231Pa in hemipelagic sediments: Is it affected by boundary scavenging?

Che Abd. Rahim Mohamed, Shizuo Tsunogai

Research output: Contribution to journalArticle

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Abstract

Sediment cores were obtained at six stations in the area across the northern Japan Trench including hemipelagic and oceanic basin zones, and analyzed for 231Pa as well as 230Th. The concentration of 231Pa in the surface sediments increased with both the distance from the coast and the increasing water depth in the slope and the trench zones except the oceanic basin. The vertical profiles varied widely from station to station, but they showed no distinct vertical trend at each station. Although the sedimentation rate of unsupported 231Pa was more strongly controlled by the accumulation rate of bulk sediments than by its concentration, its sedimentation rates were about 200 times larger in the continental slope and the trench zones than in the oceanic basin. Furthermore, the ratios of 231Pa/230Th decreased offshore. The boundary scavenging, therefore, is more pronounced for the removal of 231Pa from the water column. The activity ratios of 231Pa/230Th in the continental slope sediments were considerably greater than the production ratio in the water column of 0.092, and also remarkably larger in the western North Pacific than in the eastern North Pacific. The difference is probably due to biogenic opal, of which fraction is larger in the settling particles in the western North Pacific.

Original languageEnglish
Pages (from-to)11-20
Number of pages10
JournalGeochemical Journal
Volume32
Issue number1
Publication statusPublished - 1998
Externally publishedYes

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Scavenging
scavenging
Sediments
sediments
stations
trench
slopes
Sedimentation
continental slope
sedimentation rate
sediment
Water
water column
basin
particle settling
water depth
opal
settling
coasts
accumulation rate

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics

Cite this

231Pa in hemipelagic sediments : Is it affected by boundary scavenging? / Mohamed, Che Abd. Rahim; Tsunogai, Shizuo.

In: Geochemical Journal, Vol. 32, No. 1, 1998, p. 11-20.

Research output: Contribution to journalArticle

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