Geochemical composition of sediment pore water samples collected in the Equatorial Pacific during October and November 2020 on R/V Kilo Moana cruise KM2012

Data Type: Cruise Results
Version: 1
Version Date: 2024-05-23

» Collaborative Research: How and Why eNd Tracks Ocean Circulation (Pacific Porewater Nd)
Haley, BrianOregon State University (OSU)Co-Principal Investigator
McManus, JamesBigelow Laboratory for Ocean SciencesCo-Principal Investigator
Rauch, ShannonWoods Hole Oceanographic Institution (WHOI BCO-DMO)BCO-DMO Data Manager

Water column, sediment, and pore water samples were collected during R/V Kilo Moana cruise KM2012 in the Equatorial Pacific during October and November 2020. This dataset includes elemental concentrations, Neodymium isotope ratios, pH, and nutrients from the sediment pore water samples.


Location: Equatorial Pacific
Spatial Extent: N:11 E:-152 S:3 W:-152
Temporal Extent: 2020-10-14 - 2020-10-24

Methods & Sampling

Water column, sediment, and pore water samples were collected following the methods in Abbott et al. (2015) during R/V Kilo Moana cruise KM2012 in October and November 2020. Pore water aliquots for REE (Rare Earth Elemental) concentration and εNd were collected by centrifuge and filtration (<0.45 micrometers (μm)). The REE aliquots were extracted from one core, while the εNd aliquots were multiple, combined extractions from corresponding layers of 20 to 25 cores. See 'Related Datasets' for the data from the water column samples and sediment cores.

Pore water aliquots for nutrient analyses were extracted using Rhizon samplers and filtered (<0.2 µm). Pore water aliquots for DOC analysis were extracted via Rhizon, filtered (<0.45 μm with GFF filter), poisoned with mercuric chloride, and stored in a glass vial.

Pore water dissolved O2 concentration was measured using a fiber-optic oxygen microsensor inserted into pre-drilled holes through the core into the sediments. The sensor readings are converted to oxygen concentration by linearly calibrating against the published bottom water O2 concentration at the study sites.

Pore water pH was measured on unfiltered samples using a portable pH sensor post-extraction via centrifugation. Analyses of pH in pore waters is notoriously difficult due to the changes in pressure upon recovery, and thus the pH data have finite utility.

Elemental concentrations, including the REEs, were analyzed at Oregon State University (OSU) using an Elemental Scientific seaFAST-pico offline preconcentration technique, and the procedure has been extensively documented as part of the GEOTRACES intercalibration effort (Behrens et al., 2016). Elemental concentrations of the εNd aliquots (~10 milliliters (mL)) were analyzed at ETH Zurich using Nobias Chelate-PA1 resin in a manual column procedure (K. Deng et al., 2022).

Isotope analysis of the εNd aliquots (400~700 mL of pore water or ~1.5 liters (L) of seawater) were done at ETH Zurich. Samples were buffered to a pH of 5.5 ± 5 and pre-concentrated using an in-house extraction manifold containing Nobias Chelate-PA1 resin. After pre-concentration, separation of Nd from the matrix elements and other REE was done using Eichrom RE and LN spec resins. Procedural blanks are <3 picograms (pg). Isotope analysis was done on an Neptune Plus MC-ICP-MS (Thermo-Fisher) following the procedure of Vance and Thirlwall (2002). Internally normalized sample data was renormalized to the 143Nd/144Nd ratio of La Jolla (Thirlwall, 1991). Repeated analysis of 8 parts per billion (ppb) La Jolla solutions results in a long-term external reproducibility of 0.27 ε (2σ). Nd isotope analysis was also quality-controlled by repeated measurements of the USGS reference materials BCR-2 (εNd = -0.11 ± 0.25, 2σ) and BHVO-2 (εNd = 6.70 ± 0.24, 2σ) at the same concentration (5-10 ppb) as the pore water samples in agreement with literature results (Jochum et al., 2005).

Nutrients were analyzed at Oregon State University using Technicon AutoAnalyzer II (phosphate and ammonium) and Alpkem RFA 300 (silicic acid, nitrate+nitrite). The method and data processing follow Gordon et al. (1993). DOC was analyzed with a V-CSN/TNM-1 (Shimadzu Corp, Kyoto, Japan) at the Scripps Institution of Oceanography following White et al. (2023).

