Dataset: GP17-OCE Bottle GTC

Excerpts from the GP17-OCE Cruise Report:
The Cutter group (ODU) and the East Coast van and winch pools provided the GEOTRACES Trace Element Carousel sampling system (GTC), including the A-frame, Dynacon winch with 7300 m of Vectran cable with conductors, clean lab van, and Seabird 9/11+ carousel/CTD with 24 x 12L Go-Flo bottles (+spares).

The GTC sensor array was re-calibrated immediately prior to the GP17-OCE cruise. The sensor array consisted of dual SBE-9 temperature and salinity sensors (calibration date: 23 June 2022), an SBE-43 dissolved oxygen sensor (calibration date: 9 Aug 2022), a Seapoint fluorometer, a Benthos altimeter, and a WetLabs C-Star transmissometer (calibration date: 12 July 2022). The "Salinity-2" sensor on the CTD physically broke after Station 36 and was replaced with a spare calibrated from the same set (and calibration values updated accordingly). The Bishop (UC Berkeley), Lam (UC Santa Cruz), and Ohnemus (UGA Skidaway) groups also installed on the GTC a birefringence sensor that detects particulate inorganic carbon (PIC) at all stations/depths (observed as "Voltage 7" in the GTC CTD data). The Fitzsimmons lab (TAMU) also installed a logging, non-conducting MAPR (Miniature Autonomous Plume Recorder) sensor suite on the rosette frame at deep casts of Stations 18 and 20 in order to collect turbidity and oxidationreductional potential data near the hydrothermal plumes.

In total, 58 GTC hydrocasts were conducted on GP17-OCE. At all stations except the super stations, 2 Go-Flo bottles were triggered per depth. At super stations, 3 Go-Flo bottles were triggered per depth in the shallow casts to accommodate larger sample volume requests; at the first super station (station 1), intermediate and deep casts had 3 Go-Flo bottles triggered per depth.

Once samples were brought into the clean van, unfiltered samples were collected immediately before connecting the Go-Flo bottles to the air pressure system (which was maintained at 12 psi). Acropak filtration was completed using Acropak-500 0.8/0.2 µm capsule filters; this is the same filter material but a larger capsule than the Acropak-200 capsules used on prior U.S. GEOTRACES cruises (which were not available for GP17-OCE due to COVID manufacturing delays). Membrane filtration was completed using 25mm 0.45 µm Supor membranes in a Swinnex filter holder, which at select euphotic zone samples was preceded by filtration through a second Swinnex filter holder containing a 25mm 5 µm polycarbonate filter.