Hygienic Chemical Examination of Bath Water Quality Change in Hot Spring Utilizing Hospital—Presumption of bath water quality changing factors by aeration and aging of hot spring— / 日本温泉気候物理医学会雑誌

ABSTRACT

 The purposes of this study were to analyze the chemical composition of some bath water in a simple alkaline hot spring utilizing a hospital and clarifying the factors that influence the concentration of each component of the hot spring water accompanying the bathing.  Water samples were collected in plastic bottles from some bath water and transported to the laboratory. The pH value, electrical conductivity, cations (sodium, potassium, magnesium and calcium ions), anions (fluorine, chlorine, nitrite, nitrate and sulfate ions) and metasilicic and metaboric acids were measured. To investigate the factors that increase concentrations of each component in bathing water, aeration examinations with air or nitrogen gas were continued for one month.  The concentrations of sulfate and nitrate ions in the bath water showed an increased tendency compared to those of the hot spring water just after welling up. After aeration with air, the concentration of sulfate ions became higher than that with nitrogen gas. On the contrary, an increase in the concentration of nitrate ions was not found in water aerated with air or nitrogen gas.  In conclusion, the oxidation of sulfur in the hot spring water may have caused the density change of the sulfate ions in the bath water. As for the nitrate ions, the increase in the concentration in the bath water seems to have been caused by perspiration during bathing, but not by oxidation for nitrogen in the hot spring water.