Sediment samples were analysed for total organic carbon contents using a GVI (now Elementar) Isoprime 1000 with Eurovector EA at Bigelow Laboratory for Ocean Sciences. Samples were measured for the total carbon (organic plus inorganic) and a separate sample split was acidified to remove carbonate and then measured for the organic fraction.

​X-ray diffraction (XRD) of freeze-dried raw samples were made at K/T GeoServices Inc. (Colorado, USA), using a Siemens D500 automated powder diffractometer equipped with a copper X-ray source (40kV, 30mA) and a scintillation X-ray detector. Semi-quantitative determinations of whole-sediment mineral amounts were done using Jade Software (Materials Data, Inc.) with the Whole Pattern Fitting option.

BCO-DMO Processing Description

- Imported sheet "BCO-DMO pore water" from original file "BCO-DMOv2.xlsx" into the BCO-DMO system.
- Renamed fields to comply with BCO-DMO naming conventions.
- Corrected bottom depth of station 4 from 505 to 5050.
- Saved the final file as "928246_v1_pore_water_geochemical_composition.csv".

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Data Files

(Comma Separated Values (.csv), 24.82 KB)
Primary data file for dataset ID 928246, version 1

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Related Publications

Abbott, A. N., Haley, B. A., McManus, J., & Reimers, C. E. (2015). The sedimentary flux of dissolved rare earth elements to the ocean. Geochimica et Cosmochimica Acta, 154, 186–200.
Behrens, M. K., Muratli, J., Pradoux, C., Wu, Y., Böning, P., Brumsack, H.-J., … Pahnke, K. (2016). Rapid and precise analysis of rare earth elements in small volumes of seawater - Method and intercomparison. Marine Chemistry, 186, 110–120. doi:10.1016/j.marchem.2016.08.006
Deng, Kai, Yang, Shouye, Du, Jianghui, Lian, Ergang, & Vance, Derek. (2022). Dominance of benthic flux of REEs on continental shelves: implications for oceanic budgets. ETH Zurich.
Gordon, L.I., J.C. Jennings, Jr., A.A. Ross, and J.M. Krest (1993) A Suggested Protocol For Continuous Flow Automated Analysis of Seawater Nutrients, in WOCE Operation Manual, WHP Office Report 90-1, WOCE Report 77 No. 68/91, 1-52.
Jochum, K. P., Nohl, U., Herwig, K., Lammel, E., Stoll, B., & Hofmann, A. W. (2005). GeoReM: A New Geochemical Database for Reference Materials and Isotopic Standards. Geostandards and Geoanalytical Research, 29(3), 333–338.
Thirlwall, M. F. (1991). Long-term reproducibility of multicollector Sr and Nd isotope ratio analysis. Chemical Geology, 94(2), 85–104.
Vance, D., & Thirlwall, M. (2002). An assessment of mass discrimination in MC-ICPMS using Nd isotopes. Chemical Geology, 185(3–4), 227–240.
White, M. E., Nguyen, T. B., Koester, I., Lardie Gaylord, M. C., Beman, J. M., Smith, K. L., McNichol, A. P., Beaupré, S. R., & Aluwihare, L. I. (2023). Refractory Dissolved Organic Matter has Similar Chemical Characteristics but Different Radiocarbon Signatures With Depth in the Marine Water Column. Global Biogeochemical Cycles, 37(4). Portico.

