Classification of water types of acid hot-spring waters in Japan

Acid hot-spring waters associated with active volcanoes in Japan have long been geochemically investigated in terms of various interests. Chemical compositions of the waters reported in previous works were compiled in order to obtain a better understanding of their formation process and to facilitate their effective utilization in a future. The waters were classified into four types: volcanic SO4 water, volcanic Cl water, steam-heated SO4 water and acid NaCl water. Most of elements for the dissolved components in the waters showed negative correlations between the concentration and pH. The compilation result possibly presents general geochemical information on the acid hot-spring waters in Japan.