Aerosol characterization, relation

Gartrell, G., Jr., and S. K. Friedlander. Relating particulate pollution to sources The 1972 California aerosol characterization study. Atmos. Environ. 9 279-299, 1975. 

Gartrell, G. and Friedlander, S. K. (1975). "Relating Particulate Pollution to Sources The 1972 Aerosol Characterization Study," Atmospheric Environment, , 279. 

Gartrell, G. Jr. Heisler, S.L. Friedlander, S.K. Relating Particulate Properties to Sources The Results of the California Aerosol Characterization Experiment. In The Character and Origin of Smog Aerosols, Hidy, G., Ed., J, Wiley, New York, 1980, 665. 

Simoneit B. R. T. (1986) Characterization of organic constituents in aerosols in relation to their origin and transport a review. Int. J. Environ. Analyt. Chem. 23, 207-237. 

In the sections that follow, mathematical methods for characterizing aerosol size and chemical properties are discussed. These are primarily of a definitional nature and are needed to provide a common basis for discussing the broad range of aerosol properties and behavior. However, aerosol characterization does not provide, directly, information on the mechanisms of aerosol formation, or temporal and spatial changes in the aerosol—that is, aerosol transport processes and aerosol tlynatnics. These and related topics are covered in later chapters. Advances in aerosol instrumentation have made it possible to measure many of the most important parameters necessary to characterize aerosols (Chapter 6). However, much rejnains to be done in developing aerosol instrumentation for research as well as industrial and atmospheric applications. 

Receptor Modeling Source Apportionment 380 Basic Concepts 380 Chemical Mass Balance Method 381 Portland Aerosol Characterization Study 382 Relating the CMB to Aerosol Dynamics 385... 

In the presence of an ensemble of aerosols characterized by a distribution function f (ra), the phase function p(0) is deduced from a function related to a specific radius ra by the relation... 

The indirect climatic impact of aerosol at the ABL is determined by numerous interactions between aerosol and the dynamics of the microphysical and optical properties of clouds. The input to the atmosphere of anthropogenic aerosol particles functioning as CCN favors an increase in cloud droplet number density. As mentioned above, the related increase in the optical thickness and albedo of clouds, with their constant water content, was called the first indirect effect , which characterizes the climatic impact of aerosol. 

Aerosol concentrations are defined in different ways depending on the application. For example, particle riumber concentrations (particles per unit volume of gas) are used to characterize dean rooms and atmospheric cloud condensation nuclei federal air pollution standards both for the atmosphere and for industrial emissions are usually stated in terms of aerosol mass per unit volume of gas. Effects of particles on viscosity depend on the ratio of the volume of particulate matter per unit volume of gas. For aerosols composed of particles all the same size, it is easy to relate the different methods of characterizing the concentration. For aerosols of mixed sizes, concentration measures are easily related only in certain cases as discussed below. 

As a result of the complex aerodynamics of the particle beam and associated skimmers, the size distribution of the particles that reach the ion source differs significantly from that in the gas samples from outside the system. To relate the measured chemical compositions to the outside aerosol, it is necessary to correct for this effect. This can be accomplished in principle by determining the elficiency of transmission of particles from the exterior into the chamber. It is also possible to use data for particle size distributions measured outside the spectrometer to characterize the external aerosol. Because the particle size distribution measured with an optical particle counter does not correspond to the aerodynamic diameter, there will be some difficulties of interpretation. 

It was mentioned in Chapter 4 that aerosol particles scatter and absorb solar radiation. These processes depend upon the concentration, size distribution, form, refractive index and absorption coefficient of the particles, as well as upon the wavelength of the radiation. In the case of water-soluble particles the extinction is also controlled by relative humidity (see Section 4.5). The energy absorbed by particles leads to an increase of temperature, while backscattering produces an energy loss for the system. Sines this energy loss may be characterized by the albedo, it is proposed to examine first the relation between albedo and temperature in surface air. 

In connection with studies related to characterization of aerosols released during simulated reactor accidents, experiments are in progress on the physical and chemical properties of copper oxide aerosols generated by fast condenser discharge technique and it is planned to extend the same to nuclear fiiels. 

A further consideration in the characterization of acid aerosols is the mix of compounds present. Newly emerging information on biological responses (see below) shows that the net H concentration is not always sufficient to predict the response. This may relate to the physical behavior of the various compounds as they pass through the respiratory tract. Given the absence of specific measurement methods for the common sulfate salts, the overall molar ratio, either hVSO or NH VSO , is a convenient descriptor for the degree of aerosol neutralization. 

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