11

Lecture 9: Case Studies in Marine Lecture 9: Case Studies in Marine Pollution Pollution

Distribution of Anthropogenic Distribution of Anthropogenic radionuclides in the Moroccan coastal radionuclides in the Moroccan coastal

waters and sedimentswaters and sediments

Moncef BenmansourMoncef Benmansour

CNESTEN, Rabat, MoroccoCNESTEN, Rabat, Morocco

IAEA Regional Training Course

Sediment Core Dating Techniques - RAF/7/008 Project

CNESTEN, Rabat, 05-09 July 2010IAEA CNESTEN

22

ContentsContents

IntroductionIntroduction

Material and MethodsMaterial and Methods

Results and DiscussionResults and Discussion

ConclusionConclusion

33

IntroductionIntroduction

Long coast (~ 3500 km), Long coast (~ 3500 km),

Development of National Development of National and Mediterranean and Mediterranean industrial activitiesindustrial activities

Marine trafficsMarine traffics

Characteristics of the Characteristics of the Mediterranean seaMediterranean sea

44

IntroductionIntroduction

IAEA regional project ( North of Africa): RAF7/004IAEA regional project ( North of Africa): RAF7/004– «Contamination assessment of the south Mediterranean sea»«Contamination assessment of the south Mediterranean sea»

Specific objectivesSpecific objectives

– Obtaining data on R.N contaminants Obtaining data on R.N contaminants 137137Cs, Cs, 239,240239,240Pu, Pu, 238238Pu, Pu, 241241Am, Am, 9090Sr, Sr, natural natural ( ( 210210Pb, Pb, 210210Po, Po, 226226Ra…), but also heavy metals and organicsRa…), but also heavy metals and organics

– Understanding the behaviour and the fate of contaminantsUnderstanding the behaviour and the fate of contaminants

– Modelling the dispersion of contaminantsModelling the dispersion of contaminants

– Development of national databases Development of national databases

55

Explored StationsExplored Stations

Morocco

AtlanticOcean

MediterraneanSea

St. 1

St. 2

St. 3St. 4

Morocco

AtlanticOcean

MediterraneanSea

St. 1

St. 2

St. 3St. 4

66

Material and MethodsMaterial and Methods

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

77

Material and MethodsMaterial and Methods

N° Name &Position

Maximal depth (m) Samplescollected

St.1 Mohammedia33°46'N; 7°28'W

300 Surface water

St.2 M'Diq35°47'N; 04°48'W

800 Water column,Sediment core

Biota

St.3 M'Diq35°47'N; 05°15'W

270 Surface water

St.4 Tangier35°52'N; 05°51'W

200 Surface water

88

99

1010

Material and MethodsMaterial and Methods

Pre-treatmentPre-treatment– Sea waterSea water ( ( 239,240239,240Pu, Pu, 241241Am, Am, 137137Cs, Cs, 9090Sr)Sr)

filtered (0.45 filtered (0.45 m) addition of tracers and carriers (addition of tracers and carriers (242242Pu, Pu, 243243Am, Am, 8585Sr, Cs, Sr…)Sr, Cs, Sr…)

sequential concentrationssequential concentrations – 239,240239,240Pu and Pu and 241241Am with MnOAm with MnO2 2 ,,137137Cs with AMP, Cs with AMP, 9090Sr with oxalic Sr with oxalic

acidacid

– Sediment cores ( depth profilesSediment cores ( depth profiles: : 239,240239,240Pu, Pu, 137137Cs Cs 210210Pb, Pb, 226226Ra)Ra)

sectioned ( 0.5 – 2 cm)sectioned ( 0.5 – 2 cm)

1111

Material and MethodsMaterial and Methods

Physical preparation Physical preparation – Freeze-dryingFreeze-drying– Homogenisation Homogenisation

Radiochemical separation Radiochemical separation ( Pu-Am)( Pu-Am)– Digestion ( HNODigestion ( HNO33))– Separation of transuranics : Pu and AmSeparation of transuranics : Pu and Am– Electrodeposition on stainless steel discsElectrodeposition on stainless steel discs

1212

•

8M HNO3/ NaNO2

Fraction Pu, Th

HCl conc. Th

HCl conc./NH4I Pu

Am, Cm, R.E, Fe, U, Po, Bi

AG1 X 8

Ppt. Oxalate Ca

9 M HCl

Pu, Fe, U, Po, Bi

AG1X 8

AG50W X 8

Pre treatement..

