19 July, 2002
My day began at 6 AM when we were scheduled to start the next station. I knew we would have no water ready to sample at that time, but I tend to be a bit anxious about schedules so I arrived right on the dot of 6. Needless to say I was early; the service cast had not even gone into the water yet! I went back to my room to work on my journals and computer filing of my pictures. I returned, took my samples and made it to breakfast by 7:30.
After lunch, it was finally time for Dr. Grebmeierís sampling. Since she is still on the Canadian icebreaker, the Sir Wilfrid Laurier, I worked with Jim Bartlett, her technician, to collect and process the benthic samples. Benthic organisms are those that live on the bottom. Iíve included lots of pictures today so you can see most of the process. In future days, Iíll tell you more about the analysis; today Iíll just describe the actual sampling procedure. As you are reading this, keep in mind that we repeat the process five times, the first to get samples from the top of the mud and the other four to provide replicates (samples taken at the same station).
We start by lowering an open van Veen grab over the side and to the bottom. When it hits bottom, it releases and closes, grabbing a sample of the bottom mud. When the first sediment sample is on deck, we use a syringe to gather a tiny mud sample for chlorophyll analysis. After that, we remove a larger amount into a special container called a Marinelli beaker. It has an indentation on the bottom designed to fit onto an instrument that measures the sample for beryllium-7 content. Once those samples have been taken we follow the same procedure for the remaining four samples. First we empty the mud into a large tub and rinse the grab to be certain all the mud is cleaned out. The sample must then be completely rinsed of mud in order to collect any organisms (and the rocks that are often present). To do this, we empty the tub into a large wooden box with a wire mesh bottom and rinse continuously until the mud is gone. Depending on the consistency of the mud, this can be a relatively short process or a longer one if the mud contains a lot of clay or gelatinous (jelly-like) material that clings to the mesh. When the mud is gone we transfer the remaining material to a plastic container where we add formaldehyde to preserve the specimens. The biological samples are transferred to the University of Tennessee for further analysis.
As you can tell, the sampling process for this parcticular experiment is very mechanical, and much is done literally by hand. Itís interesting to compare our work with some of that going on around us. While others lower sophisticated, computer-controlled instruments into the water to sample and gather data, we use a metal grab, buckets, sieving boxes and a hose!
We have one more station ďtonight.Ē Technically, we arrive at midnight, so I guess it is really a July 20 station. Most people will try to catch some sleep so they wonít be too tired while trying to complete their work. My job includes collecting water from the service cast which is done right at the beginning and then doing the benthic sampling which occurs at the very end (we donít want to mess up other samples with our mud in the water). It will be a long night!
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