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Flowers yes, fragrance no

world Updated: Apr 15, 2008 22:58 IST
Flowers yes

If you haven’t been taking the time to stop and smell the roses, you might want to do it fast and enjoy it while it lasts.

A new study by scientists at the University of Virginia indicates that air pollution is destroying the fragrance of flowers and disrupting the ability of pollinating insects like bees to follow scent trails to the flowers.

The scientists set up a model and discovered that scent molecules produced by the flowers mix with pollutants such as ozone. These molecules are very volatile and quickly bond with pollutants that destroy the aroma.

The scientists also discovered that area of fragrance around flowers had decreased significantly in the last 200 years.

"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," said Jose D. Fuentes, a professor of environmental sciences at the University of Virginia and a co-author of the study.

The result is that the scent of flowers now emanates over a smaller area. And the higher the pollution, the lower the scent. This makes it harder for pollinating insects like bees to find flowers and to get food. It also means that not enough of flowering plants get pollinated.

“We know that pollinators are in trouble,” said Dr. Fuentes. Beekeepers in 24 US states have reportedly told the U.S. Department of Agriculture that some of them have lost up to 90 percent of their honeybees.

The drop in bee population in particular has been blamed on everything from genetically engineered food crops to viruses.

This could have serious implications for the world’s food production. Three-quarters of the world's flowering plants require pollination from the likes of bees or butterflies to survive. Last year, California had to import bees from Australia to help pollinate crops.

Dr Fuentes and his team of researchers, including Quinn McFrederick and James Kathilankal theorize that this pollution, especially in the summer, may have played a role in the decline in the populations of bees and butterflies in the recent years. “The landscape for the pollinators is being fragmented,” said Dr. Fuentes. “Pollutants in the lower level of the atmosphere have been increasing rapidly.”

Trivandrum native, James Kathilankal, 29, moved to Virginia after finishing his Masters from Haryana Agricultural University. Now a fourth year PhD candidate, Kathilankal hopes to finish his degree by next month.

Kathilankal said the project was exciting but it raises some important issues. “Now people have to think how to practically apply it to the real world.” Dr. Fuentes said Kathilankal modified a computer model to measure how much of a chemical reaction can occur in time frame within an area.

The team then used the mathematical model to see how the scents of flowers travel with the wind. They calculated scent levels and distances that scents can travel under different conditions, from relatively unpolluted pre-industrial revolution levels, to the conditions now existing in rural areas downwind from large cities.

Kathilankal said the simulation showed how chemical signals could be affected by increasing air pollution.

Dr. Fuentes added "it quickly became apparent that air pollution destroys the aroma of flowers, by as much as 90 per cent from periods before automobiles and heavy industry."