Radioactive Pollutants in Marine Environment
Radioactive Pollutants in Marine Environment José Marcus Godoy IRD/CNEN/MCT PUC-Rio
Presentation Topics • Natural radioactivity in the marine environment; • Application to environmental studies; • Radioactive contaminants: – Natural radionuclides • Phosphate fertilizers • Oil Production off-shore
– Artificial radionuclides • Nuclear tests fall-out • Nuclear reactors • Reprocessing plants
Natural Radioactivity in the Marine Environment • Uranium: – Concentration in seawater related to the salinity; – Open seawater ≈ 3 µg/L; – Conservative behaviour; – 234U/238U activity ratio = 1.15
•
226Ra
and 228Ra
– Higher activities closer to the shoreline and to estuarine regions; – Conservative behaviour; – Open seawater ≈ 1 Bq m-3
•
210Pb
– Different sources: • Atmospheric fall-out, local dependency; • 226Ra/222Rn decay in the water column, flux depend on the water column depth; • 222Rn emanation from bottom sediments.
– Non-conservative behavior, accumulation on the sediments (210Pb dating) – Concentration level about 10 Bq m-3
•
222Rn
– Different sources: • 226Ra decay in the water column; • 222Rn emanation from the bottom sediments; • SGD
– Concentration ranges from Bq m-3 to kBq m-3 levels
•
40K
≈ 13 kBq m-3
Application to Environmental Studies • Sediments dating – Shallow waters: 210Pb/226Ra disequilibrium, 210Pb excess; – Deep waters: 230Th/234U disequilibrium, 230Th excess.
• Cold-water corals (deep-sea corals): 230Th/234U disequilibrium, 234U excess. • Water mixing processes – Submarine groundwater discharge (SGD): radium isotopes (228Ra, 226Ra, 224Ra, 223Ra), 222Rn; – Estuarine regions: : radium isotopes and uranium.
Natural Radionuclides as Marine Pollutants • Phosphate industry – Discharged circa of 0.5 GBq of 226Ra, 210Pb and 210Po per kt of phosphogypsum; – Clear evidences of 210Po accumulation on shellfishes. West Irish Sea example • 100 Bq kg-1 (1991) • 1992 process was changed and new effluent plant starts • 15 Bq kg-1 (1999)
– Brazil: Santos estuarine region, “Fosforita” region Pernambuco.
• Oil production off-shore – Mainly, 226Ra and 228Ra in produced water; – Concentration depends on the platform operation management as the use of additives or seawater injection; – Strongly correlated with Ba; – Releases decrease with the platform operation time; – Environmental impact • After 500m released compounds reach the BG levels; • Artificial reef; • An integrated study of this new established environment is needed.
Artificial Radionuclides – Nuclear test fall-out
137Cs
in seawater, Southeastern Brazil ≈ 1 Bq
m-3
137Cs
deposition North:South ratio ≈ 4:1
Magand&Arnaud STOTEN 385, 312314, 2007
Artificial Radionuclides • Nuclear reactors – Local impact; – Main radionuclide = 3H (conservative behavior); – Secondary radionuclides = 60Co, 58Fe, 137Cs. Nonconservative behavior, accumulation in sediments, algae, mussels.
• Reprocessing plants – Local and regional impacts (Windscale/Sellafield) – Main radionuclide = 3H; – Secondary radionuclides = 90Sr, 106Ru, 137Cs.
1.4
1000
1.2 1.0
Concentração (Bq kg-1)
210
Pbexcess / Bq kg
-1
-1
V = 0.34 cm y 2 R = 0.988
100
Sampling point 4
10
0.8 0.6 0.4 0.2 0.0 137
Cs Bi
-0.2
207
-0.4 -0.6
1 0
2
4
6
8
10
12
14
Sediment layer depth / cm
16
18
20
22
0
2
4
6
8
10
Profundidade (cm)
12
14
16
18
• [email protected] • [email protected]
Presentation Topics • Natural radioactivity in the marine environment; • Application to environmental studies; • Radioactive contaminants: – Natural radionuclides • Phosphate fertilizers • Oil Production off-shore
– Artificial radionuclides • Nuclear tests fall-out • Nuclear reactors • Reprocessing plants
Natural Radioactivity in the Marine Environment • Uranium: – Concentration in seawater related to the salinity; – Open seawater ≈ 3 µg/L; – Conservative behaviour; – 234U/238U activity ratio = 1.15
•
226Ra
and 228Ra
– Higher activities closer to the shoreline and to estuarine regions; – Conservative behaviour; – Open seawater ≈ 1 Bq m-3
•
210Pb
– Different sources: • Atmospheric fall-out, local dependency; • 226Ra/222Rn decay in the water column, flux depend on the water column depth; • 222Rn emanation from bottom sediments.
– Non-conservative behavior, accumulation on the sediments (210Pb dating) – Concentration level about 10 Bq m-3
•
222Rn
– Different sources: • 226Ra decay in the water column; • 222Rn emanation from the bottom sediments; • SGD
– Concentration ranges from Bq m-3 to kBq m-3 levels
•
40K
≈ 13 kBq m-3
Application to Environmental Studies • Sediments dating – Shallow waters: 210Pb/226Ra disequilibrium, 210Pb excess; – Deep waters: 230Th/234U disequilibrium, 230Th excess.
• Cold-water corals (deep-sea corals): 230Th/234U disequilibrium, 234U excess. • Water mixing processes – Submarine groundwater discharge (SGD): radium isotopes (228Ra, 226Ra, 224Ra, 223Ra), 222Rn; – Estuarine regions: : radium isotopes and uranium.
Natural Radionuclides as Marine Pollutants • Phosphate industry – Discharged circa of 0.5 GBq of 226Ra, 210Pb and 210Po per kt of phosphogypsum; – Clear evidences of 210Po accumulation on shellfishes. West Irish Sea example • 100 Bq kg-1 (1991) • 1992 process was changed and new effluent plant starts • 15 Bq kg-1 (1999)
– Brazil: Santos estuarine region, “Fosforita” region Pernambuco.
• Oil production off-shore – Mainly, 226Ra and 228Ra in produced water; – Concentration depends on the platform operation management as the use of additives or seawater injection; – Strongly correlated with Ba; – Releases decrease with the platform operation time; – Environmental impact • After 500m released compounds reach the BG levels; • Artificial reef; • An integrated study of this new established environment is needed.
Artificial Radionuclides – Nuclear test fall-out
137Cs
in seawater, Southeastern Brazil ≈ 1 Bq
m-3
137Cs
deposition North:South ratio ≈ 4:1
Magand&Arnaud STOTEN 385, 312314, 2007
Artificial Radionuclides • Nuclear reactors – Local impact; – Main radionuclide = 3H (conservative behavior); – Secondary radionuclides = 60Co, 58Fe, 137Cs. Nonconservative behavior, accumulation in sediments, algae, mussels.
• Reprocessing plants – Local and regional impacts (Windscale/Sellafield) – Main radionuclide = 3H; – Secondary radionuclides = 90Sr, 106Ru, 137Cs.
1.4
1000
1.2 1.0
Concentração (Bq kg-1)
210
Pbexcess / Bq kg
-1
-1
V = 0.34 cm y 2 R = 0.988
100
Sampling point 4
10
0.8 0.6 0.4 0.2 0.0 137
Cs Bi
-0.2
207
-0.4 -0.6
1 0
2
4
6
8
10
12
14
Sediment layer depth / cm
16
18
20
22
0
2
4
6
8
10
Profundidade (cm)
12
14
16
18
• [email protected] • [email protected]
