抄録
Hydrogen and oxygen isotope measurements of rain and of snow samples collected from Nagaoka in Niigata pref., Japan, were examined. Their variations of isotopic composition changed considerably within a few days. The rain samples were collected daily from 10/15 to 10/18 during the 10th typhoon of 1998. The snow samples were collected on 2/24 and 2/25 in 1999. Oxygen and hydrogen isotope ratios of the rain and the snow samples were measured with a Micromass PRISM mass spectrometer using an equilibrium technique of carbon dioxide and hydrogen with platinum, respectively.
The following two results were obtained:
(1) The average values of δD and δ18O of the rain and the snow samples were between -32.5 and -62.9 per mil, and between -7.7 and -9.8 per mil, respectively.
(2) The d value calculated using the obtained δD and δ18O were between 2.46 and 22.06 for the rain and between 28.84 and 37.46 for the snow.
Surprisingly, the isotopic composition of water precipitated in Japan changed rapidly based on the obtained results. The implication of these results suggests that analyzing isotopic ratios may lead to a prediction of a possible disaster caused by heavy rain or snow.
