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Moncef Benmansour CNESTEN, Rabat, Morocco

IAEA Regional Training Course Sediment Core Dating Techniques - RAF/7/008 Project CNESTEN, Rabat, 05-09 July 2010. CNESTEN. IAEA. Lecture 9: Case Studies in Marine Pollution Distribution of Anthropogenic radionuclides in the Moroccan coastal waters and sediments. Moncef Benmansour

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Moncef Benmansour CNESTEN, Rabat, Morocco

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  1. IAEA Regional Training Course Sediment Core Dating Techniques - RAF/7/008 Project CNESTEN, Rabat, 05-09 July 2010 CNESTEN IAEA Lecture 9: Case Studies in Marine Pollution Distribution of Anthropogenic radionuclides in the Moroccan coastal waters and sediments Moncef Benmansour CNESTEN, Rabat, Morocco

  2. Contents • Introduction • Material and Methods • Results and Discussion • Conclusion

  3. Introduction • Long coast (~ 3500 km), • Development of National and Mediterranean industrial activities • Marine traffics • Characteristics of the Mediterranean sea

  4. Introduction • IAEA regional project ( North of Africa): RAF7/004 • «Contamination assessment of the south Mediterranean sea» • Specific objectives • Obtaining data on R.N contaminants 137Cs, 239,240Pu, 238Pu, 241Am, 90Sr, natural ( 210Pb, 210Po, 226Ra…), but also heavy metals and organics • Understanding the behaviour and the fate of contaminants • Modelling the dispersion of contaminants • Development of national databases

  5. Explored Stations

  6. Material and Methods R.V: Charif El Idrissi -INRH- Technical Staff: CNESTEN (2), IAEA (2) INRH (3)

  7. Material and Methods

  8. Material and Methods • Pre-treatment • Sea water ( 239,240Pu, 241Am, 137Cs, 90Sr) • filtered (0.45 mm) • addition of tracers and carriers (242Pu, 243Am, 85Sr, Cs, Sr…) • sequential concentrations • 239,240Pu and 241Am with MnO2 ,137Cs with AMP, 90Sr with oxalic acid • Sediment cores ( depth profiles: 239,240Pu, 137Cs 210Pb, 226Ra) • sectioned ( 0.5 – 2 cm)

  9. Material and Methods • Physical preparation • Freeze-drying • Homogenisation • Radiochemical separation ( Pu-Am) • Digestion ( HNO3) • Separation of transuranics : Pu and Am • Electrodeposition on stainless steel discs

  10. Material and Methods • Other R.N • 137Cs in sea water • Dilution of AMP precipitate in NaOH 10M • 210Pb and 210Po in sediment • Total digestion ( HNO3, HCl, HF, HClO4) • Spontaneous deposition in silver discs • R.N Mesurements • g spectrometry • HPGe detector (Canberra) – n-type, 45% - • a spectrometry: • Semi-conductor detectors (Si) EG&G Ortec

  11. Preparation and Radiochemical Laboratories

  12. Analysis Laboratories

  13. Alpha Spectrometry: 239,249Pu & 241Am 242Pu 239,240Pu 241Am 243Am 238Pu

  14. Alpha spectrometry: 210Po

  15. Gamma spectrum

  16. Quality Control

  17. Heavy Metal Analyses in Sediment • Preparation of sediment: • dry-freezing • ground • sieving (63mm) • digestion: teflon reactors, HNO3 H2SO4, Aqua-Regal, HF • Measurements: • Atomic Absorption System • hydrure system for Hg, graphite oven

  18. Petroleum HC Analyses • Sediment • extraction by soxhlet extractors and hexane/dichloromethane • Purification • dosage CPG « HP plus-Agilent 6890 », Spectrofluometer (P.E) • Water • extraction by carbon tetrachloride • separation from O.M • Measurements by IR

  19. RESULTS

  20. Waters

  21. Waters 2170 Bq.m-2 23 Bq.m-2

  22. Data in Bibliography

  23. Data in Bibliography

  24. Data in bibilography

  25. Data in bibilography

  26. Data in bibilography

  27. Data in bibilography

  28. Sediment: 137Cs and 239,240Pu 284 Bq/m2 32 Bq/m2 Peaks 1963: Global Fallout ?

  29. Sediment: 210Pb

  30. Dating of Sediment Core: 210Pb Dashed line is the best fit corresponding to the CIC-CSR model while the continuous line corresponds to the CM-CSR model

  31. Dating of Sediment Core: 210Pb • CIC-CSR Model: • Initial Concentration and sedimentation rate constant w = 0.10 ± 0.02 g cm-2 y-1 F = A(0) w, 720 ± 150 Bq m-2 y-1.

  32. Dating of Sediment Core: 210Pb • CRS Model: Constant Rate of supply is Constant but Sedimentation rate vary Mean value: w = 0.10 g.cm-2 y-1 F = l I, 712 ± 25 Bq m-2 y-1.

  33. Dating of Sediment Core: 210Pb • CM-CSR Model: Constant Mixing and constant Sedimentation Rate km is an effective mixing coefficient given in terms of the diffusion coefficient D and the bulk density (Abril 2003b) w=0.092 ± 0.003g cm-2 y-1 F = 670 ± 25 Bq m-2 y-1.

  34. Reconstruction of 137Cs, 239,240Pu Profiles with boundary conditions Cw : radionuclide concentration in overlying water

  35. Historical records of 137Cs, 239,240Pu in water

  36. Reconstruction of 137Cs, 239,240Pu profiles in sediment

  37. Laissaoui, M. Benmansour N. Ziad, M. Ibn Majah J. M. Abril and S. Mulsow. Anthropogenic radionuclides in the water column and a sediment core from the Alboran Sea: application to radiometric dating and reconstruction of historical water column radionuclide concentrations.Journal of Paleolimnology 40 (2008) 823-833 • M. Benmansour, A. Laissaoui, S. Benbrahim, M. Ibn Majah, A.Chafik and P.Povinec. Distribution of anthropogenic radionuclides in Moroccan coastal waters and sediments. Radioactivity in the Environment. Book Series. 8 ( 2006) 145-150

  38. Heavy metals

  39. Total hydrocarbons

  40. Summary • Levels of Anthropogenic R.N ( 137Cs , 239,240Pu, 241Am) in surface sea water and sediment - Morocco coast – • Vertical distributions of R.N in water column and sediment core • Use of 210Pbex , 137Cs, 239,240Pu: sedimentation rate, chronology of contaminants • Main source of R.N : Global fallout • Heavy metals (Mn, Hg) important in the sediment surface • Cr high / Cd, Hg, and / previous studies • No significant contamination by HC

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