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Lichen Radionuclide Baseline Research

Lichen Radionuclide Baseline Research

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Lichen Radionuclide Baseline Research

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  1. Lichen Radionuclide Baseline Research By Loda Griffeth

  2. Overview • Definitions • Importance • Background: Radiation in Alaska • Past Research • Current Research

  3. 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 Gy*Quality Factor (Q) • Megaton (MT) = 4.18 X 1015 Joules

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

  5. Radiation in Alaska • Bilibino Nuclear Power Plant • Fort Greely Nuclear Power Plant • Amchitka – Underground Nuclear Tests

  6. 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

  7. Bilibino Nuclear Power Plant Fairbanks: 2012-km and Nome: 1304-km

  8. 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

  9. Project Year Est. Yield Depth (m) Purpose Longshot 1965 80kt 716 Seismic Testing Milrow 1969 ~1 Mt 1220 Seismic Calibration Cannikin 1971 ~ 5 Mt 1790 Device Testing Amchitka Island • Summary of the three nuclear test conducted on the island. • Hydrological study • Sampling • Long term monitoring

  10. 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)

  11. Vegetation Moss Lichen Mushrooms Lake Sediment Soil Subsistence Foods White Fish Caribou Bowhead Whale Previous Research Sampling Materials

  12. 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

  13. Previous Research Transport via Western Canada:

  14. Current Research • Objectives • Sampling Methodology • Gamma Counter • Data • Results • Future Research

  15. 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

  16. 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.

  17. 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 >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.

  18. * Indicates one of several types of lichen collected from site. Sampling Sites

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

  20. Gamma Counter Canberra Germanium Detector:

  21. Gamma Counter Genie 2000 Spectroscopy and Analysis Software:

  22. 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 Results

  23. Results

  24. Results

  25. Results

  26. 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

  27. 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

  28. 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)