Radium, thorium, uranium, and /sup 210/Pb in deep-sea sediments and sediment pore waters from the North Equatorial Pacific

Journal Article · Fri Oct 31 23:00:00 EST 1980 · Am. J. Sci.; (United States)

DOI:https://doi.org/10.2475/ajs.280.9.849· OSTI ID:6820131

Cochran, J K; Krishnaswami, S

Determination of radium, thorium, uranium isotopes, and /sup 210/Pb in sediments and sediment pore waters from North Equatorial Pacific deep-sea clay-silicous oozes shows that the radium and uranium isotopes are mobile in the pore water. The concentration-depth profiles of radium can be understood in terms of a diagenetic model which takes into account mixing of sediment particles by bioturbation, molecular diffusion in the pore water, adsorption onto particle surfaces, as well as radioactive production and decay. The /sup 234/U//sup 238/U activity ratios in several samples are higher than the seawater value, indicating some enrichment of /sup 234/U in the pore water. However, the absolute concentrations of /sup 238/U and /sup 234/U are 25% lower than those in seawater, suggesting that the sediments form a sink for uranium isotopes. /sup 210/Pb is present in the pore water at concentrations approx. 20% that of /sup 226/Ra. The origin of /sup 210/Pb in the pore water is uncertain and could be due either to its in situ mobilization in the sediments or subsequent production in the laboratory from the decay of /sup 222/Rn. /sup 230/Th is present in measurable concentrations in the pore waters, but its distribution does not show any systematic trend with depth or other parameters. The most likely source of /sup 230/Th appears to be minute amounts of sediment particles collected in the pore waters during the squeezing operation.

• Research Organization: Yale Univ., New Haven, CT
• OSTI ID: 6820131
• Journal Information: Am. J. Sci.; (United States), Journal Name: Am. J. Sci.; (United States) Vol. 280:9; ISSN AJSCA
• Country of Publication: United States
• Language: English

Related Subjects

520302* -- Environment
Aquatic-- Radioactive Materials Monitoring & Transport-- Aquatic Ecosystems & Food Chains-- (-1987)
54 ENVIRONMENTAL SCIENCES
ACTINIDES
ALKALINE EARTH METALS
ALPHA DECAY RADIOISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
ECOLOGICAL CONCENTRATION
ELEMENTS
EVEN-EVEN NUCLEI
GROUND WATER
HEAVY NUCLEI
HYDROGEN COMPOUNDS
INTERSTITIAL WATER
ISOTOPE RATIO
ISOTOPES
LEAD 210
LEAD ISOTOPES
METALS
NUCLEI
OXYGEN COMPOUNDS
PACIFIC OCEAN
RADIOECOLOGICAL CONCENTRATION
RADIOISOTOPES
RADIUM
SEA BED
SEAS
SEAWATER
SEDIMENTS
SINKS
SURFACE WATERS
THORIUM
URANIUM
WATER
YEARS LIVING RADIOISOTOPES