Sonia Kreidenweis, professor at Colorado State University and her research group managed to identify an atmospheric region unchanged by human activities in the Southern Ocean.
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Kreidenweis’s group, which works in the Department of Atmospheric Science, found that the air in the boundary layer that feeds the lowest clouds over the Southern Ocean is pristine, free of particles and aerosols, produced by human activities or transported from distant lands. The findings were published in the Proceedings of the National Academy of Sciences.
Climate change makes it almost impossible for there to be areas where the air is really clean and untouched by people, but the Kreidenweis team found it in Antarctica.
According to Thomas Hill, the project’s deputy researcher, through a statement:
“We were able to use the bacteria in the air over the Southern Ocean as a diagnostic tool to infer the key properties of the lower atmosphere. For example, that the aerosols that control the properties of SO clouds are strongly linked to oceanic biological processes, and that Antarctica appears to be isolated from the dispersion of microorganisms to the south and the deposition of nutrients from the southern continents. Overall, it suggests that SO is one of the few places on Earth that has been minimally affected by anthropogenic activities. ”
The researchers collected bioaerosol samples aboard the Research Vessel Investigator, a research vessel from the Australian National Marine Facility. Graduate student Kathryn Moore tested the air in the marine boundary layer, the lower part of the atmosphere that has direct contact with the ocean, aboard the ship as it sailed south from Tasmania to the edge of the Antarctic ice. Research scientist and first author Jun Uetake examined the composition of airborne microbes captured from the ship. The atmosphere is full of these microorganisms dispersed hundreds of thousands of kilometers by the wind.
Using DNA sequencing, source tracking, and rewind trajectories, Uetake determined that the origins of the microbes were marine, from the ocean. Bacterial composition also differed over wide latitudinal areas, suggesting that aerosols from distant land masses and human activities, such as pollution or soil emissions caused by change in land use, did not travel to the south in the Antarctic air.
The air over the Southern Ocean it was so clean there was too little DNA to work, the researchers conclude.