9:;< J. Hot Spring Sci.7 /37 +/3ῌ+0/ ,**30, +

r x y z+ ,

Chemistry Unlocks Geneses of Hot Springs
Tetsuro NODA+ ,

Abstract
Once hot spring waters are taken in hand, those chemical analyses allow reliable reconstruction of subsurface origin and condition of them. So far various chemical (geochemical) investigations have been performed on hot springs and the surrounding settings, which beneﬁcially forced, in combination with other scientiﬁc ﬁelds, not only forillustrating regional hot spring situations but also for solving earth science mysteries. Incontrast, hot springs closely contact with human activity often bring about anthropogenic
issues, where hot spring chemistry would be expected to provide a key to reduce such
issues.
Here taking an example for chemical research on hot springs followed by its application in public, the author would introduce a methodology to determine source waterclassiﬁcation for hot springs and estimate the source water chemical compositions as wellas those mixing ratios in the hot springs. Furthermore chemistry plays an important rolein conﬁrming the degree of linkage between subsurface aquifers which would be practically utilized on consideration of the very recent task “A guideline for conservation of hotsprings”.
Key words : chemical unlocking, genesis of hot springs, source water, conservation of hotsprings=<>7 ?@AB9:CDEFGHI7 JKLMDNFOPQRKSTDUVRWHX
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 -*/ῌ2/01  ! +ῌ+ῌ+ "#$ 1+Institute for Geo-Resources and Environment, National Institute of Advanced Industrial Science and Technology, AIST Tsukuba Central 1 Higashi +ῌ+ῌ+ Tsukuba, Ibaraki -*/ῌ2/01, Japan.
,%&'()*+,)-./01 +*2ῌ**+. 234 .ῌ,ῌ- NOF 45+ / 6 , Nittetsu Mining Consultants Co., LTD., NOF Shiba Building, ,ῌ-, Shiba .-Chome, Minato-Ku, Tokyo +*2ῌ**+., Japan.

159

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4 + ®5? Op_ Fq_ 0_0¯Fq D_`a r°_ sr°_ f]tFq Od_  sf] #u  ^ ++ ¨23¥W  ^±²,NVDD/_/23 >³ />0´R8D]v#"12D] 0]wµ©*­"x +s Op_ yD0 D]v NaCl ¶,?,0D · />0¸z./?eUl*¹KºHf ,8 G
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Table + Species and chemical characteristics ofthe proposed source waters +   !"!"#$# 
 NaCl  ClῌSO.   NaCl   NaCl    SO.  HCO- SO.   NaCl

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Fig. +ῌ+ Frequency histogram of hot spring
concerning to water temperature

Fig. +ῌ, Frequency histogram of hot spring
concerning to pH value

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Fig. +ῌ- Frequency histogram of hot spring
concerning to chloride content
 +ῌ-  Cl162

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Fig. +ῌ. Frequency histogram of hot spring
concerning to total soluble material +ῌ. 
 TSM /3 d P,**31)*4]',Nῌ>9^_`@;
Table ,Source water classiﬁcation criteria ,"-%&'(῏   ῐ ῐ ῍    ῐ !

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Fig. , Determination process of source
water compositions and mixing ratios
by way of source water-mixing calculation

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p9qr!4sTable - Source water chemical compositions obtained by using of numerical calculation for hot springwaters at the Hohi area -  A B
NaCl 
NaCl ++2*+-/43**+2.*++2+,.
1-+.4,/
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Na mg/L
K mg/LCa mg/L
Mg mg/LCl mg/L
SO. mg/L
HCO- mg/L
SiO, mg/L
Li mg/L
B mg/LF mg/LAs mg/L
NH. mg/LdD d+2O * !"#,.*$,//

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Table .

 C E F ,,.
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0123

Source water mixing ratios in hot spring waters at the Hohi area .

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 D C D E F !4 

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14,*4//24/**+4/*lm(no3 /3  ,**3 

Fig. - Hot spring model based on “A guideline for conservation of hot springs”
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Noda, T. and Shimada, K. (+33-) : Water mixing model calculation for evaluation of deep geothermal water. Geothermics, ,,, +0/ῌ+2*.
165