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

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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 <sup>231</sup>Pa as well as <sup>230</sup>Th. The concentration of <sup>231</sup>Pa 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 <sup>231</sup>Pa 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 <sup>231</sup>Pa/<sup>230</sup>Th decreased offshore. The boundary scavenging, therefore, is more pronounced for the removal of <sup>231</sup>Pa from the water column. The activity ratios of <sup>231</sup>Pa/<sup>230</sup>Th 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.

Journal

  • GEOCHEMICAL JOURNAL

    GEOCHEMICAL JOURNAL 32(1), 11-20, 1998-02-01

    GEOCHEMICAL SOCIETY OF JAPAN

References:  21

Cited by:  1

Codes

  • NII Article ID (NAID)
    10008802367
  • NII NACSIS-CAT ID (NCID)
    AA00654975
  • Text Lang
    ENG
  • Article Type
    Journal Article
  • ISSN
    00167002
  • NDL Article ID
    4427744
  • NDL Source Classification
    ZM41(科学技術--地球科学)
  • NDL Call No.
    Z53-R488
  • Data Source
    CJP  CJPref  NDL  J-STAGE 
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