The air up there
By Amira Zamin
The Shepson Research Group prepares to launch the 45-foot-long research balloon that collects air samples. The helium-filled balloon is made of a polymer-coated nylon and requires 10 people to manage is when it's on the ground. The balloon is powered and controlled through a cable and tether system that holds up 1,000 pounds of torque. This is connected to a winch developed specifically for this balloon by the Jonathan Amy Facility for Chemical Instrumentation.
At the moment, most of the Arctic Ocean is covered in this sheet of ice, and in 50 years, it's likely to be mostly gone," Paul Shepson, a professor in chemistry and in earth and atmospheric sciences, explains.
In a joint project with the University of Fairbanks and Environment Canada, members of the Shepson Research Group spent the spring semester in northern Alaska collecting samples that would allow them to begin to assess the impact losing the Arctic ice could have on climate worldwide.
"[People] are contributing to an enormous change in the Arctic," explains Shepson. As atmospheric temperatures rise worldwide, the ice caps, home to polar bears and seals, among others, are melting. "Within our lifetime, the habitat for these animals will be gone."
In Barrow, Alaska, 340 miles north of the Arctic Circle, the team collected air samples at various altitudes over snowpacks and ice cracks, known as leads, to develop a profile of the release of a chemical called acetaldehyde.
"[Acetaldehyde] is a precursor to a molecule called PAN, which is carcinogenic and related to production of ozone, a human respiratory irritant," says Shepson. Acetaldehyde is emitted by cars, some production facilities, and is also contained in tobacco smoke. It is in the same family of chemicals as formaldehyde, a chemical commonly used in embalming and another environmental contaminant.
The ice sheets provide a mechanism for temporarily locking up some of these chemicals, since they get absorbed into these frozen masses. But when sunlight hits, they are released.
"There are chemical compounds that help clean the atmosphere that are emitted from sunlit snow packs. And there are chemicals that are removed from the atmosphere that then re-enter the snowpacks, some of which are toxic," says Shepson. The same is true of cracks in the ice.
This emission into the atmosphere and re-entry into the snow and ice sets up the two research foci of the trip: first, to understand how gases like acetaldehyde get trapped in snow and ice to begin with to achieve a better understanding of ice cores and how they record past atmospheres in their frozen layers; second, to learn how these chemicals can be photochemically produced in snow and ice and then released into the atmosphere, where they affect air quality. This understanding is important, since the amount of sea ice and snowcover is decreasing in the Arctic. The profile the team is establishing through its research will help answer how substantial the impact of this change could be.
Shepson's study lays the groundwork for a broader 2007 study. 2007-08 has been designated "International Polar Year," and environmental agencies worldwide have committed to funding Arctic and Antarctic projects that year. One such project, called OASIS (Ocean, Atmosphere, Sea Ice, and Snow pack), will study the interaction of chemical species among those four areas. 