Using high-resolution imaging, researchers from MIT's Department of Mechanical Engineering observed the effect of raindrops falling on dry soil laden with bacteria. When falling at speeds mimicking those of a light rain, at temperatures similar to those in tropical regions, the drops released a spray of mist, or aerosols. Each aerosol carried up to several thousand bacteria from the soil. The researchers found the bacteria remained alive for more than an hour afterward.
If this airborne bacteria were lofted further by wind, it could travel a good distance before settling back on the ground to colonize a new location. The researchers estimated that the total number of bacteria dispersed by raindrops can range from 10,000 trillion to 800,000 trillion cells per year. As a result, global precipitation may contribute to releasing 1.6 to 25 percent of the total amount of bacteria from land.
Posted by Dr. Tim Sandle