The study suggests that the Southern Ocean that encircles Antarctica is one of very few places on Earth that has been minimally affected by anthropogenic or human activities.
Scientists have identified an atmospheric region that has the cleanest air on the Earth, in a first study of its kind. They have found that the region in Southern Ocean remains unchanged by human-related activities.
The study, led by Professor Sonia Kreidenweis of Colorado State University, found the boundary layer air that feeds the lower clouds over the Southern Ocean to be pristine – free from aerosols or any other pollutants.
The research team zeroed-in on the air directly over the remote Southern Ocean (SO) that encircles Antarctica as it suspected that it would be least affected by human-activities and dust from continents. They set out to discover what was in the air and where it came from, according to an article in phys.org website.
“We were able to use the bacteria in the air over the Southern Ocean as a diagnostic tool to infer key properties of the lower atmosphere,” said research scientist Thomas Hill, the co- author on the study. “For example, that the aerosols controlling the properties of SO clouds are strongly linked to ocean biological processes, and that Antarctica appears to be isolated from southward dispersal of microorganisms and nutrient deposition from southern continents. Overall, it suggests that the SO is one of very few places on Earth that has been minimally affected by anthropogenic activities,” he added.
The air in the marine boundary layer- the lower part of the atmosphere that has direct contact with the ocean - was sampled and then analysed using tools like DNA sequencing, source tracking, and wind back trajectories.
Based on the results of their study, scientists noted that “over the Southern Ocean, sea spray emissions dominate the material available for forming liquid cloud droplets. Ice-nucleating particle concentrations, rare in seawater, are the lowest recorded anywhere on the planet.
In fact, the air over the Southern Ocean was so clean that scientists found there was very little DNA to work with.
The findings of the study have been published in Proceedings of the National Academy of Sciences.
Source - HINDUSTAN TIMES