Cesium-137 in Alaskan Lichens, Caribou and Eskimos

Abstract

Cesium-137 concentrations in Alaskan arctic ecosystem components during the period 1962-1965 varied with seasonal and environmental conditions, emphasizing the important influence of ecologic factors upon fallout accumulation in the lichen-caribou(reindeer)-man food chain.Concentrations in lichens at Anaktuvuk Pass, Alaska increased with time and varied among several species. Caribou flesh contained maximum 137Cs levels during winter periods and lowest values during summer months corresponding to lichen utilization. Body burdens in natives utilizing the caribou as a food base reflected the 13?Cs cycle in caribou flesh, but lagged by a few months. Maximum values occurred during summer and minimum values were found during mid-winter.Biological half-time of 137Cs was estimated to be about 13 years in lichens by measuring retention of 134Cs artificially applied to natural lichen communities, three to five weeks in caribou and about 65 days in Eskimos.Cesium-I37 concentrations increased by about a factor of two at each successive trophic level of the food chain. The trend with time was one of steady increase, although unusual variations occurred during 1964 and 1965 and were believed to be associated with caribou migration patterns. Recent data suggest 137Cs body burdens of the Anaktuvuk Pass Eskimos will continue to increase during the summer of 1966 in contrast to the downward trend reported in Scandinavia. CESIUM-137 is generally recognized as a most important constituent of worldwide radioactive fallout resulting from nuclear weapons tests. Its importance is nowhere greater than in the arctic and subarctic regions of the northern hemisphere, where the unique features of the lichen-caribou (reindeer)-man food chain have created a situation of increasing interest to workers in the fields of radiation ecology and radiological health. O u r radiation ecology studies in Alaska began in 1959 and have progressed from a description of the general spectra of fallout radionuclides in arctic biota to a definition of seasonal cycles, rates and routes of radionuclide movement * This paper is based on work performed under United States Atomic Energy Commission Contract t 5 383within the ecosystems, with particular attention to 90Sr and 13'Cs. Cesium-137 has been of greatest importance in these studies, not only because of its public health aspects, but also because its convenient gamma emission and biological concentration permits effective study of its transfer within the natural systems. The results of these studies and those ofother northern regions have been remarkably consistent. The 137Cs situation in the arctic regions may be briefly described as depending upon (1) the extremely effective retention of 137Cs by lichens, (2) the importance of lichens as a winter food for caribou and reindeer, and (3) the dependence upon caribou and reindeer for food by many northern peoples.The transfer of 13'Cs u p the food chain in this series of steps or stages, known as trophic levels, illustrates the simple and thus delicately balance...

Radionuclide Contaminant Burdens in Arctic Marine Mammals Harvested During Subsistence Hunting

“…Even these 137 Cs activities have declined significantly from maxima at the time of nuclear weapons testing, when 137 Cs activities in lichens and caribou flesh in excess of 1000 Bq per g dry weight (rather than per kg) were readily observed (Hanson, 1967). The activities of 137 Cs in marine mammals that we report here are also as much as five orders of magnitude below levels reported on a wet weight basis in reindeer in Fennoscandia following the Chernobyl accident in 1986 (Eikelmann et al, 1990;Åhman and Åhman, 1994).…”

“…First, seminal work undertaken during the era of atmospheric testing of nuclear bombs demonstrated the relatively long biologically active half-life of radionuclides such as 90 Sr and 137 Cs in arctic tundra vegetation. This contamination resulted in significant radionuclide contaminant burdens in arctic herbivores such as caribou, which are used for subsistence by indigenous people of the Arctic (Hanson, 1967 Livingston, 1988;Kershaw and Baxter, 1995). Finally, the 1986 Chernobyl nuclear power plant accident in the former Soviet Union (FSU) resulted in the release of 137 Cs, among other radionuclides, which contaminated tundra vegetation used by Komi reindeer herds in arctic Fennoscandia.…”

External and Internal Irradiation of Swedish Reindeer Breeders 1950-1970

“…However, comparisons with results from Finland(84*85) Norway(s6) and Alaska (87) show that the average levels are approximately the same even if differences can be found between individual groups. (87) The highest individual 137Cs content found in man, 4.8 $5, has been reported in the USSR;(67) nevertheless RAMZAEV et U Z . @~) point out that the levels in reindeer breeders in the USSR are in accordance with the levels in other reindeer breeders.…”

A survey of radioactive fallout data in Alaska

“…11 Table 8: Estimated annual radiation doses from 13'Cs body burdens of (Hanson, 1967). Table 10 demonstrates the seasonal effect on body burdens.…”