Tony Rathburn was invited to participate on an April. 2006 research cruise aboard the ice breaker, R/V Nathaniel B. Palmer, from Punta Arenas, Chile to the Larsen Ice Shelf on the Antarctic Peninsula. This expedition is part of a collaborative project between Hamilton College, Colgate University, Southern Illinois University, and Montclair State College. The Chief Scientist is Eugene Domack from Hamilton College.
Last year, this group discovered the first active methane seep in the
Antarctic. One of the goals of this expedition is to sample this newly
discovered methane seep that had been located under an ice shelf. The ice
shelf broke up recently, allowing access to the area for the first time last
year. More information about the cruise and participants can be found at the
Hamilton College web site: (www.hamilton.edu/news/exp
This project is funded through grants from the National Science Foundation Office of Polar Programs.
Greetings from R/V Palmer. Headed south. Will cross the Drake Passage in 8 hours. Supposed 2 be extra rough this year. May take 3 days to cross. Will be calm in ice. Lots of icebergs this year--may not get 2 where we want.
Seas OK so far... Headed to the Larson B Ice Shelf on the eastern side of the Antarctic Peninsula south of Chile. Italian geologists aboard conducting seismic surveys.
Rough seas on the 13th. The fog lifted for a short while before sunset, so we could see our surroundings a bit better. The seas are calm and we are sailing between small islands now. Icebergs are everywhere, making it difficult to go where we want to. Ice is blocking spots where sampling was planned. I sat on the bridge today as the sun was setting. The wind was HOWLING outside, and the scenery was spectacular. Sampling may start tomorrow, so I probably won't get a chance to sit on the bridge again for any length of time. The sun sets at 4:00, and by the time the cruise is over, the sun will be setting at 3:30. We are now headed for Prince Gustav Channel. The ice scraping by the ship sounds like a freight train going by. Occasionally, we bump a piece of ice that resounds through the ship with a bang. Fortunately, the ship's hull is super-reinforced, and is built to break through ice, so there is no danger. It is amazing to think that they used to sail here in wooden sail boats. I saw 2 killer whales today alongwith a number of birds--petrels, I think.
We couldn't sample again today because of the floating ice. The ship had to break through thick ice today, so progress was slow for much of the day. It was a sunny day with icebergs and icy island scenery all around. The sunset was amazing today, with a nearly full moon hanging over a blue and orange horizon. Once again, I spent part of the day sitting in a comfortable chair on the bridge, editing a manuscript and enjoying the scenery. In the early morning hours, I think that we will try to recover a mooring that was deployed a year or two ago. Hopefully, we will be collecting mud soon.
We can see bits of the coast for much of the way, and today we are
sailing by a 25 mile-long iceberg that was once part of an ice shelf
attached to the coast. Apparently this ice shelf has been in place for
thousands of years, so global warming has begun to take its toll. We are using sonar to map the seafloor and subsurface sediments. We are towing seismic instruments that send out powerful sound waves to penetrate seafloor sediments and give us an idea of what the subsurface sediment layers are like. The decision to conduct this seismic survey was based on the amount of ice blocking our way to the next site and the fact that there is open water adjacent to the large ice berg (open water is useful for seismic surveys as ice can interfere with the quality of the data we collect). The prevailing winds will probably close this open water with ice, so we are taking the time now to make this survey and hope that the winds will clear some of the ice from our path for the next site. We have an observer on watch constantly to monitor any marine mammal that might come by. If swimming mammals get too close we turn the seismic instruments
off so that we don't harm the sensitive hearing of whales and seals. I was on sea mammal watch earlier today and took the opportunity to climb onto the ice tower of the ship to do my observations. It is the tallest inhabitable point on the ship, much like an enclosed version of the crows nest of sailing ships. It was a sunny day with views of the large iceberg on one side, scattered ice on the other, and mountain and glacier scenery on the peninsula behind us. Changes in the blue layers of stratified ice and cracks in the ice cliff of the ice berg made it difficult keep one's attention on whale watching.
It is another sunny day today, and we are ramming the sea ice to get to
our next site. The ice is 2 to 3 feet think in places, and we push until
we can't go any further, then back up a short distance and ram the
ice. Breaking the ice is typically not the problem. When the ice gets
packed together but wind and/or land/ice berg barriers, it has not place to go when we plow into it. This is what typically makes it harder to move through the sea ice. We plow through some parts to get to open cracks in the ice where we can make better headway. As a result, our route through sea ice is typically not a straight line, and progress can be slow (3 or 4 knots in some areas), especially when we are in an ice breaking/ramming mode. Our next site is a mooring recovery site where we will pick up a set of instruments that have been collecting water column data (temperature, current movement, salinity, etc. for over a year. There are a couple of ice bergs parked near this site (we know this from satellite imagery relayed to the ship on a daily basis), however, so we will have to evaluate whether we can collect them or not once we get closer.