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Related Datasets

Haley, B., McManus, J. (2024) Geochemical composition of sediment samples collected in the Equatorial Pacific during October and November 2020 on R/V Kilo Moana cruise KM2012. Biological and Chemical Oceanography Data Management Office (BCO-DMO). (Version 1) Version Date 2024-05-23 doi:10.26008/1912/bco-dmo.928400.1 [view at BCO-DMO]
Haley, B., McManus, J. (2024) Geochemical composition of water column samples collected in the Equatorial Pacific during October and November 2020 on R/V Kilo Moana cruise KM2012. Biological and Chemical Oceanography Data Management Office (BCO-DMO). (Version 1) Version Date 2024-05-23 doi:10.26008/1912/bco-dmo.928152.1 [view at BCO-DMO]

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Station_NumberStation number unitless
LatitudeLatitude of sampling site in degrees North degrees North
LongitudeLongitude of sampling site in degrees East (negative values are West) degrees East
DateDate of sampling unitless
bottom_depthDepth to seafloor meters (m)
nominal_depthDue to the nature of pore water sampling, the exact depth of sampling is not exact. We have provided the best median-depth for the sample taken such that it is comparable to other data/pore water/sediment. The resolution we used for these "nominal depths" is 0.5 cm. centimeters (cm)
La_pMREE concentration: Lanthanum (filtered at picomolar (pmol/L)
Ce_pMREE concentration: Cesium (filtered at picomolar (pmol/L)
Pr_pMREE concentration: Praseodymium (filtered at picomolar (pmol/L)
Nd_pMREE concentration: Neodymium (filtered at picomolar (pmol/L)
Sm_pMREE concentration: Samarium (filtered at picomolar (pmol/L)
Eu_pMREE concentration: Europium (filtered at picomolar (pmol/L)
Gd_pMREE concentration: Gadolinium (filtered at picomolar (pmol/L)
Tb_pMREE concentration: Terbium (filtered at picomolar (pmol/L)
Dy_pMREE concentration: Dysprosium (filtered at picomolar (pmol/L)
Ho_pMREE concentration: Holmium (filtered at picomolar (pmol/L)
Er_pMREE concentration: Erbium (filtered at picomolar (pmol/L)
Tm_pMREE concentration: Thulium (filtered at picomolar (pmol/L)
Yb_pMREE concentration: Ytterbium (filtered at picomolar (pmol/L)
Lu_pMREE concentration: Lutetium (filtered at picomolar (pmol/L)
Co_nMTrace metal concentration: Cobalt (filtered at nanomolar (nmol/L)
Ni_nMTrace metal concentration: Nickel (filtered at nanomolar (nmol/L)
Cu_nMTrace metal concentration: Copper (filtered at nanomolar (nmol/L)
Zn66_nMTrace metal concentration: Zinc (filtered at nanomolar (nmol/L)
Zn68_nMTrace metal concentration: Zinc (filtered at nanomolar (nmol/L)
Mo_nMTrace metal concentration: Molybdenum (filtered at nanomolar (nmol/L)
Cd_nMTrace metal concentration: Cadmium (filtered at nanomolar (nmol/L)
Pb_nMTrace metal concentration: Lead (filtered at nanomolar (nmol/L)
U_nMTrace metal concentration: Uranium (filtered at nanomolar (nmol/L)
Ca_mmol_LMajor ion: Calcium (Filtered at millimolar (mmol/L)
Ca_errorCalcium error of analysis millimolar (mmol/L)
K_mmol_LMajor ion: Potassium (Filtered at millimolar (mmol/L)
K_errorPotassium error of analysis millimolar (mmol/L)
Mg_mmol_LMajor ion: Magnesium (Filtered at millimolar (mmol/L)
Mg_errorMagnesium error of analysis millimolar (mmol/L)
Na_mmol_LMajor ion: Sodium (Filtered at millimolar (mmol/L)
Na_errorSodium error of analysis millimolar (mmol/L)
S_mmol_LMajor ion: Sulfur (Filtered at millimolar (mmol/L)
S_errorSulfur error of analysis millimolar (mmol/L)
Sr_umol_L_1Major ion: Strontium (Filtered at micromolar (umol/L)
Sr_error_1Strontium error of analysis micromolar (umol/L)
B_umol_LMajor ion: Boron (Filtered at micromolar (umol/L)
B_errorBoron error of analysis micromolar (umol/L)
Ba_umol_LMajor ion: Barium (Filtered at micromolar (umol/L)
Ba_errorBarium error of analysis micromolar (umol/L)
Li_umol_LMajor ion: Lithium (Filtered at micromolar (umol/L)
Li_errorLithium error of analysis micromolar (umol/L)
P_umol_LMajor ion: Phosphorus (Filtered at micromolar (umol/L)
P_errorPhosphorus error of analysis micromolar (umol/L)
Si_umol_LMajor ion: Silicon (Filtered at micromolar (umol/L)
Si_errorSilicon error of analysis micromolar (umol/L)
Sr_umol_L_ICPOESMajor ion: Strontium (Filtered at micromolar (umol/L)
Sr_error_ICPOESStrontium error of analysis micromolar (umol/L)
Nd143_Nd144Isotope ratio of Neodymium-143 to Neodymium-144 unitless
SD2_int_1Two sigma standard deviation of 143Nd/144Nd integrated measurements unitless
eNdNeodymium isotope composition given in epsilon notation (deviation of 143Nd/144Nd ratio from CHUR) unitless
SD2_int_2Two sigma standard deviation of 143Nd/144Nd integrated measurements in epsilon notation unitless
DOC_uMDissolved organic carbon (Filtered at micromolar (umol/L)
pcnt_STDEVTwo sigma standard deviation of DOC measurements unitless
Oxygen_Optode_pcnt_asDissolved oxygen concentration percent saturation
NO3_NO2_uMTotal dissolved nitrate plus nitrite micromolar (umol/L)
PO4_uMTotal dissolved phosphate micromolar (umol/L)
Si_uMDissolved silicious acid micromolar (umol/L)

