Aerosol size distributions

Fig. 7-12 Schematic of an atmospheric aerosol size distribution. This shows the three mass modes, the main sources of mass for each mode, and the principal processes involved in inserting mass into and removing mass from each mode (m = mass concentration. Dp = particle diameter). (Reproduced with permission from K. T. Whitby and G. M. Sverdrup (1983). California aerosols their physical and chemical characteristics. In "The Character and Origin of Smog Aerosols" (G. M. Hidy, P. K. Mueller, D. Grosjean, B. R. Appel, and J. J. Wesolowski, eds), p. 483, John Wiley, New York.)...

The aerosol size distribution for mine aerosols can be represented adequately by the function (Davies, 1974) ... 

An aerosol size distribution can, therefore, be described in terms of the count median diameter, d, and the geometric standard deviation, a These parameters were obtained from experimental data using a diffusion battery method (Busigin et al., 1980). A diffusion battery is an assembly of a number of cylindrical or rectangular channels. The relative penetration of aerosols through different sizes of diffusion batteries at specified flow rates allows the aerosol size distribution to be calculated. 

Table IV. Activity and Aerosol Size Distributions, Count Median Diameter (CMD) and the Geometric Standard Deviation (indicated in brackets)...

Mine Date Activity size distributions, AMD ( um) Aerosol size distribution ... 

Aerosol size distribution measurements were not made. 

Figure 8. Aerosol size distributions for Jan. 30 (track mine).

Busigin, A., A.W. van der Vooren and C.R. Phillips, Measurement of the Total and Radioactive Aerosol Size Distributions in a Canadian Uranium Mine, Amer. Ind. Hyg. Assoc. J. 42 310-314 (1981). 

The deposition rate of the attached fraction, plotted in Figure 3, is calculated from the aerosol size distribution assuming diffusion and electrophoresis to be the most important deposition mechanisms (Raes et al.,1985a). The accuracy of the absolute values was checked by forming the aerosol mass balance after the generation of a high aerosol concentration.In Table II is compared the decay of the... 

Approaching from another direction, Sinclair et al (1978) and Knutson et al (1984) report that diffusion battery measurements of radon daughter aerosol-size distributions often show a small peak which could be interpreted as the unattached fraction. Its position would indicate diffusion coefficients from 0.0005 to 0.05 cm /sec. 

Recent advances in measurement methods have allowed for the more complete determination of the aerosol size distribution for particles incorporating Po-218. 

Willeke, K., and K. T. Whitby. Atmospheric aerosols Size distribution interpretation. J. Air PoUut. Control Assoc. 25 529-534, 1975. 

Sverdrup, G.M., "Parametric Measurement of Submicron Atmospheric Aerosol Size Distributions " Ph.D. Thesis, Particle Technology Laboratory University of Minnesota, Minneapolis 55455, 1977. 

FIGURE 9.7 Schematic of an atmospheric aerosol size distribution showing four modes. The original hypothesis of Whitby and co-workers is shown by the solid, trimodal curves, and the fourth, ultrafine particle mode, as well as the two peaks sometimes observed in the accumulation mode are shown by the dashed lines (adapted from Whitby and Sverdrup, 1980). 

In a similar vein, the time scales to achieve equilibrium for inorganics have been examined by Meng and Seinfeld (1996), who show that small (submicron) particles can come to equilibrium with the gas phase in less than a few hours typically but that larger particles may not. The major factors determining the time needed to reach equilibrium are the aerosol size distribution,... 

Hoppel, W. A., G. M. Frick, and R. E. Larson, Effect of Nonprecipitating Clouds on the Aerosol Size Distribution in the Marine Boundary Layer, Geophys. Res. Lett., 13, 125-128 (1986). 

Kim, Y., H. Sievering, J. Boatman, D. Wellman, and A. Pszenny, Aerosol Size Distribution and Aerosol Water Content Measurements during Atlantic Stratocumulus Transition Experiment Marine Aerosol and Gas Exchange, J. Geophys. Res., 100, 23027-23038 (1995). 

Eldering, A., and R. M. Glasgow, Short-Term Particulate Matter Mass and Aerosol-Size Distribution Measurements Transient Pollution Episodes and Bimodal Aerosol-Mass Distributions, Atmos. Environ., 32, 2017-2024 (1998). 

Deshler, T D. J. Hofmann, B. J. Johnson, and W. R. Rozier, Balloonborne Measurements of the Pinatubo Aerosol Size Distribution and Volatility at Laramie, Wyoming during the Summer of 1991, Geophys. Res. Lett., 19, 199-202 (1992). 

Steele, H. M., and R. P. Turco, Retrieval of Aerosol Size Distributions from Satellite Extinction Spectra Using Constrained Linear Inversion, J. Geophys. Res., 102, 16737-16747 (1997a). 

Jayaraman et al. (1998) measured the aerosol optical depth, aerosol size distribution, and the solar flux close to the coast of India, over the Arabian Sea, and then... 

Hoppel, W. A., and G. M. Frick, Submicron Aerosol Size Distributions Measured over the Tropical and South Pacific, Atmos. Environ., 24A, 645-659 (1990). 

King, M. D., B. M. Herman, and J. A. Reagan, 1978. Aerosol size distributions obtained by inversion of spectral optical depth measurements, J. Atmos. Sci., 35, 2153-2167. 

Stable aerosol generation is important to maintain a stable atmosphere in the chamber. Good stability of the aerosol size distribution and mass output was observed for Pb aerosol over... 

Distortion of the particle size during the sampling process is a concern in the use of this probe on an aircraft. Compressional heating due to deceleration of the particles may distort the size distribution, because evaporation of water from aerosol particles reduces their diameters. Likewise, particle sizes can be reduced by use of a heater, incorporated into some models of this probe, to prevent icing when supercooled clouds are being flown through. One study (88) indicated that the probe heater removes most of the water from aerosol particles sampled at relative humidities of 95%. Thus, size distributions of aerosol particles measured with the probe heater on correspond to that of the dehydrated aerosol. These results were confirmed by a later study (90) in which size distributions of aerosols measured with a nonintrusive probe were compared to size distributions measured with a de-iced PCASP probe. Measurement of the aerosol size distribution with the probe heater on may be an advantage in certain studies. 

The additional channels in the lower portion of the size spectrum overlap the sizes measured by the ASASP and the PCASP probes and have allowed intercomparisons between aerosol size distributions measured by these two probes (90). Dye et al. have evaluated the capabilities of this probe for measuring the number density and size distribution of atmospheric aerosols (98). 

---