The atmospheric aerosol system: An overview

Abstract

Aerosols could play a critical role in many processes which impact on our lives either indirectly (e.g., climate) or directly (e.g., health). However, our ability to assess these possible impacts is constrained by our limited knowledge of the physical and chemical properties of aerosols, both anthropogenic and natural. This deficiency is attributable in part to the fact that aerosols are the end product of a vast array of chemical and physical processes. Consequently, the properties of the aerosol can exhibit a great deal of variability in both time and space. Furthermore, most aerosol studies have focused on measurements of a single aerosol characteristic such as composition or size distribution. Such information is generally not useful for the assessment of impacts because the degree of impact may depend on the integral properties of the aerosol, for example, the aerosol composition as a function of particle size. In this overview we discuss recent work on atmospheric aerosols that illustrates the complex nature of the aerosol chemical and physical system, and we suggest strategies for future research. A major conclusion is that man has had a great impact on the global budgets of certain species, especially sulfur and nitrogen, that play a dominant role in the atmospheric aerosol system. These changes could conceivably affect climate. Large-scale impacts are implied because it has recently been demonstrated that natural and pollutant aerosol episodes can be propagated over great distances. However, at present there is no evidence linking anthropogenic activities with a persistent increase in aerosol concentrations on a global scale. A major problem in assessing man's impact on the atmospheric aerosol system and on global budgets is the absence of aerosol measurements in remote marine and continental areas. This dearth is especially acute for the southern hemisphere, where we could expect natural sources to predominate because of the relatively low level of industrial development and energy utilization.

X‐ray photoelectron spectroscopic studies of the heterogenous reaction of gaseous nitric acid with sodium chloride: Kinetics and contribution to the chemistry of the marine troposphere

“…However, the ratio of chlorine to sodium is often less than that in sea water [Junge, 1956;Martens et al, 1973;Cicerone, 1981;Prospero et al, 1983;Keene et al, 1990] and appears in some cases to be related to the presence of oxides of nitrogen [Martens et al, 1973], which is consistent with finding excess nitrate in the particles. While nitrate may not account for all of the "missing chlorine" [Keene et al, 1990[Keene et al, , 1993aStelson, 1992, 1993], it represents a significant fraction.…”

Estimation of the effect of long-range transport on seasonal variation of aerosols over northeastern India

“…There are several literatures describing the large-scale transport of dust particles (e.g. Prospero et al, 1983;Uematsu et al, 1983;Tyson et al, 1996;Kaufman et al, 2000;Moorthy and Satheesh, 2000;Satheesh and Srinivasan, 2002). In addition to the advection by air masses, the increased solar heating (Fig.…”

Proxies and Measurement Techniques for Mineral Dust in Antarctic Ice Cores

“…Mineral dust aerosol is an important part of the climate system (1)(2)(3). Apart from sea salt it is the most abundant primary aerosol and influences the radiative energy budget of the atmosphere (4).…”