Thorium-234/uranium-238 disequilibrium as an indicator of scavenging rates and particulate organic carbon fluxes in the Northeast Water Polynya, Greenland

Reveals deficiencies relative to equilibrium with ²³⁸U that are related to uptake onto sinking particles. The deficiencies are generally enhanced in the upper 50 m of the water column (Polar Water), a zone of high suspended particle, particulate organic carbon, and pigment concentrations. Removal of ²³⁴Th from the water column is balanced, within the uncertainties, by inventories of excess ²³⁴Th in bottom sediments, with both water column deficiences and sediment inventories greater in 1993 than 1992. This indicates that on the timescale of several half-lives of ²³⁴Th (~100 days) the polynya is in balance with respect to ²³⁴Th (and probably the particles with which it is associated). -from Authors