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...
Data from several field studies of plutonium were evaluated to identify environmental factors that result in redistribution of this element within ecosystems.When released to terrestrial ecosystems, plutonium is almost quantitively transferred to and retained by soils. Thus, processes which transport soil within ecosystems predominate in the transport of environmental plutonium.Erosion of soils by wind and water is the principal means of translational movement of plutonium within terrestrial ecosystems. Soil erosion processes also dominate in the transport of soil plutonium to biological surfaces particularly in arid and semi-arid regions of the US.Understanding the relationships between soil erosional processes and plutonium transport within ecosystems is essential for prediction of plutonium fate and effects.
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