| Contributors | Affiliation | Role |
|---|---|---|
| Owens, Jeremy D. | Florida State University - National High Magnetic Field Lab (FSU - NHMFL) | Principal Investigator |
| Nielsen, Sune G. | Woods Hole Oceanographic Institution (WHOI) | Co-Principal Investigator |
| Li, Siqi | Florida State University - National High Magnetic Field Lab (FSU - NHMFL) | Student |
| Rauch, Shannon | Woods Hole Oceanographic Institution (WHOI BCO-DMO) | BCO-DMO Data Manager |
Collection protocols for the South Atlantic Ocean seawater samples (Owens et al., 2017): a "trace metal-clean" titanium rosette with a PTFE-coated CTD system was used and deployed using a plasma rope to collect the seawater samples. Seawater samples were filtered through 0.2-micrometer (μm) filter capsules and transferred into 1-liter (L) HDPE bottles in a trace metal clean container. Then seawater samples were acidified at WHOI (Woods Hole Oceanographic Institution) to pH ~2 using concentrated distilled HCl.
Collection protocols for the Black Sea seawater samples (Cruise Report 64PE373 on RV Pelagia): an ultra-clean titanium CTD system was deployed to collect the seawater samples. The collected seawater was filtered with 0.2 μm Sartobran 300 filter cartridges (Sartorius) and acidified on board to pH ~2 with Baseline grade Seastar HCl. (See: https://www.geotraces.org/ga04-2/)
Here we describe the general protocols for chemical procedures. The in-lab column chromatography procedures to pre-concentrate and purify seawater vanadium (V) for concentration and isotope composition measurement are described in detail in Li et al. (under review). The chemical reagents utilized were trace-metal clean.
For seawater V concentration measurement, the column chromatography utilizing Bio-rad AG 50W-X12 cation resin was used to pre-concentrate V (Li et al., under review). The acidified seawater samples (pH ~2) were doped with H2O2 solution to contain 2% H2O2 before being loaded onto the resin column. Vanadium was yielded with weakly acidic H2O2 solution (0.01 M HCl + 2% H2O2) with the matrix metal elements being retained on the resin.
For seawater V isotope composition measurement, a four-column chromatography (Wu et al., 2019) was used to pre-concentrate and purify seawater V. Details of further improvements on this column chromatography method have been described in Li et al. (under review). The pre-cleaned Hitachi Nobias Chelate PA-1 resin and Bio-rad AG1-X8 anion resin were utilized to pre-concentrate and purify seawater V. The first column utilized Nobias Chelate PA-1 resin. Seawater samples were buffered to pH at 6.0 ± 0.1 with acetic acid and ammonia solutions before being loaded onto the column. Then V was yielded with 3 M HNO3. The following three columns utilized Bio-rad AG1-X8 anion resin to further purify seawater V, and the yielded V from the previous column was redissolved in 0.01 M HCl + 2% H2O2 solution before being loaded onto the column. Then, clean the resin column after the complete dripping of the sample solution using 0.01M HCl + 2% H2O2. Finally, V was yielded with 6M HCl and 2M HNO3.
The artificial seawater standards SW Matrix-AA and SW Matrix-BDH were made as in-lab standards for isotope composition measurement. The matrix elutes of two seawater samples were yielded after the first Nobias resin column and were separately doped with pure V solution standards, ~900 nanograms (ng) AA-V (SW Matrix-AA) and ~900 ng BDH V (SW Matrix-BDH). The two artificial seawater standards were processed parallelly with seawater samples with the same chemical procedures.
- Imported original file "Seawater vanadium concentrations and isotope compositions_Update.xlsx" into the BCO-DMO system.
- Flagged "N/A" as a missing data value (missing data are empty/blank in the final CSV file).
- Renamed fields to comply with BCO-DMo naming conventions.
- Made the south latitude values negative.
- Saved the final file as "957165_v1_vanadium_concentrations_and_isotope_compositions.csv".
- Saved the "NASS-6 V concentration" sheet as a PDF and attached as a Supplemental File.
