UCI Researchers Find Nature Can Make Its Own Industrial Chemicals : Science: NASA study discovers that sources such as wildfires produce atmospheric gases. It aims to gauge man’s pollution.
Chemicals more commonly associated with industry also are produced in the atmosphere by natural sources such as wildfires in the Canadian wilderness, a team of UC Irvine researchers has found.
Ethene, propane, butane and toluene gases were detected in air samples collected over Canada’s Hudson Bay region over a six-week period last summer, according to UCI chemistry research specialist Donald Blake, who led one of nine scientific teams participating in the project sponsored by the National Aeronautics and Space Administration.
The chemicals were collected in plumes of smoke and gases released by wildfires and other sources in the lowland and forested regions of eastern Canada, said Blake, who is presenting the findings today at the American Geophysical Union conference in Baltimore.
The collection project, known as the Atmospheric Boundary Layer Experiment, is an effort to determine the natural levels of various trace gases in the atmosphere. That will provide a reservoir of data against which to measure any future changes caused by mankind’s activities, said Blake, co-author of the study with UCI chemist F. Sherwood Rowland, who in 1974 first discovered that chlorofluorocarbons, or CFCs, were eroding the Earth’s protective ozone layer.
Both man-made and naturally occurring chemical sources such as “wildfires and fossil fuel combustion, emit similar gases,” Blake said. “And it is often difficult to determine what the source of a gas is.”
Because the UCI team has developed the expertise to measure CFCs and chlorinated gases in the atmosphere, Blake said, they were able to better determine whether the chemical samples were generated by man or nature.
For example, Blake said, they found large quantities of isoprene, a hydrocarbon released by trees. In the atmosphere, isoprene breaks down quickly in the presence of sunlight, and in the process forms ozone and carbon monoxide, gases normally associated with pollution in urban and industrial areas.
This and other chemicals were detected among the 1,500 samples collected by the UCI team on the ground and aboard a plane at altitudes ranging from 500 to 20,000 feet.
“We are now going to be able to very accurately observe changes in the concentrations of gases that were measured during the summer of 1990 over the Canadian wetlands,” Blake said.
The NASA project aims to collect data on atmospheric gases around the globe. As part of the data-gathering effort, Blake said, he and the UCI team next will take samples in the South Pacific in September.
The UCI team is also sampling the atmosphere in selected locations to measure concentrations of methane, a key culprit in global warming and the depletion of the ozone shield.
In samples collected in the Pacific region, Rowland has determined that methane is increasing at a slower rate in the atmosphere than was seen in the early 1980s. If methane emissions can be controlled and reduced, Rowland and other scientists say, it may be possible to avert the serious climatic changes that could result from the globe warming an average 3 to 5 degrees Fahrenheit by the middle of the 21st Century.
Most methane is released by natural sources such as swamps, rice paddies, belching cattle, landfills and coal deposits. But leaks of natural gas used for heating and cooking is a small but significant portion of atmospheric methane. Rowland’s group also has taken experimental samples in Eastern European and Asian cities and has found very high levels of methane, believed to be escaping from aging and leaking natural gas lines and appliances.
