Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
  • BCO-DMO Curation Notes
• Related Publications
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

Sediment samples were collected by the HOV Alvin using PVC push cores. Upon arrival at the surface the cores were described and cataloged prior to being sectioned into discrete depth intervals. Porewater was separated from the sediment using a manually-actuated porewater press as described by Joye et al., 2004. Following the collection of porewater, the pressed sediment sample (mud-cake) was stored at -20°C for solid-phase analysis. Porewater and sediment samples were preserved and analyzed as follows:

1) Nutrients (DOC, TDN, NOx, NO2, NH4, PO4, TDP): Water sample was filtered through a pre-rinsed 0.2 um regenerated cellulose Target2 syringe filter (Thermo Scientific, Prod. No. F25047), collected into an HDPE bottle and stored frozen at -20°C until analysis.  Individual analytes were analyzed as follows:

• DOC was determined using high temperature catalytic combustion and an NDIR detector following the method described in Sugimura and Suzuki, 1988.  
• TDN was determined using high temperature combustion and a chemiluminescence detector following the method described in Watanabe et. al, 2007.
• NOx was determined using chemical reduction and a nitric oxide detector following the method described by Garside, 1982.  
• NO2 was determined using the colorimetric method described by Bendschneider and Robinson, 1952 (A new spectrophotometric method for the determination of nitrite in sea water. J. Mar. Res., 11: 87) as reproduced by Parsons, Marta, and Lalli, 1984.
• NH4 was determined using the colorimetric method described by Solorzano, 1969.
• PO4 was determined using the colorimetric method described by Strickland and Parsons, 1972.
• TDP was determined using the colorimetric method described by Solorzano and Sharp, 1980. 

2) NH4: Water sample was filtered through a pre-rinsed 0.2 μm regenerated cellulose Target2 syringe filter (Thermo Scientific, Prod. No. F25047) into a 15 mL centrifuge tube, preserved with phenol reagent and stored at 5°C until analysis using the colorimetric method described by Solorzano, 1969. Samples were analyzed on a Hach DR 3900 spectrophotometer.

3) Alkalinity: Water sample was filtered through a pre-rinsed 0.2 μm regenerated cellulose Target2 syringe filter (Thermo Scientific, Prod. No. F25047) into a 15 mL centrifuge tube and stored at 5°C until analysis. Alkalinity was determined using the spectrophotometric method described by Sarazin et al., 1999. Samples were analyzed on a Hach DR 3900 spectrophotometer.

4) H2S: 2.0 mL unfiltered water sample was collected into a 15 mL centrifuge tube containing 500 uL of 20% zinc acetate and stored at 5°C until analysis.  H2S was determined using the colorimetric method described by Cline, 1969.  Samples were analyzed on a Hach DR 3900 spectrophotometer.

5) VFA: Water sample was filtered through a pre-rinsed 0.2 μm regenerated cellulose Target2 syringe filter (Thermo Scientific, Prod. No. F25047) into a 7 mL scintillation vial and stored frozen at -20°C until analysis. VFA (Glycolate, Lactate, Acetate, Formate, iso-Butyric Acid, Butyric Acid, iso-Valeric Acid, Valeric Acid) analysis was performed on a Dionex UltiMate 3000 HPLC with Hamilton PRP-1 Guard Column (Prod. No. 79445), Brownlee NewGuard RP-8 7 µm 15 x 3.2 mm guard column (Prod. No. 0711-0090) and Brownlee SPHERI-5 RP-8 5 µm 250 x 4.6 mm analytical column (Prod. No. 4427064) following the method of Albert and Martens, 1997.

6) SO4: Water sample was filtered through a pre-rinsed 0.2 μm regenerated cellulose Target2 syringe filter (Thermo Scientific, Prod. No. F25047) into a 7 mL scintillation vial. Samples were acidified with 10 μL of concentrated HNO3 per 1 mL sample, sealed with a PTFE lined cap, and stored at room temperature until analysis. Sample analysis was performed with a Dionex Integrion HPIC using KOH eluent supplied by a Dionex EGC 500 KOH Eluent Generator Cartridge (Prod. No. 075778), Dionex CR-ATC Continuously Regenerated Trap Column (Prod. No. 088662), Dionex ADRS 600 Dynamically Regenerated Suppressor (Prod. No. 088666), Dionex IonPac AG18 Guard Column (Prod. No. 060551), Dionex IonPac AS18 Analytical Column (Prod. No. 060549) and Dionex CRD 200 Carbonate Removal Device (Prod. No. 062983). See Weston et al., 2006.

