Cycling of fallout (Pu, /sup 241/Am, /sup 137/Cs) and natural (U, Th, /sup 210/Pb) radionuclides in Washington continental slope sediments

Journal Article · Wed Jul 01 00:00:00 EDT 1987 · Geochim. Cosmochim. Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(87)90181-5· OSTI ID:7222723

Carpenter, R; Beasley, T M; Zahnle, D; Somayajulu, B L.K.

This paper reports activity profiles of Pu isotopes, /sup 241/Am, /sup 137/Cs, /sup 210/Pb, U and Th isotopes in Washington continental slope sediments from 332-1415 m water, identify major processes responsible for them, and compare results with those previously reported for Washington shelf sediments. Specific activities of all nuclides but /sup 137/Cs are higher in slope surface sediments than shelf surface sediments. These higher specific activities, which are due to more efficient scavenging by finer grained particles and higher concentrations of dissolved nuclides in slope waters, do not cause proportionally higher slope sediment radionuclide inventories, because they are counterbalanced by 5-10 fold lower sediment accumulation rates on the slope. /sup 239,240/Pu activities and inventories in slope sediments correlate with those of excess /sup 210/Pb, as in shelf sediments, but with higher ratios of /sup 210/PbPu in slope deposits. /sup 241/Am/sup 239,240/Pu activity and inventory ratios in slope sediments average twice ratios in shelf sediments, due primarily to greater particle affinity and preferential downward transport of /sup 241/Am. AmPu activity ratios change little with depth in slope sediments, suggesting insignificant separation of the two nuclides during diagenesis. /sup 239,240/Pu/sup 137/Cs ratios are 2-3 times greater in slope than shelf sediments, due to a combination of preferential scavenging of Pu and greater /sup 137/Cs loss b decay and desorption. PuCs activity ratios decrease with depth in more porous slope sediments, due to downward migration of /sup 137/Cs.

• Research Organization: Univ. of Washington, Seattle (USA)
• OSTI ID: 7222723
• Journal Information: Geochim. Cosmochim. Acta; (United States), Journal Name: Geochim. Cosmochim. Acta; (United States) Vol. 51:7; ISSN GCACA
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580400* -- Geochemistry-- (-1989)
ACTINIDE ISOTOPES
ALKALI METAL ISOTOPES
AMERICIUM ISOTOPES
CESIUM ISOTOPES
CHEMICAL ANALYSIS
CHEMICAL COMPOSITION
CHEMISTRY
CONTINENTAL MARGIN
CONTINENTAL SHELF
CONTINENTAL SLOPE
DECAY
DESORPTION
DIAGENESIS
ENVIRONMENTAL TRANSPORT
FALLOUT
FALLOUT DEPOSITS
FEDERAL REGION X
GEOCHEMISTRY
HYDROGEN COMPOUNDS
ISOTOPE RATIO
ISOTOPES
LEAD ISOTOPES
MASS TRANSFER
NORTH AMERICA
OXYGEN COMPOUNDS
PACIFIC OCEAN
QUANTITATIVE CHEMICAL ANALYSIS
RADIOCHEMICAL ANALYSIS
RADIOISOTOPES
RADIONUCLIDE MIGRATION
SEAS
SEAWATER
SEDIMENTS
SURFACE WATERS
THORIUM ISOTOPES
URANIUM ISOTOPES
USA
WASHINGTON
WATER