UC Irvine researchers discover how airborne sea salt particles may influence air pollut...( Finding Helps Identify How Chlorine...)

Finding Helps Identify How Chlorine, Ozone and Other Greenhouse Gases Develop From Ocean/Air Interactions

Irvine, Calif., April 13, 2000 -- UC Irvine researchers who study the chemistry of ocean/air interactions have discovered how airborne sea salt particles may be involved in helping to determine the levels of some greenhouse gases as well as air quality in coastal urban areas.

In collaboration with other molecular scientists, Barbara Finlayson-Pitts, a UCI professor of chemistry, and Donald Dabdub, a UCI assistant professor of mechanical and aerospace engineering, have been able to show that sea salt particles--a common ingredient of coastal and ocean air--undergo a previously unrecognized chemical reaction in daylight to release chlorine molecules, which can influence ozone levels in the lower atmosphere.

Their findings appear in the April 14 issue of Science.

In sunlight, these molecules decompose into highly reactive chlorine atoms. When these atoms are formed in the presence of pollutants emitted from fossil fuel energy sources such as oil, coal and gasoline, they may lead to the formation of ozone, which is recognized as an air pollutant. Because ozone has documented health effects at quite low levels, both state and federal authorities have established quality standards for this pollutant.

"The ocean is two-thirds of the earth's surface, so to understand global climate issues and the chemistry of air pollution in coastal regions, you need to understand the role of sea salt particles," Finlayson-Pitts said. "Our study suggests that sea salt particles may be a factor that needs to be taken into account in assessing levels of greenhouse gases and air pollutants such as ozone in the air."

In this study, UCI researchers observed the reaction of hydroxyl radicals (equivalent to water, H2O, with a hydrogen atom removed) with tiny particles composed of water and sodium chloride--the basis of sea salts. The hydroxyl r
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Contact: Tom Vasich
tmvasich@uci.edu
949-824-6455
University of California - Irvine
12-Apr-2000