Barium concentration and isotopic data from SAFe, collected during the 2nd GEOTRACES Intercalibration cruise (R/V Knorr KN195-08) in the eastern North Pacific during May 2009

Website: https://www.bco-dmo.org/dataset/770368
Data Type: Cruise Results
Version: 2
Version Date: 2019-08-06

Project
» U.S. GEOTRACES Pacific Meridional Transect: Tracing Basin-scale Nutrient Cycling and Carbon Export with Dissolved and Particulate Barium-isotopic Distributions (GEOTRACES PMT Barium)
ContributorsAffiliationRole
Horner, Tristan J.Woods Hole Oceanographic Institution (WHOI)Principal Investigator
Rauch, ShannonWoods Hole Oceanographic Institution (WHOI BCO-DMO)BCO-DMO Data Manager

Abstract
Barium concentration and isotopic data from SAFe, collected during the 2nd GEOTRACES Intercalibration cruise, KN195-08, on R/V Knorr in the eastern North Pacific during May 2009.


Coverage

Spatial Extent: N:30.0003 E:-140 S:30 W:-140.0003
Temporal Extent: 2009-05-18 - 2009-05-20

Acquisition Description

Samples were collected on the GEOTRACES carousel, filtered to 0.2 μm or 0.45 μm (depending on filter type), acidified to pH ≈ 2 with hydrochloric acid, and stored for several years prior to processing. Aliquots containing five milliliters of seawater were cleanly subsampled from each sample, weighed, and an appropriate quantity of ¹³⁶Ba–¹³⁵Ba double spike added. Following spike–sample equilibration, barium was co-precipitated with calcium carbonate via dropwise addition of sodium carbonate. The resultant precipitate was dissolved in hydrochloric acid and twice passed through cation-exchange columns to purify Ba from matrix elements.

Samples were aspirated, desolvated, and analyzed using a 100 μL/min nebulizer, Aridus II desolvation system, and ThermoFisher Neptune multi-collector ICP-MS, respectively. All instrumentation was sitated at the WHOI Plasma Facility. Barium-isotopic compositions were calculated from simultaneous monitoring of ion beams corresponding to m/z 131 (Xe, xenon), 135 (Ba), 136 (Xe; Ba; Ce, cerium), 137 (Ba), 138 (Ba; La, lanthanum; Ce), 139 (La) and 140 (Ce).

Problem report:
Sample 4722 (surface) unclear if sample was filtered, and—if so—what filter cutoff was used.


Processing Description

Data reduction was performed in MATLAB using the baseline-corrected ion beam output from the instrument software. Barium-isotopic compositions were calculated using an iterative, three-dimensional geometric interpretation of the double spike problem, with additional nested loops for interference corrections. All sample compositions are reported as parts per one thousand deviations (i.e., ‰; per mille) relative to NIST SRM 3104a.

Quality Control: Refer to the Certified Reference Materials (CRMs) supplemental file (PDF).

"_FLAG" columns follow the ODV flag scheme, defined as:
1 = Good Value: Used when replicate samples were analyzed for a particular concentration/isotopic composition.
2 = Probably Good Value: Used when the reported value reflects analysis of a single replicate.
3 = Probably Bad Value: Used when a value appears abnormally high or low (oceanographically inconsistent) based on adjacent depths or typical profile variability and shape using the context of relevant nearby stations.
6 = Value Below Detection Limit: Used when value is below the detection limit for that given element. Empty values are reported rather than zero or a detection limit value.

BCO-DMO Processing:
- modified parameter names (replaced spaces w/ underscores; removed units);
- replaced blanks (no data) with "nd";
- 06 August 2019: replaced version 1 with version 2 of dataset (corrections made in Ba_138_134_D_DELTA_BOTTLE column).


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Related Publications

Bates, S. L., Hendry, K. R., Pryer, H. V., Kinsley, C. W., Pyle, K. M., Woodward, E. M. S., & Horner, T. J. (2017). Barium isotopes reveal role of ocean circulation on barium cycling in the Atlantic. Geochimica et Cosmochimica Acta, 204, 286–299. doi:10.1016/j.gca.2017.01.043
Geyman, B. M., Ptacek, J. L., LaVigne, M., & Horner, T. J. (2019). Barium in deep-sea bamboo corals: Phase associations, barium stable isotopes, & prospects for paleoceanography. Earth and Planetary Science Letters, 525, 115751. doi:10.1016/j.epsl.2019.115751

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Parameters

ParameterDescriptionUnits
GEOTRC_EVENTNOThe event # from the cruise report unitless
latLatitude (positive values = North) decimal degrees
longLongitude (negative values = West) decimal degrees
Filter_typeType (and cutoff) of filter used unitless
GEOTRC_SAMPNOUnique GEOTRACES sample ID unitless
DepthSample depth meters (m)
Ba_D_CONC_BOTTLEDissolved Ba (barium) concentration nanomoles per kilogram (nmol/kg)
Ba_D_CONC_BOTTLE_stdevOne-sigma uncertainty about the barium concentration nmol/kg
Ba_D_CONC_BOTTLE_FLAGODV quality flag for Ba_D_CONC_BOTTLE unitless
Ba_138_134_D_DELTA_BOTTLEDissolved Ba-isotopic composition per mil deviation rel. to NIST SRM 3104a
Ba_138_134_D_DELTA_BOTTLE_stdevOne-sigma uncertainty about the dissolved Ba-isotopic composition per mil
Ba_138_134_D_DELTA_BOTTLE_FLAGODV quality flag for Ba_138_134_D_DELTA_BOTTLE unitless
NotesAny issues or concerns unitless


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Instruments

Dataset-specific Instrument Name
GEOTRACES carousel
Generic Instrument Name
GO-FLO Bottle
Generic Instrument Description
GO-FLO bottle cast used to collect water samples for pigment, nutrient, plankton, etc. The GO-FLO sampling bottle is specially designed to avoid sample contamination at the surface, internal spring contamination, loss of sample on deck (internal seals), and exchange of water from different depths.

