Publication Date:
2023-08-28
Description:
Determination of radium, thorium, uranium isotopes, and 210Pb 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 234U/238U activity ratios in several samples are higher than the seawater value, indicating some enrichment of 234U in the pore water. However, the absolute concentrations of 238U and 234U are 25% lower than those in seawater, suggesting that the sediments form a sink for uranium isotopes. 210Pb is present in the pore water at concentrations approx. 20% that of 226Ra. The origin of 210Pb 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 222Rn. 230Th 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 230/Th appears to be minute amounts of sediment particles collected in the pore waters during the squeezing operation.
Keywords:
BC; Box corer; Date/Time of event; DEPTH, sediment/rock; DISTANCE; Distance, maximum; Distance, minimum; DOMES-A47-16; DOMES Site B, Pacific Ocean; DOMES Site C, Pacific Ocean; Elevation of event; Event label; Latitude of event; Lead-210; Lead-210, standard deviation; Lead-210 excess; Lead-210 excess, standard deviation; Longitude of event; NOAA and MMS Marine Minerals Geochemical Database; NOAA-MMS; Oceanographer; Pacific Ocean; Radium-226; Radium-226, standard deviation; RP8OC75; RP-8-OC-75; RP8OC7503; RP8OC75-47-16; RP8OC75-52-39; RP8OC75-57-58; Sample ID; Sample type; Thorium-228/Thorium-232 activity ratio; Thorium-228/Thorium-232 activity ratio, standard deviation; Thorium-230; Thorium-230, standard deviation; Thorium-230/Thorium-227 activity ratio; Thorium-230/Thorium-227 activity ratio, standard deviation; Thorium-230/Thorium-232 activity ratio; Thorium-230/Thorium-232 activity ratio, standard deviation; Thorium-232; Thorium-232, standard deviation; Uranium-234/Uranium-238 activity ratio; Uranium-234/Uranium-238 activity ratio, standard deviation; Uranium-238; Uranium-238, standard deviation
Type:
Dataset
Format:
text/tab-separated-values, 462 data points
Permalink
