Adsorbers for in-situ collection and at-sea gamma analysis of dissolved Thorium-234 in seawater
Adsorbers for in-situ collection and at-sea gamma analysis of dissolved Thorium-234 in seawater
Date
1994-07
Authors
Hartman, M. C.
Buesseler, Ken O.
Buesseler, Ken O.
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DOI
10.1575/1912/589
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Keywords
Thorium-234
Mn02 adsorber
seawater
Cape Hatteras (Ship) Cruise
Malcolm Baldridge (Ship) Cruise
Discoverer (Ship) Cruise
Mn02 adsorber
seawater
Cape Hatteras (Ship) Cruise
Malcolm Baldridge (Ship) Cruise
Discoverer (Ship) Cruise
Abstract
Two polypropylene cartridge types (Beta Pure and Hytrex II) were tested in the laboratory as adsorbers for in-situ collection of
dissolved Thorium-234 (234TH) in seawater. Using a uranyl nitrate tracer, we determined that a Mn02 impregnated 3.25-inch Hytrex
II cartridge with a flow rate of 8 liters/minute would collect 234TH with a greater than 60% effciency. The smaller size and
composition of the 3.25 inch Hytrex II cartridge enabled it to be pressed into a permanent 1-inch "puck" for direct gamma
counting. This protocol significantly reduced the handling between collection and counting. When field tested in the Gulf of Maine
as a large volume (>500 liters) collector, the new adsorbers produced a greater than 80% collection effciency and a dissolved 234TH concentration which was consistent with independent samples collected at the same station and depth. These adsorbers were used
successfully for the in-situ collection of 234TH in large volumes of seawater during the 1992 NOAA and NSF sponsored JGOFS
EqPac program, with a mean collection efficiency of 0.79 +/- 9% (n=104 cartridge pairs).
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Citation
Hartman, M. C., & Buesseler, K. O. (1994). Adsorbers for in-situ collection and at-sea gamma analysis of dissolved Thorium-234 in seawater. Woods Hole Oceanographic Institution. https://doi.org/10.1575/1912/589