Lake Fryxell dissolved oxygen profiles, McMurdo Dry Valleys, Antarctica

Dissolved oxygen (DO) profiles were collected in Lake Fryxell, located in the McMurdo Dry Valleys region of Antarctica, on 18 November 2012 and 6 January 2025 to document decadal changes in water column oxygen structure. In 2012, a 50-µm Unisense oxygen microelectrode (90% response time less than 2 s) coupled to a Richard Brancker Concerto CTD recorded oxygen at 1 Hz and CTD parameters at 6 Hz during ice-penetrating profiling. In 2025, the same microelectrode and picoammeter were paired with an In-Situ Rugged TROLL 100 logger and sampled at 1 Hz. Electrodes were calibrated at ambient temperature using air-saturated and deoxygenated (sodium dithionite) water prior to deployment.