Lichen%20Radionuclide%20Baseline%20Research

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Lichen Radionuclide Baseline Research
By Loda Griffeth
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Overview

• Definitions
• Importance
• Background Radiation in Alaska
• Past Research
• Current Research

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Definitions

• Units
• Becquerel (Bq) 1 Disintegrations/sec (dps)
• Curie (Ci) 3.7 X 1010 dps
• Gray (Gy) 1 Joule/kg of material
• Sievert (Sv) 1 GyQuality Factor (Q)
• Megaton (MT) 4.18 X 1015 Joules

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Importance

• Arctic is a sink for radioactive contamination
• Effect on subsistence lifestyles
• Major source nuclear weapons testing (1960s)
• Other sources nuclear power plants and
  Chernobyl fallout.

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Radiation in Alaska

• Bilibino Nuclear Power Plant
• Fort Greely Nuclear Power Plant
• Amchitka Underground Nuclear Tests

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Bilibino Nuclear Power Plant

• Chukotka, Russia
• Above Arctic Circle
• 4 - Light water graphite-12MW (LWGR-12)
• Built 1974 (30 yrs)
• No containment structure
• Shutdown 2006-2010

Source www.rosatom.com/english/stations/bilibino/
bil_1.htm
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Bilibino Nuclear Power Plant
Fairbanks 2012-km and Nome 1304-km
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Ft. Greely Nuclear Power Plant

• Near Delta Junction
• Operated 1962-1971
• 1.5-MW Stationary Medium Power (SM-1A)
• 1997 leakage detected
• Clean-up and decommissioning is on-going

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Amchitka Island

• Summary of the three nuclear test conducted on
  the island.

• Hydrological study
• Sampling
• Long term monitoring

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Previous Research
Research conducted in 1987, a year after the
Chernobyl accident

• Sampling Locations
• Barrow (71N, 156W)
• Colville River (70N, 151W)
• Anaktuvuk Pass (68N, 151W)
• Nome (64N, 165W)
• Fairbanks (64N, 147W)

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Previous Research
Sampling Materials

• Vegetation
• Moss
• Lichen
• Mushrooms
• Lake Sediment
• Soil

• Subsistence Foods
• White Fish
• Caribou
• Bowhead Whale

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Previous Research
Results from a radiocesium study conducted in 1987

• Cs-137 levels were low in all samples
• Deposition of Cs-137 varied by a factor of 28
• Cs-137 was greater in samples collected in
  Fairbanks
• Cs-137 levels were generally lower in soils than
  lichen

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Previous Research
Transport via Western Canada
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Current Research

• Objectives
• Sampling Methodology
• Gamma Counter
• Data
• Results
• Future Research

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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

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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 100C.
• Ash for 24-hours at 450C and store in tared
  plastic bags.

Upper Right Lichen abundance at Moose Pass.
Lower Right Sampling area at Moose Pass
containing Cadina stellaris.
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Methodology - Soil

• Metal corer 5x10-cm
• Split 8-10-cm plugs into 1-5-cm and 6-10-cm
  plugs
• Obtained replicate samples from lichen plots
  1-2 additional samples per site.
• Dried and ashed samples
• Sifted samples discarded particles gt2-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.
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Sampling Sites
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Data

• Lichen Samples (30)
• Soil Samples (46)
• 35 Analyzed
• Replicate measurements to ensure precision
• Multiple vials to ensure homogeneity

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Gamma Counter
Canberra Germanium Detector
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Gamma Counter
Genie 2000 Spectroscopy and Analysis Software
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Results

• Cosmogenic Nuclide
• Be-7
• Fission Product
• Cs-137
• U-235??
• Primordial Nuclides
• K-40
• Decay Series

• Decay Series
• Bi-214
• Pb-214
• Pa-234M
• Ra-226

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Results
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Results
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Results
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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

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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

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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)