Evaluation of Radioactive Contamination in Aquatic Organisms by Means of the Statistic and the Information Theory

青 山勲,井 上 頼輝:京 都大学工学部 衛生工学教室,京 都市左京区吉田本町,〒606 1 Present address: Institute for Agricultural and Biological Sciences , Okayama University, 2-20-1 Chyuo, Kurashiki 710. 青 山 勲:岡 山大学農業生物研究所,倉 敷市中央2-20-1,〒710 Concentration of radionuclides in aquatic organisms is affected by various environmental and phisiological factors. The concentration factor is, cosequently, widely ranged . In this paper, uncertainty on the concentration process of radionuclides by organisms was evaluated from the viewpoint of the statistic and the information theory. The concept of entropy was introduced as a measure of uncertainty of information and an information source of the stochastic process on the basis that the distribution of the concentration in organisms obeyed the Poisson distribution and that its change with time could be expressed by the stochastic process. Entropy was calculated by a following equation as a measure of the uncer tainty in predicting the most reliable state of con -entration step in aquatic organisms out of n states when the frequency distribution of the concentration Q(q1, q2•c•cqn)was obtained,