Southern Ocean GasEx Blog

Dispatches from the Southern Ocean Gas Exchange Experiment

Patience is a virtue

Posted by sogasex on March 19, 2008

By Roberta Hamme, University of Victoria

This is my sampling mantra, often repeated under my breath. Once our water sampling bottles (called Niskin bottles) get back on deck, there is a mad rush to collect subsamples as soon as possible. To remove water from the Niskin bottle, you have to let in air at the top. As you do this, the gases in the water start to exchange with the headspace and the samples begin to degrade. Everyone works fast to collect his or her samples. Everyone, that is, except me.

I got excited about this cruise, because I wanted the chance to directly see the effect of breaking waves and bubbles on noble gases. My lab at University of Victoria makes highly accurate measurements of dissolved gases like neon, argon, krypton and xenon, some of which are very sensitive to bubble-mediated gas exchange. However, the tiniest bubble of air pulled into the sample will destroy it. To prevent air contamination, I flush the necks of my flasks with carbon dioxide (a gas I don’t measure) and use a complicated collection of tubing to isolate the water from the air as it enters my flasks. All this takes close to forever when folks are anxiously waiting to sample after you, which is where the patience comes in.

I remind myself, sometimes over and over again, to be careful while I collect these samples. It’s easy to make a mistake, and we’ve learned the hard way how important precision is to our analysis. My colleagues have been extremely gracious about the difficulties my slow sampling impose on the group, all helped by our “bottle cop” (sometimes referred to as “your majesty”) who directs when each person may sample which bottle. Last night was particularly exciting, when I discovered that my carbon dioxide tank was empty. I would have been very sad to miss out on our first post-storm sampling! Many thanks go out to Paul Schmieder (LDEO) and Paul Covert (PMEL) who helped me get the spare tank onto the deck in record time and secured it while I rushed back to my exercise in patience.

noblegassampling-scaled.jpg

Here I am collecting my noble gas samples. Can you see the love?

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