Radionuclude Levels in Caribou of Northern Alaska in 1995-96

Caribou (Rangifer tarandus) were sampled (1995-96) from a mortality event near the Project Chariot site (the location of a radiotracer experiment in northwestern Alaska during the 1960s) and reference sites. Radionuclide levels in muscle and bone and the cause(s) of the mortality were determined because of local residents' concerns. Bone gross alpha mean activity (n = 65) was 130.0 Bq/kg, and varied significantly (p < 0.01) from 73.3 to 168.0 Bq/kg among locations. Bone gross beta mean activity was 510.4, and muscle gross beta mean activity was 9.78 Bq/kg. Bone strontium-90 mean activity (n = 58) was 137.8 Bq/ kg. Muscle potassium-40 mean activity (n = 65) was 83.0 Bq/kg, and varied significantly from 76.0 to 104.4 Bq/kg among locations. Muscle cesium-137 mean activity (n = 65) was 6.67 Bq/kg, ranged significantly from 0.74 to 15.6 Bq/kg by location, and increased with increasing body condition score. Bone potassium-40 mean activity ranged from 18.9 to 47.4 Bq/kg, and muscle strontium-90 ranged from 8.89 to 20.0 Bq/kg. Radionuclide concentrations were at expected levels. In some cases, they were low compared to those in Canadian caribou studies.