- The Washington Times - Monday, April 14, 2008

Pausing by the flower bed for a nice, deep whiff? Better take one soon. The very scent of flowers is fading under the noxious fumes of air pollution, according to University of Virginia researchers.

As it floats on the air, the familiar but delicate fragrance of roses or lilies is being chemically degraded by ozone and components from car or power plant emissions, said Jose Fuentes, an environmental scientist at the university that led the study.

“It’s a very distinct possibility that we will expect to smell a scent that just isn’t there. The fragrance would be compromised,” Mr. Fuentes said.

In earlier eras, the smell of flowers could travel for miles. These days, the “scent trail” is down to about 200 yards, the researchers found.

“It quickly became apparent that air pollution destroys the aroma of flowers, by as much as 90 percent from the period before automobiles and heavy industry. The more air pollution in a region, the greater destruction of flower scents,” Mr. Fuentes said.

Although he has sympathy for the human nose, Mr. Fuentes is far more concerned about the dampening effect of decreased flower fragrance on bees, butterflies and other pollinators.

“The only way they can locate their food — the flower nectar — is to detect the flowers,” he said.

The researchers charted the chemical effect of polluted air on the three organic compounds that make up most flower scents, creating a mathematical model that precisely tracked the dispersal of the scent over a given distance. They plugged in wind velocity, temperature, plant undergrowth and other data measured at a Virginia farm to reveal some distinct odor challenges.

In relatively unpolluted areas, the scents retained more than 80 percent of their original concentrations 1,000 yards away. When the air was heavy with pollution, the scents were down to a quarter of their concentration just 600 feet from the flower.

Mr. Fuentes theorizes that the loss of these scent trails is contributing to the mysterious drop in the world’s bee population in recent years — a loss blamed on everything from genetically engineered food crops to a virus. According to the U.S. Department of Agriculture, beekeepers in 24 states have reported that bees are simply “vanishing,” with some losing up to 90 percent of their honeybees.

It is serious business. Agriculture officials appearing before the House Agriculture subcommittee last year reported the new phenomenon “colony collapse disorder,” in which bees vanished or perished — ultimately driving up honey prices. Three-quarters of the world’s flowering plants require pollination from bees or butterflies to flourish, the lawmakers learned.

“Humans will also be affected. That zucchini you get at the supermarket couldn’t grow unless it was pollinated by a bee,” Mr. Fuentes said. “And those airborne pollutants can also potentially harm the plant which absorbs them.”

He is also researching the possibility that “pheromone trails emitted by animals for defense or mate attraction” could also be compromised by air pollution, along with specific volatile compounds that flowers emit “to attract natural enemies of plant pests.”

The research was published in the academic journal Atmospheric Environment and was funded by the National Science Foundation.

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