[en] Since 27 January 1997, the measurements of radon (Rn-222) exhaled from the ground have been made continuously by the use of PICO-RAD detector (Packard instrument Co.) at monitoring stations on Ashiya active fault. The fault may have been slipped by the Kobe earthquake (magnitude 7.2, 17 January 1995). The variation of relative radon exhalation on the fault was large. We guessed the large variation of relative radon exhalation on the fault was caused by not only the influence of meteorology but also the influence of other factors. (author)

[en] Thermal neutron activaton analysis with measurement of ³²P Cerenkov radiation by liquid scintillation spectrometer was used to determine phosphorus in cannabis. After irradiation of the sample, wet ashing was carried out with conc. nitric acid and 70% perchloric acid. The solution in l M perchloric acid transferred to an inorganic ion-exchange column containing acid aluminium oxide and phosphorus was quantitatively eluted with 1M hydrofluoric acid. The ³²P radioactivity of each fraction of the eluate was counted with Cerenkov radiation by a liquid scintillation spectrometer from 2 to 7 weeks after the irradiation. The activity curve decayed with ³²P half-life. The isotope channel ratio technique was applied for the quench correction. The optimal experimental conditions for chemical separation of phosphorus and for measuring the ³²P Cerenkov radiation were also examined. (Author)

[en] The volatilization losses of mercury before, during and after neutron irradiation were studied. To minimize the losses, thiourea, L-cysteine, thioacetamide and ammonium sulfide were added to the standards, respectively. It was possible to minimize the losses by preserving the standard at -20 deg C after irradiation. No loss was observed in the biological materials after irradiation. (author)

[en] Examinations were made on optimal experimental conditions for instrumental determination of various elements in cannabis by neutron activation analysis, without any radiochemical separation, and the following conditions were found to be useful. Irradiation samples to be used are about 300 mg of the leaves or stem bark, and about 100 mg of the root. For soil sample, about 50 mg is used for the determination of short half-life nuclides and about 300 mg for long half-life nuclides. For short half-life nuclides, the samples are irradiated for 1 min, activity is measured for 200 sec after a decay of 3 min, and for 400 sec after a decay of 10 min. For long half-life nuclides, the samples are irradiated for 60 min and the activities are measured for 4 K sec after 1 week and for 10 K sec after 1 month. Use of supersonic waves is also convenient for cleansing of the samples. Thirty-five kinds of interesting elements were determined by this method from cannabis cultivated in Maizuru area. (Author)

[en] Room experiments were conducted to investigate the effects of an air cleaner on radon mitigation. Radon concentration, equilibrium equivalent radon concentration and unattached fraction were measured during the experiments. Two types of filtration were tested using the air cleaner which has a high efficiency particulate air filter (HEPA-filter) and a deodorizing activated carbon (carbon-filter). One is the filtration with the HEPA-filter plus carbon-filter and the other is the filtration with only the HEPA-filter. The effective doses from radon progeny were significantly decreased. Both filtration methods were effective for the mitigation of effective dose due to radon progeny. (author)

[en] Instrumental neutron activation analysis has been performed on human hair of the normal Japanese individuals to define the baseline levels of trace elements. A statistical analysis which is not influenced by detection limits, has been carried out to elucidate the variations of elemental concentrations in terms of age, sex and hair treatment. Correlation coefficients have been calculated between the logarithmic concentrations of the elements determined in the groups classified according to sex, age and hair treatment. Their significant levels have been evaluated. (author)

[en] With the aim of indicating environmental pollution effects by heavy metals on humans using hair, nondestructive activation analysis was applied to 382 normal Japanese hair samples (background level). Elemental contents of hair could be determined for Ag, Al, As, Br, Ca, Cd, Cl, Co, Cr, Cu, Fe, Hg, I, K, La, Mg, Mn, Na, S, Sb, Sc, Se, Sm, Ti, V and Zn. As these elements in hair have wide concentration ranges, the differences in concentration distribution between groups (sex, age, permanent treatment and regional difference) are discussed. A method for hair sampling is presented. (author)