Dr. Kevin Arrigo is a Professor in the Department of Environmental Earth System Science at Stanford University. He is the Chief Scientist for NASA’s ICESCAPE (Impact of Climate change on the Eco-Systems and Chemistry of the Arctic Pacific Environment) mission this summer onboard US Coast Guard Cutter HEALY.

“The Arctic Ocean is unique in that it is almost completely surrounded by land,” relates Karen Frey, an Assistant Professor at Clark University, as she flashes a map on the screen.

Because of this unusual geography, numerous rivers swollen from the spring thaw disgorge their contents onto its broad, shallow coastal areas. Karen tells us how this makes the Arctic Ocean particularly vulnerable to contemporary changes taking place on the Arctic tundra, such as accelerating permafrost melt. As these previously frozen soils melt, they release compounds that have been stored there for thousands of years. These compounds drip into the groundwater and eventually end up in the network of rivers and streams that criss-cross the tundra in spring and summer.

Karen is interested in how much of this stuff is reaching the Arctic Ocean in rivers and what impact it is having on coastal ecosystems. Some of these compounds are easy to track because they give the water a distinctive yellow-brown color. Called colored dissolved organic matter (CDOM), they form when decaying vegetation gets wet – similar to what happens when you dip your tea bag into a cup of hot water. Although these compounds are chemically benign, they reduce water clarity – which is bad for phytoplankton – and release carbon dioxide and carbon monoxide when they get blasted by the Sun’s UV rays.

So Karen and her graduate students Luke Trusel and Christine Wood are collecting water samples and measuring how much CDOM is there and how it changes when exposed to light. They are also dropping optical instruments into the ocean through holes in the sea ice to see how CDOM changes the color of the water. CDOM absorbs lots of blue light – the same color preferred by algae for photosynthesis. Too much CDOM and the algae can’t make food at peak efficiency – to the detriment of the entire ecosystem.

Karen believes that it important to know how far the effects of river water extend. Although in any particular spot, most water will be plain old ocean water, a small amount will have flowed in from rivers and the rest will have been released from melting ice. Each of these water sources has its own unique chemical signature that Karen can easily measure. By collecting a tiny amount of water, about enough to fill a shot glass, she can determine what parts of the Arctic Ocean are most vulnerable to changes taking place on land.

Check out the rest of the Armed with Science ICESCAPE series! You can also visit NASA’s Arctic Voyage 2010 blog or Twitter account, or get updates from Ensign Emily Kehrt, HEALY’s Public Affairs Officer.

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