Fluxes of234Th,210Po and210Pb determined by sediment trap experiments in pelagic oceans

  • Koh Harada
  • Shizuo Tsunogai


Sediment trap experiments were carried out in two oceans, the eastern Pacific Ocean and the Antarctic Ocean, which have very different biological productivities. The natural radionuclides,234Th,210Po and210Pb were used as tracers of reactive metals. Larger particulate fluxes of these radionuclides were found in the seas where total mass fluxes were larger, although the concentrations of these radionuclides in the settling particles were somewhat smaller. The concentrations of234Th in the settling particles varied widely and irregularly with depth, whereas the concentrations of210Po and210Pb in the settling particles steadily increased with increasing water depth. The ratios of210Po/210Pb in the settling particulates were larger than unity which the ratio of234Th/excess210Po as larger than234Th/210Po in the deep water. These results suggest that, when the particles sink through the water column, these radionuclides are being absorbed by settling particles in the order234Th>210Po>210Pb. The observed particulate fluxes of210Pb are about one eighth of those calculated from the disequilibria between226Ra and210Pb at the stations in the subtropical eastern Pacific, although the observed fluxes are the same as the calculated ones in the northern North Pacific and the Antarctic Ocean. Thus, there must be a horizontal flow carrying these reactive metals from the oligotorophic ocean to the biologically productive ocean where the metals are removed by settling particles even in deep water.


