| Autor: |
Morimoto, T., Lee, S. H., Amano, H., Oda, K., Chumichev, V. B., Gastaud, J., Berezhnov, V. I., Chaykovskaya, E., Chung, C. S., Hong, G. H., Pettersson, H. B. L., Kim, S. H., Kim, C.K., Hirose, K., Nikitin, A. |
| Předmět: |
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| Zdroj: |
Science of the Total Environment. 9/30/1999, Vol. 237-238, p213. 0p. |
| Abstrakt: |
Assessment of contamination of anthropogenic radionuclides from pastdumping of radioactive waste in areas of the Okhotsk Sea, NW PacificOcean and the Sea of Japan/East Sea has been performed. Two joint Japanese-Korean-Russian scientific expeditions were carried out in 1994-1995, where seawater and seabed sediments were samples from 22 sites. Results of sediment analysis are reported here, where concentrations of 90Sr, 137Cs, 238Pu, 239,240Pu and 241Am in surface layer and bulk sediments showed on large spatial variations, ranging between <0.04 and 0.75 Bq kg-1 dry wt., <0.2 and 7.2 Bq kg-1 dry wt., <0.001 and 0.08 Bq kg-1 dry wt., 0.006 and 2.0 Bq kg-1 dry wt., 0.03 and 1.8 Bq kg-1 dry wt., respectively. However, the concentrations are comparable with those foundin reference sites outside the dumping areas and they generally fallwithin ranges previously reported for non-dumping areas of the investigated seas. Estimates of sediment inventories indicated differencesin radionuclide load between shelf/slope and basin type sediments aswell as dependence on water depth. Except for the shallow areas, most of the inventories of 90Sr, 137Cs and Pu isotopes are still to be found in the water column. Total inventories (in water+sediment) show a surplus of 137Cs and Pu-isotopes compared to expected integrated global fall-out deposition, which is consistent with previous observations in non-dumping areas in the seas investigated. Analysis of sediment 238Pu/239,240Pu activity ratios showed values in accord with that of global fall-out. Analysis of radionuclide depth distributions in core samples from areas of the Sea of Okhotsk showed sedimentation rates of 0.2-0.4 g cm-2 year-1 and 0.03 g cm-2 year-1 for shelf and basin areas respectively, w [ABSTRACT FROM AUTHOR] |
| Databáze: |
GreenFILE |
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