Aerosol chemistry

Thanks to all colleagues and friends from the former Aerosol Chemistry group, especially Dr. Francesca Guglielmo for inspiration, education and endless debugging support. 

During the last two decades or so several chemistry-transport models have been developed in Europe and elsewhere. They are already widely applied for PM exposure and health-related issues, at local, urban and regional scales, but an effort is still needed to take more advantage of this third generation models (Chemical Transport Models including aerosol chemistry) on epidemiological studies. 

Moldanova J, Ljungstrom E (2001) Sea-Salt Aerosol Chemistry in Coastal Areas A Model Study. J Geophys Res 106 1271... 

To study the chemistry of highly concentrated particles in bulk solution one must avoid mass transfer limitations and the effects of container surfaces. Both of these problems are eliminated by directly using aerosol particles. Two approaches have been used to study aerosol chemistry (1) aerosol reactors in which the evolution of a suspension of particles is followed, and (2) experiments in which the changes occurring in a single particle can be followed. 

Vong,R.J., Simultaneous Observations of Rainwater and Aerosol Chemistry at a Remote Mid-latitude Site, PhD Dissertation, University of Washington, Seattle,WA., 1985. 

Table 2.4 Treatments of aerosol chemistry and microphysics of on-line models... 

Talbot, R. W., M. O. Andreae, H. Berresheim, P. Aitaxo, M. Garstang, R. C. Harriss, K. M. Beecher, and S. M. Li. 1990. Aerosol chemistry during the wet season in central Amazonia The influence of long-range transport. Journal of Geophysical Research 95 16955-16970. 

Novakov T., The role of soot in aerosol chemistry. AIAA-82-0088, 1982, 4 pp. 

Moldanova J. and Ljungstrbm E. (2001) Sea-salt aerosol chemistry in coastal areas a model study. J. Geophys. Res. 

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. 

Analyses of observations of negative ion densities can be used to derive the abundance of H2SO4, as shown, for example, by Arnold and Fabian (1980), Arijs et al. (1981), and Ingels et al. (1987). These observations confirm that the gaseous stratospheric H2SO4 concentration is largely determined by the equilibrium between the aerosol and vapor phases. The gas and aerosol chemistry of sulfur are discussed in detail in the excellent review by Turco et al., (1982). 

It is important to note that denitrification was observed but was rather limited in degree in the Arctic springs of 1993, 1996, and 1997 (Santee et al., 1998 1999), so that the observations of ozone depletion of the order of 60-120 DU in each of these years are not associated with extensive denitrification. Rather, as in the Antarctic and consistent with current understanding of liquid aerosol chemistry, the evidence suggests that heterogeneous reactions in the sunlit atmosphere are... 

Figure 6.23. The top panel shows the total tropospheric chlorine content estimated from the baseline scenario in WMO/UNEP (1998) this is based on a gas-by-gas analysis like those shown in Figure 6.22. The bottom panel shows the changes in the 5-year running mean ozone observed over Switzerland (Staehelin et al., 1998a,b) compared to a model calculation for 45°N applying the same time averaging, with and without considering the effects of volcanic enhancements in aerosol chemistry (from the model of Solomon et al., 1996 1998). The major eruptions since 1980 were those of El Chichon in 1982 and Mt. Pinatubo in 1991. Updated from Solomon (1999).

Chemistry of air pollution, (e.g., photochemical origin of smog acid rain discovery of the relevance of biogenic emissions aerosol chemistry, formation, and microphysics)... 

Trace component behavior (2) control of pollutant plumes in groundwater (1) biogeochemical cycles (10) aerosol chemistry and clouds (2) chemical weather (1) chemistry-climate links (2) air pollution processes (1)... 

As part of the biogeochemical cycle, the injection of iodine-containing gases into the atmosphere, and their subsequent chemical transformation therein, play a crucial role in environmental and health aspects associated with iodine - most importandy, in determining the quantity of the element available to the mammalian diet. This chapter focuses on these processes and the variety of gas- and aerosol-phase species that constitute the terrestrial iodine cycle, through discussion of the origin and measurement of atmospheric iodine in its various forms ( Sources and Measurements of Atmospheric Iodine ), the principal photo-chemical pathways in the gas phase ( Photolysis and Gas-Phase Iodine Chemistry ), and the role of aerosol uptake and chemistry and new particle production ( Aerosol Chemistry and Particle Formation ). Potential health and environmental issues related to atmospheric iodine are also reviewed ( Health and Environment Impacts ), along with discussion of the consequences of the release of radioactive iodine (1-131) into the air from nuclear reactor accidents and weapons tests that have occurred over the past half-century or so ( Radioactive Iodine Atmospheric Sources and Consequences ). 

All the experiments described above give strong indications for the atmospheric reactivity of several PAH with gaseous pollutants or with oxygen in the presence of light. However, in these simulation experiments, both the particle material and the exposure conditions used are often chosen as a function of the available experimental facilities. Thus, simplifications are Introduced (choice of carrier, use of single PAH, etc.) which are certainly appropriate for fundamental studies, but make it difficult to extrapolate kinetic data obtained in laboratory exposures to the actual gas-aerosol chemistry in the atmosphere. 

Due to their importance in clouds, climate and climate change, significant efforts are now being made to incorporate aerosol chemistry and physics into regional and global climate models (see, for example. References [130-132]). 

Table 5.1 classifies how chemical regimes meet in the climate system. We see that almost normal conditions occur and extreme low and high temperatures border the climate system. The chemistry described in the following chapters concerns almost these normal conditions of the climate system. We focus on the troposphere and the interfaces. For example, aqueous phase chemistry in cloud droplets does not differ principally from surface water chemistry (aquatic chemistry) and much soil chemistry does not differ from aerosol chemistry (colloidal chemistry). Plant chemistry, however, is different and only by using the generic terms (Chapter 2.2.2.S) of inorganic interfacial chemistry can we link it. The chemistry of the atmosphere is widely described (Seinfeld and Pandis 1998, Wameck 1999, Finlay-son-Pitts and Pitts 2000, Wayne 2000, Brasseur et al. 2003) and the branches in atmospheric chemistry are well defined (Fig. 5.2). 

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

Design Criteria. Perhaps the most important aspect to be considered relative to biological studies with aerosols is that the aerosol produced be representative in size of the fine particulates, in nature. Additionally, aerosol chemistry and concentrations which are found naturally should be considered. Only conditions been given proper attention Exposure chambers should be non-corrosive... 

Besides in chemistry itself, applications are nowadays found in environmental research and monitoring. For example, applications related to the study of our atmosphere are not uncommon, specifically exploring which natural and man-made processes influence it and the monitoring of pollutants is highly important, as is the investigation of aerosol chemistry. These and other examples are summarized in Chapter 28. 

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