In what is believed to be the first study of its kind, researchers used genomic techniques to document the presence of significant numbers of living microorganisms -- principally bacteria -- in the middle and upper troposphere（对流层）, that section of the atmosphere approximately four to six miles above Earth's surface. Whether the microorganisms routinely inhabit this portion of the atmosphere -- perhaps living on carbon compounds also found there -- or whether they were simply lofted¹ there from Earth's surface isn't yet known. The finding is of interest to atmospheric² scientists, because the microorganisms could play a role in forming ice that may impact weather and climate. Long-distance transport of the bacteria could also be of interest for disease transmission models.

 

The microorganisms were documented in air samples taken as part of NASA's Genesis and Rapid Intensification³ Processes (GRIP) program to study low- and high-altitude air masses associated with tropical storms. The sampling was done from a DC-8 aircraft over both land and ocean, including the Caribbean Sea and portions of the Atlantic Ocean. The sampling took place before, during and after two major tropical hurricanes -- Earl and Karl -- in 2010.

 

The research, which has been supported by NASA and the National Science Foundation, was scheduled to be published online January 28th by the journal Proceedings⁴ of the National Academy of Sciences.

 

"We did not expect to find so many microorganisms in the troposphere, which is considered a difficult environment for life," said Kostas Konstantinidis, an assistant professor in the School of Civil and Environmental Engineering at the Georgia Institute of Technology. "There seems to be quite a diversity of species, but not all bacteria make it into the upper troposphere."

点击收听单词发音