UPI NewsTrack Science and Technology News

CHICAGO, Nov. 27 (UPI) -- U.S. scientists say they found metabolically active bacteria in the brine of an Antarctic lake sealed for thousands of years under more than 65 feet of ice.

Researchers at the University of Illinois at Chicago, writing in the Proceedings of the National Academy of Sciences, said the finding sheds light on the limits of life in extreme environments.

The brine has been isolated from the surface environment, and from any external sources of energy, for at least 2,800 years, they said.

"This provides us with new boundary conditions on the limits for life," researcher Peter Doran said. "The low temperature or high salinity on their own are limiting, but combined with an absence of solar energy or any new inputs fromglobal smog created by traffic, industry and other human activities, they said.

Using eight years of data collected by the satellites, the researchers at Tel Aviv University tracked pollution trends for 189 cities where the population exceeds 2 million.

More than 50 of these metropolitan areas, including New York, Tokyo and Mumbai, have populations that exceed 5 million.

The researchers used data gathered by three aerosol-monitoring satellites, called MODIS-Terra, MODIS-Aqua, and MISR, which NASA launched from 2000 through 2002.

Northeastern China, India, the Middle East and Central Africa are currently experiencing the most increases in air pollution, the researchers said.

Among the cleanest cities were Houston, with a 31 percent decrease over the time period; Curitiba, Brazil, with a 26 percent decrease; and Stockholm, Sweden, with a 23 percent decrease, they said.

Research leader