“CTD on deck!” and thumbs up with a smile, thats what the scientists of Angola Basin cruise M121 want to get from me when they are eagerly waiting to sample the “liquid gold” that keeps our cruise going.

No – that’s not beer that I’m talking about. It’s seawater, the stuff that surrounds us for 3 weeks now! And I’m not the bartender but I belong to the CTD team of M121. CTD stands for conductivity, temperature, density which implies that we have sensors measuring these parameters (and a range of other attributes of seawater), mounted to a cylindrical shaped frame that also carries 24 bottles…

Control unit of trace metal clean CTD winch system (Photo by Veit)

Our most important job is to deliver seawater from any depth in the ocean below our feet – at any time. Seawater, that keeps the scientist busy all day and all night on board of RV Meteor. 240 Liters per cast, enough to fill a bathtub with ice-cold water (temperature can be as low as 2ºC down below 2000 meters) in which we could chill our drinks. Luckily we have enough refrigerators to do that job and so we can use the seawater for all kinds of other purposes…

The first ones to come and feast on our precious good are always the oxygen lady (see last post) and the guys from the nutrients lab. But there are more to come… some carrying huge canisters others tiny bottles. Some are always there – no matter the date or time – some are more shy and come only when they really need more. It is a spectacular sight how the delegates of different kingdoms in science meet at the “waterhole” to get their water. They joke and laugh with each other before they return to their respective laboratory. After a few minutes, when everybody is satisfied it becomes quiet again around the CTD.

A particularly interesting task, that were asked to do by a group of scientists, was to fix a laundry bag full of polystyrene boxes that they painted with funny sketches and totems of good luck to our instrument before we send it down to 5900 m depth…

When  they return to the surface will have shrunk to only a fifth of the original size, very much to the amusement of the scientist.

We from the CTD team are happy to take care of all our scientist’s wishes and problems, be it seawater from any depth, mounting polystyrene figurines to our instrument or even if they just need someone to have a beer for the sunset…but only when not on duty 😉