18 August, 2001
In Search of Plumes
Dr. Hedy Edmonds, a chemical oceanographer from the University of Texas Marine Science Institute, has been in search of hydrothermal plumes on our expedition. She has brought with her 4 MAPRs (Miniature Autonomous Plume Recorders)--instruments that are attached to the wires that go down in the search for rocks. When the data collected by the MAPR shows signs of a hydrothermal plume, the big daddy is pulled out-- the CTD.
The Healy has an instrument on board called a CTD, which stands for conductivity, temperature, and depth. This instrument is used to collect water samples around hydrothermal vents on the ocean floor. If you recall, the CTD hadn't been working, but the Coast Guard electronic technicians repaired it and it's ready to go.
Yesterday the MAPR went down in an area 3 times and the data it collected showed the existence of a hydrothermal plume. This morning the decision was made to turn the Healy around and head back 7 hours to this area and drop the CTD. The CTD collects much more information than a MAPR can. It is a huge piece of equipment with 24 bottles on it. Each bottle can hold 12 liters of water. The CTD works by sending data concerning the water's conductivity (ability to conduct electricity, which is used to calculate salinity), temperature, and its depth immediately to a monitor. This allows the scientist to "fire" close each bottle and therefore trap water samples from specific depths. The ship moves along, sometimes towing the CTD like a yo-yo, while the 24 bottles are filled around a plume area. These water samples are then taken to a lab where they are analyzed for amounts of helium, methane, and manganese-three tracers of hydrothermal plumes.
Besides the hunt for plumes, everyone has been on the search for polar bears. We had a nice surprise yesterday afternoon when one was sighted very close to the ship. It was our first close look and it was exciting. The bear would lumber along an ice floe, jump into the water and swim along, then gracefully climb out onto the next ice floe. The crew watched this huge animal in amazement as it continued its progress. It was quite a sight!
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