DAY 10: ENCOURAGING CTD RESULTS! TWO GOOD SEDIMENT SAMPLES!!
08.07.2008 The spirits of those on board were particularly encouraged by the positive results from the large (24 cylinder) CTD results. The use of this larger machine with the current meter has allowed us to take more samples on a drop, and to get a better sense of which direction we should be taking in the continued search for thermal vents.
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Text by Courtney Flanagan and photos by Anne Karin Wallace
As this diary is written, the CTD is going down again for more samples. Every evening we have a group meeting in order for every one who wants to attend to be caught up on what is happening. In listening to the description of the results from the CTD, this writer was particularly struck by how important it has been for our success to have the current meter working on this CTD. The meter tells us both the speed and the direction of the current. It also uses the doppler effect (sending down sound waves) to measure the distance of the CTD from the bottom. Learn more about using a CTD.
Last night there were also three drops of the gravity corer. The first was excellent, the second not so helpful, and the final one this morning good again. This is a good example of how life is in the microcosm world aboard a research vessel - it shows the ups and downs of life in science research! It made for a long night for the geologists, but they were ultimately happy to get some significant samples.
The procedures followed each time a core comes up go something like this:
It is cut into lengths of about 1.5 meters, and then each length is halved lengthwise.
Note in the picture how carefully the core operator pulls a thin-wired hand saw through the cut, and then follows it with a thin spatula-type tool - all to make the cut as clean as possible.
Once the core is halved, it is observed and photographed carefully for its color, structure, type of grain etc. One half of the core is carefully wrapped and stored as an archive. At the same time, each length is measured and marked so that it will be clear from what depth a sample has been taken.
First to directly work with the sediment is the geologist, on our ship Rita Fonseca. She begins by taking the temperature. On this cruise, because of the sticky quality of the sediment, she has also taken a very small sample of the sediment to measure pH and Eh in the lab. Next up to the core is the microbiologist, who takes again a quite small sample in order to examine the microbiological life. Tamara Baumberger takes out the pore water from the core to learn more about the chemical reactions taking place in each layer. Back at the home lab, tests will be given to determine the element and mineral content. Once the pore water is out, larger samples of the sediment are removed for study.
In this way, we learn about the geology, chemistry and microbiology of each level of a the core sample.
