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 language | English |
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Pages (from-to) | 15-28 |
Number of pages | 14 |
Journal | Marine Chemistry |
Volume | 74 |
Issue number | 1 |
DOIs | |
Publication status | Published - 2001 |
Externally published | Yes |
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