Wednesday 04 February, 2004

Anchor Station: Box Core
Because we are now on an anchor station, the work for the regular night shift continues for 24 hours without a break. Therefore, they have divided their normal work crew into two groups to allow people to get some rest. However, there is a lot of work to be done. So, I´m enjoying my first opportunity to help with core, CTD and BLISP deployment and core processing. The box core requires six people to deploy and recover. There is a winch operator from the ship´s crew, and that person will change with the watches (which are 4 hours on, 8 hours off). On the fantail during deployment, the following workers are required: A-frame operator (I filled this role tonight), two people to hold tag lines which prevent the coring device from swinging, a person to pull the support pins and the safety pin, and someone to direct the winch and A-frame operation and oversee the entire procedure.

After the box core is deployed, the safety line across the open fantail is secured and the deck is cleared while the core makes its decent and rise. When the box core lands on the sea floor, the weight of the center column forces the box into the seabed, and the core is collected. As the core is lifted, the shovel arm rotates under the box and closes off its bottom opening, keeping the sediment in place. Back on deck, you can see the core hit as the cable slackens, and at this point we return to our places on the fantail for recovery. Tag lines to hook the equipment are readied by taking a long pole and tying the tag line to a large hook (with a bowline knot). When the hook is attached to the frame of the core, it slides off the pole, and the line is used to guide the recovery. It is important to hold onto the pole and line tightly to prevent the hook from slipping off. I got to "run the tag line" during a CTD recovery and got it hooked on the first try, but it wasn´t easy! To accomplish this, you must stand at the edge of the ship, reach the pole down to get the hook in the right spot, hook the instrument and then hold the tag line tightly. It´s trickier than it sounds! Once the box core is hooked the winch and A-frame are operated at the same time to raise the core back onto the deck.

After recovery, a metal tray is pushed between the bottom of the box and the shovel that holds the mud in place. This allows the box to be removed without losing the sample. The work gets muddy starting now! I stood by with a shovel to collect extra mud caught in the core. Inevitably, you miss some of the mud and must scoop it up with your hands. But it´s fun, and the mud feels soft and silky. Truly the best mud pies could be made from this stuff!!!

After the box has been removed, a meter long 15-cm (6-in) round piece of PVC pipe is slid into the mud. Next a clear rectangular box is placed in the core to collect sediment for x-rays that are taken of each core. Once cleaned, this rectangular "slab" is taken to the science lab/darkroom to be processed. John Crockett taught today´s lecture about sediment processes and at the end showed us a selection of x-radiographs from recent cores.

Back on deck, the excess mud from the core is left on deck during an anchor station to keep from disturbing future cores (waiting on the seabed) and adding sediment to the water that will affect the BLISP and CTD results.

The last step, before data processing, is to cut the core. The circular PVC core is placed on a stand. Rotating the stand down exposes a portion of the sediment and in this way individual centimeters of sediment are sampled. An assembly line is set up with one person cutting the core. Another person opens sample bags that have already been labeled with the anchor station location, core number, date, and cm layer. Portions of each core slice are given to Miguel Goñi and Natalie Monacci for their carbon research. They collect sediment in small bags as well as tiny containers for water content (of the sediment) measurements. There´s also a person who cleans the metal spatulas used to cut the core in order to keep the layers of mud separate. And last, but not least, John Crockett always assigns someone to select the music for the core cutting, possibly the most important job. J/K Once a station is all finished, the decks and equipment are cleaned using seawater hoses, and everything is prepared for the next core. While the work is hard, muddy and repetitive, the music and camaraderie of the team makes the mood festive and the process a lot of fun!

Weather (Today's weather and location at 0900)

Air Temperature: 28.54°C (83.73°F)
Water Temperature: 29.78°C (85.6°F)
Salinity: 31.52
Barometric Pressure: 1008.0 cmbar
Precipitation: 31.2 mm (last 24 hours)

Location
Longitude: 8° 36.903' S
Latitude: 143° 58.521' E

Menu
Breakfast: Bacon, ham, eggs, potatoes, fresh fruit
Lunch: Ribs and beans, franks and fries
Dinner: Salisbury steak, fish and potatoes
Dessert: Toffee bars