No abstract

A small amount of strontium ion (20 mg) was simply separated from a large amount of calcium ion (0.5-13.6 g) by liquid-liquid extraction using dicyclohexyl 18-crown-6 chloroform solution. The extraction was applied to a part of the procedure for determining radiostrontium in ash of milk. The overall recovery of strontium was 75% on the average for 5-10 g of milk ash. Decontamination factors for Mg, Ca, Ru, I, Cs, Ba, and La in the final fraction were 1 X 10s, 1 X 104, >1 X 10®, >1 X 10®, >2 X 10®, 2 X 10®, and 3 X 104, respectively. The chemical procedure for three samples took about 2 days.

Atmospheric aerosols were collected onto a Fluoropore filter in order to determine the iodine by means of instrumental neutron activation analysis. The collection filter was found to be the best material among the nine filters examined, for it has the lowest blank values for iodine as well as for other halogens and sodium. The iodine concentrations in Tokyo were found to be 1.7–12.7 ng m−3. Of the soluble iodine, 10% or less was in the form of IO3−.

A small amount of Sr2+ (0.7∼20 mg) was simply separated from a large amount of Ca2+(1.5 g) by liquid–liquid extraction using dicyclohexyl-18-crown-6 chloroform solution. Average recovery of Sr2+ was 97 %, and the amount of Ca2+ in the final strontium fraction of the separation was decreased to 10−4∼10−5 part of the initial amount.

Concentrations of 137Cs, 134Cs and potassium were surveyed in 32 mushrooms and 24 substrates (upon which the mushrooms grow) obtained from fields in Japan. Radiocesium concentrations (137Cs+134Cs) in mushrooms and substrates in the forests of Mt. Fuji varied widely from 17 to 1083Bq/kg in fresh mushroom samples, and in dry substrate samples they were in the range of 66 to 531Bq/kg, whereas levels of potassium remained essentially constant. 134Cs released from the Chernobyl reactor was determined in some mushrooms and some substrates from the sub-alpine forest of Mt. Fuji. Mushroom-to-substrate concentration ratios of 137Cs were much higher than tree leaves-or mosses-to-substrates concentration ratios near the study locations, and were larger by 100-to 1000-fold than the reported transfer factors of 137Cs from soils to leaf vegetables, root crops or potatoes. Significant correlations between ignition loss of substrates and concentration of 137Cs in mushrooms, and between pH value in substrates and concentration of 137Cs in mushrooms or mushroom-to-soil concentration ratio of 137Cs were found, suggesting possible 137Cs uptake mechanisms. The effective dose equivalent received by the general public was calculated to be 57x10-6 Sv based on the annual intake of 3.7kg of mushrooms and the maximum concentration detected in this study, 1083Bq/kg. It is estimated that this value is less than 2.4% of the annual effective dose equivalent received from natural sources, 2.4x10-3 Sv.