Measuring the marine carbon is tough work – within seawater, carbon takes many forms and there are four main parameters scientists measure to constrain the system. These parameters are concentration of hydrogen ions (pH), total alkalinity (TA), dissolved inorganic carbon (DIC), and the partial pressure of carbon dioxide (pCO2). Marine carbon-chemist extraordinaire Caroline Fradette (NOAA PMEL) knows just how complicated sampling such parameters can be.
“We’ve been thinking about two things on WCOA – an appropriately sized “noodle” and proper sample headspace.”
The former isn’t referring to pasta and the latter doesn’t mean all the samples must meditate prior to analysis. When sampling parameters like TA and DIC, a flexible plastic tube (the noodle) is used to ensure the water isn’t exposed to air when moving from the sample collection bottle to the flask used in analysis. However, the noodle will displace a certain amount of seawater when removed from the analysis container, leaving a small amount of air (the headspace) present.
“The typical headspace should be approximately 1% of the sample volume”, notes Caroline, “but our regular noodles were too inconsistent”. Luckily scientists at sea are incredibly ingenuitive and have backups and swaps of just about any piece of equipment. The *new-dles* start with a regular flexible tube followed by a smaller and firmer piece at the end. Not only does this setup provide more consistency for measurements, but it has also created quite an audibly-satisfying sampling experience!
Press play to listen to the sound of seawater sampling
The WCOA cruises provide “climate-quality” data and involve people working around the clock (see day AND night shift). This means consistency is key when it comes to sampling. Luckily just about everyone is excited about this change for both the data and our ears!
