Rolling Seas and the Multi

July 17, 2010

Location: Mid-Atlantic
Lat/Lon: 38*24.2674'N / 48* 32.3969'W
Air Temp: 26.10*C / 78.98*F
Wind Speed: 0.96 kts
Humidity: 82.9%
Water Temp: 25.84*C / 78.51*F
Salinity: 36.04 psu
Depth: 5011 m / 5 km / 3.1 miles!

A squall caught us in the middle of bringing up the long core yesterday evening! Researcher Paola and teacher Bob bravely stuck it out in the man basket, shooting "bullets" down the long core to extrude the liner. As the core was extruded, long cracks along the PVC were exposed - one section was completely sheared off. Slippery and heavy with mud, the core was removed, cut, juggled, taped, labeled and lugged into the lab. Towards the end a rainbow made its appearance and the sea calmed...some.

As night came upon us and the multi core was on it's way back the ship, the wind whipped up and the waves followed suit. Last night we had the roughest seas to date on the trip! It was difficult to simply stand and work, let alone try to walk down the hall or stairs! We worked until early morning on the deck processing samples from the multi core and the boat lights illuminated the rolling white caps, giving you glimpses of the waves. "Wave heights" is what I should be calling them - but they felt and looked more like "wave depths". We gritted out teeth to hold back the sickness brewing in our stomaches. Descending to our staterooms we grabbed for patches, pills and pillows to sooth our rolling innards.

So what WERE we doing on the deck so late? Ah - today we'll go over the "multicore".

This coring apparatus is designed to sample the upper portion of the seafloor sediments with careful attention to maintaining the structure of these fragile sediments. Both the long core and the gravity cores can mangle and lose the top sediments. The multicore captures them carefully. There are sites for 8 rigged plastic tubes on the multicore. In the photo to the right Susan is
working the crane, carefully lowering it to the deck while Pete climbs up to help free the rig from the crane hook. Look carefully at the plastic tubes. That day only four were sent down. You can see the short sequences of sediment at the bottom of each. The gravity core also helps to inform the coring team about whether or not a multicore is appropriate, how many tubes should be sent down and how much weight should be included. If the sediment is very soft they do not want to use too much weight.

When the multicore has been brought up the science team quickly removes each of the tube sets, hangs them on wall mountings and begins to visually assess them. Decisions are made about what each will be used for; some are used for archiving, some for sampling. This is a great picture of multicore processing. Isabelle, in the blue jumpsuit, is gathering samples of each layer that will be preserved with seawater. Marti, her back is to us, is getting the next core from the rack. Kathryn, in the teal tank, is controlling the extrusion of the core. Sarah, in yellow, is preparing to collect samples that will be further processed for study in the R/V Knorr Lab. Paola, in green to the right, is removing the edges of the core layer before plopping it into the water-filled sample jar.

These sample jars will have "rose bengal" dye applied to them which will stain the foraminifera that were alive at the point of collection. This gives the researchers a real snapshot of productivity at the sampling site. The forams cannot survive long after they have been brought to the surface so this sampling and treatment must be done quickly. Here is Paola swirling the rose bengal in the hood in the second floor lab.

So this is what we were doing last night so late. And it's what we'll be doing again tonight, so late! The word right now (16:35 GMT-2) is that there is trouble with the winch so if it's fixed, the long core will be sent down and return about 5 hours later. Then the multicore will be sent down and it will likely take about 5 hours to return. Both cores must be extruded and processed. After the multi, there may be a short transit to a new site where a CDT will be done. This will bring us clear until daybreak tomorrow. So the word is: get sleep while you can!

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