October 22, 2010

Stressed Plants Clean Air Better Than Once Thought

Researchers have discovered that plants, especially some trees under stress, are better at ridding the air of certain chemicals than previously thought, according to a study published in the journal Science.

"Plants clean our air to a greater extent than we had realized," Thomas Karl of the U.S. National Center for Atmospheric Research (NCAR) in Boulder, Colorado, and lead author of the study, said in a statement. "They actively consume certain types of air pollution."

Scientists have already known that plants take in carbon dioxide, a naturally occurring gas that builds up in the atmosphere and traps heat beneath it. But they did not know that some plants actually take in a class of chemicals known as oxygenated volatile organic compounds (oVOCs).

OVOCs, which can cause long-term health problems and affect the environment adversely, form in the atmosphere from hydrocarbons and other chemicals from natural and human-made sources.

OVOCs can contribute to lung inflammation and swelling and bring on asthma attacks, according to the American Lung Association.

Karl worked with other scientists to find that deciduous plants -- those that shed their leaves seasonally -- take in these compounds as much as four times more rapidly than was originally believed.

Plants remove oVOCs from the air better in dense forests, and the process is even more evident at the top of the forest canopy, where up to 97 percent of oVOC removed from the air had been observed, researchers said.

The researchers studied poplar trees specifically, and found that when they were under stress, due to physical wounds or exposure to ozone pollutants, they increased their uptake of oVOCs drastically.

The researchers believe that the uptake of oVOCs is part of a larger metabolic cycle. It is kind of a service provided by nature.

The subject is being discussed this week in Nagoya, Japan, at an international meeting aimed at making target goals for 2020 to fight losses in biodiversity.


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