June 20, 2009
56° 42' 24.1340 N
I was downstairs in the lab by 6 a.m. to sample off the first CTD cast of station 20-CN8. 2-liter POC samples were taken at depths of 1, 40, and 50 meters while 3-liter samples for thorium testing were taken at 1, 10, 20, 30, 40, 50, and 70 meters. We are a long ways from any landmass but the shelf remains relatively shallow at only 75 meters in depth here. The samples were brought back to the main lab for processing. Once the filtrations were set up, Matt Baumann and I went back down to the CTD platform to sample from the Prod CTD.
The Prod CTD is a CTD cast specifically for those scientists who are studying the primary productivity zone of the ocean. The studies may require depths in addition to those offered by the standard CTD cast and samples are typically collected soon after sunrise. This is done to allow the observation of one complete photosynthetic cycle of the phytoplankton during the experiment.
In addition to his own work on particle export and carbon/thorium flux, Matt is lending a hand to Dr. Michael Lomas of the Bermuda Institute of Ocean Sciences (BIOS). Dr. Lomas's project is attempting to identify the phytoplankton diversity in marginal ice zones. Marginal ice zones are regions of the ocean that are only seasonally covered by ice. The 7 depths at which we collected samples were determined by the trace of the CTD as it was lowered near the ocean floor. Lomas's study does not maintain consistency by sampling at the same depths at every site but rather at the same PAR zones.
PAR stands for photosynthetic active radiation and is a measurement of the sunlight that penetrates into the ocean. A sample collected at a PAR of 100 % would be collected at the surface before any of the sunlight has been absorbed or reflected by the water. A sample collected at a PAR close to zero would be near the bottom of the photic zone, where very little of the sunlight remains. 2-liter samples of water are collected at depths of 1, 7, 15, 22, 30, 37, and 58 meters and run through two filters. The first liter of seawater is pulled through a 47 mm glass fiber filter that will trap all phytoplankton larger than one micron in size. The second liter of seawater is passed through a 5-micron polycarbonate, which has a pore size large enough to let the smaller phytoplankton pass through and trap the larger ones. Both filters are then removed and frozen in an -80°C freezer chest for analysis back at BIOS. Here scientists will use the analytical technique of HPLC (high performance liquid chromatography) to identify the pigments present in the samples and thus deduce the species of phytoplankton present or community structure.
Matt got me set up with the filters, gave some instructions on how to process the samples when the filtrations were complete and set off to work on his samples in the other lab. It felt nice that he trusts me enough already to let me start to ease his workload. Of course I shouldn't read into it too much because this task is hard to mess up.
After completing the filtrations for Matt and freezing the samples, I made my way up to the lounge to get caught up on some writing. I did not submit an entry for yesterday for two reasons. First, not much happened. It was a non-sampling day for my team and things were relatively low key. I wandered around the ship, watched some CTD casts and read for a while which was quite nice. I often don't have the time at home to sit down and appreciate a good book. I borrowed my wife's Kindle for the trip and am about halfway through Dan Brown's The Last Symbol which I am enjoying, though not as much as the previous three I have read, Deception Point, Angels and Demons, and The Da Vinci Code.
I also spent a good deal of yesterday working on and revising my two postings from Friday. These two were the first time that I was writing about something scientific so I decided it was best to run them by Pat and Matt first. It turns out that I did not have as good a grasp on the material as I thought I did. Pat was very patient with me and after going back over the science once (or twice) more, he gave it his seal of approval and out it went.
I ended up back in lounge Sunday afternoon with all of the things that I might need, camera, Kindle, laptop, and some Jolly Ranchers. Pat and I are on slightly different schedules right now. He sleeps in the late afternoon so that he can help out in the early morning hours with another group's bongo net tow. So that I don't disturb him, I gather my stuff together and leave the room for several hours so he can get some sleep.
I also brought with me my laundry. Scientists are permitted to do laundry on Friday, Saturday, and Sunday. My stateroom is assigned Sunday. The laundry room is in the bowels of the ship, well below the waterline. From my room you go down three decks, turn right, and just before you think you can't go any farther, there it is. Laundry day could not have come much later as I was running out of options when I opened my closet.
As the day wore on, the seas got worse. Up until this point we had been very fortunate but a low pressure system was moving in from our southwest bringing with it high seas and 35 mph winds. Around 7 p.m. I decided to head to bed. Tomorrow would be any early morning anyway and the pitching and rolling of the ship was starting to get to me a little. I took my nightly dose of Bonine, climbed up into bed and set may alarm for 4:00 a.m.