Antarctic Glacier Stream Provides New Clues on Evolution of Dissolved Organic Matter
07.02.2011 - Land & Geology, Ice & Snow, Flora & Fauna, Antarctic
Every austral summer, a supraglacial stream forms on Cotton Glacier in the McMurdo Dry Valleys, a mostly ice-free region on Antarctica. As sediment from the surrounding mountain range builds up on the glacier, its darkened surface absorbs the sun, creating a meltwater river on Cotton Glacier, a unique feature. A team of scientists headed by an associate research professor at Montana State University-Bozeman is currently looking into the chemistry and biology of the stream, placing a special emphasis on the evolution of dissolved organic matter (DOM).
While organic matter is hard to find in Antarctica, it is present in the streams of the Dry Valleys. It has a complex chemical structure that could be found elsewhere in the world, but not in the meltwater at Cotton Glacier. Over time, the DOM form the Cotton Glacier chemically changes to resemble other forms of carbon, but the primordial nature offers scientists a way to understand the evolution of the organic matter over time from a chemical component, and its use by microorganisms.
The evolved DOM, the scientists say, is not just food for microscopic creatures but serves as a type of “sunscreen” for many types of organisms, absorbing ultraviolet light. Since it does not exist at Cotton Glacier, there is no “sunscreen”, which could be a problem in the ozone-depleted Antarctic. The organisms, however, have developed alternative strategies to cope with the absence of humic(dark organic matter)-based sunscreen. Besides these, the team is interested in the physical processes of the supraglacial stream on the Cotton Glacier, and hopes to geo-reference the images taken by a remote-controlled helicopter that has a camera and GPS.
