Abstract:

Water samples from CTD casts and vehicle-mounted bottles collected on the Atlantis, GOMRI, Nautilus, Ronald Brown, and Schmidt between 2010 and 2014. Dissolved O2 and potential density data derived from surface-deployed and vehicle-mounted CTD measurements taken on the R/V Atlantis, R/V Ronald Brown, and E/V Nautilus in the Gulf of Mexico and Florida from 2010 to 2014.

Suggested Citation:

Erik Cordes. 2017. Carbonate data from water samples, and Dissolved O2 and Potential Density, Gulf of Mexico, October 14, 2010 to May 13, 2014. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7F47M55

Publications:

Georgian, S. E., Dupont, S., Kurman, M., Butler, A., Strömberg, S. M., Larsson, A. I., & Cordes, E. E. (2016). Biogeographic variability in the physiological response of the cold-water coral Lophelia pertusa to ocean acidification. Marine Ecology, 37(6), 1345–1359. doi:10.1111/maec.12373

Purpose:

Physiological and genetic responses of the deep-water coral, Lophelia pertusa, to ongoing ocean acidification in the Gulf of Mexico.

Data Parameters and Units:

bicarbonate_ion (Bicarbonate ion concentration - micromoles per kilogram (umol/kg)); carbonate_ion (Carbonate ion concentration - micromoles per kilogram (umol/kg)); comments (Comments - unitless); cruise_id (Official cruise identification - unitless); cruise_name (Project investigator's cruise name - unitless); day (Day of sampling; DD - ); depth (Depth at which sample was taken - meters); DIC (Dissolved inorganic carbon values - micromoles per kilogram (umol/kg)); DO (Dissolved oxygen concentration - micromoles per kilogram (umol/kg)); input_pH (pH measurement of sample (total scale) - total pH scale); instrument (Instrument used to collect water samples: V= vehicle-mounted bottle or CTD - unitless); lat (Latitude - decimal degrees); lon (Longitude - decimal degrees); measured_temp (Temperature of sample after being standardized in 25 degree celsius water bath for 10-20 minutes. - celsius); measurement_location (Location where water sample was taken: WC= water column or B= bottom - unitless); month (Month of sampling; MM - unitless); nTA (Salinity normalized total alkalinity - micromoles per kilogram (umol/kg)); omega_aragonite (saturation state of aragonite - unitless); pCO2 (Carbon dioxide concentration - microatomospheres (uatm)); pHT (pH measured on the total hydrogen scale - total pH scale); potential_density (Sigma-t density of seawater - kilogram per cubic meter (kg/m^3)); pressure (Pressure at depth - decibar (dbar)); revelle_factor (A measure inversely proportional to the capacity for seawater to absorb atmospheric CO2 - unitless); salinity (Salinity of water sample - practical salinity units (PSU)); sample_ID (Sample ID number - unitless); site (Site code where sample was taken; see lat/lons for exact location. - unitless); site (Site where samples were taken - unitless); TA (Total alkalinity of sample - micromoles per kilogram (umol/kg)); TA_DIC (Total alkalinity and dissolved inorganic carbon ratio - unitless); temperature (Temperature at depth - celsius); year (Year of sample; YYYY - unitless); year (Year of cruise; YYYY - unitless)

Methods:

pH was measured on the total hydrogen scale (pHT) within one hour of sample collection. Each water sample was placed in a 25 degrees C water bath for 10–20 minutes to standardize temperature (mean temperature over all pH measurements of 22.2 +/- 2.6 degrees C). pHT was then measured in duplicate using the Orion 5 Star pH meter and glass electrode (ROSS Ultra pH/ATC Triode 8107BNUMD) calibrated with Tris–HCL buffer solution obtained from the Dickson Lab (Batch 22). Electrode performance was regularly checked against standard Tris-HCl and AMP-HCl buffers in artificial seawater (Nemzer et al. 2005; Dickson et al. 2007). Temperature was measured using the integrated temperature sensor on the ROSS Ultra pH/ATC Triode from 2010–2013, and using a handheld thermocouple (Omega HH81A) in 2014. Total alkalinity (TA) was measured in triplicate by acid titration on a Mettler–Toledo DL15 autotitrator using 0.1 mol L–1 HCl buffered in 0.6 mol L–1 NaCl (modified from SOP 3b, Dickson et al. 2007). The autotitrator was calibrated daily on the NBS scale using certified reference buffers (Orion), and certified reference materials (Dickson Lab, batches 138 and 141) were measured periodically to ensure accuracy (within +/- 10 umol kg-1). CO2SYS software (Pierrot et al. 2006) was used to correct pHT values for in situ temperature and pressure, and to calculate the entire carbonate system from TA, pHT, temperature, salinity, and pressure. For all calculations, we used the carbonic acid constants (K1 and K2) of Mehrbach et al. (1973) refitted by Dickson and Millero (1987), and the aragonite solubility product (Ksp) from Mucci (1983). The effects of nutrients (phosphate and silicate) on the carbonate system were assumed to be negligible (eg. Cai 2003; Yates and Halley 2006). TA and dissolved inorganic carbon (DIC) values were corrected for in situ salinity values using the mean salinity of all sites (35.3 psu) to yield salinity-normalized TA (nTA) and DIC (nDIC). CTD data (temperature, salinity, pressure, and dissolved oxygen) were collected both as water column data from ship deployments and as bottom–water data from a vehicle–mounted CTD. In all years, a SBE 9/11+ CTD was used for water column measurements, while vehicle-mounted CTD usage varied by year: SBE 19 (2010), SBE 37-SI (2012), and SBE 49 (2013, 2014). All dissolved oxygen measurements were collected using a SBE 43 dissolved oxygen sensor. CTD and dissolved oxygen measurements were vertically binned every meter in order to smooth water column profiles prior to additional analyses.

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