Atmospheric aerosols have arisen naturally for eons from sea spray, volcanic emissions, wind entrainment of mineral dust, wildfires, and gas-to-particle conversion of hydrocarbons from plants and dimethylsulfide from the oceans. However, over the industrial period the natural background aerosol has been greatly augmented by anthropogenic contributions, i.e., those produced by human activities. Consequently, much recent research focuses on the effects of human activities on the atmosphere and through them, on the environment and Earth's climate. For these reasons consideration of the geochemistry of the atmosphere, and of atmospheric aerosols in particular, must include the effects of human activities. Although comprising only a small fraction of the mass of Earth's atmosphere, aerosol particles are highly important atmospheric constituents. Special interest has focused on aerosols in the troposphere, the lowest part of the atmosphere, extending from the land or ocean surface typically to ~8 km at high latitudes, ~12 km in mid latitudes, and ~16 km at low latitudes. That interest arises in large part because of the importance of aerosol particles in geophysical processes, human health impairment through inhalation, environmental effects through deposition, visibility degradation, and influences on atmospheric radiation and climate. This chapter provides an overview of the loading, geographical distribution, and chemical and physical properties of both natural and anthropogenic atmospheric aerosols, of means of measuring these properties, and of the processes controlling their production, reaction, transport, and ultimate removal -- the "life cycle" of tropospheric aerosols.
This page was last updated 2003-08-22.
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