In the 18 years he's been an atmospheric chemist at PurdueUniversity, Paul Shepson has visited the Arctic many times, andthrough many countries. Now the head of the chemistry department,Shepson made "a trip of a lifetime" to Barrow this March. While Shepson has spent many such trips studying the unique Arcticatmosphere and the chemical gases found there, the big differencethis time was the ride. They called it ALAR (Aircraft Laboratoryfor Atmospheric Research) and it provided his team with both a ridenorth and a unique vehicle for data collection. Shepson's team used ALAR to collect atmospheric samples fromvarying heights above the ground, and over a variety of surfaces.
"We're interested in the composition of the atmosphere, in partwith respect to greenhouse gases," Shepson said, adding that hisresearch focuses on the measure of chlorine, bromine and ozone atdifferent elevations. Focused on ozone The atmospheric composition varies depending on what's on theground, and how far away that ground is. Air over a forested area,for instance, contains different chemical levels than that overtundra, which is different from air over sea ice, or open water. The greenhouse gas ozone is of particular interest, Shepson said,being both damaging and vital.
"It has the ability to clean itself of pollutants, it's anessential element in the atmosphere," he said. "In the Arctic,ozone isn't able to do its job of helping to clean the atmospherenear as well because it's dry." The Arctic's lack of humidity impedes ozone's natural ability tochew up pollutants, Shepson said, but this cold climate has anotherbuilt-in housekeeper. Sea ice "When you make ice, the process of freezing sea water excludes mostof the salt," Shepson said. That sea salt comes out onto thesurface of the ice, and into the air. The chlorine and bromineexuded by that salt are, like ozone, good at processing pollutants.
"Our interest is in climate change in the Arctic and how sea icewill change this natural cleaning," Shepson said. The sea ice is vital to the Arctic way of life, for both the peoplewho depend on it and the delicate details of nature that balanceupon it. This is where Shepson's research cuts into that cyclical dancescientists of many fields are watching the change in sea ice,relating to changes in air chemistry, relating to changes inclimate, relating to changes in ecosystems, and so on. This cycleof change, Shepson said, all comes back to man-made emissions. "All climate scientists know that the planet is warming," Shepsonsaid.
"(It's warming) two to three times faster in the Arctic. Andwe know that it's warming because of humans...There's a connectionbetween climate change and what we do." Those are the facts, Shepson said, the unknown is in the details such as the Arctic atmospheric chemistry that he's analyzing. Weird chemistry Shepson's lab will take years to digest and decipher the multitudeof data collected during more than a month in the Arctic, but theydid make some initial observations that surprised them, he said. "We saw lots of this weird chemistry that involves sea salt in theair over the North Slope when we expected to only see it over seaice," Shepson said. Basically, they were seeing the salty evidence of bromine andchlorine over the tundra, an occurrence they hadn't expected.
As he continues to process data, Shepson isn't looking for anyparticular pattern, he said, or to prove any particular theory. Hejust hopes to provide an accurate description of what the Arcticair is made of. For a closer look at the team's time in Alaska, click here . This story first appeared the The Arctic Sounder. I am a professional writer from Tea, which contains a great deal of information about ceramic incense holder , perfume bottle supplier, welcome to visit!
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