Scentless Spring? Flower Smells Blocked by Pollution

Brian Handwerk
for National Geographic News
April 11, 2008

Soon it may be harder to stop and smell the roses.

Growing levels of air pollution from power plants and automobiles have reduced the potency of flower fragrances by up to 90 percent as compared with pre-industrial levels in the United States, a new study has found.

The trend is unpleasant for human noses, but may be life-threatening for pollinators such as bees and butterflies.

"Many insects find flowers by detecting the scent produced by those flowers," said study lead author Jose D. Fuentes, an environmental scientist at the University of Virginia in Charlottesville.

"This [pollution] makes it increasingly difficult for pollinators to locate the flowers [and feed on their nectar]."

Flowers also stand to suffer when this symbiotic relationship falters.

If insects can't find enough flower-based food to survive, their movements won't pollinate plant species.

(Read how flowering plants changed the world.)

Overwhelming Ozone

Flowers produce volatile scent molecules that bond with pollutants such as ground-level ozone, in the process breaking down the plants' sweet smell.

With more pollution in the air, the aromatic molecules don't remain potent as long and travel shorter distances on the wind.

The new study's model suggests that in the mid-19th century, when pollution levels were first recorded, scent molecules would have been able to travel some 3,300 to 3,900 feet (1,000 to 1,200 meters).

Continued on Next Page >>


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