Working through the night and shrinking cups

By Stefan Gary

There are always people awake on the RRS James Clark Ross. Round-the-clock operations mean that even at night we need officers on the bridge, deck crew ready to get the CTD in the water, scientists to take and process samples, and a cook in the kitchen to prepare a midnight meal.

I am on the midnight to noon shift. Every morning, I wake up at about 11PM, shower, and then make my way to the main lab to catch up on what has happened since I fell asleep. I greet this moment with anticipation because I’m curious to see how much progress my colleagues have made “overevening.” Most days things have gone according to plan, but every once in a while there are important changes because instruments need repairing, or the sampling plan has altered. Last night, I found out that we were going to be able to put cups down to 3100 metres deep on CTD station 95.

Cups! The long-awaited polystyrene cup station is finally here! The intense pressure several thousand metres below the surface of the sea is capable of crushing a polystyrene cup into a nearly rock-solid mass. This is because they are made of plastic that has gas bubbles blown into it while it solidifies in a cup-shaped mold in the factory. The trapped bubbles provide insulation between your hand and your hot drink, but will be crushed by the weight of the water at the bottom of the sea.

What is particularly fun about pressure is that it acts evenly in all directions. This means that the whole cup is squashed evenly, and the result is a nearly identically shaped cup, except it’s been shrunk. Theoretically, anyway.

About an hour later, I have to figure out how to strap a menagerie of 20 creatively decorated polystyrene cups to the CTD frame without any chance of a cup getting caught in a sampling bottle when it closes, blocking an instrument, or falling off during the 2 hours it takes the CTD to go down and back up again. In the end, we put each cup in a sock and cable-tied the socks, in a single bouquet, to the CTD frame.

During the station, I was worried that we’d lose some cups, but they all made it back up, with some surprising results. The cups don’t always shrink perfectly. Some people tried to stuff paper inside the cups to help them keep their shape but we found out it is possible to overstuff, resulting in cups that now look very odd indeed.

Why did we wait so long before the cup station? It turns out that some types of polystyrene may have been created by blowing a type of chemical called a chlorofluorocarbon (CFC) through the foam to create the bubbles. There is a team of scientists aboard who are making extremely precise measurements of CFC in ocean waters (down to the picomole = 10-12 moles!). CFC from the polystyrene could spoil the samples they collect, but since no CFCs were being measured on this station we had the all clear to send down the cups.

After the station, I realised that folks on the day shift didn’t know about the cup-station in time to decorate their cups. So, on the next stations with no CFC sampling, more cups were strapped to the CTD.

Finally, although being on the night shift might seem arduous, now that I am accustomed to the new sleep pattern, it’s my favourite shift. It’s a little quieter than during the day and because we’re at high latitude, the nights are short and we can see sunrise and sunset.

Images: Sunset and sunrise (photos by Felicity Williams), Carolyn and Mark with their socks of cups (photo by Felicity Williams), socks tied to the CTD frame (photo by Stefan Gary), and some shrunken cups (photo by Jen Clarke)

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