The capture of radionuclide fallout by tree leaves and the removal mechanism were examined using 7Be as a tracer for about two years. Measurement of 7Be and 40K were performed for the leaves of tea, loquat and fir trees, and the tendency of seasonal variations was investigated. The model, which evaluates the capture and removal of radionuclide fallout on the leaf surface was made on the deposition flux of 7Be and precipitation. Conformity and parameter values derived were analyzed. Consequently, massive changes in the concentrations of 7Be in the leaves have been recorded according to tree species. The above-mentioned model was effective for evaluating the 7Be concentration in the leaves of tea and loquat. The environmental half-life of the 7Be concentration was 24 days for tea leaves and 66 days for loquat leaves.
The International Commission on Radiological Protection (ICRP) is currently revising its recommendations and plans to publish the new set of recommendations in 2005. The present recommendations were adopted in 1990 and have been complemented by additional publications over the last twelve years. A radical revision is not envisaged, rather a coherent statement of current policy and a simplification in its application. The Commission will propose the following major changes: a primary emphasis on the protection of individuals from single sources, followed by the requirement to optimise protection; extending the existing concept of ‘dose constraint’ to cover a range of situations to give the levels that bound the optimisation process for a single source; clarification of the dosimetric quantities; and a framework for protection of the environment. This paper presents some of the proposed changes in the Commission's recommendations for its 2005 Recommendations.
Much has been achieved in recent years in attempting to develop a more comprehensive and internally consistent means of protecting the environment with respect to ionising radiation. This has involved an examination of some basic ethical issues, how these may or may not relate to basic principles of environmental protection, and how these in turn interface with different means of environmental management. The further development of such a framework, however, is likely to require some detailed discussion of some of our basic understanding and interpretation of radiation effects in a broader context than has been achieved in the past.
The effects of three chelating agents, CBMIDA, 3, 4, 3-LIHOPO, and Ca-DTPA, for removing Pu-239 in rats were compared. Forty female Wistar rats, 2 months old, were pre-injected intraperitoneally with 37, 000Bq/kg of plutonium nitrate and divided into four groups. Thereafter the rats of three groups were injected intraperitoneally with three chelating agents at a dose of 30μmol/kg, equivalent to a daily recommended human dose of Ca-DTPA, at intervals of 24hr for 3 days, beginning 30min after plutonium injection on the first day of treatment. Urine and feces were collected every 24hr. On day 4, the rats were sacrificed to obtain organs including the liver, kidney, and spleen, as well as the femur and serum. The amounts of excreted plutonium in urine of the CBMIDA and Ca-DTPA groups were increased significantly over that in the 3, 4, 3-LIHOPO and control groups, while those in the feces of the 3, 4, 3-LIHOPO group were increased significantly over the other groups on the first day. The total amount of excreted plutonium by 3 day-treatments was highest in the 3, 4, 3-LIHOPO group. The toxicity of each agent was discussed. It is concluded that at the same doses, the effect of 3, 4, 3-LIHOPO was superior to CBMIDA and Ca-DTPA for removing plutonium in rats.