16 June - Rockall and the "clean van"

By Chris Marsay, PhD student, trace metals chemistry, NOCS

My work on this cruise is centred on the study of “trace metals” (and iron in particular) in the ocean. So-called because they are generally only found in trace amounts (just a few parts per trillion is typical for iron in open ocean waters), these elements can nevertheless play an important role in the biology of phytoplankton. But because they are present in such low concentrations in seawater, samples are easily contaminated unless special care is taken during their collection and treatment.

For this reason, most of my work takes place not in one of the ship’s laboratories, but in a specially designed “clean van” located on the back deck. This container is fitted with a filtered air supply to prevent potential contaminating particles (dust, flakes of rust, soot from the ship’s stacks) circulating inside and ruining samples.

In the couple of days before leaving port, much of the setting up time needed for the trace metal work is spent giving everything inside the van a thorough scrub down to get rid of any dust that may have settled inside while it had been unused and in storage with the power off. Then, our boxes of equipment can be moved inside, one at a time and each one wiped down beforehand. After giving the van another good clean, the equipment can finally be unpacked and set up on the benches.  Even so, when not in use, most of the equipment is kept in plastic bags to minimise chances of contamination.

Of course, all of this effort in providing a clean working environment would be pointless if the scientists working inside the van were bringing in rust and dust every time they entered the van. To prevent this the van is accessed through a small anteroom, with one door opened to get into the van, then once this is closed, a second door opened to enter the clean laboratory.

This way the laboratory area is never directly open to any gusts of wind blowing around the deck. On top of this, once it is in use, those entering the van have to don a pair of white coveralls (complete with hood) and some shoe covers whenever they enter, as well as gloves.
As well as helping to prevent contamination of the samples, this generally provides some amusement for the other scientists as they peer in through the windows……

 
Chris and Sebastian in the cleanest part of the ship, sampling for trace metals.