Edwards lab and Robertson conduct Winkler training

The Edwards lab and Charles Robertson conducted a campus-wide training session to teach the Winkler titration method to measure dissolved oxygen on Monday, October 26. The lesson focused on best practices and how to avoid common pitfalls. He also demonstrated tests to double check reagents and make sure a scientist is getting the best possible measurements using World Ocean Circulation Experiment protocols.

Charles Robertson explains the technique to (l-r) Tina Frazier, Kate Doyle and Katie Miller.

Charles Robertson explains the technique to (l-r) Tina Walters, Kate Doyle and Katie Miller.

The impetus behind the lesson was Catherine Edwards’ AUV, Modena, whichcame back from the Gulf of Mexico and needed a calibration on its oxygen sensor.

“Because we needed both optode (optical sensor) and CTD measurements, we collected in situ samples in the tank, which gave an opportunity for anyone on campus to calibrate their instruments simultaneously,” Catherine said.


Catherine Edwards supervises the removal of the AUV Modena from the water tank as Tina Walters, Katie Doyle (partially hidden), Thais Bittar and Christina Codden look on.

The teame did a three-point calibration, collecting samples with the tank fully oxygenated with bubblers and a recirculating pump. They then pumped in nitrogen to purge the tank of dissolved oxygen, getting down to about ten percent saturation.

“Not bad,” Catherine said.

They also took a mid-point sample in the 40 percent range, which is comparable to the conditions found in the Gulf of Mexico.  In total, the glider and six other instruments were calibrated.

In addition to Charles and Catherine, the participants included Christina Codden, Thais Bittar, Tina Walters, Kate Doyle and Katie Miller, a Habersham School intern with Gray’s Reef.


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