SCIENCE

By soaking up the sun's energy, the dust also warmed the atmosphere, contributing to an increase in surface winds. Researchers say that promoted evaporation and fostered greater ocean churning, pulling up colder waters. The waters cooled quickly in the two weeks after the largest of the dust storms.

The 2006 season saw five hurricanes and four tropical storms, compared with 15 hurricanes and 12 tropical storms in 2005.

"This research is the first to show that dust does have a major effect on seasonal hurricane activity," said William Lau, lead author and chief of the Laboratory for Atmospheres at NASA's Goddard Space Flight Center.

The study appeared in Eos, a publication of the American Geophysical Union.

-- Christopher Lee

'Buckyballs,' Bacteria Coexist

Bacteria appear not to be harmed when the soil they live in becomes contaminated with "buckyballs" -- microscopic spheres of carbon that are being manufactured in increasing quantities for a variety of applications.

Buckyballs are a kind of nanoparticle: atomic-scale constructs with novel properties that make them useful in electronic devices, fabrics, cosmetics and other products. Earlier studies had shown they can kill soil bacteria in laboratory dishes, raising concerns that their release could upset soil ecosystems.

Now researchers at Purdue University have performed the first tests of buckyball toxicity on bacteria in actual soil. Using a variety of measures of microbial health -- including bacterial respiration, enzyme activity and various chemical analyses -- they showed that buckyball concentrations of up to 1,000 micrograms per gram of soil had no discernible impact.

It may be that natural chemicals in soil buffer the toxic effects seen in the laboratory, researchers conclude in the April 15 issue of the journal Environmental Science & Technology.

Still, noting that different kinds of nanoparticles have very different toxicities, a number of organizations have recently called for beefed-up environmental risk studies. Last week, a government commission in Britain criticized that country's lagging effort to assess nanotechnology's potential hazards. And an international coalition of 336 trade unions in 120 countries in March called for a moratorium on nanotech products in food and agriculture.

A U.S. report in December also called for more research. And last month, members of Congress asked the Government Accountability Office to study whether enough U.S. nano research funding is going into safety studies.

-- Rick Weiss