For the first time in the history of the U. S. marine Antarctic Program,
a crew member was lost at sea yesterday. The crew member was an
experienced person aboard the R/V Gould. It happened at some point during an 8 hour interval, and all attempts to locate him were to no avail. The Gould is the primary resupply ship for Palmer Station on the Antarctic Peninsula, and they were returning from Antarctica when the tragedy occurred. No one saw what happened, so the circumstances surrounding his disappearance remained unknown. Many of the crew members and scientists aboard the R/V N. B. Palmer knew the lost crew member, and are taking it very hard. We were prepared to aid in the search and recovery efforts, but are at least 4 days away from the search site, and could do nothing to help. This casts a somber mood on the cruise as we continue to mourn the loss of a comrade while maintaining a professional attitude toward the work
that we set out to do.
We are currently mapping the sea floor adjacent to an ice shelf. This is
anarea that was previously covered with ice and therefore couldn't be mapped
until part of the ice shelf broke off. Once again, we are taking advantage
of open water where the ice won't interfere with our mapping
activities. At daylight we plan to recover a couple of moorings that
contain instruments that have been monitoring physical properties of the
water column over the past year. The idea behind this is to find out if
the temperature and/or other characteristics of the water have changed tothe point where the water is helping to melt the local ice shelves from
below, and promoting their break up. We deployed a CTD (conductivity, temperature, depth) with niskin bottle rosette today. This gave us the current profile of salinity and temperature of the water near the current ice shelf. We also collected a surface water sample for an assessment of diatom abundances.
Today was a spectacularly beautiful day, and I would bet that literally
thousands of photographs were taken with a few hours. As a result of openwater near the ice shelf and coast, we are using multibeam sonar to map the seafloor near the coast. As a result, we are provided with amazing views of the ice shelf only 50 yards away. Deep blues contrast with white snow,making the icy shoreline an incredible sight. Together with the mountains in the background, the coastal views made for a photographer's paradise. Just about everyone who was not on watch was on the bridge through much of the day taking photos. In places the ice shelf was reflected in the ice and water below, making the scenes doubly pleasing to the eye. As beautiful as the scenery is, one is constantly reminded that this scenery is born from global climate change. The beauty is somewhat mitigated by the knowledge that access to it was created by the loss of very large expanses of ice shelves that have been in place for thousands of years, perhaps signalling the beginning of drastic changes for the planet.
It is yet another sunny day here, with little wind so far. We are
towing the seismic guns again today, trying to get information about the
layers of sediment beneath the sediment-water interface. The "guns" we are towing emit bursts of sound at regular intervals, and you can see a large bubble rise to the surface when each gun (we are towing 2 guns) emits a signal. You can also feel the sound if you are in the right places on the ship. The sound penetrates the seafloor and reflects back off sediment layers. This reflected sound is picked up by "listening devices" and is converted into an electronic signal that can be plotted on paper and/or a computer screen. The Italian team of 3 scientists aboard are in charge of this system. Ice can interfere with the sound signals, so the signals are not always great when we are moving through sea ice. It is hoped that we can target good places for coring using information from this system, and that we can also infer the timing and characteristics of glacial movements and consequent sediment deposition and erosion based on these seafloor sediment profiles.
There are quite a number of bare mountains in the region, with glaciers in between them. Last night as the sun was setting we traveled up into a valley that had previously been covered with a small ice shelf. The wall of deep blue ice at the head of the valley dwarfed the ship, and together with rocky, mountainous terrain on either side of the ice wall made for a memorable experience. The mountains were steep, and large igneous intrusions marked by contacts of contrasting colored rocks were easily discernable from the ship. The height of the spot where the ice shelf had been attached was evidenced by a area of dirty ice draped like a ribbon around the mountains of the bay that we were in.
I didn't get much sleep last night as we were trying to recover a mooring
that had been deployed last year. We were unsuccessful, but then took a Smith-Macintyre grab sample and a Kasten core of the seafloor near the ice shelf edge. This area was covered by an ice shelf only 2 months ago. I found lots of foraminifera in the mud and on the rocks that were recovered from the grappling hook attempts to recover the mooring and from cast off samples from the grab sample. My late night and very early morning and lack of sleep was rewarded with a very colorful sunrise at the edge of the ice
We are only able to multibeam map the seafloor for the rest of the day as few
Raytheon staff are working today. At this point, we do not know
whether we will be able to get more samples or not. We are currently at
the seep site and plan to multibeam the area to get a better map. There are foraminifera and a variety of calcareous creatures in the grab from the ice edge (seen from the 1mm sieve of cast of mud). I also looked at mud and stones brought up from the grappling hook from the Scar inlet mooring site. Several live forams and ostracode carapaces in that mud. Hopefully, I will have more mud to examine. We saw a couple of emperor penguins yesterday and one at a fair distance today. None of these were really close enough to photograph, though there is a rumor that there was one close enough to the ship early this morning
to get a good photo.
