The overarching objective of the Hypoxia 2021 — C2021-06 cruise is to provide a new and informed assessment of the relationship between the reactivity of natural organic matter and the benthic ecosystem functioning in estuarine environments, with a focus on the hypoxic conditions in the deep waters. For this purpose, the cruise had assembled a team of researchers from three Québec institutions, ISMER-UQAR, McGill University and Concordia University, whose work is largely focused on the fate of the organic matter in natural environments as well as the benthic ecological processes it sustains. This initiative, supported by NSERC's Shiptime Program (NSERC — Shiptime 556538-2021), took place in August 2021 from the Estuary to the Gulf of St. Lawrence and via the Saguenay Fjord.
This dataset presents the vertical profiles of practical salinity, temperature, dissolved oxygen, fluorescence, transmissivity, and density of a dozen stations, from the surface to 350 m deep. Although the probes were calibrated by the manufacturer during the year, discrete salinity samples were taken throughout the water column and analyzed on a Guildline Autosal 8400 salinometer calibrated with standard IAPSO (International Association for the Physical Sciences of the Oceans) seawater and CTD profiles reprocessed after the mission. Similarly, dissolved oxygen concentrations were determined by Winkler chemical titration (Grasshoff et al., 1999) on about forty discrete water samples collected directly from Niskin bottles. The relative standard deviation, based on repeated analyses of samples taken from the same Niskin bottle, was less than 1%. These measurements were also used to calibrate the SBE-43 oxygen probe mounted on the rosette.
The team on board consisted of 12 people, professors, young researchers and students. A biogeochemical database on discrete water samples is associated with this physicochemical dataset.
10.26071/ogsl-77037b6e-c1b8
