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Sampling Under the Shadow of the Pressure Ridge

01/17/2011, 12:16 PM by Steven Baer
Nitrogen Snow Ninjas - The Bronk Team<br/><br/>Credit: Deb Bronk
Nitrogen Snow Ninjas - The Bronk Team
Photo Credit: Deb Bronk

The ArcticNitro teams began their fieldwork in September, 2010. PI Deb Bronk describes her teams’ research: “The Bronk group is focusing on defining the competition between phytoplankton and bacteria for available nitrogen. As part of our study, we are doing experiments with humics, which are the tea colored compounds that run off the land when permafrost melts. These humics can decrease the amount of light in the water, which phytoplankton need, while providing a source of carbon, which bacteria require. As the permafrost melts, we hypothesize that bacteria will be able to outcompete phytoplankton for nitrogen more often.”

“I'm attaching my favorite picture - we call ourselves Nitrogen Snow Ninjas! Quinn Roberts (Bronk lab field manager) is on the left, I'm in the middle, and Steven Baer (Ph.D. student in my lab) is on the right.” (see image)

Steven wrote this post about their experience.

"As the ice shifts and moves off the coast, pressure ridges form. Essentially, thick sheets of ice collide and are pushed upward. Since the entire landscape is white and more white, it is difficult to get perspective on the size of these pressure ridges."

"From a distance they look small and potentially passable, but as you get closer, you realize that they are towering structures, sometimes up to 15 meters (50 feet) high and many kilometers long, with few if any passages through to spots further from the coast. Up close, they are a jumbled mass of ice "boulders" that are a beautiful contrast of white and brilliant blue colors."

"We established our sampling station at the furthest point that we could safely travel to within a reasonable amount of time, which ended up being about 6.5 km (4 miles) offshore. Mostly, we followed the trails of whaling crews, who camp out on the edge of the spring ice for their annual subsistence whale hunt."

"While these crews now use snow machines instead of dog teams, and explosive charges on their harpoons, they still use traditional methods and seal-skin boats to maintain their cultural history of surviving in this harsh environment. The science teams however, hauled out as much modern technology as we could muster. We tethered sleds to the back of snow machines and set up a tent to protect us from the wind and try to keep our equipment from freezing up."

"With an ice auger, we drilled 3 holes through the 0.6 m (2 foot) thick ice; one for depth sampling, one for pump sampling, and one for drainage. One team (Tara and Karie) used their Niskin bottle to get water at a variety of depths for bacterial production. Another team (Debbie, Quinn, Rachel, and Steven) used the pump to fill a series of bottles for stable isotope nutrient studies. A third team (Victoria, Zach, and Melissa) used the pump water to get DNA and RNA samples."

"Under the shadow of the pressure ridge, we were able to collect sea water and perform our experiments. We learned some hard lessons about the effect of cold on plastic, as it became brittle and broke, or rapidly froze up once exposed to the Arctic air. We rigged together replacements and figured out ways to keep our equipment from freezing, and took notes on how to improve our methods going forward."

"One more note about pressure ridges: since they are the highest ground available, and also sometimes provide openings in the ice, they are well traveled by polar bears. There's just no avoiding these awesome predators."

You'll meet more of the ArcticNitro team in the days to come as we venture into the dark January days of Barrow!

Lollie

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