Dataset: Concentrations of size-fractionated particulate thorium and protactinium isotopes (Th-232, Th-230, Pa-231) in seawater collected during the U.S. GEOTRACES Arctic cruise (HLY1502, GN01) on USCGC Healy from August to October 2015

This dataset has not been validatedFinal no updates expectedDOI: 10.26008/1912/bco-dmo.834741.3Version 3 (2021-08-25)Dataset Type:Cruise Results

Principal Investigator: Robert F. Anderson (Lamont-Doherty Earth Observatory)

Principal Investigator: R. Lawrence Edwards (University of Minnesota Twin Cities)

Co-Principal Investigator: Hai Cheng (University of Minnesota Twin Cities)

Co-Principal Investigator: Martin Q. Fleisher (Lamont-Doherty Earth Observatory)

Contact, Analyst: Sebastian M. Vivancos (Lamont-Doherty Earth Observatory)

Analyst: Xianglei Li (University of Minnesota Twin Cities)

Analyst: Pu Zhang (University of Minnesota Twin Cities)

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


Program: U.S. GEOTRACES (U.S. GEOTRACES)

Project: U.S. Arctic GEOTRACES Study (GN01) (U.S. GEOTRACES Arctic)

Project: Collaborative Research: U.S. GEOTRACES Arctic Section: Thorium-230, Thorium-232, and Protactinium-231 tracers of trace element supply and removal. (GEOTRACES Arctic Th Pa)


Abstract

This dataset contains concentrations of size-fractionated particulate thorium and protactinium isotopes (Th-232, Th-230, Pa-231) in seawater collected during the U.S. GEOTRACES Arctic cruise (HLY1502, GN01) on USCGC Healy from August to October 2015. This is compiled data produced by two laboratories with the following associations: Lamont-Doherty Earth Observatory of Columbia University (LDEO) and the University of Minnesota (UMN). All data have been deemed intercalibrated by the International ...

Show more

This dataset contains concentrations of size-fractionated particulate thorium and protactinium isotopes (Th-232, Th-230, Pa-231) in seawater collected during the U.S. GEOTRACES Arctic cruise (HLY1502, GN01) on USCGC Healy from August to October 2015. This is compiled data produced by two laboratories with the following associations: Lamont-Doherty Earth Observatory of Columbia University (LDEO) and the University of Minnesota (UMN). All data have been deemed intercalibrated by the International GEOTRACES Standards and Intercalibration (S&I) Committee.

Naming Conventions:
Parameter names in the form such as "Th_232_SPT_CONC_PUMP" are adopted based on a recommendation from the GEOTRACES community (https://www.geotraces.org/parameter-naming-conventions/).

The "small particulate" (SPT) data refers to the particle size class 0.8-51 µm and is sometimes also called the "suspended" size fraction. The "large particulate" (LPT) data refers to particles greater than 51 µm and is sometimes referred to as the "sinking" size fraction. The particulate samples were collected by in-situ pumping over two loaded filter holders/flowpaths. One filter holder/flowpath was loaded with paired 0.8 µm Pall Supor800 polyethersulfone filters behind a 51 µm Sefar polyester mesh prefilter ("Supor-side") and the other filter holder/flowpath was loaded with paired 1 µm Whatman QMA quartz fiber filters behind a 51 µm Sefar polyester mesh prefilter ("QMA-side") (see Xiang and Lam, 2020 for particulate sampling methodology). Analysis of the paired Supor filters represents a particle size class approximating 0.45-51 µm (Bishop et al., 2012), while the top filter alone represents 0.8-51 µm and it is this size class referred to here as the "small particulate" fraction. We measured a select number of top and bottom Supor filters separately for radionuclides and found that the bottom filters had radionuclide levels that were indistinguishable from procedural blanks ("dipped" filter blanks). Therefore, whether or not samples were analyzed as paired Supor filters, or the top Supor filter alone, we infer the "small particulate" data to represent the 0.8-51 µm particle size class or "suspended" size fraction. The "large particulate" data is based on the analysis of the QMA-side 51 µm Sefar polyester mesh prefilters. Only a selection of "large particulate" samples were analyzed and those analyses were all performed at the University of Minnesota (UMN).

Units of Measurement:
Radionuclide concentrations are given as micro-Becquerel (10e-6 Bq, µBq or micro-Bq) per kilogram seawater for Th-230 and Pa-231, and picomole (10e-12 mol, pmol) per kilogram seawater for Th-232. A Becquerel is the SI unit for radioactivity and is defined as 1 disintegration per second. These units are recommended by the GEOTRACES community.


Related Datasets

No Related Datasets

Related Publications

General

Auro, M. E., Robinson, L. F., Burke, A., Bradtmiller, L. I., Fleisher, M. Q., & Anderson, R. F. (2012). Improvements to 232-thorium, 230-thorium, and 231-protactinium analysis in seawater arising from GEOTRACES intercalibration. Limnology and Oceanography: Methods, 10(7), 464–474. doi:10.4319/lom.2012.10.464
General

Chen, J. H., Edwards, R. L., & Wasserburg, G. J. (1986). 238U, 234U and 232Th in seawater. Earth and Planetary Science Letters, 80(3-4), 241–251. doi:10.1016/0012-821x(86)90108-1
Methods

Anderson, R. F., Fleisher, M. Q., Robinson, L. F., Edwards, R. L., Hoff, J. A., Moran, S. B., … Francois, R. (2012). GEOTRACES intercalibration of 230Th, 232Th, 231Pa, and prospects for 10Be. Limnology and Oceanography: Methods, 10(4), 179–213. doi:10.4319/lom.2012.10.179
Methods

Bishop, J. K. B., Lam, P. J., & Wood, T. J. (2012). Getting good particles: Accurate sampling of particles by large volume in-situ filtration. Limnology and Oceanography: Methods, 10(9), 681–710. doi:10.4319/lom.2012.10.681
Methods

Cheng, H., Edwards, R. L., Hoff, J., Gallup, C. D., Richards, D. A., & Asmerom, Y. (2000). The half-lives of uranium-234 and thorium-230. Chemical Geology, 169(1-2), 17–33. doi:10.1016/s0009-2541(99)00157-6