Dataset: Porewater geochemistry, including methane, CO2, sulfate, and sulfide from Guaymas Basin hydrothermal sediments collected on R/V Atlantis cruise AT15-56 in Nov-Dec 2009

Data not availableVersion 1 (2023-02-24)Dataset Type:Cruise Results

Principal Investigator: Andreas Teske (University of North Carolina at Chapel Hill)

Co-Principal Investigator: Daniel B. Albert (University of North Carolina at Chapel Hill)

Co-Principal Investigator: Barbara J. MacGregor (University of North Carolina at Chapel Hill)

Co-Principal Investigator: Christopher S. Martens (University of North Carolina at Chapel Hill)

BCO-DMO Data Manager: Shannon Rauch (Woods Hole Oceanographic Institution)


Project: Microbial carbon and sulfur cycling in the hydrothermally altered sediments of Guaymas Basin (Guaymas Basin Vents)


Abstract

Porewater geochemistry of Guaymas Basin hydrothermal sediments (Southern Spreading segment, 27°00.44'N and 111°24.55'W, 2000 m water depth) including methane, CO2, sulfate, and sulfide, were measured during R/V Atlantis cruise AT15-56 to Guaymas Basin in 2009. Sampling was conducted on Alvin dives 4562 to 4573. The association of bacterial and archaea communities with hydrothermal seepage and the habitat preferences of various types of microbes were investigated by geochemical and microbiologica...

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Geochemical Analyses:
Sulfate concentration measurements were completed shipboard; after centrifuging sediment-filled 15-milliliter (ml) tubes, the overlying porewater was filtered through 0.45-micrometer (um) filters, acidified with 50 microliters (ul) of 50% HCl and bubbled with nitrogen for 4 minutes to remove sulfide. Sulfate concentrations were then measured shipboard using a 2010i Dionex Ion Chromatograph (Sunnyvale, CA, USA) through Ag exchange columns (Dionex) so as to remove Cl (Martens et al., 1999). For sulfide, 1 ml porewater samples were combined with 0.1 molar (M) zinc acetate and concentrations were analyzed spectrophotometrically on the ship (Cline, 1969).

Headspace methane concentrations were determined onboard by standard gas chromatography with a flame ionization detector (FID), specifically using a HACH Carle Series 100 AGC Gas Chromatograph (GC) with an Alltech Molecular Sieve 5A packed column (80/100 mesh, 3.05 meters (m) length, 3.2 millimeter internal diameter (mm ID)) and an 80 degree Celsius (C) isothermal temperature profile. Stable isotopic compositions of the same methane samples were measured post-cruise at the University of North Carolina (UNC) via gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) on a Finnigan MAT 252 Isotope Ratio Mass Spectrometer, using an HP 5890 Series II Gas Chromatograph with an HP Plot Q column (30 m length, 0.32 mm ID, 20 um film thickness) and a 30 degree C isothermal temperature profile.

To measure DIC, 2 ml of unamended porewater from each sediment horizon were injected into evacuated serum vials (30 ml) and stored upside down at -20 degrees C. At UNC, the samples were thawed, and DIC was reacted to gaseous CO2 by adding 1 ml of a 30% phosphoric acid solution to each serum vial and shaking vigorously before GC analysis (Kelley et al., 1990). Stable isotopic values and concentrations of DIC were analyzed via coupled GC (Hewlett Packard 5890) and Isotope Ratio Mass Spectrometer (Finnigan MAT 252).

Porewater concentrations of dissolved organic acids were measured via High-Pressure Liquid Chromatography (HPLC) after the cruise, using a Beckman Model 332 gradient liquid chromatograph combined with an ISCO V4 UV/VIS detector and a Shimadzu CR3-A integrator (Albert and Martens, 1997).


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Results

McKay, L. J., MacGregor, B. J., Biddle, J. F., Albert, D. B., Mendlovitz, H. P., Hoer, D. R., … Teske, A. P. (2012). Spatial heterogeneity and underlying geochemistry of phylogenetically diverse orange and white Beggiatoa mats in Guaymas Basin hydrothermal sediments. Deep Sea Research Part I: Oceanographic Research Papers, 67, 21–31. doi:10.1016/j.dsr.2012.04.011
Results

McKay, L., Klokman, V. W., Mendlovitz, H. P., LaRowe, D. E., Hoer, D. R., Albert, D., Amend, J. P., & Teske, A. (2016). Thermal and geochemical influences on microbial biogeography in the hydrothermal sediments of Guaymas Basin, Gulf of California. Environmental Microbiology Reports, 8(1), 150–161. Portico. https://doi.org/10.1111/1758-2229.12365
Results

Su, L., Teske, A. P., MacGregor, B. J., McKay, L. J., Mendlovitz, H., Albert, D., Ma, Z., & Li, J. (2023). Thermal Selection of Microbial Communities and Preservation of Microbial Function in Guaymas Basin Hydrothermal Sediments. Applied and Environmental Microbiology, 89(3). https://doi.org/10.1128/aem.00018-23
Results

Teske, A., de Beer, D., McKay, L. J., Tivey, M. K., Biddle, J. F., Hoer, D., Lloyd, K.G., Lever, M.A., Roy, H., Mendlovitz, H., & MacGregor, B. J. (2016). The Guaymas Basin Hiking Guide to Hydrothermal Mounds, Chimneys, and Microbial Mats: Complex Seafloor Expressions of Subsurface Hydrothermal Circulation. Frontiers in Microbiology, 7. doi:10.3389/fmicb.2016.00075
Methods

Albert, D. B., & Martens, C. S. (1997). Determination of low-molecular-weight organic acid concentrations in seawater and pore-water samples via HPLC. Marine Chemistry, 56(1–2), 27–37. https://doi.org/10.1016/s0304-4203(96)00083-7