An intercomparison of small- and large-volume techniques for thorium-234 in seawater

Ken O. Buesseler, Claudia Benitez-Nelson, Michiel Rutgers van der Loeff, John Andrews, Lary Ball, Glen Crossin, Matthew A. Charette

Research output: Contribution to journalArticlepeer-review

113 Citations (Scopus)

Abstract

In this paper, an intercomparison of methods for the determination of 234Th in seawater is discussed. Samples were collected either from a shore-based 600 m water source, or from standard bottle casts in deep waters off Hawaii and the Southern Ocean. We compared large-volume techniques, which rely upon Mn cartridges for the collection of dissolved 234Th and its detection via gamma counting (> 200-1 samples), with small volume methods that employed either direct beta counting, or beta counting after radiochemical purification (2-20-1 samples). Unique to this study is the presentation of small volume (2 and 5 1) 234Th methods. This new technique is an adaptation of 20-1 methods that are based on the coprecipitation of thorium with Mn oxides followed by direct beta counting of the precipitate. The small volume Mn coprecipitation methods were found to be superior to other methods due to ease of sample collection, processing and low overall analytical uncertainties.

Original languageEnglish
Pages (from-to)15-28
Number of pages14
JournalMarine Chemistry
Volume74
Issue number1
DOIs
Publication statusPublished - 2001
Externally publishedYes

Bibliographical note

Funding Information:
We are particularly indebted to Dr. Tom Daniels for his assistance in providing us a temporary home at NELHA, and thanks to Dr. Dave Karl for the opportunity to collect extra samples on the JGOFS HOT cruises to further refine these methods. We thank Volker Strass and his hydrographic team for supplying Rosette samples during the R/V Polarstern expedition. We are pleased to acknowledge financial support from the US National Science Foundation Division of Ocean Sciences and Office of Polar Programs. In addition, support was provided to MAC as part of the WHOI Postdoctoral Fellowship Program and to C B-N, as part of the University of Hawaii SOEST Young Investigator Program and NOAA/UCAR Postdoctoral Fellowship in Global Change. This is WHOI contribution #10267, JGOFS contribution #562, and AWI contribution #10008.

ASJC Scopus Subject Areas

  • Oceanography
  • General Chemistry
  • Environmental Chemistry
  • Water Science and Technology

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