We were unsuccessful in our attempts to recover 2 of the moorings. Each time, the grappling hook came up empty (except for the few rocks and bits of mud we recovered on the first few attempts). We are now headed back to the spot where methane seep communities were seen on the underwater video from last year's cruise. We will try to map the area better, then sample it within the next 3 days. I will try to get together with the head marine science technician to get the multicorer (on this ship, it is called the megacorer) ready.
We stopped mapping at midnight, and took a Kasten core in the seep area. There may have been a bacterial mat at the surface, but it was difficult to discern this after the core had been capped and brought into the lab. We tried to go to another area to the north to take a core, but there were too many icebergs there, so we came back to the inlet with the ice wall and have been mapping the sea floor sediments here using the seismic guns. We will eventually take sediment samples and a CTD here. As we were transiting, we snaked around large icebergs which were various shades of blue and white. Dispersed among these icebergs were bergs that have overturned, showing their dark greenish underbelly. It is now an overcast day, with a blanket of low, grey clouds that lies only part way up the steep slopes of the surrounding mountains in the inlet. As a result, we are losing light even earlier than usual today. Normally it gets too dark for mammal observing around 6:00PM; sunset is around 4:00.
Last night we were taking benthic camera images of the seafloor near
the edge of a glacier (which is 100 meters higher than the ship), and part of the glacier calved off into the water near the ship. The resulting
waves rocked the ship greatly, and broke the cable to the benthic camera, leaving it on the seafloor. My roommate was on watch in the winch room when the iceberg hit the water and he watched the berg bob in the water, sending out several waves. The first two waves sent flying everything was wasn't tied down. It is easy to get accustomed to the calm seas, but the rule is to always have things secured for waves. Of course, all of my gear was secured, and, though the sudden rocking of the ship woke me up, I just turned over and went back to sleep. Today we took a grab sample, a triple core (3 small cores hooked together) and a kasten core of the seafloor near the ice wall fjord. Sampling these kept us busy most of the day. Tonight was relatively calm and not too cold (about 24 degrees F), with a bit of snow falling down. A nice night to work on deck.
We are still making very slow progress toward the east. We have been
ramming the ice for 12 hours, and without a change in wind, it will take us a few days to get out of the pack ice. When we back up, we sometimes take on large chunks of ice on the corners of the back deck of the ship. I went out to take some photos, and discovered two Italian scientists chipping away at an 8 foot tall pile of ice on the port side of the ship. Apparently, one of their streamers was buried under the ice. They were chipping away at the ice, and throwing it back to the sea one chunk at a time. It was quite cold out there as the wind is blowing (the wind chill is around -40 degrees F). There is only room for a couple of people in the corner, and I don't think that they have yet been able to remove the ice to get to their instrument. I would guess that whatever progress they made will be quickly reversed once we back into another large chunk of ice.
We were getting nowhere battling the pack ice and jumped pieces of
icebergs to the north, so, though we want to go north, we headed south to find a better route through the ice. We had fairly easy traveling south
through most of yesterday, and eventually found an avenue to the east and began heading in that direction late last night. We made good progress for a while, but this morning we have come up against thick ice again. There is nothing to do but ram our way slowly toward the east in our quest to find open water and a passage to the north. We have about 4 days before we need to start heading toward Chile.
I gave a talk today on the ecology and geochemistry of methane
seeps. Faculty, students and crew members attended. There was a good question and answer session afterwards. The day started out bright and sunny, but visibility was reduced quickly as fog settled in. We passed very close to a number of very large icebergs as we weaved through the sea ice, trying to travel in cracks in the ice. I was on the bridge when the ship had to stop and reverse as we were heading for a collection of various sized icebergs that appeared out of the fog dead ahead. The going was slow for a while but we are in relatively thin ice now (a good thing in oceanographer thinking), and are able to travel at faster speeds. The temperature is 11 degrees F, but the wind chill puts the effective temperature well below zero.
Commentary provided by Tony Rathburn
Dr. Tony Rathburn
- Assistant Professor
Department of Geography, Geology and Anthropology
Science Building Rm 189-B
Indiana State University
Terre Haute, IN 47809
Phone: (812) 237-2269
Fax: (812) 237-8029