- Saved the "Seawater standards" sheet as a PDF and attached as a Supplemental File.
| File |
|---|
957165_v1_vanadium_concentrations_and_isotope_compositions.csv (Comma Separated Values (.csv), 3.23 KB) MD5:2f8d342855f38928e2ac26af06a5dd35 Primary data file for dataset ID 957165, version 1 |
| File |
|---|
NASS-6_V_Concentrations.pdf (Portable Document Format (.pdf), 103.13 KB) MD5:55379f445ae9ea3997797ebbbf4ea808 Supplemental file for dataset ID 957165, version 1. Column Descriptions: [V]measured, "measured seawater vanadium concentration", ng/g [V]average, "the average seawater vanadium concentration calculated from duplicate and replicate measurement", ng/g [V]certified, "the certified vanadium concentration for the NASS-6 seawater standard", ng/g |
Seawater_Standards.pdf (Portable Document Format (.pdf), 362.67 KB) MD5:59d2d07ffedfc09eb79c42f30c2c135f Supplemental file for dataset ID 957165, version 1. Column descriptions: V doped, "amount of V doped to the in-lab seawater matrix", ng V yielded, "yielded amount of V from the column chromatography method", ng δ51V, "vanadium isotope composition", ‰ per mil 2SD , "2 standard deviation", ‰ per mil N, "duplicate measurement", unitless |
| Parameter | Description | Units |
| Cruise_ID | Cruise identifier | unitless |
| Location | Location description | unitless |
| Station | Station number | unitless |
| Sample_ID | Sample ID number. The "dup" and the number in the bracket indicate the re-dilution and remeasurement of the same solution. | unitless |
| Longitude | Longitude of collection location | degrees East |
| Latitude | Latitude of collection location; negative values = South | degrees North |
| Date | Year and month of sample collection | unitless |
| Depth | Depth below the sea surface | meters (m) |
| Salinity | Salinity (The salinity data are from Conway et al. (2016) and Horner et al. (2015).) | PSU |
| Seawater_V_ng_g | Seawater vanadium concentration in ng/g | nanograms per gram (ng/g) |
| Seawater_V_nmol_kg | Seawater vanadium concentration in nmol/kg. The seawater V concentration is averaged with duplicate measurements. The uncertainty 1RSD is calculated with duplicate measurements, otherwise the instrumental measurement precision with 1RSD better than 5% is assigned. | nanomoles per kilogram (nmol/kg) |
| one_RSD | One relative standard deviation | percent (%) |
| Seawater_V_normalized_nmol_kg | The seawater V concentration is normalized to salinity = 35‰. | nanomoles per kilogram (nmol/kg) |
| Yielded_V | Yielded vanadium after column chromatography | nanograms per gram |
| Yielding_rate | Yielding rate | percent (%) |
| d51V | delta 51V; Vanadium isotope composition | per mil (‰) |
| two_SD | Two standard deviations | per mil (‰) |
| number_duplicates | Number of duplicate measurements | unitless |
| Dataset-specific Instrument Name | Agilent 7500ce Inductively Coupled Plasma Mass Spectrometry (ICP-MS) |
| Generic Instrument Name | Agilent 7500ce inductively coupled plasma mass spectrometer |
| Dataset-specific Description | The vanadium concentrations were measured with the Agilent 7500ce Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Thermo Element 2 ICP‑MS. |
| Generic Instrument Description | The Agilent 7500ce is a laboratory benchtop inductively coupled plasma mass spectrometer (ICP-MS) for metal analysis. The instrument comprises a sample introduction system (micromist glass concentric nebuliser, quartz Scott-type spray chamber, peristaltic pump), an interface of nickel cones and dual on-axis extraction lenses, a vacuum system, mass flow controllers (plasma, auxiliary, makeup, and carrier gas and two Octopole Reaction System (ORS) reaction gas lines), a shieldtorch system (STS), an all-solid state digitally-driven 27 MHz RF generator and an off-axis Omega lens. The octopole cell of the ORS can be used with no gas, operated in collision mode using pure He cell gas or used in H2 reaction mode for ultra-trace Se analysis and semiconductor applications. All three of these modes come as standard in the 7500ce model. The instrument has been discontinued. |
| Dataset-specific Instrument Name | CTD |
| Generic Instrument Name | CTD - profiler |
| Dataset-specific Description | Seawater samples were collected with a "trace metal-clean" titanium rosette with a PTFE-coated CTD system in the South Atlantic and an ultra-clean titanium CTD system in the Black Sea. |
| Generic Instrument Description | The Conductivity, Temperature, Depth (CTD) unit is an integrated instrument package designed to measure the conductivity, temperature, and pressure (depth) of the water column. The instrument is lowered via cable through the water column. It permits scientists to observe the physical properties in real-time via a conducting cable, which is typically connected to a CTD to a deck unit and computer on a ship. The CTD is often configured with additional optional sensors including fluorometers, transmissometers and/or radiometers. It is often combined with a Rosette of water sampling bottles (e.g. Niskin, GO-FLO) for collecting discrete water samples during the cast.
