An introduction to the use of Thorium-234 as a tracer of sinking particles in the ocean

Thorium-234 (234Th) is a naturally occurring radionuclide in the ocean, formed from decay of its Uranium-238 “parent” which is delivered to the oceans via weathering and rivers. Quite simply, lower levels of 234Th means more of the Thorium that is attached to the sinking particles is being removed. These same particles carry organic carbon and associated elements from the surface to the deep sea. Starting in the early 1990’s scientists realized that if they measured carbon on the same particles, they could estimate the sinking flux of carbon, which is a key parameter in considering the ocean’s role in the global carbon cycle and climate.

Your data will be included in the 234Th global compilation that soon will be hosted in PANGAEA and regularly updated: "Revisiting 50 years of 234Th data: a comprehensive global oceanic data base". The aim of this compilation is to enable users to view and download ocean thorium data from all over the world. More information can be found here: Global 234Th data base .

Jennifer Kenyon collecting 234Th samples.
Photo: Ken Buesseler

Sam Clevenger adding tracer to 234Th samples.
Photo: Ken Buesseler

4-L filtration racks.
Photo: Ken Buesseler

Last modified January 13, 2020