7) Cl: Water sample was filtered through a pre-rinsed 0.2 μm regenerated cellulose Target2 syringe filter (Thermo Scientific, Prod. No. F25047) into a 7 mL scintillation vial. Samples were acidified with 10 μL of concentrated HNO3 per 1 mL sample, sealed with a PTFE lined cap, and stored at room temperature until analysis. Sample analysis was performed with a Dionex Integrion HPIC using KOH eluent supplied by a Dionex EGC 500 KOH Eluent Generator Cartridge (Prod. No. 075778), Dionex CR-ATC Continuously Regenerated Trap Column (Prod. No. 088662), Dionex ADRS 600 Dynamically Regenerated Suppressor (Prod. No. 088666), Dionex IonPac AG18 Guard Column (Prod. No. 060551), Dionex IonPac AS18 Analytical Column (Prod. No. 060549) and Dionex CRD 200 Carbonate Removal Device (Prod. No. 062983).  See Weston et al., 2006.

8) Na: Water sample was filtered through a pre-rinsed 0.2 μm regenerated cellulose Target2 syringe filter (Thermo Scientific, Prod. No. F25047) into a 7 mL scintillation vial. Samples were acidified with 10 μL of concentrated HNO3 per 1 mL sample, sealed with a PTFE lined cap, and stored at room temperature until analysis. Sample analysis was performed with a Dionex Integrion HPIC using Methanesulfonic Acid eluent supplied by a Dionex EGC 500 MSA Eluent Generator Cartridge (Prod. No. 076779), Dionex CR-CTC Continuously Regenerated Trap Column (Prod. No. 088663), Dionex CDRS 600 Dynamically Regenerated Suppressor (Prod. No. 088670CMD), Dionex IonPac CG12A Guard Column (Prod. No. 046076), Dionex IonPac CS12A Analytical Column (Prod. No. 046075).

9) K: Water sample was filtered through a pre-rinsed 0.2 μm regenerated cellulose Target2 syringe filter (Thermo Scientific, Prod. No. F25047) into a 7 mL scintillation vial. Samples were acidified with 10 μL of concentrated HNO3 per 1 mL sample, sealed with a PTFE lined cap, and stored at room temperature until analysis. Sample analysis was performed with a Dionex Integrion HPIC using Methanesulfonic Acid eluent supplied by a Dionex EGC 500 MSA Eluent Generator Cartridge (Prod. No. 076779), Dionex CR-CTC Continuously Regenerated Trap Column (Prod. No. 088663), Dionex CDRS 600 Dynamically Regenerated Suppressor (Prod. No. 088670CMD), Dionex IonPac CG12A Guard Column (Prod. No. 046076), Dionex IonPac CS12A Analytical Column (Prod. No. 046075).

10) Mg: Water sample was filtered through a pre-rinsed 0.2 μm regenerated cellulose Target2 syringe filter (Thermo Scientific, Prod. No. F25047) into a 7 mL scintillation vial. Samples were acidified with 10 μL of concentrated HNO3 per 1 mL sample, sealed with a PTFE lined cap, and stored at room temperature until analysis. Sample analysis was performed with a Dionex Integrion HPIC using Methanesulfonic Acid eluent supplied by a Dionex EGC 500 MSA Eluent Generator Cartridge (Prod. No. 076779), Dionex CR-CTC Continuously Regenerated Trap Column (Prod. No. 088663), Dionex CDRS 600 Dynamically Regenerated Suppressor (Prod. No. 088670CMD), Dionex IonPac CG12A Guard Column (Prod. No. 046076), Dionex IonPac CS12A Analytical Column (Prod. No. 046075).

11) Ca: Water sample was filtered through a pre-rinsed 0.2 μm regenerated cellulose Target2 syringe filter (Thermo Scientific, Prod. No. F25047) into a 7 mL scintillation vial. Samples were acidified with 10 μL of concentrated HNO3 per 1 mL sample, sealed with a PTFE lined cap, and stored at room temperature until analysis. Sample analysis was performed with a Dionex Integrion HPIC using Methanesulfonic Acid eluent supplied by a Dionex EGC 500 MSA Eluent Generator Cartridge (Prod. No. 076779), Dionex CR-CTC Continuously Regenerated Trap Column (Prod. No. 088663), Dionex CDRS 600 Dynamically Regenerated Suppressor (Prod. No. 088670CMD), Dionex IonPac CG12A Guard Column (Prod. No. 046076), Dionex IonPac CS12A Analytical Column (Prod. No. 046075).

