Wind Riders

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Vast quantities of microbial species are hitching rides on the trans-Pacific winds from Asia to North America.

A new study led by David J. Smith, who recently completed a Ph.D. in biology and astrobiology at the UW and is now working for NASA, is one of the first of its kind and shows that living microbial species are able to travel to the Northwest from across the Pacific Ocean.

The research took place in the winter and spring of 2011 and was based on air samples taken by Smith’s team from atop Mt. Bachelor — located in the Cascade Mountains of central Oregon — from two large dust plumes that originated in Asia. The air samples were then processed and analyzed to look for microorganisms. The study was published in December 2012 in the journal of Applied and Environmental Microbiology.

Scientists have been tracking pollution carried across the globe by the jet streams for years, and have also studied microbes in the air. However, Smith’s work is the first to have looked for life traveling long distances at such a high altitude.

“There have been other studies that have been closer to the [earth’s] surface and more regional, trying to figure out what’s floating around in the air, and those studies found a pretty high diversity [of life] as well,” Smith said, “so we went up to the top of a mountain … and said ‘Well, let’s just look and see what makes it up at this height.’”

Smith added, “We wanted to see: Could cells actually leap the biggest oceanic gap on the planet? There was no reason to believe that they couldn’t.”

The team was able to identify the DNA of more than 2,000 species of microbes, both dead and living. Smith said they had expected to find microbes, but did not expect to find so many different species.

“It was surprising and not surprising,” Smith said. “Not surprising in the sense that we expected to find them, but it was surprising to find such incredible diversity of types [of microbes].”

Dan Jaffe, co-author of the report and professor at UW Bothell, said while these findings are not necessarily dangerous, they are significant to the more general study of life in harsh environments.

“I think the implications have to do with how life can survive in harsh environments and what the factors are, why some species can survive and others can’t, and the fact that maybe microorganisms could survive long distances,” Jaffe said. “NASA is very interested in whether this means microorganisms could survive in space and could survive from one planet to another.”

Peter Ward, professor at the UW and co-author of the published study, believes the findings also have historical, health, and geopolitical implications.

“This gives us a mechanism [to see] how life can spread across a planet that does not have oceans, or when the oceans are frozen,” Ward said.

This could help scientists trying to understand how life was maintained and distributed during Earth’s two ice ages.

Ward also said the studies suggest toxic viruses from one end of the planet could potentially be easily spread across the oceans through the atmosphere.

Ward said these findings should act as a wake-up call to the U.S. coal industry which exports coal — a major producer of greenhouse gases — to China.

“This shows that we have a global atmosphere and shows how quickly Chinese atmosphere makes it way to the United States,” Ward said.

Smith also believes these findings are important in the struggle against global warming. As human activity leads to increased desertification, the atmosphere contains more dust, which gives microbes something to latch onto. This will likely lead to a higher concentration of microbes in the atmosphere that could potentially threaten human health.

“Even though this is a harmless phenomenon that is occurring, humans are changing the surface of our planet and we’re also creating more pollution into the atmosphere,” Smith said. “So even though it is harmless now, it may not be harmless in the years ahead.”

Although the report was published recently, it is already attracting interest from a very diverse scientific community, including microbiologists and atmospheric scientists.

Smith hopes to continue similar research beyond his work at Mt. Bachelor by expanding his focus. He plans to move beyond studying the exchange between Asia and North America, and look into the transfer of microbes within similar global circulations that exist all over the planet.