Acid aerosol, description

Acid aerosol, description, 58 Acidification effects of airborne sulfur compounds, 62-63,64/... 

Descriptions of analytical methods for strong acid and acidic sulfate content of atmospheric aerosols have been reviewed (6-10). Methods for acidic aerosol determination are reviewed in this chapter according to the measurement principle either filter collection and post-collection extraction, deriv-atization or thermal treatment, and analysis or in situ collection (real-time or stepwise) and analysis. 

In 1987, NAPAP added inhalation health effects to their "final" assessment, which is scheduled for completion by the end of 1990 a descriptive account of the "state of the science" was released in 1989 (Graham et al., 1989). In 1988, CASAC requested EPA to take steps toward listing acid aerosols as a criteria pollutant these steps included a 1988 symposium on measurements (Tropp, 1989) and plans for an intercomparison of measurement methods in 1990. NIEHS sponsored several new epidemiological studies focusing on acid aerosols, beginning in 1988. 

Aerosol Dynamics. Inclusion of a description of aerosol dynamics within air quaUty models is of primary importance because of the health effects associated with fine particles in the atmosphere, visibiUty deterioration, and the acid deposition problem. Aerosol dynamics differ markedly from gaseous pollutant dynamics in that particles come in a continuous distribution of sizes and can coagulate, evaporate, grow in size by condensation, be formed by nucleation, or be deposited by sedimentation. Furthermore, the species mass concentration alone does not fliUy characterize the aerosol. The particle size distribution, which changes as a function of time, and size-dependent composition determine the fate of particulate air pollutants and their... 

The composition of liquid-water clouds and processes responsible for this composition are of obvious current interest in conjunction with the so-called acid precipitation phenomenon since clouds constitute the immediate precursor of precipitation. Additionally, cloud composition is of interest because impaction of cloud droplets on surfaces may directly deliver dissolved substances onto natural or artificial materials. In-cloud processes also influence clear-air composition since dissolved substances resulting from such reactions are released into clear air as gases or aerosol particles upon cloud evaporation. It is thus desired to gain enhanced description of the composition of clouds and the mecha-... 

In the quadrature method of moments (QMOM) developed by McGraw [131], for the description of sulfuric acid-water aerosol dynamics (growth), a certain type of quadrature function approximations are introduced to approximate the evolution of the integrals determining the moments. Marchisio et al [122, 123] extended the QMOM for the application to aggregation-breakage processes. For the solution of crystallization and precipitation kernels the size distribution function is expressed using an expansion in delta functions [122, 123] ... 

---