12) Fe(II): Water sample was filtered through a pre-rinsed 0.2 μm regenerated cellulose Target2 syringe filter (Thermo Scientific, Prod. No. F25047) into a 15 mL centrifuge tube and analyzed following a modified version of Stookey, 1970.  Samples were analyzed on Hach DR 3900 and Shimadzu UV-1601 spectrophotometers.

13) pH: Sediment pH was determined using an Oakton pH5S pH spear (Prod. No. 3563452) and measured immediately during core sectioning.

14) Eh: Sediment Eh was measured using a Mettler Toledo InLab Redox ORP Electrode (Prod. No. 51343203) and a Fisherbrand Accumet AP125 Portable Meter (Prod. No. 13-636-AP125A).

15) Salinity: Porewater salinity was determined using a Fisherbrand handheld refractometer (Prod. No. 12-561-335).

16) DIC: Water sample was filtered through a pre-rinsed 0.2 μm regenerated cellulose Target2 syringe filter (Thermo Scientific, Prod. No. F25047). A 2.0 mL sample was injected into a N2-purged serum vial crimp-sealed with a butyl rubber stopper.  Samples were stored frozen at -20°C until analysis. Sample analysis was performed after thawing and acidifying samples with concentrated HCl to pH 0.  DIC concentration was determined by injecting headspace samples onto a Shimadzu GC-2014 FID-Methanizer with Supelco Carboxen 1010 PLOT 30 m x 0.53 mm Fused Silica Capillary Column (Prod. No. 25467).  Weston et al. 2006

17) Gases: Methane, Ethane, Propane, iso-Butane, n-Butane and n-Pentane samples (3 cc whole sediment) were collected into a glass serum vial, preserved with 2 mL 2M N2-purged NaOH, crimp-sealed with a butyl rubber stopper and stored at room temperature until analysis.  Concentrations were determined by headspace analysis using an SRI 8610 GC-FID with Agilent J&W HP-PLOT Al2O3 S Capillary Column, 50 m, 0.53 mm, 15.00 μm (Prod. No. 19095P-S25E). See Joye et al., 2004.

18) SOM:  Sediment samples collected and analyzed for porosity were subsequently analyzed for Sediment Organic Matter.  SOM was determined by drying a sample of known mass at 80C, weighing, ashing at 500C, weighing and calculating weight loss on ignition.

19) TPN: The pressed sediment sample (mud-cake) was dried at 60C and then homogenized via grinding. TPN was determined by the method described by Gordon, Jr., 1969 as reproduced by Sharp, 1974. Samples were analyzed on a ThermoFinnigan FlashEA 1112 series NC Soil Analyzer.

20) TPC: The pressed sediment sample (mud-cake) was dried at 60C and then homogenized via grinding. TPC was determined by the method described by Gordon, Jr., 1969 as reproduced by Sharp, 1974. Samples were analyzed on a ThermoFinnigan FlashEA 1112 series NC Soil Analyzer.

21) POC: The pressed sediment sample (mud-cake) was dried at 60C, homogenized via grinding and then acidified via fuming in a desiccator with concentrated HCl.  POC was determined by the method described by Gordon, Jr., 1969 as reproduced by Sharp, 1974. Samples were analyzed on a ThermoFinnigan FlashEA 1112 series NC Soil Analyzer.

22) Calculated Values (NO3, DIN, DON, DOP, PIC):  These values were calculated as follows:

• NO3 = NOx - NO2
• DIN = NOx + NH4
• DON = TDN - DIN
• DOP = TDP - PO4
• PIC = TPC - POC
   

DOC and TDN data were processed using Shimadzu TOC-Control V software. NOx and CH4 data were processed using SRI Instruments PeakSimple software. VFA, SO4, Cl, Na, K, Mg, and Ca data were processed using DIONEX Chromeleon software. DIC data was processed using Shimadzu GCsolution software.

This section documents curation actions performed prior to publication review with the submitter, and additional information relevant to understanding and reusing this dataset. It distinguishes changes made to the submitted (meta)data from unresolved issues and/or enhancements that improve future reuse and interoperability.

