Nobuaki Matsuoka

Chemical composition and radioactivity in hokutolite (plumbian barite) collected at Peito hot spring, Taiwan

Abstract Chemical composition and radionuclide concentrations were determined for hokutolite, plumbian barite, collected at Peito hot spring, Taiwan. The hokutolite, precipitated on the surface of the base rock, was scraped into 20 layers from the surface. Barium and Pb were determined by inductively coupled plasma-atomic emission spectroscopy, and 228Ra, 226Ra and 210Pb were determined by γ-ray spectrometry. Comparison of the 228 Ra 226 Ra activity ratio at the surface of the hokutolite with that of the hot spring water suggests that the hokutolite has been isolated from the stream for 60 years. Significantly low fractions of (Ba, Pb)SO4 and changes in Ba Pb mole ratio in the middle layers of the hokutolite suggest a change of growth condition at that time. Using the smooth and continuous decline in 228 Ra 226 Ra activity ratio observed in the upper layers of the hokutolite, the growth rate of 0.17 mm year−1 was estimated.

Sulfur Isotope Variations in Atmospheric Sulfur Oxides, Particulate Matter and Deposits Collected at Kyushu Island, Japan

Atmospheric sulfur oxides, particulate matter and deposits (wet and dry deposits) were collected from July 1998 to June 1999 at Kyushu Island, Japan. The isotopic composition of sulfur (δ34S) was measured to identify the source of sulfur in the samples. The monthly δ34S values were always low in the order of the sulfur oxides, sulfate in particulate matter and deposits. The δ34S values of the sulfur oxides ranged from −2.7 ‰ to −0.4 ‰ and were close to those of fossil fuels used in Japan. The δ34S values of sulfate in the particulate matter and deposits correlated with seasalt contribution, so that the δ34Snss value was calculated for non-seasalt sulfate. The δ34Snss values of sulfate in the particulate matter and deposits trended higher in winter than summer, suggesting the possibility of isotopic fractionation during chemical transformation (SO2 to SO42−) and of contribution of sulfate derived from sulfur sources with higher δ34S values.

Concentrations of radiocarbon and isotope compositions of stable carbon in food

The 14C activities and/or á13C values were measured for tree rings, rices, edible oils, flavors, beers, chickens and eggs. The 14C activity in 1999 ranged from 14.4 to 14.8dpm/g.C for those of tree rings and rices. The 14C activities of oils were in good agreement with the present atmospheric one. The 14C activities of flavors could differentiate petrochemically derived compounds from natural products. On the other hand, the Δ13C value could distinguish between C3 and C4 plants for the main ingredient of oils, flavors and beers. For chickens and eggs, & Delta;13C values reflected their diet. In addition, large variation of Δ13C values was observed among components of eggs.

Meteorological analysis of tritium concentrations in rain water collected in Fukuoka, Japan, from 1987–1991

Abstract Tritium concentrations in rain water collected in Fukuoka, Japan, from April 1987 to July 1991, were measured. The tritium concentration of each ‘rain’ showed a large variation from 0.06–3.39 Bq 1 −1 , with an average value of 0.62 Bq 1 −1 . Weather conditions significantly affected the tritium concentration in rain. Higher tritium concentrations were observed when air-mass moved dominantly from the Asian Continent to Fukuoka. The annual average concentrations were no longer decreased after 1987 in Fukuoka.