Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Related Publications
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

Hydrographic, nutrient and oxygen data from CTD bottles during R/V Pelican cruises.

Nutrient Analysis Equipment and Techniques:

Nutrient samples were collected, filtered (0.2 µm Acropak-200 polyethersulfone filters, Pall) and frozen on board until analysis on shore up to 3 months later. Nutrient analyses (phosphate, silicate, nitrate+nitrite, nitrite, ammonium, and urea) were performed on 6-channel Astoria-Pacific autoanalyzer using standard methods (WHPO 1994). Ammonia analyses were based on Solorzano (1969), using phenol/hypochlorite in alkaline medium with a sodium nitroprusside catalyst. Urea analyses were based on Aminot and Kerouel (1982) using diacetyl monoxime in acid solution.

Dissolved Oxygen Analysis Equipment and Techniques:

Samples were collected for dissolved oxygen analyses soon after the rosette was brought on board. Using a Tygon or silicone drawing tube, nominal 125 ml volume-calibrated iodine flasks were rinsed 3 times with minimal agitation, then filled and allowed to overflow for at least 3 flask volumes. Reagents (MnCl2 then NaI/NaOH) were added to fix the oxygen before stoppering. The flasks were shaken twice (>1 minute inversions) to assure thorough dispersion of the precipitate. The lip of the flask stopper was the filled with ultrapure water to prevent access to atmospheric oxygen during the up to 3 hours between sample collection and analysis.

Oxygen flask volumes were determined gravimetrically to determine flask volumes at TAMU Geochemical and Environmental Research Group (GERG). This is done once before using flasks for the first time and periodically thereafter when a suspect volume is detected.

Dissolved oxygen analyses were performed with an automated Winkler oxygen titrator (Langdon Enterprises, Miami) using amperometric end-point detection. Thiosulfate (nominally 0.01 N) was standardized against 0.01 N potassium iodate prior to sample analysis.

Salinity Analysis Equipment and Techniques:

Salinity samples were drawn into 200 mL Kimax high-alumina borosilicate bottles, which were rinsed three times with sample prior to filling to the shoulder. The bottles were sealed with plastic insert thimbles to reduce evaporation. PSS78 salinity (UNESCO 1981) was calculated for each sample from the measured conductivity ratios. 

A Guildline Autosal 8400B salinometer (S/N 65715) was used for salinity/conductivity measurements. The salinity analyses were performed after samples had equilibrated to laboratory temperature, usually within 6 weeks after collection. The salinometer was standardized for each group of analyses using OSIL standard seawater, with frequent use of a secondary deep water standard to check for drift during runs. 

SBE Data Processing Version 7.26.6.28 was used to process the raw Sea-Bird CTD data (.hex) into a human-readable format (.cnv). The order of functions ran via SBE Data Processing was: Data Conversion, Filter, Align CTD, Cell Thermal Mass, Loop Edit, Derive, and Bin Average.

BCO-DMO Processing Notes:
- combined three years of data into one dataset
- added conventional header with dataset name, PI name, version date
- modified parameter names to conform with BCO-DMO naming conventions
- created date_time field with the format yyyy-mm-dd hh:mm

NSF Award Abstract:
A new Research Experiences for Undergraduates (REU) Site will be located at Texas A&M University's campus in College Station, TX. The Geochemical and Environmental Research Group (GERG) and the Department of Oceanography will host 10 REU students for 10 weeks each summer, and the program will focus on innovative ocean observing technologies. Students will have access to a suite of ocean data acquisition technologies incorporated in TAMU's offshore buoy system, glider technology, remote real-time measurements from moored instrumentation, shipboard field surveys with CTD profiling and water sampling. A group project to develop and deploy a glider mission in the Gulf of Mexico onboard a research vessel will promote team building. Training modules on sensors, data analysis, graphical representation of oceanographic data, data management, and science writing will be provided. Students will participate in weekly REU seminars, and at the program end, they will demonstrate their communication skills with a final written report and a seminar presentation at the GERG REU Student Research Symposium. Although the program is open to students who are US citizens or permanent residents attending any university, local recruitment efforts will be coordinated with faculty in the NSF-funded Alliance for Graduate Education and the Professoriate (AGEP) program which supports mentoring of STEM majors across TAMU branch campuses (Kingsville, Corpus Christi, Prairie View and West Texas).

Related Projects:
This project is a renewed/continued by project "REU Site: Observing the Ocean" (OCE-1849932); see: https://www.bco-dmo.org/project/877594.