Fighting bubbles…

On board the R/V Atlantis we have many instruments through which we pump surface water or air to analyze their content while under way or at a station (parked in the middle of the ocean). Unfortunately, something as harmless as a bubble can make a lot of problems for us, as it affects our measurements very strongly (in particular measurements of light scattering as bubble scatter light very efficiently – think of trying to see a fish through breaking waves).

To make the measurements, we pump surface waters into the lab and run them through many instruments, each measuring different properties of ocean particles (which include virus, bacteria and plankton, the tiny micro-organism that are the base of the oceanic food chain).

The pumps we use to obtain ocean water have to be gentle enough not to affect the micro-organisms we are interested in, but strong enough to push the water up 15ft, where our lab is. In order not to sample many bubbles, we pass the water through a de-bubbler, an ingenious device that separates air from water as in a centrifuge (but with no moving parts, only the flowing water is moving through it). However, even with the de-bubbler we kept getting bubbles through our instruments for the first few days of the cruise. We added another one to the system, but still bubbles were making it through. Finally, Catie, the Alvin’s scientific technician and J.T. the Alvin’s chief engineer, went to the front hatch to tune the pump and, surprise, bubbles stopped flooding our instruments. What a relief! Science can begin for real!

Written by Emmanuel Boss

Tags: NAAMES-III 2017