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Dataset-specific Instrument Name
Alpkem RFA 300
Generic Instrument Name
Alpkem RFA300
Generic Instrument Description
A rapid flow analyser (RFA) that may be used to measure nutrient concentrations in seawater. It is an air-segmented, continuous flow instrument comprising a sampler, a peristaltic pump which simultaneously pumps samples, reagents and air bubbles through the system, analytical cartridge, heating bath, colorimeter, data station, and printer. The RFA-300 was a precursor to the smaller Alpkem RFA/2 (also RFA II or RFA-2).

Dataset-specific Instrument Name
Generic Instrument Name
Generic Instrument Description
A machine with a rapidly rotating container that applies centrifugal force to its contents, typically to separate fluids of different densities (e.g., cream from milk) or liquids from solids.

Dataset-specific Instrument Name
GVI (now Elementar) Isoprime 1000
Generic Instrument Name
Elemental Analyzer
Generic Instrument Description
Instruments that quantify carbon, nitrogen and sometimes other elements by combusting the sample at very high temperature and assaying the resulting gaseous oxides. Usually used for samples including organic material.

Dataset-specific Instrument Name
MC800 multi-corer
Generic Instrument Name
Multi Corer
Generic Instrument Description
The Multi Corer is a benthic coring device used to collect multiple, simultaneous, undisturbed sediment/water samples from the seafloor. Multiple coring tubes with varying sampling capacity depending on tube dimensions are mounted in a frame designed to sample the deep ocean seafloor. For more information, see Barnett et al. (1984) in Oceanologica Acta, 7, pp. 399-408.

Dataset-specific Instrument Name
Elemental Scientific seaFAST-pico
Generic Instrument Name
SeaFAST Automated Preconcentration System
Generic Instrument Description
The seaFAST is an automated sample introduction system for analysis of seawater and other high matrix samples for analyses by ICPMS (Inductively Coupled Plasma Mass Spectrometry).

Dataset-specific Instrument Name
Rhizon samplers
Generic Instrument Name
Sediment Porewater Sampler
Generic Instrument Description
A device that collects samples of pore water from various horizons below the seabed.

Dataset-specific Instrument Name
V-CSN/TNM-1 (Shimadzu Corp)
Generic Instrument Name
Shimadzu TOC-V Analyzer
Generic Instrument Description
A Shimadzu TOC-V Analyzer measures DOC by high temperature combustion method.

Dataset-specific Instrument Name
Technicon AutoAnalyzer II
Generic Instrument Name
Technicon AutoAnalyzer II
Generic Instrument Description
A rapid flow analyzer that may be used to measure nutrient concentrations in seawater. It is a continuous segmented flow instrument consisting of a sampler, peristaltic pump, analytical cartridge, heating bath, and colorimeter. See more information about this instrument from the manufacturer.

