わが国の原子力発電所周辺海域における海産生物, 海底土および海水中^<137>Cs濃度の長期傾向

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The results of the long-term trend analyses of the ^<137>Cs data obtained during the marine environmental radioactivity monitoring program sponsored by the Ministry of Education, Culture, Sports, Science and Technology and carried out from 1983 to 2000 by the Marine Ecology Research Institute are presented. In 86.8% of the marine biota, 75.6% of the sediments, 100% of the surface seawater and 91.1% of the bottom seawater, a statistically significant decrease of ^<137>Cs concentrations was observed. The ^<137>Cs concentrations in the bottom seawater and sediments below the depth of 200 m decreased more slowly than those above the 200 m depth. The ^<137>Cs concentrations in the marine biota, surface seawater, and bottom seawater and sediments above 200 m decreased by similar annual rates of 0.039, 0.041, 0.045 and 0.041 year^<-1>, respectively. Those of the bottom seawater and sediments below the 200 m depth (200〜500 m) decreased by the rates of 0.025 and 0.026 year^<-1>, respectively. These results suggest that an equilibrium in <137>Cs concentrations in the seawater and sediments, including the marine biota above the 200 m depth, is attained both above and below the depth of 200 m.
日本保健物理学会の論文