Dataset: Dissolved Macronutrient Concentrations from Depth Profiles and Incubation Experiments from STING I Cruise AE2305 on R/V Atlantic Explorer in the Gulf of Mexico from February to March 2023

ValidatedRelease Date:2025-03-01Final no updates expectedDOI: 10.26008/1912/bco-dmo.929305.1Version 2 (2024-02-06)Dataset Type:Cruise Results

Principal Investigator: Kristen Nicolle Buck (Oregon State University)

Co-Principal Investigator: Rene Maurice Boiteau (Oregon State University)

Co-Principal Investigator: Phoebe Dreux Chappell (Old Dominion University)

Co-Principal Investigator: Timothy M. Conway (University of South Florida)

Co-Principal Investigator: Angela N. Knapp (Florida State University)

Co-Principal Investigator: Chris Smith (United States Geological Survey)

Co-Principal Investigator: Joseph Tamborski (Old Dominion University)

Scientist: Salvatore Caprara (University of South Florida)

Student: Caitlyn Elizabeth Parente (University of South Florida)

BCO-DMO Data Manager: Sawyer Newman (Woods Hole Oceanographic Institution)


Project: Collaborative Research: Linking iron and nitrogen sources in an oligotrophic coastal margin: Nitrogen fixation and the role of boundary fluxes (Gulf of Mexico DON and Fe)


Abstract

Concentrations of inorganic dissolved macronutrients, including phosphate, nitrate plus nitrite (N+N), silicic acid, and nitrite, from phytoplankton shipboard incubation experiments and depth profiles collected on STING I cruise AE2305 on R/V Atlantic Explorer in the Gulf of Mexico from February to March 2023. This project investigates how groundwater discharge delivers important nutrients to the coastal ecosystems of the West Florida Shelf. Preliminary studies indicate that groundwater may s...

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Water column samples were collected in February and March 2023 aboard the R/V Atlantic Explorer using a trace metal clean rosette (SeaBird) outfitted with 12-L Niskin-X samplers (Ocean Test Equipment), a trace metal clean pump, or a custom surface pump “towfish” system (Mellett and Buck, 2020). Seawater samples for macronutrient analysis were filtered through 0.2 µm Pall Acropak Super membrane filter capsules, collected in acid-cleaned and triple-rinsed 15-mL Falcon tubes, and stored in ziplock bags in the fridge until analyzed shipboard following recommended practices (Becker et al., 2020), typically within 24 hours of collection. 

Samples were analyzed shipboard for phosphate, nitrate+nitrite, silicate, and nitrite on a QuAAtro39 AutoAnalyzer (SEAL Analytical) according to standard colorimetric methods (Strickland and Parsons, 1972). All reagents were prepared in dedicated labware with high purity Milli-Q (>18 MΩ cm) water. Working standards were prepared fresh daily in an artificial seawater (ASW; 35 g/L sodium chloride, 0.5 g/L sodium bicarbonate) matrix using calibrated volumetric pipettes. 

Nine-point standard curves were analyzed at the beginning of each run with multiple reagent blanks. Quality control checks were analyzed every twelfth sample with ASW blanks and standards. The highest standard from the calibration curve was analyzed approximately every twenty samples to check for drift during the runs. Subsamples of reference material for nutrients in seawater (Konso) were measured in each run (see Table 1 below). 

Detection limits for each parameter were determined from three times the standard deviation of replicate lowest standards. Limits of detection were 0.035 µM for phosphate, 0.048 µM for nitrate+nitrite, 0.051 µM for silicate, and 0.012 µM for nitrite. Values below detection are reported as 0 µM with accompanying QC Flag 6. 

 

 


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Related Publications

Methods

Becker, S., Aoyama, M., Woodward, E. M. S., Bakker, K., Coverly, S., Mahaffey, C., & Tanhua, T. (2020). GO-SHIP Repeat Hydrography Nutrient Manual: The Precise and Accurate Determination of Dissolved Inorganic Nutrients in Seawater, Using Continuous Flow Analysis Methods. Frontiers in Marine Science, 7. https://doi.org/10.3389/fmars.2020.581790
Methods

Mellett, T., & Buck, K. N. (2020). Spatial and temporal variability of trace metals (Fe, Cu, Mn, Zn, Co, Ni, Cd, Pb), iron and copper speciation, and electroactive Fe-binding humic substances in surface waters of the eastern Gulf of Mexico. Marine Chemistry, 227: 103891. doi:10.1016/j.marchem.2020.103891
Methods

Strickland, J. D. H. and Parsons, T. R. (1972). A Practical Hand Book of Seawater Analysis. Fisheries Research Board of Canada Bulletin 157, 2nd Edition, 310 p.