Pu, Fe, U, Po, Bi

Th

12 M HNO3

DDCPCa, Pb, Ra

AG1X 4

1M HNO3/93% CH3OH

Fe

NH4SCN/HCl/CH3OHTerres Rares

AmCH3OH/HCl

1313

Material and MethodsMaterial and Methods

Other R.NOther R.N– 137137Cs in sea waterCs in sea water

Dilution of AMP precipitate in NaOH 10MDilution of AMP precipitate in NaOH 10M

– 210210Pb and Pb and 210210Po in sedimentPo in sediment Total digestion ( HNOTotal digestion ( HNO33, HCl, HF, HClO, HCl, HF, HClO44)) Spontaneous deposition in silver discs Spontaneous deposition in silver discs

RR.N Mesurements.N Mesurements– spectrometryspectrometry

HPGe detector (Canberra) – n-type, 45% - HPGe detector (Canberra) – n-type, 45% - – spectrometryspectrometry: :

Semi-conductor detectors (Si) EG&G OrtecSemi-conductor detectors (Si) EG&G Ortec

1414

Preparation and Radiochemical Laboratories

1515

Analysis Laboratories

1616

242Pu239,240Pu

238Pu

243Am

241Am

Alpha Spectrometry: 239,249Pu & 241Am

1717

Alpha spectrometry: 210Po

1818

Gamma spectrumGamma spectrum

1919

Quality ControlQuality Control

Activité (Bq/kg)IAEA 385sédiment

Radioélément

V.D V.R137Cs 33.9 1.9 33.5

239,240Pu 2.92 0.13 2.90241Am 3.60 0.20 3.78210Pb 35.2 2.7 35.4

40K 612 34.1 612238U 25.7 1.8 29.6234U 25.8 1.8 27.2235U 1.22 1.4 1.24

230Th 30.5 2.9 30.5232Th 31.9 3.0 33.9

2020

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

2121

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

2222

RESULTSRESULTS

2323

WatersWatersTable 1: 137Cs, 239+240Pu and 241Am activity concentrations in surface sea water and in the water column.

Station 137Cs (mBq L-1)

239,240Pu

(Bq L-1)

241Am

(Bq L-1)

241Am/239,240Pu 239,240Pu/137Cs

St. 1 (Tangier) (35°52’N, 5°51’W)

3.110.23

8.290.94

N.D.

N.D.

0.00270.0003

St. 2 (Mdiq) (35°47’N, 4°48’W)

0m 2.320.18 8.290.87 1.50.0.20 0.180.03 0.00350.0004

250m 2.460.18 23.22.3 N.D. N.D. 0.00890.0010

500m 2.500.19 32.75.4 7.61.2 0.230.05 0.01140.0020

900m 2.290.16 27.12.4 N.D. N.D. 0.01180.0013

St. 3 (Mdiq) (35°47’N, 5°15’W)

2.370.14

8.821.39

1.560.50

0.170.02

0.00370.0006

Reported uncertainties are 1; N.D. means not determined

2424

800

600

400

200

0

0.00 0.01 0.02 0.03 0.04 0.05 1 2 3 4

Pu/ Cs ratios

Cs

Pu800

600

400

200

0

1 2 3 4

Pu/ Cs ratios

Cs

Pu

Specific activities (mBq/L)

Dep

thin

wa

ter

(m)

800

600

400

200

0

0.00 0.01 0.02 0.03 0.04 0.05 1 2 3 4

Pu/ Cs ratios

Cs

Pu800

600

400

200

0

1 2 3 4

Pu/ Cs ratios

Cs

Pu

Specific activities (mBq/L)

Dep

thin

wa

ter

(m)

Waters Waters

2170 Bq.m-2

23 Bq.m-

2

2525

Data in Bibliography Data in Bibliography

2626

Data in BibliographyData in Bibliography

2727

Data in bibilographyData in bibilography

2828

Data in bibilographyData in bibilography

2929

Data in bibilographyData in bibilography

3030

Data in bibilographyData in bibilography

3131

Sediment: Sediment: 137137Cs and Cs and 239,240239,240PuPu

0

2

4

6

8

10

0 0,2 0,4 0,6 0,8 10

2

4

6

8

10

0 0,2 0,4 0,6 0,8 10

2

4

6

8

10

0 0,2 0,4 0,6 0,8 1

239+240Pu (Bq/kg)

Dep

th(c

m)

0

2

4

6

8

10

12

0 2 4 6 86 8

137Cs (Bq/kg)

Dep

th(c

m)

0

2

4

6

8

10

0 0,2 0,4 0,6 0,8 10

2

4

6

8

10

0 0,2 0,4 0,6 0,8 10

2

4

6

8

10

0 0,2 0,4 0,6 0,8 1

239+240Pu (Bq/kg)

Dep

th(c

m)

0

2

4

6

8

10

0 0,2 0,4 0,6 0,8 10

2

4

6

8

10

0 0,2 0,4 0,6 0,8 10

2

4

6

8

10

0 0,2 0,4 0,6 0,8 1

239+240Pu (Bq/kg)

Dep

th(c

m)

0

2

4

6

8

10

12

0 2 4 6 86 8

137Cs (Bq/kg)

Dep

th(c

m)

0

2

4

6

8

10

12

0 2 4 6 86 8

137Cs (Bq/kg)

Dep

th(c

m)

Peaks 1963: Global Fallout ?

