Abstract
Contents of nitrogen and oxygen gases in about three hundred hot-spring waters were measured. The nitrogen is rich in the springs of low and moderate temperature and poor in those of high temperature. The relation between the flow temperatures and the nitrogen contents differs from the Winkler’s solubility curve, that is, supersaturation predominates at low and moderate temperature, and unsaturation at high temperature. The magmatic water which may be contained in hot-spring water does not play an important role to make such temperature-nitrogen relation. Oxygen contents are little in every spring and the oxygen consumption under the ground may have contributed to make oxygen-poor waters. Some examples of geographical distribution of the nitrogen and the oxygen consumption are shown for some spas, suggesting the flow direction of hot-spring water and the relation with the usual ground-water. Annual and daily variations of the nitrogen and oxygen contents in hot-spring water are discussed together with the variations of other physical and chemical factors of the springs.
