Publication Date:
2022-05-25
Description:
Author Posting. © The Authors, 2005. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Marine Chemistry 100 (2006): 282-288, doi:10.1016/j.marchem.2005.10.016.
Description:
The recently developed 2‐5 L small‐volume MnO2 coprecipitation method for
determining 234Th in seawater has provided a new way to substantially increase, both
temporally and spatially, the sampling resolution of 234Th and 234Th‐based particulate
organic carbon export estimates in the upper ocean. In this study, we further optimize
the technique by reducing reagent quantities and the use of an additional water bath
heating step. This optimization allows the filtration of the MnO2 precipitate onto a
25‐mm diameter, 1.0 μm pore size QMA filter to be completed within 〈 30 minutes for
unfiltered waters from the South China Sea. In addition, we have modified the MnO2
purification procedure to allow for alpha spetrometric measurements of 234Th recoveries.
Results from recovery experiments suggest that reagent amounts can be reduced to
0.0375 mg KMnO4 and 0.1 mg MnCl2∙4H2O per liter of sample, while still maintaining
high 234Th recovery. This study further confirms that the addition of a yield monitor is
necessary for the application of this small‐volume method.
Description:
Support for this work came from the Natural Science Foundation of China through grants
#40206011, #49825162, and #90211020. This study was also supported by the China Ministry of
Education through a program for Changjiang Scholars and Innovative Research Teams in
Universities (PRSIRT).
Keywords:
Thorium-234
;
MnO2 coprecipitation
;
Beta counting
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
Format:
303369 bytes
Format:
application/pdf
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