284 Bq/m2 32 Bq/m2

3232

Sediment: Sediment: 210210PbPb

Table 2. Vertical distribution of 210Pb, 226Ra and bulk density in the sediment core from the southwest Mediterranean Sea sampled in December 1999 (35°47’N, 04°48' W; depth 800m).

Depth (cm)

Bulk density (g/cm3)

Total 210Pb (Bq/kg)

226Ra (Bq/kg)

Excess 210Pb (Bq/kg)

0 – 0.5 0.321 680 40 28 5 650 40

0.5 - 1 0.313 690 40 28 5 660 40

1 - 2 0.454 600 30 25 4 580 30

2 - 3 0.645 620 30 23 4 600 30

3 - 4 0.577 435 16 30 4 405 16

4 - 5 0.684 316 16 21 3 295 16

5 - 6 0.716 264 12 24 3 240 12

6 - 7 0.697 237 15 34 4 203 16

7 - 8 0.639 219 11 33 4 186 12

8 - 9 0.604 210 40 24 3 190 40

10 - 12 0.609 121 15 28 5 93 16

3333

Dating of Sediment Core: Dating of Sediment Core: 210210PbPb

y = 716,38e-0,32x

R2 = 0,98

0

100

200

300

400

500

600

700

800

0 2 4 6 8 10 12

Mass depth [g/cm2]

Uns

uppo

rted

21

0P

b [B

q/kg

]

Dashed line is the best fit corresponding to the CIC-CSR model while the continuous line corresponds to the CM-CSR model

3434

Dating of Sediment Core: Dating of Sediment Core: 210210PbPb

CIC-CSR Model: CIC-CSR Model: – Initial Concentration and Initial Concentration and

sedimentation rate constantsedimentation rate constant

)()0()( m

wExpAmA

w = 0.10 ± 0.02 g cm-2 y-1

F = A(0) w, 720 ± 150 Bq m-2 y-1.

3535

Dating of Sediment Core: Dating of Sediment Core: 210210PbPb

CRS Model: Constant Rate of supply is CRS Model: Constant Rate of supply is Constant butConstant but Sedimentation rate Sedimentation rate varyvary

0

0.05

0.1

0.15

0.2

0 2 4 6 8 10 12 14

Se

dim

en

tatio

n r

ate

[g

/(cm

^2

y)]

Depth [cm]

0

20

40

60

80

100

120

0 2 4 6 8 10 12 14

CR

S a

ge

s [

y]

Depth [cm]

0

0.05

0.1

0.15

0.2

0 2 4 6 8 10 12 14

Se

dim

en

tatio

n r

ate

[g

/(cm

^2

y)]

Depth [cm]

0

20

40

60

80

100

120

0 2 4 6 8 10 12 14

CR

S a

ge

s [

y]

Depth [cm]

Mean value: w = 0.10 g.cm-2 y-1

F = I, 712 ± 25 Bq m-2 y-1.

mm AIw /

m

m dmmAI ')'(

3636

Dating of Sediment Core: Dating of Sediment Core: 210210PbPb

CM-CSR Model: Constant Mixing and CM-CSR Model: Constant Mixing and constant Sedimentation Rateconstant Sedimentation Rate

2

2

;2

4;)()(

Dk

k

kwwxmxExp

xkw

FmA m

m

m

m

km is an effective mixing coefficient given in terms of the diffusion coefficient D and the bulk density (Abril 2003b)

w= 0.092 ± 0.003 g cm-2 y-1

F = 670 ± 25 Bq m-2 y-1.

y = 716,38e-0,32x

R2 = 0,98

0

100

200

300

400

500

600

700

800

0 2 4 6 8 10 12

Mass depth [g/cm2]

Uns

uppo

rted

21

0P

b [B

q/kg

]

3737

Reconstruction of Reconstruction of 137137Cs, Cs, 239,240239,240Pu Pu ProfilesProfiles

)()( wA

mm

Ak

mA

t

Am

with boundary conditions

0)(

),0()(0

mA

twAm

AktF

mm

dtwCkFdt wd Cw : radionuclide concentration in overlying water

dt

dF

hZCkCwk

dt

Cd atwhwd

w 1

3838

Historical records of Historical records of 137137Cs, Cs, 239,240239,240Pu in Pu in water water

