Scientists find missing piece of air particle equation hiding in the walls

Apr 07, 2014
Credit: NASA

Laboratory chamber walls have been stealing vapors, causing researchers to underestimate the formation of secondary organic aerosol in the atmosphere.

A study published April 7 in PNAS Online Early Edition describes how a team of scientists, including researchers from the University of California, Davis, showed that vapor losses to the walls of laboratory chambers can suppress the formation of secondary organic aerosol, which in turn has contributed to the underprediction of SOA in climate and models.

SOA impacts air quality and climate and makes up a major fraction of particulate matter in the atmosphere. Yet SOA concentrations have been significantly underestimated in regional air quality models.

Nearly all models of secondary organic aerosols are tied to observations of their formation in laboratory chamber experiments. However, the effect of vapor loss to chamber walls previously had been neglected.

"To accurately predict the health and of particles, we need to accurately predict their abundance in the atmosphere," said co-author Christopher Cappa, professor of civil and environmental engineering at UC Davis.

Secondary organic aerosols are formed primarily through chemistry that occurs in the .

"If, along the path from moving from the gas phase to the particle phase, another surface steals that gas-phase material, you wouldn't form as much of the particle as you would think," Cappa said. "That's what we've demonstrated is happening: The walls of these chambers act as a sponge for the vapors and compete with the particles for these vapors."

Researchers from UC Davis and the California Institute of Technology conducted a series of experiments in a 24 cubic meter environmental chamber using the volatile organic compound toluene, which is emitted from motor vehicles and is an important SOA precursor.

Cappa said the researchers' next steps are to assess the vapor effect more broadly for other compounds to more fully understand these wall effects and make better predictions for the future.

Explore further: Brown carbon works both sides of the climate equation

More information: Influence of vapor wall loss in laboratory chambers on yields of secondary organic aerosol, www.pnas.org/cgi/doi/10.1073/pnas.1404727111

add to favorites email to friend print save as pdf

Related Stories

Brown carbon works both sides of the climate equation

Feb 04, 2014

There is an atmospheric particle not satisfied with only a single role in the climate. The ambitious culprit? Brown carbon aerosol steps outside the box and acts to both warm and cool the climate. A brown ...

Recommended for you

Aging Africa

Aug 29, 2014

In the September issue of GSA Today, Paul Bierman of the University of Vermont–Burlington and colleagues present a cosmogenic view of erosion, relief generation, and the age of faulting in southernmost Africa ...

NASA animation shows Hurricane Marie winding down

Aug 29, 2014

NOAA's GOES-West satellite keeps a continuous eye on the Eastern Pacific and has been covering Hurricane Marie since birth. NASA's GOES Project uses NOAA data and creates animations and did so to show the end of Hurricane ...

EU project sails off to study Arctic sea ice

Aug 29, 2014

A one-of-a-kind scientific expedition is currently heading to the Arctic, aboard the South Korean icebreaker Araon. This joint initiative of the US and Korea will measure atmospheric, sea ice and ocean properties with technology ...

User comments : 0