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1 Lecture 9: Case Studies in Marine Pollution Distribution of Anthropogenic radionuclides in the Moroccan coastal waters and sediments Moncef Benmansour.

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Presentation on theme: "1 Lecture 9: Case Studies in Marine Pollution Distribution of Anthropogenic radionuclides in the Moroccan coastal waters and sediments Moncef Benmansour."— Presentation transcript:

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

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

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

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

5 5 Explored Stations

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

7 7 Material and Methods N°Name & Position Maximal depth (m)Samples collected St.1Mohammedia 33°46'N; 7°28'W 300Surface water St.2M'Diq 35°47'N; 04°48'W 800Water column, Sediment core Biota St.3M'Diq 35°47'N; 05°15'W 270Surface water St.4Tangier 35°52'N; 05°51'W 200Surface water

8 8

9 9

10 10 Material and Methods Pre-treatment Pre-treatment –Sea water ( 239,240 Pu, 241 Am, 137 Cs, 90 Sr) filtered (0.45 filtered (0.45 m) addition of tracers and carriers ( 242 Pu, 243 Am, 85 Sr, Cs, Sr…) addition of tracers and carriers ( 242 Pu, 243 Am, 85 Sr, Cs, Sr…) sequential concentrations sequential concentrations – 239,240 Pu and 241 Am with MnO 2, 137 Cs with AMP, 90 Sr with oxalic acid –Sediment cores ( depth profiles: 239,240 Pu, 137 Cs 210 Pb, 226 Ra) sectioned ( 0.5 – 2 cm) sectioned ( 0.5 – 2 cm)

11 11 Material and Methods Physical preparation Physical preparation –Freeze-drying –Homogenisation Radiochemical separation ( Pu- Am) Radiochemical separation ( Pu- Am) –Digestion ( HNO 3 ) –Separation of transuranics : Pu and Am –Electrodeposition on stainless steel discs

12 12

13 13 Material and Methods Other R.N Other R.N – 137 Cs in sea water Dilution of AMP precipitate in NaOH 10M Dilution of AMP precipitate in NaOH 10M – 210 Pb and 210 Po in sediment Total digestion ( HNO 3, HCl, HF, HClO 4 ) Total digestion ( HNO 3, HCl, HF, HClO 4 ) Spontaneous deposition in silver discs Spontaneous deposition in silver discs R.N Mesurements R.N Mesurements – spectrometry HPGe detector (Canberra) – n-type, 45% - HPGe detector (Canberra) – n-type, 45% - – spectrometry: Semi-conductor detectors (Si) EG&G Ortec Semi-conductor detectors (Si) EG&G Ortec

14 14 Preparation and Radiochemical Laboratories

15 15 Analysis Laboratories

16 Pu 239,240 Pu 238 Pu 243 Am 241 Am Alpha Spectrometry: 239,249 Pu & 241 Am

17 17 Alpha spectrometry: 210 Po

18 18 Gamma spectrum

19 19 Quality Control

20 20 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

21 21 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

22 22 RESULTS

23 23 Waters

24 24 Waters 2170 Bq.m Bq.m -2

25 25 Data in Bibliography

26 26 Data in Bibliography

27 27 Data in bibilography

28 28 Data in bibilography

29 29 Data in bibilography

30 30 Data in bibilography

31 31 Sediment: 137 Cs and 239,240 Pu Peaks 1963: Global Fallout ? 284 Bq/m 2 32 Bq/m 2

32 32 Sediment: 210 Pb

33 33 Dating of Sediment Core: 210 Pb Dashed line is the best fit corresponding to the CIC- CSR model while the continuous line corresponds to the CM-CSR model

34 34 Dating of Sediment Core: 210 Pb CIC-CSR Model: 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.

35 35 Dating of Sediment Core: 210 Pb CRS Model: Constant Rate of supply is Constant but Sedimentation rate vary CRS Model: Constant Rate of supply is Constant but Sedimentation rate vary Mean value: w = 0.10 g.cm- 2 y- 1 F = I, 712 ± 25 Bq m -2 y -1.

36 36 Dating of Sediment Core: 210 Pb CM-CSR Model: Constant Mixing and constant Sedimentation Rate CM-CSR Model: Constant Mixing and constant Sedimentation Rate k m is an effective mixing coefficient given in terms of the diffusion coefficient D and the bulk density (Abril 2003b) w= ± g cm- 2 y -1 F = 670 ± 25 Bq m -2 y -1.

37 37 Reconstruction of 137 Cs, 239,240 Pu Profiles Reconstruction of 137 Cs, 239,240 Pu Profiles with boundary conditions C w : radionuclide concentration in overlying water

38 38 Historical records of 137 Cs, 239,240 Pu in water

39 39 Reconstruction of 137 Cs, 239,240 Pu profiles in sediment

40 40 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) 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) 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) 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)

41 41 Heavy metals

42 42

43 43 Total hydrocarbons

44 44

45 45 Summary Levels of Anthropogenic R.N ( 137 Cs, 239,240 Pu, 241 Am) in surface sea water and sediment - Morocco coast – Levels of Anthropogenic R.N ( 137 Cs, 239,240 Pu, 241 Am) in surface sea water and sediment - Morocco coast – Vertical distributions of R.N in water column and sediment core Vertical distributions of R.N in water column and sediment core Use of 210 Pb ex, 137 Cs, 239,240 Pu: sedimentation rate, chronology of contaminants Use of 210 Pb ex, 137 Cs, 239,240 Pu: sedimentation rate, chronology of contaminants Main source of R.N : Global fallout 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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