27 July, 2002

Due to the great depth (2000 meters) at this station, we only did the Haps core sampling for the mud at the bottom. The five van Veen grabs would take up too much “wire time” (the time it takes to send the equipment down and back). The multi-Haps core sampler should pull up four cores at a time and, by sending it down twice, Jackie will have more than enough samples. However, it is not unusual to run into problems, especially at these depths, both due to equipment and changing drift conditions. Today we had to send the corer down three times in order to get the samples we needed. Thanks to Steve Roberts, the JOSS (Joint Office of Science Support) data management person on board, I have a record of the sampling process. Be sure to check it out in the series of pictures below.

Keep in mind as you look at the pictures that Jackie Grebmeier’s interest is the benthic organisms. It’s important to understand what lives at the bottom and the characteristics of their environment (the sediments) in order to see what part they play in the overall scheme of carbon cycling. When the cores come up, sub samples of the sediments from one of them are taken for a variety of tests. A chlorophyll test gives an indication of the phytoplankton present in the sediment. Remember that phyto means plant and phytoplankton contain chlorophyll, a green pigment found in all plants. Another sample is collected for HPLC analysis. This is high performance liquid chromatography, a fancy name for a process that separates out the phytoplankton by the pigments (colors) they contain. Another sub sample yields TOC (total organic carbon) and TON (total organic nitrogen). The results can provide an indication of the source of the organic material in the mud, a ratio of marine (salt water) to terrestrial (terra = land) organisms. Carbon-13, an isotope of carbon, will be analyzed from the same sub-sample and will provide similar information. Lastly, we preserve the samples for analysis for a series of radio-isotopes such as beryllium-7, lead- 210, cesium-137, plutonium, and radium. These are called tracers because they tell us what forms of carbon and how much arrives at the sediment surface from overlying water column processes.

Once all the cores are on deck and the sub-samples are removed, Jackie chooses two cores for her 12-24 hour respiration experiments. (Check out the journal photos for July 22.) When she is finishes with those, they are sieved to remove all mud and to preserve the organisms left behind. We then take one of the other cores collected to cut into sections to be canned and brought back to the University of Tennessee for further analysis. That’s the time when we get to come inside and actually work with the mud. When it’s not full of byssal threads from mussels in the core, it’s an easy job. We take off one centimeter (a little less than ½ inch) slices at a time for the first four sections. After that we remove two centimeter slices until the core is finished. Because we are near the end of the sampling at each station, we are often working into the early morning hours or even through the night. In case you think that is difficult, check out the last picture to see what our surroundings look like while we are on deck!

Jackie Grebmeier designed this multi-Haps core. The original design only takes one core at a time. This one takes four. Jackie is the one at the end with the white hat.

Everything must be checked before the Haps goes into the water. Once it reaches the bottom, the tension on the wire releases and the cores drop into the sediment.

There is always an MST (marine science technician) on deck to direct whatever sampling operation is going on. He or she works with another MST who controls the operation of the winch. Together they make certain that the equipment is deployed correctly and safely.

While we are waited for the Haps core to return to the surface I sieved the core from Jackie's respiration experiments. At this depth (2000 meters) there are very few organisms.

It takes at least one and a half hours for the Haps core to get to the bottom and back when it is this deep. Sometimes, when standing on the back of the ship, I am reminded that little separates me from water that is 2000 meters deep!

Lee Cooper, co-chief scientist on board, removes one of the core samples after the Haps comes back on deck. Some of the analysis is his work.

Once we select one core for sectioning, we start at the top with one centimeter slices. This looks like a two centimeter slice that Jim Bartlett (science technician for Lee Coper and Jackie Grebmeier)and I are getting from further down in the core.

As we remove each layer of mud, we collect a sample into carefully labeled cans which will be taken back to the University of Tennessee where the mud will be analyzed.

Working into the early morning hours has its advantages. Look at the view we get from the back deck!