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Distribution and Characteristics of Hot Springs
in Gifu Prefecture
Hiroshi TERAO
Gifu Prefectural Institute of Health and Environmental Sciences

AbstractThis paper is described on the hot or mineral springs in Gifu Prefecture, central
Japan. According to the latest report by Ministry of the Environment, there are .20 hotor mineral spring wells in 03 cities, towns, and villages in all 33 ones. Geographically, Gifu
Prefecture is divided - areas. The northern area is mainly high mountainous region
named the Hida Mountains and the Hakusan Volcano. The central area is low mountainous region named the Nanhi Heights, and the southern area is mainly low land named theNobi Plains and contains its nearby mountains. Each area have many spring wells. InOkuhida Hot Spring Zone, in the northern area, for example Nakao, Shinhotaka, andOshirakawa Spa, there are many hot spring water wells compared with another areas.
Especially, only in this site, we can see water vapor wells. In the Nobi Plains, there aremany deep drilled wells, ranging from +,*** to +,/** m, but water temperatures are below/*.
The most famous spa in Gifu Pref. is Gero Spa located along the Hida River in thecentral area. Max water temperature is above 2*, but Gero Spa is apart from volcano
and the mechanism of spring out has been not investigated su$ciently. I introduce aprevious study concerned with the origin of hot spring waters in this site using oxygenisotopic composition d +2O and major chemical composition as indicators. In result, I
elucidated that three kinds of origin of water are in existence. The ﬁrst is originated frommainly river water and the second is precipitation near this site. The other is mixture ofriver water and hot water reservoir in deep site.
Key words : Gifu Prefecture, Gero Spa, Oxygen isotopic composition :   

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Fig. + Map showing the distribution of hot springs in
Gifu Prefecture.

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Photo + Landscape of Gero Spa and the Hida
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±¨6ABCDEFG++
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112

Fig. . Contour map of the d +2O values of ,,hot spring water samples. (@)

Fig. / Contour map of the temperatur of ,,hot spring water samples. (A)Fig. 0 Relationship between Na ion and Cl
ion concentrations of hot spring waters at
Gero Spa.

Fig. 1 Relationship between d +2O value andCl ion concentration of hot spring watersat Gero Spa.

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