This term applies to profiling CTDs. For fixed CTDs, see https://www.bco-dmo.org/instrument/869934. |
| Dataset-specific Instrument Name | Neptune Multi-collector-ICP-MS |
| Generic Instrument Name | Thermo Finnigan Neptune inductively coupled plasma mass spectrometer |
| Dataset-specific Description | The vanadium isotope compositions were measured with the Neptune Multi-collector-ICP-MS. |
| Generic Instrument Description | A laboratory high mass resolution inductively coupled plasma mass spectrometer (ICP-MS) designed for elemental and isotopic analysis. The instrument is based on a multicollector platform, comprising eight moveable collector supports and one fixed center channel equipped with a Faraday cup and, optionally, an ion counter with or without a retardation lens. The Faraday cup is connected to a current amplifier, whose signal is digitized by a high linearity voltage to frequency converter. The instrument was originally manufactured by Thermo Finnigan, which has since been replaced by Thermo Scientific (part of Thermo Fisher Scientific). This model is no longer in production. |
| Dataset-specific Instrument Name | Thermo Element 2 ICP‑MS |
| Generic Instrument Name | Thermo Fisher Scientific ELEMENT 2 inductively coupled plasma mass spectrometer |
| Dataset-specific Description | The vanadium concentrations were measured with the Agilent 7500ce Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Thermo Element 2 ICP‑MS. |
| Generic Instrument Description | The Thermo Scientific Element 2 ICP-MS is a double-focussing magnetic-sector-field Inductively Coupled Plasma Mass Spectrometer equipped with a discrete dynode detector system, linear over nine orders of magnitude - from ppq to ppm concentrations. Other features include: Sensitivity (Concentric Nebuliser) greater than 1 x 10^9 counts per second (cps)/ppm ln; Dark noise less than 0.2 cps; Mass resolution 300, 4,000, 10,000 (10 percent valley, equivalent to 5 percent height), 600, 8,000, 2,000 (FWHM); Signal stability better than 1 percent RSD over 10 minutes or 2 percent RSD over 1 hour; Mass stability: 25 ppm / 8 hours; Magnetic scan speed: m/z 7 to 240 to 7 in less than 150 ms, Electronic scan speed: 1 ms/jump, independent of mass range. |
| Website | |
| Platform | RRS Discovery |
| Report | |
| Start Date | 2010-10-18 |
| End Date | 2010-11-22 |
| Description | UK GEOTRACES cruise |
| Website | |
| Platform | R/V Pelagia |
| Report | |
| Start Date | 2013-07-13 |
| End Date | 2013-07-25 |
| Description | GEOTRACES Section Cruise GA04N |
NSF Award Abstract:
Discovering, testing, and developing chemical proxies (relic materials) in marine sediments that reveal how strongly or weakly oxidizing near-surface environmental conditions were in the Earth's geological past are immensely important for understanding interactions between ocean chemistry, biological evolution and extinctions, and climate. To date scientists do not have a proxy for low but non-zero oxygen conditions -- the sort of conditions that are likely to have dominated in biologically important periods of Earth history. In this project, researchers will study the relationship between bottom water oxygen concentration and the isotopes of the trace metal vanadium (V) in a range of oxygen conditions in the modern ocean. Based on pilot data, theoretical calculations and dissolved seawater V concentrations they believe that stable V isotope ratios of core top sediments will correlate systematically over a range of bottom water oxygen conditions. By analyzing these materials, the research team expects to establish the relationship between V isotopes and bottom water oxygen concentrations. Given the importance of chemical proxies to quantify past climate change, the results of this study will be of great importance to the modern and paleoceanographic community, as well as for modelers to better understand a broad range of oxygen variability in Earth history.
Although recent investigations have provided a wealth of information about the redox conditions of the ancient oceans, there is a significant gap in understanding low oxygen conditions throughout Earth history. Therefore, it is important to develop new paleoredox proxies that can provide additional and complementary knowledge about ocean redox conditions during these important periods of Earth history. In this study, scientists will analyze bulk sediments and their organic and ferromanganese mineral fractions to investigate the V isotopic variability within the various sedimentary components. (These samples comprise organic rich to ferromanganese rich sediments due to a range in bottom water oxygen concentrations.) Reconstructing marine low oxygen conditions using vanadium isotopes would fill a void in the paleoredox proxy toolbox. Developing, calibrating, and fingerprinting the V isotopic variability in modern sediments is required to be able to apply vanadium isotopes as an accurate paleoredox proxy.
| Funding Source | Award |
|---|---|
| NSF Division of Ocean Sciences (NSF OCE) | |
| NSF Division of Ocean Sciences (NSF OCE) | |
| National Aeronautics & Space Administration (NASA) | |
| Alfred P. Sloan Foundation (Sloan) |