11 August, 2002
The 3000 meter stations always take longer and give people a little time to catch up. Of course, if you are the one sampling or waiting for the CTD to come up, you have to remember that it will take approximately three hours from the deck to the bottom and back up again. So, even though your time in between sampling is longer, your time actually working might easily be longer as well. We ended up with great cores this morning, but the entire process took nearly seven hours from beginning to end. It was interesting to stand on deck and look out at the nearly ice free water around us. Only the icicles dropping off the equipment reminded us that we are indeed still in the Arctic Ocean.
I first met Ari Balsom when I visited Jackie Grebmeier's lab at the University of Tennessee in Knoxville. Ari is a research technician and graduate student at UT Knoxville, and she has worked with Jackie and Lee Cooper on two previous cruises to the Arctic. On this SBI spring cruise, Ari is working for Ken Dunton a professor at the University of Texas in Austin. When I asked Ari about the focus of her work she said, "You are what you eat!" Ari is taking large water samples from shallow depths in order to filter them and get POM (Parcticulate Organic Matter). That means that her filters will be covered with tiny parcticles when she is done. The filters will be preserved and analyzed (with a mass spectrometer) for two isotopes, carbon-13 and nitrogen-15. The carbon 13 concentration can tell you where that carbon came from, whether it was from the ocean (marine) or from land (terrestrial). On an interesting side note, Ari told me that carbon-13 is a very common "tracer." For example, archaeologists who study Aztec remains can use the carbon-13 in those remains to tell them when the Aztecs started eating cultivated corn!
Ari is also taking zooplankton and benthic animal samples (we always sieve one core for Ari) to see how much carbon-13 has made it to the bottom. Once again, these samples can be analyzed to tell if what the animals are eating comes from a marine or a terrestrial source. Essentially, the analysis of carbon-13 helps us to figure out where the carbon in the organisms and in the water comes from.
Nitrogen-15 gets more concentrated (there's more of it) the higher up you go on the food chain. By analyzing the nitrogen-15, you can identify the organism's trophic level (where it fits on the food chain). It will tell you who's eating what and who is eating whom. Jackie and Lee are both analyzing the same tracers in the sediment samples we take, but the samples Ari wants are only from the fresh material on the surface of the mud. In summary, Ari's work for Ken Dunton includes filtering water to bring back the preserved filters with their POM (Parcticulate Organic Matter), identifying and drying zooplankton to be brought back to the University of Texas, and identifying and preserving benthic organisms for later analysis.
Each time we bring up cores or van Veen grabs, we always take three small samples of surface mud from the top 1 centimeter (less than ½ inch) for Ari. These samples are for a different purpose. Ari will analyze them herself to see how the populations of bacteria and viruses change in the sediments as we move from the shelf to the slope and down into the basin. She will use a procedure that she has adapted for use in the Arctic where this work is rarely done. Bacteria are nature's recyclers. They break down dead organic matter and return nutrients and other materials to the environment. Bacteria are tiny but viruses are even tinier! Viruses get inside bacteria and use the materials in the bacteria in order to reproduce more viruses. When the bacteria finally split open and all the viruses are released, nutrients are released back into the water as well. You can see how important it is to understand more about how these two organisms relate. It's all a part of the effort to understand the "microbial (micro = tiny and bio = life) loop" in the ocean. Remember Rex and Matt's work with bacteria (see the journal for July 26) and you can see how it all fits together. As with other topics, there is little known about these populations in the Arctic Ocean. Scientists aren't even certain if the bacteria and viruses living in the sediments are independent communities or if they are settling out from the water above. These are just two more important questions that scientists on this cruise are working to answer.
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