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J.M. Abril Department of Applied Physics (I); University of Seville (Spain)

IAEA Regional Training Course on Sediment Core Dating Techniques. RAF7/008 Project. J.M. Abril Department of Applied Physics (I); University of Seville (Spain). Lecture 1: Radionuclides of the environment and general aspects Concentration and distribution factors. k d variability

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J.M. Abril Department of Applied Physics (I); University of Seville (Spain)

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  1. IAEA Regional Training Course on Sediment Core Dating Techniques. RAF7/008 Project J.M. Abril Department of Applied Physics (I); University of Seville (Spain) • Lecture 1: Radionuclides of the environment and general aspects • Concentration and distribution factors. • kd variability • Granulometric speciation • kd in saturated porous media : “intrinsic” values • Experiments on depth penetration patterns J.M. Abril, University of Seville

  2. Some radionuclides and other hazardous materials, such as heavy metals, are highly particle-reactive. Their uptake by suspended particulate matter (SPM) and bottom sediments plays an important role in the fate of these pollutants. Remember: Depending on the pollutant, 1 gram of SPM can uptake more activity (or units of pollutants) than 1 m3 of water. J.M. Abril, University of Seville

  3. Naturally occurring particulate matter in aquatic systems usually exhibits areas with uncompensated negative charges. • The uptake is a surface-mediated phenomenon. SPM has very high specific surface area (SSA) J.M. Abril, University of Seville

  4. Kdprovides a convenient means to describe the relationship between radionuclide concentrations in SPM or bottom sediments and water • Notes: • Field observation • Laboratory experiments • Dynamic equilibrium J.M. Abril, University of Seville

  5. J.M. Abril, University of Seville

  6. Concentration facfors J.M. Abril, University of Seville

  7. J.M. Abril, University of Seville

  8. Concentrationfacfors J.M. Abril, University of Seville

  9. Kd variability For many radionuclides, field kd values from different environments, can vary within a range of more than two orders of magnitude (IAEA, 1985) J.M. Abril, University of Seville

  10. Kd vs. particle-size Basic model handling spherical particles Pores and free edges J.M. Abril, University of Seville

  11. Definitions: as , ac, ξ J.M. Abril, University of Seville

  12. Man-made radionuclides interacting with “natural” particles J.M. Abril, University of Seville

  13. Naturally occurring radionuclides • ac > 0 • The full equation has to be used • Two extreme behaviors depending on radionuclide solubility • Depleted outer layer for relatively soluble radionuclides • Enriched outer layer for highly particle-reactive radionuclides J.M. Abril, University of Seville

  14. J.M. Abril, University of Seville

  15. Caesium J.M. Abril, University of Seville

  16. J.M. Abril, University of Seville

  17. “Many particles” effects in kdvariability SPM in natural waters is mainly present in the form of flocs (or aggregates) mixed with single mineral particles. J.M. Abril, University of Seville

  18. J.M. Abril, University of Seville

  19. Global effects of particle size spectra and mineralogical composition J.M. Abril, University of Seville

  20. J.M. Abril, University of Seville

  21. Understanding spatial speciation… Bathymetric map for lake HÁRSVATTEN (Sweden). J.M. Abril, University of Seville

  22. Z Hydrodynamic transport Settling velocity Stokes’ Law Path length J.M. Abril, University of Seville

  23. J.M. Abril, University of Seville

  24. J.M. Abril, University of Seville

  25. 210Pb J.M. Abril, University of Seville

  26. Competition with cations related to SALINITY [ S ] J.M. Abril, University of Seville

  27. More details in: Parts I and II 27 J.M. Abril, University of Seville

  28. J.M. Abril, University of Seville

  29. A phosphate fertilizer factory pumped into the Odiel river (SW Spain) a suspension of PG particles (NORM material). We wanted to know how these radionuclide-enriched material was spread onto bottom sediments Direct gamma measurements of radionuclide concentrations would provide concentrations under MDL J.M. Abril, University of Seville

  30. kd C(r) PG susp F1 r r C(r) kd F2 Natural p. r r J.M. Abril, University of Seville

  31. kd r J.M. Abril, University of Seville

  32. Materials and methods 3-5 kilograms of sediments were collected at each sampling point The samples were dried (24 h at 110°C), mechanically disaggregated and sieved in a sieving-pile. J.M. Abril, University of Seville

  33. 234Th J.M. Abril, University of Seville

  34. 226Ra J.M. Abril, University of Seville

  35. Benoit and Hemond, 1991. Geochimica et Cosmochimica Acta 55, 1963-75. Evidence for diffusive redistribution of 210Pb in lake sediments 99.95 % in solids Bickford Reservoir (USA) J.M. Abril, University of Seville

  36. Bickford Reservoir (USA) J.M. Abril, University of Seville

  37. Bickford Reservoir (USA) J.M. Abril, University of Seville

  38. Radionuclide uptake by sediment columns H. Barros and J.M. Abril J.M. Abril, University of Seville

  39. J.M. Abril, University of Seville

  40. J.M. Abril, University of Seville

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