Dataset: AT37-06 Sediment geochemistry
Deployment: AT37-06_Alvin_Dives

Methodology:

Sediment samples were collected from hydrothermal areas of Guaymas Basin in the Gulf of California during cruise AT3706 of R/V Atlantis in December 2016. Push cores were obtained using the human-occupied deep diving vehicle Alvin during dives 4867 to 4872. Porewater was extracted from the sediment by centrifugation and then filtered through a 0.2 μm syringe filter. Samples for quantification of concentrations of dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), volatile fatty acids and alcohols were immediately frozen and stored at −20 °C or −80 °C (i.e. alcohols) before analysis.

Instruments:

The in situ temperature in the sediment was measured with Alvin’s external heatflow probe (McKay et al., 2012). DIC was measured with: Shimadzu Instruments GC-2014 Gas Chromatograph with FID Detector and Methanizer. The concentration of DOC was measured with a Shimadzu TOC-V equipped with a nondispersive infrared detector (Joye et al., 2004). The concentrations and stable carbon isotopic compositions of VFAs were analyzed by a liquid chromatography coupled to isotope ratio mass spectrometry (DELTA Plus XP IRMS) via a LC Isolink interface (ThermoFinnigan) (Heuer et al., 2006). Methanol and Ethanol were measured with: a purge and trap system connected to an SRI Instruments 8610C Gas Chromatograph with FID Detector.

Issues of note:

Due to the limited volume of porewaters, methanol and ethanol were not determined for most of the samples collected from Dives 4867 to Dive 4870.

Missing data identifiers:
* B.D.: Below detection limit.
* nd：Not determined. nd is the default missing data identifier in the BCO-DMO data system.