The cleanest pocket of air on Earth? It's in the Southern Ocean, between Tasmania and Antarctica - National Post

The cleanest air on Earth lies in a pocket of sky between Tasmania and Antarctica, scientists say. 

A team of researchers at Colorado State University conducted a bioaerosol study of the Southern Ocean from Tasmania to Antarctica — the first of its kind — and drew air samples at the marine boundary level, where the atmosphere meets the ocean surface. 

“We were able to use the bacteria in the air over the Southern Ocean (SO) as a diagnostic tool to infer key properties of the lower atmosphere,” microbian ecologist Thomas Hill, from Colorado State University, told Science Alert.

Via modelling and analysis, the team noted that the samples were free of aerosol particles — a sure indicator of human activity, like fossil fuel burning, agriculture and fertilizer production — blown in from other parts of the world. The samples were also split into latitudinal zones, so that the team could observe how the air changed as they moved further south. 

Kathryn Moore collects bioaerosol samples in the Southern Ocean. Kendall Sherrin/CSU

Via wind patterns, airborne microorganisms can travel vast distances. However, the bacterial make-up of the samples suggested that the closer they were taken to Antarctica, the cleaner they became. This suggests that aerosols from distant land masses and human activities are not travelling south into Antarctic air.

Instead, the samples appear to be composed of microorganisms from the ocean and little else. 

“It suggests that the SO (Southern Ocean) is one of very few places on Earth that has been minimally affected by anthropogenic activities,” Hill said. 

The results counter similar studies that were carried out in oceans in the subtropics and the Northern Hemisphere, which concluded that most microbes came from upwind continents.

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2020-06-04 19:13:00Z
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