Radionuclide Settling Deep Water Pacific Ocean Mass Flux 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Bacon, M.P., D.W. Spencer and P.G. Brewer (1976):210Pb/226Ra and210Po/210Pb disequilibria in seawater and suspended particulate matter. Earth Planet. Sci. Lett.,32, 277–296.Google Scholar
  2. Bacon, M. P., C.-A. Huh, A. P. Fleer and W. G. Deuser (1985): Seasonally in the flux of natural radionuclides and plutonium in the deep Sargasso Sea, Deep-Sea Res.,32, 273–286.Google Scholar
  3. Bhat, S.G., S. Krishnaswami, D. Lal, Rama and W. S. Moore (1969): Th-234/U-238 ratios in the ocean, Earth Planet. Sci. Lett.,5, 483–491.Google Scholar
  4. Bishop, J.K.B., J.M. Edmond, D.R. Ketten, M.P. Bacon and W.B. Silker (1977): The chemistry, biology and vertical flux of particulate matter from the upper 400 m of the equatorial Atlantic Ocean, Deep-Sea Res.,24, 511–548.Google Scholar
  5. Brewer, P.G., Y. Nozaki, D.W. Spencer and A.P. Fleer (1980): Sediment trap experiments in the deep North Atlantic: isotopic and elemental fluxes, J. Mar. Res.,38, 703–728.Google Scholar
  6. Chung, Y. and H. Craig (1980):226Ra in the Pacific Ocean. Earth Planet. Sci. Lett.,49, 267–292.Google Scholar
  7. Chung, Y. and H. Craig (1983):210Pb in the Pacific: the Geosecs measurements of particulate and dissolved concentrations. Earth Planet. Sci. Lett.,65, 406–432.Google Scholar
  8. Craig, H., S. Krishnaswami and B.L.K. Somayajulu (1973):210Pb-226Ra: Radioactive disequilibrium in the deep sea. Earth Planet. Sci. Lett.,17, 295–305.Google Scholar
  9. Deucer, W.G., E.H. Ross and R.F. Anderson (1981): Seasonality in the supply of sediment to deep Sargasso Sea and implications for the rapid transfer of matter to the deep ocean. Deep-Sea Res.,28, 495–505.Google Scholar
  10. Harada, K. and S. Tsunogai (1985): A practical method for the simultaneous determinations of234Th,226Ra,210Pb and210Po in seawater. J. Oceanogr. Soc. Japan,41, 98–104.Google Scholar
  11. Honjo, S., S.J. Manganini and J.J. Cole (1982): Sedimentation of biogenic matter in the deep ocean. Deep-Sea Res.,29, 609–625.Google Scholar
  12. Honjo, S. (1982): Seasonality and interaction of biogenic and lithogenic particulate flux at the Panama Basin. Science,218, 883–884.Google Scholar
  13. Krishnaswami, S., B.L.K. Somayajulu and Y. Chung (1975):210Pb/226Ra disequilibrium in the Santa Barbara basin. Earth Planet. Sci. Lett.,27, 388–392.Google Scholar
  14. Krishnaswami, S. and M.M. Sarin (1976): Atlantic surface particulates: Composition, settling rates and dissolution in the deep sea. Earth Planet. Sci. Lett.,32, 430–440.Google Scholar
  15. Ku, T-L. and M-C. Lin (1976):226Ra distribution in the Antarctic Ocean. Earth Planet. Sci. Lett.,32, 236–248.Google Scholar
  16. Matsumoto, E. (1975):234Th-238U radioactive disequilibrium in the surface layer of the ocean. Geochim. Cosmochim. Acta,39, 205–212.Google Scholar
  17. Moore, W.S., K.W. Bruland and J. Michel (1981): Fluxes of uranium and Thorium series isotopes in the Santa Barbara Basin, Earth Planet. Sci. Lett.,53, 391–399.Google Scholar
  18. Noriki, S., K. Harada and S. Tsunogai (1985): Sediment trap experiment in the Antarctic Ocean. p. 161–170.In: Marine and Esturine Geochemistry, ed. by A.C. Sigleo and A. Hattori, Lewis Pub., Chelsea.Google Scholar
  19. Noriki, S. and S. Tsunogai (1986a): Particulate fluxes and major components of settling particles from sediment trap experiment in the Pacific Ocean. Deep-Sea Res., in press.Google Scholar
  20. Noriki, S. and S. Tsunogai (1986b): Sediment trap comparison experiments: Existence of light particles collected in the narrow sediment traps. J. Oceanogr. Soc. Japan,42, 119–123. (in Japanese).Google Scholar
  21. Nozaki, Y. and S. Tsunogai (1976):226Ra,210Pb and210Po disequilibria in the western North Pacific. Earth Planet. Sci. Lett.,32, 313–321.Google Scholar
  22. Nozaki, Y., J. Thomson and K.K. Turekian (1976): The distribution of210Pb and210Po in the surface waters of the Pacific Ocean. Earth Planet. Sci. Lett.,32, 304–312.Google Scholar
  23. Rama, M. Koide and E.D. Goldberg (1961):210Pb in natural waters. Science,134, 98–99.Google Scholar
  24. Shannon, L.V., R.D. Cherry and M.J. Orren (1970): Polonium-210 and lead-210 in the marine environment, Geochim. Cosmochim. Acta,34, 98–99.Google Scholar
  25. Spencer, D.W., P.G. Brewer, A. Fleer, S. Honjo, S. Krishnaswami and Y. Nozaki (1978): Chemical fluxes from a sediment trap experiment in the deep Sargasso Sea. J. Mar. Res.,36, 493–521.Google Scholar
  26. Tsunogai, S. and K. Harada (1980):226Ra and210Pb in the western North Pacific. p. 165–191.In: Isotope Marine Chemistry, ed. by E.D. Goldberg, Y. Horibe and K. Saruhashi, Uchida Rokakuho Pub., Tokyo.Google Scholar
  27. Tsunogai, S., M. Uematsu, S. Noriki, N. Tanaka and M. Yamada (1982): Sediment trap experiment in the northern North Pacific: Undulation of settling particles. Geochem. J.,16, 129–147.Google Scholar
  28. Turekian, K.K., Y. Nozaki and L.K. Benninger (1977): Geochemistry of atmospheric radon and radon products. Ann. Rev. Earth Planet. Sci.,5, 227–255.Google Scholar

Copyright information

© Oceanographical Society of Japan 1986

Authors and Affiliations

  • Koh Harada
    • 1
  • Shizuo Tsunogai
    • 1
  1. 1.Faculty of FisheriesHokkaido UniversityHakodate

Personalised recommendations