UC Irvine researchers discover how airborne sea salt particles may influence air pollution levels

April 12, 2000

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 radical is always present in air. The researchers found unique chemical reactions on the surface of the sea salt particles rather than inside the particles, as had been previously observed.

Until now, it was believed that a reaction between hydroxyl and sea salt required that the hydroxyl radical be absorbed into the liquid particle before reacting. It also was believed that chlorine would not be formed unless the particles were acidic. Neither of these two activities was observed in this study. The discovery of hydroxyl reactions on the surface of sea salt particles further suggests that the creation of atmospheric chlorine through sea salt interaction may be greater than previously realized.

"This finding implies that this unique chemistry occurring on sea salt particle surfaces is yet another way of getting chlorine into the air," Finlayson-Pitts said. "Because they're so highly reactive, these chlorine atoms are important in the understanding of the formation and the fate of a number of trace gases vital to global climate issues."

In continuing this research, Dabdub will introduce this information on sea salt chlorine creation into a complex computer modeling program that analyzes and predicts the air quality of the South Coast Air Basin of California--a highly populated coastal area that records some of the highest levels of air pollution in the United States--to see its impact on levels of ozone and other pollutants.

Participating in this study with Finlayson-Pitts and Dabdub are Eladio Knipping of UCI's Department of Mechanical and Aerospace Engineering; Matthew Lakin, Krishna Foster, R. Benny Gerber and Douglas Tobias of UCI's Department of Chemistry, and Pavel Jungwirth of the J. Heyrovsky Institute of Physical Chemistry, Academy of Science in the Czech Republic.

The study was funded by the U.S. Department of Energy, the National Science Foundation, the North Atlantic Treaty Organization (NATO) and the UCI Council on Research, Computing and Library Resources.
-end-
Contact: Tom Vasich
949-824-6455
tmvasich@uci.edu


A complete archive of press releases is available on the World Wide Web at http://www.communications.uci.edu

University of California - Irvine

Related Air Pollution Articles from Brightsurf:

How air pollution affects homeless populations
When air quality worsens, either from the smoke and ozone of summer or the inversion of winter, most of us stay indoors.

Exploring the neurological impact of air pollution
Air pollution has become a fact of modern life, with a majority of the global population facing chronic exposure.

Spotting air pollution with satellites, better than ever before
Researchers from Duke University have devised a method for estimating the air quality over a small patch of land using nothing but satellite imagery and weather conditions.

Exposure to air pollution during pregnancy is associated with growth delays
A new study by the Barcelona Institute for Global Health (ISGlobal) has found an association between exposure to air pollution during pregnancy and delays in physical growth in the early years after birth.

Nearly half of US breathing unhealthy air; record-breaking air pollution in nine cities
Amid the COVID-19 pandemic, the impact of air pollution on lung health is of heightened concern.

Air pollution linked to dementia and cardiovascular disease
People continuously exposed to air pollution are at increased risk of dementia, especially if they also suffer from cardiovascular diseases, according to a study at Karolinska Institutet in Sweden published in the journal JAMA Neurology.

New framework will help decide which trees are best in the fight against air pollution
A study from the University of Surrey has provided a comprehensive guide on which tree species are best for combating air pollution that originates from our roads -- along with suggestions for how to plant these green barriers to get the best results.

Air pollution is one of the world's most dangerous health risks
Researchers calculate that the effects of air pollution shorten the lives of people around the world by an average of almost three years.

The world faces an air pollution 'pandemic'
Air pollution is responsible for shortening people's lives worldwide on a scale far greater than wars and other forms of violence, parasitic and insect-born diseases such as malaria, HIV/AIDS and smoking, according to a study published in Cardiovascular Research.

Air pollution in childhood linked to schizophrenia
Children who grow up in areas with heavy air pollution have a higher risk of developing schizophrenia.

Read More: Air Pollution News and Air Pollution Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.