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Lichen Radionuclide Baseline ResearchBy Loda Griffeth
Overview
DefinitionsImportanceBackground: Radiation in AlaskaPast ResearchCurrent Research
Definitions
UnitsBecquerel (Bq) = 1 Disintegrations/sec (dps)Curie (Ci) =3.7 X 1010 dps Gray (Gy) = 1 Joule/kg of materialSievert (Sv) = 1 Gy*Quality Factor (Q)Megaton (MT) = 4.18 X 1015 Joules
Importance
Arctic is a sink for radioactive contaminationEffect on subsistence lifestylesMajor source – nuclear weapons testing (1960’s)Other sources – nuclear power plants and Chernobyl fallout.
Radiation in Alaska
Bilibino Nuclear Power PlantFort Greely Nuclear Power PlantAmchitka – Underground Nuclear Tests
Bilibino Nuclear Power Plant
Chukotka, RussiaAbove Arctic Circle4 - Light water graphite-12MW (LWGR-12)Built 1974 (30 yrs)No containment structureShutdown 2006-2010
Source: www.rosatom.com/english/stations/bilibino/bil_1.htm
Bilibino Nuclear Power Plant
Fairbanks: 2012-km and Nome: 1304-km
Ft. Greely Nuclear Power Plant
Near Delta JunctionOperated 1962-19711.5-MW Stationary Medium Power (SM-1A)1997 leakage detectedClean-up and decommissioning is on-going
Amchitka Island
Hydrological studySamplingLong term monitoring
1220 ~1 Mt1969MilrowDevice Testing1790~ 5 Mt1971Cannikin
Seismic CalibrationSeismic Testing71680kt1965Longshot
PurposeDepth (m)Est. YieldYearProject
• Summary of the three nuclear test conducted on the island.
Research conducted in 1987, a year after the Chernobyl accident:
Previous Research
Sampling LocationsBarrow (71N, 156W)Colville River (70N, 151W)Anaktuvuk Pass (68N, 151W)Nome (64N, 165W)Fairbanks (64N, 147W)
Previous Research
VegetationMossLichenMushrooms
Lake SedimentSoil
Subsistence Foods
White FishCaribouBowhead Whale
Sampling Materials
Previous Research
Cs-137 levels were low in all samplesDeposition of Cs-137 varied by a factor of 28+Cs-137 was greater in samples collected in FairbanksCs-137 levels were generally lower in soils than lichen
Results from a radiocesium study conducted in 1987
Previous ResearchTransport via Western Canada:
Current Research
ObjectivesSampling MethodologyGamma CounterDataResultsFuture Research
Objectives Establish composition and spatial distribution
radionuclides in Alaska
Assess known and potential lichen indicator species
Derive correlation between baseline lichen data and radiological data
Derive correlation between current baseline lichen data and potential bioconcentration effects in caribou
Methodology - Lichen
Separate lichen from other natural materials, store in sealed, tared plastic bags. Sample area – 1/4-meter (smaller, if lichen abundance is low).Drying time – 24-hours at 100°C.Ash for 24-hours at 450°C and store in tared plastic bags.
Upper Right: Lichen abundance at Moose Pass. Lower Right: Sampling area at Moose Pass containing Cadina stellaris.
Methodology - Soil
Metal corer 5x10-cm Split 8-10-cm plugs into 1-5-cm and 6-10-cm plugsObtained replicate samples from lichen plots & 1-2 additional samples per site.Dried and ashed samplesSifted samples – discarded particles >2-mm size
Upper Right: Soil sampling using a metal corer at Moose Pass along the Seward Highway.
Lower Right: Soil sample collected at Moose Pass along the Seward Highway.
Sampling Sites
* Indicates one of several types of lichen collected from site.
Data
Lichen Samples (30)Soil Samples (46)35% Analyzed
Replicate measurements to ensure precisionMultiple vials to ensure homogeneity
Gamma Counter
Canberra Germanium Detector:
Gamma CounterGenie 2000 Spectroscopy and Analysis Software:
Results
Cosmogenic Nuclide
Be-7
Fission ProductCs-137U-235??
Primordial NuclidesK-40Decay Series
Decay SeriesBi-214Pb-214Pa-234MRa-226
Results
Activity in Lichen Samples
-6.50
-6.00
-5.50
-5.00
-4.50
-4.00
Bethel Eagle Summit SH - Moose Pass SH - TurnagainPass
Wickersham Dome
Location
Lo
g(C
s-1
37
mC
i/mL
)
-7.00
-6.80
-6.60
-6.40
-6.20
-6.00
-5.80
-5.60
-5.40
-5.20
-5.00
Lo
g(U
-23
5 m
Ci/m
L)
Avg. Cs-137 Cs-137 Avg. U-235 U-235
Results
Activity in Soil Samples
-7.50
-7.00
-6.50
-6.00
-5.50
-5.00
-4.50
-4.00
Barrow Bethel Denali Highway Moose Pass Turnagain Pass
Location
Lo
g(C
s-1
37
mC
i/mL
)
-7.00
-6.80
-6.60
-6.40
-6.20
-6.00
-5.80
-5.60
-5.40
-5.20
-5.00
Lo
g(U
-23
5 m
Ci/m
L)
Avg. Cs-137 Cs-137 Avg. U-235 U-235
ResultsCorrelation Graph
-7.50
-7.00
-6.50
-6.00
-5.50
-5.00
-4.50
-4.00
60 62 64 66 68 70 72
Latitude
Lo
g(C
s-1
37m
Ci/m
L)
Results
Cs-137 – Good Model
Activity increases with Latitude
Higher activity in lichen than activity in soil samples
Low activity in Seward Hwy (SH) and Denali highway (DH) samples
U-235 – Good to Marginal Model
Activity increases with latitude and longitude
Bethel samples have high activity
Low activity in Seward Hwy and Denali Hwy samples
Higher activity in lichen than activity in soil samples
Future Research Establish composition and spatial distribution
radionuclides in Alaska
Assess known and potential lichen indicator species
Derive correlation between baseline lichen data and radiological data
Derive correlation between current baseline lichen data and potential bioconcentration effects in caribou
Acknowledgements
John Kelley (IMS)
Larry Duffy
Adrienne Orr
Stan Read and Doug Dasher (ADEC)
Richard Stolzberg
Chemistry Department
Pacific Northwest National Laboratories
Laodong Guo and Celine Gueguen (IARC)