Aerosol chemical composition

The average number and volume concentration of the major aerosol types are summarized in Table 8.5. 

FIGURE 8.23 Measured size distributions of aerosol sulfate, nitrate, ammonium, chloride, sodium, and hydrogen ion in Claremont, CA (Wall et al. 1988). 

TABLE 8.6 Concentrations (ng m 3) and Size Distribution of Various Elements Found in Atmospheric Particles 

TABLE 8.7 Comparison of Ambient Fine and Coarse Particles 

Formation pathways Chemical reactions Nucleation Condensation Coagulation Cloud/fog processing Mechanical disruption Suspension of dusts 

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When considering the impact of uptake by aerosol, the chemical composition of the aerosol is also likely to be significant. Bates et al. (1998, 2001) measured strong variations in the chemical composition of the Aitken, accommodation and sea-salt dominated coarse modes that would influence the free radical uptake rates, particularly the extent of aerosol acidification. Without data on the size segregated aerosol chemical composition during SOAPEX-2 and the relevant laboratory data, it is not possible to calculate accurate accommodation coefficients. 

Identification of organic components of ambient aerosols and estimation of the contributions of various pathways are of immediate interest for control strat es and could by achieved by using the existing monitoring networks so as to provide more information on aerosol chemical composition. In view of the adverse effects (e.g., on health and visibility) associated with submicrometer aerosols, an air quality standard for submicrometer particles might be more adequate than the present standard for total suspended particles. 

Lehrer, E., D. Wagenbach, and U. Platt, Aerosol Chemical Composition during Tropospheric Ozone Depletion at Ny Alesund/Svalbard, Tellus, 49B, 486-495 (1997). 

Feilberg, A., and T. Nielsen, Effect of Aerosol Chemical Composition on the Photodegradation of Nitro-Polycyclic Aromatic Hydrocarbons, submitted to Environ. Sci. Technol. (1999b). 

Keywords Aerosols, Chemical composition, Long-range transport, Wildfires... 

Lanz VA, Prevot ASH, Alfarra MR, Weimer S, Mohr C, DeCarlo PF, Gianini MFD, Hueglin C, Schneider J, Favez O, D Anna B, George C, Baltensperger U (2010) Characterization of aerosol chemical composition with aerosol mass spectrometry in central Europe an overview. Atmos Chem Phys 10 10453-10471. doi 10.5194/acp-10-10453-2010... 

Also special care should be taken to reduce uncertainties on emission data and measurements. The validation of an aerosol model requires the analysis of the aerosol chemical composition for the main particulate species (ammonium, sulphate, nitrate and secondary organic aerosol). To find data to perform this kind of more complete evaluation is not always easy. The same applies to emissions data. The lack of detailed information regarding the chemical composition of aerosols obliges modellers to use previously defined aerosols components distributions, which are found in the literature. Present knowledge in emission processes is yet lacunal, especially concerning suspension and resuspension of deposited particles [37]. 

The observational program included getting information about the content and properties of atmospheric aerosol and most substantial optically active MGCs (03, CO, NOx, S02, etc.), but concentrated on aerosol studies to retrieve data on direct and indirect aerosol RF (ARF). The most interesting (and in many respects unexpected) results were connected with detection of a thick aerosol layer in the troposphere (an important feature of aerosol chemical composition consisted in the presence of a considerable black carbon component) and distinct manifestations of the long-range transport of both aerosol and MGCs. 

The influence of aerosols on radiative forcing depends on the balance between three essential quantities single-scattering albedo, upscatter fraction, and optical depth—all are sensitive functions of the aerosol chemical composition and size distribution in the 0.1 to 1.0 pm range [1,14]. Aerosol climate forcing, AF, depends on geophysical and aerosol parameters and can be expressed as... 

Andreae, M. O., T. W. Andreae, H. Annegarn, F, Beer, H. Cachier, W, Elbert, G. W. Harris, W. Maenhaut, I. Salma, R. Swap, F. G. Wienhold, and T. Zenker. 1998. Airborne studies of aerosol emissions from savanna fires in southern Africa 2. Aerosol chemical composition. Journal of Geophysical Research 103 32119-32128. 

Lehrer E., Wagenbach D., and Platt U. (1997) Aerosol chemical composition during tropospheric ozone depletion at Ny Alesund/Svalbard. Tellus 49B, 486-495. 

Further in.sighl into atmospheric aerosol dynamics can be obtained by analyzing variations in aerosol chemical composition with lime at a given sampling site. Many long-time... 

The inputs to these calculations are [TA], [TN], temperature, and relative humidity, and the results are the gas and aerosol chemical compositions (Figure 9.22). 

The link between aerosol chemical composition and CCN behavior is still not completely understood. Whereas behavior of soluble inorganic aerosols is relatively well established, much less is known about the ability of organic aerosols (alone or mixed with inorganic components) to serve as CCN. 

Lee, C., Kim, Y.J., Tanimoto, H., Bobrowski, N., Platt, U., Mori, T., Yamamoto, K., Hong, C.S. High CIO and ozone depletion observed in the plume of Sakurajima volcano, Japan. Geophys. Res. Lett. 32, L21809 (2005). doi 10.1029/2005GL023785 Lehrer, E., Wagenbach, D., Platt, U. Aerosol chemical composition during tropospheric ozone depletion at Ny Alesund/Svalbard. Tellus B 49,486-495 (1997)... 

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