknown aspects of the processes depicted in Figure 2. There are many feat ires of atmospheric aerosol chemistry that must be elucidated before we understand fully the formation and growth of atmospheric particles. 

Table VII. Problems in Atmospheric Aerosol Chemistry (Continued)...

Atmospheric aerosols have a direct impact on earth s radiation balance, fog formation and cloud physics, and visibility degradation as well as human health effect[l]. Both natural and anthropogenic sources contribute to the formation of ambient aerosol, which are composed mostly of sulfates, nitrates and ammoniums in either pure or mixed forms[2]. These inorganic salt aerosols are hygroscopic by nature and exhibit the properties of deliquescence and efflorescence in humid air. That is, relative humidity(RH) history and chemical composition determine whether atmospheric aerosols are liquid or solid. Aerosol physical state affects climate and environmental phenomena such as radiative transfer, visibility, and heterogeneous chemistry. Here we present a mathematical model that considers the relative humidity history and chemical composition dependence of deliquescence and efflorescence for describing the dynamic and transport behavior of ambient aerosols[3]. 

Andreae MO, Crutzen (1997) Atmospheric aerosols biogeochemical sources and role in atmospheric chemistry. Science 276 1052-1058. 

Recently was estimated an expected impact on the global chemistry of the atmosphere of the indirect heterogeneous photocatalytic reactions under the much more abundant near ultraviolet, visible and near infrared solar light [2]. As photocatalysts may serve atmospheric aerosols, i.e. ultrasmall solid particles that sometimes are embedded into liquid droplets. Aerosols are known to contain Ti02, Fc203, ZnO and other natural oxides, as well as metal sulfides of volcanic or antropogenic origin, that may serve as semiconductor photocatalysts (see Fig.5). Aerosols are known to be concentrated mainly in the air layers near the surface of the Earth, i.e. in the troposphere, rather than stratosphere. 

This review of the chemistry and physics of microparticles and their characterization is by no means comprehensive, for the very large range of masses that can be studied with the electrodynamic balance makes it possible to explore the spectroscopy of atomic ions. This field is a large one, and Nobel laureates Hans Dehmelt and Wolfgang Paul have labored long in that fruitful scientific garden. The application of particle levitation to atmospheric aerosols, to studies of Knudsen aerosol phenomena, and to heat and mass transfer in the free-molecule regime would require as much space as this survey. 

Macias, E.S. Radcliffe, C.D. Lewis, C.W. Sawicki, C.R., Proton Induced y -ray Analysis of Atmospheric Aerosols for Carbon, Nitrogen and Sulfur Composition, Analytical Chemistry. 1978, 50, 1120-1124. 

The papers in this volume were presented at the ACS symposium Chemical Composition of Atmospheric Aerosol Source/Air Quality Relationships sponsored by the Divisions of Nuclear Chemistry and Technology and Environmental Chemistry. This combination reflects the interdisciplinary nature of much of this work which draws from such diverse fields as nuclear chemistry, chemical and mechanical engineering, environmental science and engineering, and applied math. 

Graedel, T. E., and C. J. Weschler, Chemistry within Aqueous Atmospheric Aerosols and Raindrops, Rev. Geophys. Space Phys., 19, 505-539 (1981). 

Andreae, M. O., and P. J. Crutzen, Atmospheric Aerosols Biogeo-chemical Sources and Role in Atmospheric Chemistry, Science, 276, 1052-1058 (1997). 

Photochemical reactions are central to organic chemistry and are playing a key role in atmospheric aerosols [1], A variety of reactions occur, and the majority of them involve more than one molecule, mostly surrounded by a cluster (e.g., water). A common approach in modeling is to simplify the system and to treat only unimolecular reactions [2, 3], However, understanding the processes involved in cluster is of great interest itself and approaches for modeling those processes need to be developed. 

Compositional analyses of size-segregated particles from ambient atmospheric aerosols are vital for understanding the sources and effects of these aerosols. Three challenges exist for analytical chemistry in the next decade ... 

Milne, P. J., and R. G. Zita. 1993. Amino acid nitrogen in atmospheric aerosols Occurrence, sources and photochemical modification. Journal of Atmospheric Chemistry 16 361-398. 

Maring, H.B. and Duce, R.A. (1987) The impact of atmospheric aerosols on trace metal chemistry in open ocean surface seawater. 1. Aluminium. Earth Planet. Sci. Letts, 84, 281-392. 

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