The Healy has now moved off of the shallow continental shelf that extends around the Arctic land border (shown in white in the map below) into the deeper center of the Arctic Ocean. In our last blog we noted that some of the questions Arctic GEOTRACES is addressing include quantifying the fluxes of trace elements and isotopes into and out of the Arctic Basin from the two oceans through choke points like the Bering Strait, as well as characterizing how much comes from rivers. Arctic GEOTRACES is also studying what regulates the Arctic shelf to deep basin exchange, and the role of sea ice in the transport of trace elements and isotopes. (Follow the expedition here.)
The oval shaped blue area in the map above is the basin of the Arctic Ocean, ranging from ~3,500 meters to ~5,000 meters at its deepest. The Healy is currently over a ridgeline named the Mendeleev Ridge, after a Russian chemist and inventor, Dmitri Mendeleev, long dead when the ridge was first discovered by fellow Soviets in 1948. Mendeleev Ridge is about 1,000 meters shallower than the deep Arctic, bottoming out at ~2,500 meters in depth. The Russians maintain that the ridge, with its long reach into the Arctic basin, gives them claim to large sections of the ocean stretching out to the North Pole. The claim remains unresolved, in part because there are so many questions that still remain about the Arctic. As we move into the basin, we will be sampling to try and better constrain what happens at the shelf/basin interface.
When we venture into the Arctic for research, for most of us there is the lingering hope that a polar bear will appear on our watch; at least as long as we are safely outside of its reach. Several polar bear have been spotted by the watchful eyes of the crew as we have moved into the more tightly packed heavy ice away from the marginal ice zone. However, today a very large bear (yes the alert text says “huge”!) was spotted, and it seemed to have us under thoughtful consideration. The following is a string of images that relay the majesty of this incredible creature in its natural environment, moving with great agility over the sea ice.
Polar bear live only in the Arctic and rely almost entirely on the marine sea ice environment for their survival. They use the ice in every part of their daily life, for travel, for hunting ringed seal, their favorite food, for breeding and in some cases for locating a birthing den. Their wide paws, which you might be able to see in these photos, distribute their weight when they walk on the sea ice, which late in the season can be quite thin in the annual ice region, melting down to only a thin crust over the water. Their large size, clearly visible in these photos, belies the fact that they are excellent swimmers, helped by their hollow fur, which traps air to keep them buoyant, as well as the stiff hair and webbing on their feet. For all their cuddly appearance, they are strong hunters. Currently polar bear range in conservation status from Vulnerable internationally, to Threatened in the U.S., primarily the result of a warming climate that is melting their habitat…sea ice.
The Arctic is approaching the annual low for sea ice extent, which occurs each year in September. An image of sea ice extent for today (shown in white) against an average of the last thirty years (outlines in yellow) shows how our annual sea ice cover has dropped. Today’s cover is 2.24 million square miles (5.79 million square kms), which is 521,200 sq. miles (1.35 million square kms) below the last 30 year average period. Aside from being of concern to the polar bear, this is part of why Arctic GEOTRACES is so important. We need to understand the role of sea ice in current circulation patterns and delivery of trace elements and isotopes in the Arctic, and then bring this more complete understanding forward to our careful examination of the changing Arctic.
Margie Turrin is blogging for Tim Kenna, who is reporting from the field as part of the Arctic GEOTRACES, a National Science Foundation-funded project.
For more on the GEOTRACES program, visit the website here.
roaming the hallways and the parking lot was full of SUV’s washed in clay, sand and
mud. When most of the second phase of the SUGAR project had come to a halt, there
was still work to be completed by the Seismic Source Team (SST). In order to
understand why, let me take you through the work schedule of the SST.
Dr. Harder and I drove to Atlanta on July 1st after completion of the ENAM
project in North Carolina and began scouting the shot-holes we would need to drill, load
and stem i.e. fill before the shot dates, which were scheduled for August 7th and 8th for
Line 2 and August 14th for Line 3. When scouting, you want to ensure that the shot-hole
locations selected have good, accessible roads and enough space for the drillers as well as
work crew to move in and out of easily. However beforehand, you want to ensure that
you have the permits to access different properties and have the correct keys for the
property entrance/exit gates, which Donna took care of. Scouting holes took 4 days
before drilling began on July 7th until July 29th.
An example of a good, accessible road for the drillers and SST to use.Pick a lock, any lock. One of the entrance/exit gates to a shot location. Thankfully, we
had the key. I just had to test it on each lock to open the gate. A typical workday would consist of waking up at 6:30 am, eating breakfast at 7
am and leaving to work at 7:30/8 am. We would arrive on site about an hour later and the
drillers would set up and begin drilling. This would take about 2-3 hours at some holes
and 3-4 hours at others. The last hole composed of hard rock took about 14 hours to
complete. That does not include the time it took for us to stem the hole. We would
prepare the charges to load into the hole when the drillers had ~20 ft left to drill. They
drilled up to ~80 ft at the 2 shot-holes on the ends of Line 2 and ~70 ft for the remaining
13 shot-holes. For Line 3, they drilled all 11 holes to ~60 ft. After drilling and loading
the charges into the ground, Dr. Harder would lead the drillers to the next shot-hole while
Galen, Yogi and I would stay behind to stem the hole with gravel, sand and plug it with
bentonite. We would also check the detonators to make sure they worked before heading
off to the next shot-hole to repeat the process. On average, we would drive anywhere
from 100 – 200 miles per day depending on what we were doing and where we needed to
Yogi (Victor Avila, left) and Galen preparing 2 charges to be lowered into the shot-hole. Each charge contains 2 detonators attached to 2 boosters indicated by the sets of wires.The drillers lowering the charge into the hole with Yogi carefully holding the detonator (orange wire) chords. On the left is the water truck and to the right is the drill rig."The Beast" with a 1.1 Explosives placard after transporting the source materials to the shot location.Galen taking a GPS waypoint of the loaded shot-hole while Ashley tests the detonators to ensure that they are working.Dr. Harder (left) and Kent splicing the wires at one of the shot-holes to connect the detonators in order to shoot. The routine changed once drilling was complete. We made our way to Vidalia
where we met with Donna, Dan and everyone at the instruments center and began
preparing our equipment for the nights we were going to shoot. Shots would start at 11
pm and last until as late/early as sunrise depending on the weather conditions as well as if
the detonators would connect. The days that the deployment team members were
flagging and deploying instruments, we were busy driving to shot-holes and cleaning the
ones that blew out. The idea is that you make the shot-hole location look the way it did
before the shot took place.
Shot-hole 7 on Line 3. It looks like a regular hole, but it is actually about 5ft deep and has a 5ft diameter cavity.Using the backhoe to clean up the above shot-hole.After clean up!!
I can honestly say there was never a dull moment while working on the SST. I
remember Donna saying at our farewell dinner something along the lines, “We do all this
work for just a disk of data, but it’s all worth it.” She could not have summed it up any
better than that.
Here’s to another successful project….salud!
Ashley Nauer - UTEP
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