Abstract:

This dataset contains values for water column respiration rates and dissolved oxygen concentrations (determined both from Winkler titrations and CTD profiles) from 2-4 depths at 7 stations during a rapid response cruise following the Hercules 265 blowout in July 2013.

Suggested Citation:

Roberts, Brian. 2014. Dissolved oxygen and respiration rate summary, Hercules 265 Rapid Response Cruise, July 2013.. Distributed by: Gulf of Mexico Research Initiative Information and Data Cooperative (GRIIDC), Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7VX0DF8

Publications:

Weber, S. C., Battles, J. J., Peterson, L., Roberts, B. J., Peterson, R. N., Hollander, D. J., … Montoya, J. P. (2015). Hercules 265 Rapid Response: Immediate ecosystem impacts of a natural gas blowout incident. Deep Sea Research Part II: Topical Studies in Oceanography. doi:10.1016/j.dsr2.2015.11.010

Purpose:

This dataset was developed as part of a rapid response effort following the Hercules 265 blowout in late July 2013. This component of the research effort addressed two main objectives: 1) determining the accuracy of DO patterns generated by CTD profiles; and 2) determining if and how water column respiration rates were altered following the blowout.

Data Parameters and Units:

Date (DD-Month-YY) - date water collected, initial (ambient) DO determined, and incubations initiated Station-site identifier Station (number) Latitude (decimal degrees) - latitude of station sampled Longitude (decimal degrees) - longitude of station sampled Cast (number) - number of cast at the station from which water samples were collected for DO and respiration rate determination Target depth (m)- meters below air-water interface that was targeted for water collection respiration rate (mmol O2 m^-3 d^-1)--rate of water column respiration (dissolved oxygen consumption) initial DO (mmol m^-3) - concentration of dissolved oxygen in BOD bottles fixed immediately after filling as determined via Winkler titrations CTD DO (mmol m^-3) - concentration of dissolved oxygen generated from CTD profiles for that depth

Methods:

Water column rates of respiration were determined for 2 – 4 depths at 7 stations (8, 10 – 15) in the vicinity of the rig (total n = 23). At each depth sampled, four 300-mL biological oxygen demand (BOD) bottles were filled from the same Niskin bottle using tygon tubing inserted into the bottom of a bottle and then allowing water to overflow the bottle by 2 – 3 volumes, taking care to expel all bubbles from the sample before capping. Half of the bottles were immediately fixed (with 1mL each of manganous sulfate and alkaline iodide solutions) and half were incubated in the dark at in situ temperatures for ~24 hours before being fixed. Once stoppers were placed in each BOD bottle, deionized water was added to fill the flared top and a secondary plastic cap was used to ensure a tight seal. All fixed samples were stored in the dark prior to titrations. Dissolved oxygen concentrations in the initial and final bottles were determined using a modification of the Winkler titration method detailed in Strickland & Parson (1972). Titrations were performed on three to five 50-mL aliquots per bottle using a Mettler Toledo DL28 auto-titrator. The mean and median coefficient of variation in DO concentrations among duplicate initial and final BOD bottles was 1.04% and 0.70%, respectively. Water column respiration rates were calculated as the rate of change in DO over time, expressed as millimol O2 m-3 d-1.

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