231Pa and 230Th in surface sediments of the Arctic Ocean: Implications for 231Pa/230Th fractionation, boundary scavenging, and advective export
Resource
Earth and Planetary Science Letters 234 (1-2): 235-248
Journal
Earth and Planetary Science Letters
Journal Volume
234
Journal Issue
1-2
Pages
235-248
Date Issued
2005
Author(s)
Abstract
Activities of 231Pa and 230Th in surface sediments from the Arctic Ocean and Greenland-Norwegian Seas are used to examine the redistribution of these water-column produced tracers between the low productivity interior basins and high particle flux marginal areas. Sediment 231Paxs/230Thxs ratios throughout the Canadian and Eurasian Basins and the high particle flux Chukchi slope region are essentially invariant (average N = 39) and significantly below the water column production ratio (0.093). 231Paxs/230Thxs ratios are also below the production ratio in the seasonally high productivity Greenland-Norwegian Sea basins (average = 0.082 ± 0.024, N = 13), though they are ∼ 30% higher than the interior Arctic. The low sediment 231Paxs/230Thxs ratios are attributed to the net export of ∼ 39% of dissolved 231Pa produced in intermediate/deep waters, as opposed to ∼ 10% of 230Th, through Fram Strait. The negligible 230Th export, combined with the reported low 230Thxs inventory of basin sediments and high 230Thxs inventory in Chukchi slope sediments, points to significant boundary scavenging of 230Th in the Arctic. The invariant 231Paxs/230 Thxs ratios further indicate that scavenging of 230Th is comparable to 231Pa (i.e., fractionation to a similar degree between the two nuclides) in both the interior basins and margins. Thus, while significant boundary scavenging of both 231Pa and 230Th occurs in the Arctic, there is a distinct lack of basin-margin fractionation and a sizable export of 231Pa. There is also likely to be export of other similarly particle-reactive radionuclides (e.g., 10Be, Pu isotopes) out of the Arctic. © 2005 Elsevier B.V. All rights reserved.
Subjects
Arctic; Protactinium-231; Scavenging; Shelf-basin exchange; Thorium-230
SDGs
Other Subjects
Artic ocean; Boundary scavenging; Surface sediments; Water columns; Protactinium; Radioactive tracers; Sediments; Thorium; Earth sciences; marine sediment; palladium; surficial sediment; thorium; Arctic Ocean; Greenland Sea; Norwegian Sea; oceanic regions; World
Type
journal article
File(s)![Thumbnail Image]()
Loading...
Name
10.pdf
Size
911.37 KB
Format
Adobe PDF
Checksum
(MD5):0d39ecc8648468b3c1213af5089feefe