Where Have All The Flowers' Scents Gone?

By John DeFore

While it may not be an answer to the mysterious collapse of certain honeybee colonies, researchers at the University of Virginia have identified one unusual threat to the continued well-being of pollinating insects and the flowers they love: Air pollution, they report in the journal Atmospheric Environment, is killing the scent of flowers.

Using mathematical models, professor Jose Fuentes and students Quinn McFrederick and James Kathilankal analyzed the behavior of scent molecules under different conditions, finding that, in highly polluted areas, natural aromas may be diminished by as much as 90 percent compared to the pre-industrial era. That’s because these molecules are highly volatile, and readily bond with substances — ozone and nitrate radicals, for instance — that change them. As Professor Fuentes put it in an announcement, “The scent molecules produced by flowers in a less polluted environment, such as in the 1800s, could travel for roughly 1,000 to 1,200 meters; but in today’s polluted environment downwind of major cites, they may travel only 200 to 300 meters.”

That’s not just a concern for those who like to stop and smell the roses: A flower’s fragrance is a necessary cue for butterflies and bees who need its nectar (a relationship that, as everyone who’s studied the birds and bees knows, is also essential for reproduction of the plants), meaning that diminished aroma can threaten their existence as well, with unknown consequences higher up the food chain.

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