Natural and anthropogenic radionuclide distributions

• Main Authors: J. Kirk Cochran, David J. Hirschberg, Hugh D. Livingston, F Ken Buesselert, Robert M. Keys
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1987
• Subjects: Arctic; Arctic Ocean; Barents Sea; Gakkel Ridge; Central Basin; Nansen Basin
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.432.1734; http://www.gfdl.noaa.gov/bibliography/related_files/jkc9501.pdf?PHPSESSID=d42e17401c44c242bcb345d6d7e9be95

Abstract-Determination of the naturally occurring radionuclides 232Th 23sTh “*Th and 2’sPb, and the anthropogenic radionuclides “‘Am 23g*2?‘u, ‘34Cs and r3’Cs in water samples collected across the Nansen Basin from the Barents Se: slope to the Gakkel Ridge provides tracers with which to characterize both scavenging rates and circulation timescales in this portion of the Arctic Ocean. Large volume water samples (- 1500 1) were filtered in situ to separate particulate (> 0.5 pm) and dissolved Th isotopes and 241Am. Thorium-230 displays increases in both particulate and dissolved activities with depth, with dissolved *??I greater and particulate a3’?h lower in the deep central Nansen Basin than at the Barents Sea slope. Dissolved “*Th activities also are greater relative to ***Ra, in the central basin. Residence times for Th relative to removal from solution onto particles are- 1 year in surface water,- 10 years in deep water adjacent to the Barents Sea slope, and- 20 years in the Eurasian Basin Deep Water. Lead-210 in the central basin deep water also has a residence time of-20 years with respect to its removal from the water column. This texture of scavenging is reflected in distributions of the particle-reactive anthropogenic radionuclide 241Am, which shows higher activities relative to Pu in the central Nansen Basin than at the Barents Sea slope. Distributions of 13’Cs show more rapid mixing at the basin margins (Barents Sea slope in the south, Gakkel Ridge in the north) than in the basin interior. Cesium-137 is mixed throughout the