5 - Atmospheric Chemistry

Abstract

This chapter focuses on some of the basic concepts and principles underlying atmospheric chemistry, as illustrated by the effects of both natural and anthropogenic trace constituents. It also focuses on gas-phase chemistry and atmospheric aerosols. Atmospheric chemistry studies were originally concerned with determining the major gases in the Earth's atmosphere. In the latter half of the past century, as air pollution became an increasing problem in many large cities, attention turned to identifying the sources, properties, and effects of the myriad of chemical species that exist in the natural and polluted atmosphere. Acid deposition led to the realization that chemical species emitted into the atmosphere can be transported over large distances and undergoes significant transformations as they move along their trajectories. In 1985, the identification of significant depletion of ozone in the Antarctic stratosphere focused attention on stratospheric chemistry and the susceptibility of the stratosphere to modification. More recently, studies of the effects of trace chemical constituents in the atmosphere on the climate of the Earth have moved to center stage.