[The reactor accident at Chernobyl': identification of radionuclides in fallout in Niigata City].

The fallout caused by the accident of Chernobyl' nuclear reactor has been monitored in Niigata City (April 30-June 3, 1986). Twelve nuclides (131I, 132I, 129Te, 129mTe, 132Te, 134Cs, 136Cs, 137Cs, 103Ru, 99mTc, 140La, 140Ba) were identified in aerosol samples. The same nuclides plus 7Be were identified in rain-water. Gaseous and particle-bound 131I were separately trapped on a glass filter and a charcoal filter, respectively. Results indicate 50-60% of atmospheric 131I is gaseous and the rest is particle-bound. Chloroform extraction of rain-water revealed that 40-60% of 131I in the rain-water sample exists in the form of IO3- and 131IO3- (131IO4-)/131I- seemed to increase with the lapse of time after the accident.