Dataset-specific Instrument Name
Neptune Plus MC-ICP-MS (Thermo-Fisher)
Generic Instrument Name
Thermo Finnigan Neptune inductively coupled plasma mass spectrometer
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.

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R/V Kilo Moana
Start Date
End Date
See more information at R2R:

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Project Information

Collaborative Research: How and Why eNd Tracks Ocean Circulation (Pacific Porewater Nd)

Coverage: Central Pacific

NSF Award Abstract:
Circulation of water is a fundamental trait of the oceans that impacts its physics, chemistry and biology; however, understanding modern and past patterns of circulation - especially in the vast bodies of deep water - is challenging because global circulation defies direct measurement. The problems with direct measurement largely stem from the vast scales of space and time that are of interest in understanding global circulation. One tool for estimating global circulation patterns that holds promise is seen in neodymium isotopes which appear to be powerful tracers of deep ocean circulation, over a variety of timescales. Unfortunately, the elemental behavior of neodymium contrasts the isotopic behavior of neodymium in the oceans, a puzzle branded the "neodymium paradox." This inconsistency of geochemical behavior opens to question the application of neodymium isotopes as a tracer of circulation. Therefore, scientists from Oregon State University, Tulane University, and Bigelow Laboratory of Ocean Sciences propose to test the hypothesis that there is a yet unconstrained (even poorly identified) source of neodymium to the oceans that can explain the discrepancies seen between the elemental and isotopic neodymium marine budgets. The scientists further seek to understand the mechanistic cause of this source and thus be able to start making global constraints on its influence. Understanding these processes will fundamentally change our interpretations of neodymium data and allow us to more accurately quantify ocean circulation with a greater degree of confidence. For outreach activities, the scientists plan to participate in open house days held at Oregon State University, da Vinci days, National Ocean Science Bowls, Salmon Bowl and Bigelow Laboratory for Ocean Sciences' Cafe Scientifique. Undergraduate students and one graduate student from Tulane University would be supported and trained as part of this project.

Scientists from Oregon State University, Tulane University, and Bigelow Laboratory for Ocean Sciences propose to test the hypothesis that there is a benthic source of neodymium (Nd) to the oceans that exerts a primary control over the distribution of this element and its isotopes (eNd) in the ocean. This benthic flux results from early diagenetic reactions that release rare earth elements (REEs) from the solid phase to pore fluid. The scientists contend this flux will explain eNd distributions throughout the modern and past global oceans. The planned research will be guided by three questions:

(1) What are the mechanisms that control the magnitude and isotope composition of the benthic flux?
(2) What are the relationships among bottom water, pore fluid, and the terminal solid phase compositions? Particularly, how and under what chemical conditions does an eNd signature become part of a preserved archival record of [Nd] and eNd?
(3) Can our understanding of the deep water benthic fluxes account for the integrated bottom water eNd as a function of apparent water mass age and circulation path (e.g., how do the pore fluid and solid phase values reconcile with the existing water column signature and water mass age data)?

To test these ideas, sediments and their pore fluids will be collected from a diverse set of deep sea sites in the Pacific Ocean that reflect slow-to-fast sedimentation rates, carbonate-, terrigenous-, volcaniclastic- and siliceous-sediment, and low-to-high organic carbon. The sediments and porewater samples, as well as samples from the overlying water column will be characterized for the following parameters: major, minor, and trace metals, Nd isotopes, carbonate chemistry, oxygen, nutrients, particulate organic carbon, particulate organic nitrogen, radiocarbon, porosity, and grain size. With these observations we will build a quantitative numeric geochemical model (e.g., PHREEQC, Geochemist's Workbench, Humic Ion Binding Model) that can capture the cardinal controls over the benthic source. Our goal is to provide a new interpretive framework for Nd and eNd, such that we can offer quantitative estimates of benthic fluxes for use in models of global circulation. This work has potentially transformative implications on our understanding and application of REEs and Nd isotope data in both the modern and ancient oceans.

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.

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Funding SourceAward
NSF Division of Ocean Sciences (NSF OCE)
NSF Division of Ocean Sciences (NSF OCE)

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