Edge of the Arctic Shelf

Northward Bound
One of the great things I have observed from my work area in the main lab is the interaction between all of the different scientists. Physical oceanographers, chemists, and biologists all sit within arm's reach of one another, and each new discovery sparks a round of discussion. These discussions often lead to changes in the science plan as we struggle to make the most of our limited time in this remote, inaccessible ocean.

This afternoon I caught up with chemical oceanographer Dave Kadko to talk about the data he is collecting on this cruise. Dave uses naturally occuring radioisotopes to trace oceanographic processes like currents and eddies.

Dave, what are you measuring and why?
"I am measuring naturally occurring quantities of the radioisotope radium. Shelf waters absorb a trace amount of radium from the sediment on the seafloor. Once these shelf water parcels move into the deeper Arctic basins, it's like starting a stopwatch. The isotopes begin to decay, and by measuring the amount of radium that is remaining, we can then tell how long it has been since the parcel of water was on the shelf. As we move into deeper water in the next few days, the CTD team will be on the lookout for these swirling parcels of shelf water, called eddies. We hope to be able to determine how old these eddies are--it's a critical piece of information in the story of how shelf waters are transferred to the deep Arctic basins. One particular isotope of radium, (Ra-224) has a very short decay time (only a few days) and has never before been measured in the Arctic, so we're excited about what we will find."

Can you describe the process of collecting this data?
"First, we collect a huge volume of water using the CTD Niskin bottles, about 25-50 gallons for a single data point. We need this much because the radium is present in such minute amounts. Aaron Silverman and I then pump the water through filters that have an affinity for heavy metals. The fibers act like a sponge, and pick up the radium from the seawater. We then analyze these filters for their radium content, and preserve the samples for further analysis back in Miami."

The following questions about arctic wildlife are from Dr. Linda Werner's sixth grade class at the Morse Pond School in Falmouth, Massachusetts.

Question: Have you seen any wolves?
Answer: The island we left from, Unalaska, does not have any wolves (though there are a lot of foxes). However, wolves can be found in the Arctic, and Jim Johnson has been lucky enough to see them while he was working on a research project on Ellesmere Island, Canada. I asked him to describe that experience.

"We were staying at the Polar Shelf Research Station in Eureka, on St. Ellesmere Island in the Canadian Archipelago. One evening around 11pm (when it was still light out) we were visited by a pack of four wolves. Their fur was as white as the snow. We all stood at the window watching them wander around outside. We tried to take pictures through the window but decided it would be better if we opened the door. Opening the door startled them at first but they became very curious. As we stood in the doorway taking pictures, one of the guys ventured outside on his stomach and started taking pictures from that position. The wolves continued to get closer but would scatter if we moved too quickly. Slowly, more of us ventured outside with our cameras and the wolves just kept coming closer until they were about 5 feet away. They stayed around our building for about two hours then they just headed off into the hills. The whole time we never felt scared of them because they looked to be curious and comfortable, plus they have no real enemies on this particular island."

Question: Have you seen any sharks?
Answer: We have not seen any sharks, but there is one species that inhabits the Arctic--the Greenland shark. It can grow to be over 20 feet long, and is often seen swimming on the surface. Inuit have used the shark's liver for fuel oil and the dried flesh as food for their sled dogs.

Question: Are penguins shy or tame?
Answer: Penguins are actually found only in the Antarctic, so I have never seen one in the wild. Some Arctic birds, such as murres and guillemots, do look very penguin-like, though! Most seabirds I have encountered are quite wary of humans, although the glaucous gulls we have seen on this trip will sometimes fly overhead to check out what we're doing.