lichen radionuclide baseline research by loda griffeth

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)