Enhancement of radiolethality of E. coli was observed by KF during irradiation. The shape of survival curve of exponential type was not altered by KF, and it was only effective at pH below 6.0 and not so influenced by oxygen and additional SH compound. Pre or post-irradiation treatment with KF did not exert any changes in viability of cells. Referring to this enhancement, effect of fluoride ion on water radiolysis was investigated, and these results were discussed in comparison with the cases of other halide ions.

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Conformational degradation of cytochrome-C induced by gamma rays in aqueous solution was studied. The formation of CO-affinitive cytochrome-C, susceptibility of cytochrome-C to proteinase and spectrophotometric titration of tyrosyl residues were investigated. These results indicate that gamma irradiation in aqueous solution degradates cytochrome-C and unfolds polypeptide to give exposed heme or tyrosyl residues which is originally embedded within a protein part.

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Factors affecting the sorption of various radionuclides by a river sediment sample in the fresh or saline water were examined, in addition, release of radionuclides in the sediments when it was exposed to the sea water was studied. Water and sediment samples were collected at several places along the Sagami River, and radionuclides employed in this experiments were ⁹⁰Sr, ¹³⁷Cs, ⁵⁴Mn, ⁶⁰Co, ⁵¹Cr and ⁵⁹Fe.
Cation exchange capacity of the river sediments less than 120 mesh fraction was 1 meq/100 g determined by CaCl₂ method, and 2 meq/100 g by the tagged cesium method, and the capacity of acid treated river sediments by NaCl method was 1 meq/100 g, respectively.
Uptakes of radionuclides by the sediments were much affected by various competing cations, and the rate of inhibition depends not only on the cationic species but also concentration of cations. The higher in the concentration of a competing cation, the more inhibitive to the uptake of radionuclides by river sediments.
Release of radionuclides which had been sorbed by the river sediments in the filtered sea water was examined during 12 days storage. Both ⁶⁰Co and ¹³⁷Cs were released easily, and never were re-absorbed. The release of ⁹⁰Sr, however, increased for the first 2 days, then gradually decreased, which might be due to the re-absorption of the nuclide by sediments in the sea water. The rate of release of ⁵⁴Mn was rather low, in addition, the amount released in the sea water decreased gradually, which might be due to the precipitation in the form of MnO₂.

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The measurement of the specific gravity of the highly radioactive fallout particles from the third Chinese nuclear test explosion was made. The specific gravity ranged from 5.2 to 6.5 and there was a tendency that the specific gravity increased with increasing darkness of the particle color. In connection with the results obtained by the electron microprobe analyses made previously, it was assumed that the specific gravity increased with increasing ratio of iron to aluminium in the matrix materials.

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Nineteen samples of sediment collected from Tokyo Bay and coastal water along Fukushima Prefecture were analyzed radiochemically. The HCl-extraction efficiencies of radionuclides in sediment were examined. Recoveries of more than 80% were obtained for Ce-144, Ru-106 and Cs137 in fine mud collected in Tokyo Bay.
The “shaver type” sampling device was designed to collected a large amount of sediment of the surface layer of 2 cm thickness.
Sr-90, Cs-137 and Ce-144 concentrations in fine mud were remarkably higher than those in sandy mud or sand. It was clearly observed that ratios of Ce-144/Sr-90 and Cs-137/Sr-90 in coastal sediments were substantially higher than those in sea water. Ce-144 and Cs-137 were found to be accumulated more effectively in the surface mud on the bottom of the sea, in comparison with Sr-90.

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