A Montana State University professor and his colleagues have found evidence suggesting that airborne bacteria are globally distributed in the atmosphere and may play a large role in the cycle of precipitation.
The research of David Sands, MSU professor of plant sciences and plant pathology, along with his colleagues Christine Foreman, an MSU professor of land resources and environmental sciences, Brent Christner from Louisiana State University and Cindy Morris, will be published today in the journal "Science."
These research findings could potentially supply knowledge that could help reduce drought from Montana to Africa, Sands said.
Sands, Foreman, Morris, and Christner -- who did post-doctorate work at MSU -- examined precipitation from locations as close as Montana and as far away as Russia to show that the most active ice nuclei are actually biological in origin. Nuclei are the seeds around which ice is formed. Snow and most rain begins with the formation of ice in clouds. Dust and soot can also serve as ice nuclei. But biological ice nuclei are different from dust and soot nuclei because only these biological nuclei can cause freezing at warmer temperatures.
Biological precipitation, or the "bio-precipitation" cycle, as Sands calls it, basically is this: bacteria form little groups on the surface of plants. Wind then sweeps the bacteria into the atmosphere, and ice crystals form around them. Water clumps on to the crystals, making them bigger and bigger. The ice crystals turn into rain and fall to the ground. When precipitation occurs, then, the bacteria have the opportunity to make it back down to the ground. If even one bacterium lands on a plant, it can multiply and form groups, thus causing the cycle to repeat itself.
"We think if (the bacteria) couldn't cause ice to form, they couldn't get back down to the ground," Sands said. "As long as it rains, the bacteria grow."
The team's wor
|Contact: David Sands|
Montana State University