Dataset: Galveston Bay Carbonate Chemistry
Deployment: WTX1

Methods & Sampling:

Samples were collected at 14 different sites quarterly from June 2017 through September 2018 in Galveston Bay and at 10 sites along the Texas coast in the Gulf of Mexico in June, August, and November of 2017 to investigate changes in water chemistry following Hurricane Harvey.

For cruises in Galveston Bay, discrete water samples were collected with a Niskin (General Oceanics) bottle at the surface (0.5 m) and ~1.2 m off the bottom. Samples collected for carbonate chemistry analysis (TA/DIC) were transferred from the Niskin to 250 mL narrow-mouth borosilicate glass bottles using a 0.2 mm polypropylene Whatman Polycap 36 Tissue Culture Grade (TC) in-line filter for total alkalinity (TA) and dissolved inorganic carbon (DIC) analysis, leaving approximately 5 mL headspace for thermal expansion. Some samples in September and November 2017 were collected using 0.2 mm Whatman Polycap 36 Aqueous Solution (AS) filters. However, no significant difference was found in the carbonate chemistry analysis for samples using either filter, therefore no distinction is made. Conductivity, temperature, and depth (CTD, SonTek Castaway™) profiles were conducted concurrently with Niskin samples at each station. Discrete water samples for TA/DIC on WTX cruises (WTX1/WTX2/WTX4) were collected using Niskin bottles (6L/6L/10L) on a Seabird CTD rosette. Carbonate chemistry water samples (TA/DIC) were collected similar to those from Galveston Bay, but no in-line filter was used. All TA/DIC samples was poisoned with 100 mL saturated mercuric chloride solution immediately after collection to inhibit biological activity, and then sealed with silicone-free type L Apiezon grease and ground glass stoppers with rubber bands and plastic clamps. TA and DIC were analyzed simultaneously on a Versatile INstrument for the Determination of Total inorganic carbon and titration Alkalinity (VINDTA) 3C in Dr. Kathryn Shamberger’s lab at Texas A&M University. The VINDTA uses coulometric titration for DIC analysis and an open cell potentiometric titration for TA analysis. Dissolved inorganic nutrient samples from all fieldwork operations were transferred from the Niskins to a a polycarbonate flask using a GF/C 0.2 micron filter, frozen, and analyzed by the Geophysical Environmental Research Group at Texas A&M University on an Astoria Analyzer.

Cruises:

Galveston Bay Cruises: 8 single-day trips on R/V Lithos or R/V Trident; conducted quarterly in Galveston Bay, TX June 2017 - September 2018. (Cruise IDs: GB0617, GB0917, GB1117, GB0318, GB0618, GB0918).

Gulf of Mexico Research cruises: aboard R/V Manta and R/V Pelican (see "Deployments" section for multi-day cruise details,  Cruise IDs: WTX1, WTX2, WTX4).

Instruments:

Galveston Bay: 

• 5L General Oceanics Niskin bottles: Dissolved seawater samples collected using 2 individual 5L General Oceanics Niskin bottles
• Sontek Castaway: CTD profiles were recorded at each site in Galveston Bay at the time of Niskin deployment using a Sontek Castaway. Data processed using Sontek processing software.

WTX 1 and 2: 

• 6 x 5L Niskin rosette: dissolved seawater samples collected using a 6-bottle rosette equipped with 6 5L-Niskin bottles and Sea-Bird SBE 25 CTD.

WTX 4: 

• 12 x 10L Niskin rosette: dissolved seawater samples collected using 12-bottle rosette equipped with 12 10L-Niskin bottles and Sea-Bird SBE 911 CTD.
   

MARIANDA VINDTA 3C

Funding note:
See "Awards" section for details of NSF-OCE funding (OCE-1760381; OCE-1800913). Additional funding from TAMU T3 Triad Grant; Texas A&M University Department of Oceanography; Texas Governor’s Fund through Texas OneGulf Center of Excellence; Texas Commission on Environmental Quality.