CURATION ACTIONS PERFORMED ON DATA

- Loaded AT50-22 Porewater Geochemistry V2.xlsx (Sheet1), header row 11, units row 12 skipped, deduplicated blank headers, missing values "", "nd", "ND" configured, preserving Excel display formatting and adjusting floating point error
- Deleted two blank spacer columns (named " (1)" and " (2)") between salinity/NO2 and DON:DOP/DOC
- Renamed columns containing disallowed characters to underscore-based names (e.g. Collection Date to Collection_Date, Lat (N) to Lat, Long (W) to Long, Depth Range to Depth_Range, Mid-point Depth to Midpoint_Depth, DIN:DIP to DIN_DIP, DON:DOP to DON_DOP, Iso-Butyric Acid to Iso_Butyric_Acid, Butyric Acid to Butyric_Acid, Iso-Valeric Acid + Succinate to Iso_Valeric_Acid_Succinate, Valeric Acid to Valeric_Acid, Tot VFA to Tot_VFA, iso-Butane to iso_Butane, n-Butane to n_Butane, n-Pentane to n_Pentane, Fe (II) to Fe_II, SOM (LOI) to SOM_LOI, Alvin Dive # to Alvin_Dive_number)
- Normalized date separators in Collection_Date from "/" to "-" for consistent DD-MM-YY format
- Combined normalized Collection_Date and Collection_Time into new Collection_DateTime string column in ISO 8601 format without seconds or timezone, since source lacked seconds and UTC offset
- Converted Collection_Date to an ISO date-typed column in UTC
- Reordered columns into a defined sequence
- Extracted non-numeric values (e.g. "BDL") from numeric-capable chemistry columns into new "_flag" columns, leaving the original numeric columns null where non-numeric
- Removed flag columns with no BDL occurrences in the sample data (TDP_flag, DIN_DIP_flag, DON_DOP_flag, DOC_flag, Tot_VFA_flag, Alkalinity_flag, DIC_flag, Cl_flag, Na_flag, K_flag, Mg_flag, Ca_flag, SOM_LOI_flag, TPN_flag, TPC_flag, POC_flag, PIC_flag, DIN_flag, TDN_flag, NH4_flag, DON_flag, PO4_flag, Lactate_flag, Methane_flag)
- Output as 1000880_v1_porewater_geochemistry.csv

CURATION ACTIONS PERFORMED ON METADATA

- BCO-DMO's standard metadata entry and text formatting steps were performed. See: https://www.bco-dmo.org/how-to/standard-curation-edits

ISSUES POTENTIALLY IMPACTING REUSE

- Collection times provided do not clarify timezone.

NSF Award Abstract:
Oceanic hydrothermal ecosystems have captivated the imagination of scientists and the general public since their discovery ~40 years ago. These habitats are characterized by extremes in temperature and pH, low oxygen concentrations, and high concentrations of toxic metals. Despite this, these ecosystems support rich and abundant microbial communities that achieve high rates of biogeochemical cycling. This project supports unprecedented studies to identify the impact of chemical regimes on microbial and viral community composition, diversity, and activity in areas in the Gulf of California along a range of hydrothermalism and dissolve oxygen levels. The project provides training opportunities for undergraduate and graduate students. Results are communicated through talks and lectures, publications, and data sharing through public repositories. The work will be shared through Ocean Discovery Camp and Clubs for diverse middle school students, displays at the Georgia Museum of Art, and a collaboration with the BBC Planet Earth III – Oceans team. Through these cumulative efforts, the project will forge a strong legacy in education and in fostering ocean literacy and promoting ocean advocacy in the general public.

The Gulf of California is a system where hydrothermal fluids flow through and alter sediment prior to discharge into deep waters. In sediments, fluid flow modulates biological dynamics through changes in carbon loading and electron accepter availability. In the water column, inorganic and organic energy sources are injected into hypoxic deep waters, creating dynamic chemical niches. This project studies how gradients in geochemistry shape and modulate the microbial and viral communities that carry out key biogeochemical reactions in sediments and in the water column of Guaymas and Pescadero Basins. The research integrates data streams from biogeochemistry, genomics, and microbiology, including single-cell activity approaches, to achieve unprecedented insight into regulatory mechanisms and dynamics. The project includes experiments and observations in the laboratory and at sea during an expedition on the R/V Atlantis with the deep submergence vehicle ALVIN in 2022. Key topics for investigation include: (1) Do variations in geochemical regimes select for metabolically plastic microbial populations? (2) Do different microbes become active under specific geochemical conditions or do the same microbes adapt to changing geochemical conditions? (3) What is the role of viruses in shaping the microbial populations present in highly dynamic hydrothermal habitats?

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.