18 February, 2001

In the Lab

Many things happen on station besides bringing the cores on deck. Once the sediment is inside the lab it is as though you were in an emergency room. Time is critical: some samples must to be collected as soon as possible, whereas others can wait until later. You can work a whole shift without stopping except to eat, and even then we have to hurry back. One of the most labor intensive activities is processing the Kasten core. Once it is on board and brought into the lab we use screwdrivers to open up the metal plates on top. You can tell when they have opened a Kasten by the smell! Here is a picture of Dr. Dunbar smelling the sediment, but you don't need to get that close. The smell is from hydrogen sulfide, which is released from the core due to the decrease in pressure between the ocean floor and the water surface. Look for the picture where our lead scientist, Amy Leventer, is looking at the inside of the core, what do you see? If you are a good observer what you should notice that the sediment is layered. The layers are called laminations and represent differences in the environment over time. One of the things that we look for from the sea floor soundings (Bathy 2000) is not only if sediment is present, but also what kind of sediment it is. The kind that we are looking for is called "diatomaceous ooze". After the Kasten core has been opened, we scrape off the top layer of sediment that was in contact with the metal plates. Usually, as the core barrel is pushed through the sediment, the outside layer gets a little "smeared", making it hard to see the layers. Painstakingly, we then describe the core, using special, symbolized drawings to represent different kinds of sediment and laminations. Photographs of the sediment are carefully taken for reference at a future date. After that, it's a real team effort; everyone needs sediment samples for different research. Small bags and bottles of sediment are collected from regular intervals or specific depths, depending on the layering. Slides are also made to look at the sediment under the microscope. By the time everyone has taken his or her samples a whole, 12 hour shift may have passed. There is very little sediment left in the Kasten core at the end!