Organic aerosols properties

Hildemann, L. M., Cass, G. R., Mazurek, M. A., and Simoneit, B. R. T. (1993) Mathematical modeling of urban organic aerosols properties measured by high-resolution gas chromatography. Environ. Sci. TechnoL, 27, 2045-2055. 

McKay C. P., Coustenis A., Samuelson R. E. et al. (2001). Physical properties of the organic aerosols and clouds on Titan. Planetary and Space Science 49 79. 

The contribution of the various classes of hydrocarbons to the formation of particulate organic compounds is a complex function of their relative ambient concentrations, gas-phase reactivity, and ability to form products whose physical properties, especially vapor pressures, are of prime importance in the physical mechanisms controlling the gas-to-aerosol conversion process. In view of the results discussed previously, cyclic olefins appear to be the most important class of organic aerosol precursors. This is due to their high gas-phase reactivity and their ability... 

Finally, receptor modeling offers a useful theme around which to organize aerosol characterization studies. Large scale field studies are expensive, and they also tend to be diffuse. Data requirements for source resolution can be used to select the chemical and physical properties of the aerosol to be measured both at receptor sites and at sources. 

The continental biosphere is a large source of hydrocarbons. Quantification of these sources in toms of geophysical (e.g. temperature, humidity, light levels) and biogeochemical (soil physical and chemical properties, land use) parameters is much needed for inclusion in atmospheric models. The hydrocarbon oxidation mechanisms in the atmosphere should also be better understood, so that formation of ozone, carbon monoxide, partially oxidized gaseous hydrocarbons, and organic aerosol can be better quantified. The formation of organic aerosol from hydrocarbon precursors and then-capability to serve as cloud condensation nuclei are issues which need to be studied in depth. 

Hygroscopic, Surface, and Colloidal Properties of Organic Aerosols 474... 

In this chapter, we made an attempt to provide a comprehensive review of the current state-of-the-art on sources, chemical nature, and physical properties of organic aerosols. This review begins with an overview of few basic concepts on atmospheric aerosols, followed by a description of the major constituents of atmospheric aerosols. The sources, transformations, and removal processes of organic aerosols are outlined and followed by an overview of the major environmental and human health issues associated with organic aerosols. The chemical and physical characterization of organic aerosols is then reviewed and is finally followed by a list of uncertainties and suggestions that require further studies. 

Most characteristic sizes of organic particles of marine aerosols do not exceed 10 pm. Data on organic aerosol are rather inadequate and do not even permit one to draw, in general terms, a reliable pattern of its optical properties. No doubt much effort is required before real possibilities appear to consider this component in a general model of aerosol. 

Of a total flux of non-methane reduced organic compounds into the atmosphere of about 1,350 Tg year [35, 36], rally 10% or so leads to organic aerosol [25, 37], However, less than 1 % of the primary organic emissions into the atmosphere have a sufficiently low volatility to remain in the condensed phase under ambient conditions, so SOA formation must be a huge part (90% or more) of the OA story [38]. The straightforward fact is that only a small fraction of all organic compoimds (by mass) in the atmosphere have what it takes to stay on or in a particle. That special property is low volatility, and most compounds acquire that low volatility via chemical transformation in the atmosphere. 

The fundamental property of interest is the equilibrium fraction of a compound in the condensed phase (vs the total in the condensed and vapor phases). With a total concentration of condensed-phase solute (often assumed to be the total concentration of organic aerosol, Cqa)> this is given very simply by... 

Koop T, Bookhold J, Shiraiwa M, Poschl U (2011) Glass transition and phase state of organic compounds dependency on molecular properties and implications for secondary organic aerosols in the atmosphere. Phys Chem Chem Phys 13(43) 19238-19255... 

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