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Estuarine K d s ~From Japanese literature~

Estuarine K d s ~From Japanese literature~. Keiko Tagami, Shigeo Uchida National Institute of Radiological Sciences.

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Estuarine K d s ~From Japanese literature~

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  1. Estuarine Kds~From Japanese literature~ Keiko Tagami, Shigeo Uchida National Institute of Radiological Sciences “If sediment concentrations are known but data for water are lacking, then distribution coefficients (Kd) values may be employed to estimate concentrations in filtered water. The Kd can also be used to estimate sediment activity concentrations from filtered water concentrations which may be necessary to calculate external dose from sediment.” (TRS Draft) For ocean margin Kds, “… to assume for all elements except carbon that 20% of the total concentration of the total concentration of the element in pelitic coastal sediments (clays and silts) represents the exchangeable phase components of the elements.” (TRS-422)

  2. Japanese literature? • For the radioactivity monitoring purpose, Japanese government have been collecting environmental radioactivity data from 1959. • Most of them were originated from fallout, but related to nuclear industries (reprocessing plants) and U.S. submarines were also included. • Among them, data for estuarine water-sediment sets were found. Most of them were collected in 1977-1982. • We calculated Kd values ([Bq/kg-sediment] / [Bq/L in estuarine water]) and compared these values with other data (including our estuarine Kd data using stable elements).

  3. Kd values for five radionuclides

  4. Geometric means 2021 GM=1248 502 202 23

  5. Kd of Sr-90 Kd observed from 1971 to 1982

  6. Kd of Cs-137 Kd observed from 1971 to 1982

  7. Kd of Co-60

  8. Kd of Ce-144

  9. Kd of Ru-106

  10. Comparison between observed Kd & calculated Kd from seawater/sediment (total Kd) Percentage of exchangeable fraction concentration to total concentration in sediment can be estimated as at each element

  11. Calculated “Fake” Kd for each element

  12. Conclusion • Probably, using 20% as exchangeable fraction of total concentration for all elements, is not realistic for some (many?) elements. • For examples, to estimate radioactivity concentrations in estuarine water from sediments, some elements which have high Kd values might be underestimated. • However, the data points were just 5, we need more data to show whether this literature survey result is reasonable or not.

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