0

1

2

3

4

5

6

7

1950 1975 2000

137-

Cs

[mB

q/L]

Date

0

0.01

0.02

0.03

0.04

0.05

0.06

1950 1975 2000

(239

+240

)Pu

[mB

q/L]

Date

3939

Reconstruction of Reconstruction of 137137Cs, Cs, 239,240239,240Pu Pu profiles in sedimentprofiles in sediment

0

1

2

3

4

5

6

7

8

0 1 2 3 4 5 6 7 8 9 10

13

7-C

s [

Bq

/kg

]

Mass depth [g/cm^2]

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 1 2 3 4 5 6 7 8 9 10

(23

9+

24

0)P

u [

Bq

/kg

]

Mass depth [g/cm^2]

0

1

2

3

4

5

6

7

8

0 1 2 3 4 5 6 7 8 9 10

13

7-C

s [

Bq

/kg

]

Mass depth [g/cm^2]

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 1 2 3 4 5 6 7 8 9 10

(23

9+

24

0)P

u [

Bq

/kg

]

Mass depth [g/cm^2]

4040

Laissaoui, M. Benmansour N. Ziad, M. Ibn Laissaoui, M. Benmansour N. Ziad, M. Ibn Majah J. M. Abril and S. MulsowMajah J. M. Abril and S. Mulsow. Anthropogenic . Anthropogenic radionuclides in the water column and a sediment radionuclides in the water column and a sediment core from the Alboran Sea: application to core from the Alboran Sea: application to radiometric dating and reconstruction of historical radiometric dating and reconstruction of historical water column radionuclide concentrations.water column radionuclide concentrations. Journal of Journal of Paleolimnology 40 (2008) 823-833Paleolimnology 40 (2008) 823-833

M. Benmansour, A. Laissaoui, S. Benbrahim, M. M. Benmansour, A. Laissaoui, S. Benbrahim, M. Ibn Majah, A.Chafik and P.PovinecIbn Majah, A.Chafik and P.Povinec. Distribution . Distribution of anthropogenic radionuclides in Moroccan coastal of anthropogenic radionuclides in Moroccan coastal waters and sediments. waters and sediments. Radioactivity in the Radioactivity in the Environment. Book Series. 8 ( 2006) 145-150Environment. Book Series. 8 ( 2006) 145-150

4141

Heavy metalsHeavy metals

4242

Cr (mg/kg)

60,00

70,00

80,00

90,00

100,00

110,00

120,00

130,00

tranches en cm

Cu (mg/kg)

0,005,00

10,0015,0020,0025,0030,0035,0040,00

tranches en cm

Cd (mg/kg)

0,000

0,100

0,200

0,300

0,400

0,500

tranches en cm

Mn (mg/kg)

0

500

1000

1500

2000

2500

tranches en cm

Fe (mg/kg)

23600

23800

24000

24200

24400

24600

Tranches en cm

Hg (mg/kg)

00,020,040,060,080,1

0,120,14

tranches en cm

4343

Total hydrocarbonsTotal hydrocarbons

4444

Mdiq (St2) 10m

Mdiq (St2) 100 m

Mdiq (St2) 250 m

Mdiq (St2) 500 m

Mdiq (St2) 900 m

Mdiq (St3) surface

Tanger (St.4)

8.30 55 11 12 72 9.3 3.5 Table 3.: HC concentrations ( mg/l) in water .

Section (cm) HC concentration 0-0.5 1.8 0.5-1 1.2 1-2 2.5 2-3 3.6 3-4 3 4-5 3 5-6 3 6-7 2 7-8 2.2 8-9 2 9-10 1

10-12 1 12-14 0.4 14-16 0.4 16-18 0.2 18-20 0.2 20-22 0.2 22-24 0.2 24-26 0.2 26-30 0.2 30-34 0.2 34-38 0.2

Table 4 : HC concentrations (ppm/dry weight) in sediment core Mdiq St.2

4545

SummarySummary

Levels of Anthropogenic R.N ( Levels of Anthropogenic R.N ( 137137Cs , Cs , 239,240239,240Pu, Pu, 241241Am) in Am) in surface sea water and sediment - Morocco coast –surface sea water and sediment - Morocco coast –

Vertical distributions of R.N in water column and sediment Vertical distributions of R.N in water column and sediment corecore

Use of Use of 210210PbPb exex , , 137137Cs, Cs, 239,240239,240Pu: sedimentation rate, chronology Pu: sedimentation rate, chronology

of contaminantsof contaminants

Main source of R.N : Global falloutMain 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