4 September, 2004

Around the Labs on the Oden

The drilling winds down - but as it does, work still goes on in the labs. Core catchers continue to come into the main lab, other samples are sent to the geochemistry lab.

When the sealed core catchers arrive in the Main Lab on Deck 1, the packages are opened and the small plastic tubes are arranged in order of core number on the lab table. They are photographed one by one by Martin Jakobsson. Alexey Krylov then examines and records the sediment type, consistency and color. Often this involves squeezing the sediment between his fingers but more often than not a quick "taste test" better helps him determine the sediment type. Some of the sediment is scooped away in small constant volume samples and processed to determine the density with a pycnometer.

Once Martin and Alexey are finished with the core samples the other scientists are free to take samples of their own for their parcticular analysis. One of my cabin-mates, Asa Wallin, helps to prepare the sediments for some of the micropaleontologists soon after they arrive in the lab. She "cooks" the sediments in seawater and a detergent to help disintegrate them. Many of the sediments are hardened and need to be broken down into much smaller parcticle sizes before the scientists can examine them for microfossils. The beakers of sediments in solution are put on a hot plate for anywhere from 20 minutes to several hours. A small magnetic rod is placed in the beaker bottom and magnets on the bottom of the hot plate cause these rods to spin so the mixture can be automatically stirred as it heats.

Once the sediments are dissolved sufficiently they are sieved to retain mineral grains from 20 - 500 microns in size. They are then ready to be made into slides and examined for microfossils.

Asa is also responsible for running the coulometer, a piece of equipment that measures the amount of carbonate in a sediment sample.

My other cabin-mate, Luzie Schnieders, works the geochemisty lab. On the Vidar, scientists David Smith and Jerry Dickens collect the microbiology and geochemistry samples from the newly cored sediments. Sediments are tested for salinity and alkalinity on the Vidar Viking. Then samples of pore water and microbiology samples (sediments specially prepared in oxygen-free packages) come over from the Vidar after each work shift change. Luzie is responsible first for storing the microbiology and pore water samples correctly at either -800C or +40C until they can be transported to Bremen, Germany for later analysis. Some pore water samples must be analyzed for the presence of ammonia and chloride in the geochemistry lab within 24 hours of collection. I have spent time with Luzie working in this lab and trying out the equipment. Another test procedure that was supposed to be done but did not run parcticularly well on Oden was the GC (gas chromatography). This process measures the amount of gases, parcticularly methane, in the sediments. There is a device called the "sniffer" aboard the Vidar to immediately detect gases such as methane, hydrocarbon and hydrogen sulfide in the newly cored sediments; some gases trapped in the sediments could produce a highly explosive situation. The procedure on Oden is a follow-up test for these gases.

Having spent time with these scientists, watching and assisting I feel much better prepared to share the experience of lab work with my students. But now a break from the lab to go out and take more pictures.

Testing pore water for the presence of chloride in the geochemistry lab.

Martin Jakobsson photographing the newly arrived sediments.

Asa working in the main lab.