Dataset-specific Instrument Name
ThermoFisher Neptune multi-collector ICP-MS
Generic Instrument Name
Inductively Coupled Plasma Mass Spectrometer
Generic Instrument Description
An ICP Mass Spec is an instrument that passes nebulized samples into an inductively-coupled gas plasma (8-10000 K) where they are atomized and ionized. Ions of specific mass-to-charge ratios are quantified in a quadrupole mass spectrometer.

Dataset-specific Instrument Name
Generic Instrument Name
GeoFish Towed near-Surface Sampler
Generic Instrument Description
The GeoFish towed sampler is a custom designed near surface (


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Deployments

KN195-08

Website
Platform
R/V Knorr
Start Date
2009-05-06
End Date
2009-05-29
Description
GEOTRACES intercalibration cruise 2  (May 2009) GEOTRACES completed the first Intercalibration cruise from June 8 to July 12, 2008, collecting water and particle samples for analysis and intercalibration. The second intercalibration cruise is planned for May 2009 in the eastern North Pacific and will include sampling near the North Pacific SAFe Station at 30°N 140°W, and the Santa Barbara Basin, 34.25°N 120°W. This International GEOTRACES intercalibration exercise aims to provide reference materials that could be distributed to the international community and reference profiles of Trace Elements and their Isotopes to ensure compatibility and consistency of GEOTRACES data. Sampling Activities: for full details see cruise synopsis or cruise report when available Pre-cruise Sampling Activity Summary: This is a 'trace metal clean' cruise, during which the researchers plan to use the following sampling devices and gear: ship's standard CTD with 24x10L Niskin bottle rosette Ken Buesseler's McLane in situ pumps and MITESS vane samplers a trace metal-clean GEOTRACES carousel with GO-Flo bottles (like the one used during IC 1 in 2008. This will be deployed using the newly developed method described by Glosten Associates. The plan is to use this system for up to 10 casts per day. a towed/stationary fish (depressor and weighted torpedo) for pumping trace metal clean water to the MLML sampling and GEOTRACES clean vans, deployed using our aluminum pivoting boom just like in 2008. We will be testing several different towed fish during the transits. Jim Bishop's MULFVS pumping system (http://www-ocean.lbl.gov/MULVFSops.html)   An EOS paper (Johnson, 2007) describes the SAFe station and efforts to establish the SAFe dissolved Fe in seawater standards.K.S. Johnson et al. 2007. Developing standards for dissolved iron in seawater, EOS 88 (11), pp. 131-132 (http://boyle.mit.edu/~ed/PDFs/Johnson(2007)EOS88_131.pdf) Cruise information and original data are available from the NSF R2R data catalog.


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Project Information

U.S. GEOTRACES Pacific Meridional Transect: Tracing Basin-scale Nutrient Cycling and Carbon Export with Dissolved and Particulate Barium-isotopic Distributions (GEOTRACES PMT Barium)


NSF Award Abstract: The goal of the international GEOTRACES program is to understand the distributions of trace chemical elements and their isotopes in the oceans. This project would measure stable isotopes of barium on a 2018 U.S. GEOTRACES expedition in the Pacific Ocean. Barium is a trace element whose distribution is relevant to all three themes of the GEOTRACES program, as barium can be used to: study chemical cycling within the oceans; trace exchanges of elements at ocean boundaries; and infer past environmental conditions. The data collected here will be the first of their kind for barium isotopes and will illuminate the geochemical cycle of this element. Moreover, conducting this work as part of the GEOTRACES program will maximize the return on investment in the barium isotope data by providing a rich interpretative framework. This project seeks to understand how the interplay between internal cycling and boundary processes sets basin-scale barium concentration and isotopic distributions in the Pacific Ocean. Despite possessing a nutrient-like dissolved profile, marine barium cycling has a fundamentally different boundary condition to the major algal nutrients: barium cycling is not driven by production of organic matter but rather by its remineralization. Respiration of sinking organic matter in the ocean's 'twilight zone' releases carbon dioxide, mineralizes nutrients, and promotes precipitation of micron-size crystals of barite. Since barite is the major vector of particulate barium in seawater, the abundance and isotopic composition of barium in the oceans is tied to global carbon and nutrient cycling at the 'dark end' of the biological carbon pump. The data collected here will be used to test hypotheses across an unprecedented range of oceanographic conditions regarding: the formation, export, and regeneration of particulate material and the connection to seafloor processes; the importance of boundary sources to regional and global trace element and isotope budgets; the formation of putative soft-metal sulfides in oxygen-minimum zones; and the origin of enigmatic suspended particles in the deep open ocean. This proposal will contribute to education by training undergraduate research fellows and through presentation of seminars and guest lectures to regional science educators through collaboration with a regional conservation organization.


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Funding

Funding SourceAward
NSF Division of Ocean Sciences (NSF OCE)

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