Coloration Mechanism of Green Colored Hot Spring Waters

J. Hot Spring Sci. 0* ++3 +--,*+* + + + +,, + +3,, /,0 Coloration Mechanism of Green Colored Hot Spring Waters Nobuki T, Mitsuo N, Natsuki F and Naoko K + AKAMATSU + ISHIOKA + UKUSHIMA + UWAHARA Abstract Chemical analyses, UV-Vis absorption spectrum and Electrospray Ionization Mass Spectrometry (ESI-MS) measurements of hot spring waters of Kunimi in Iwate Pref. and Kumanoyu in Nagano Pref., which are the representative green colored hot springs in Japan, were conducted to elucidate their coloration mechanism. Reproduction experiments verified a hypothesis The green coloration is due to the composition with yellow color of the polysulfide ion produced by the reaction with sulfur and hydrogen sulfide in neutral ph and the blue color brought from the Rayleigh scattering of light by sulfur or calcium carbonate colloidal particle. There were all sample waters in the stable region of HS when we plotted ph and ORP values on a diagram of Eh-pH concerning for the sulfur chemical species. The maximum absorption at,-* nm which is due to hydrogen sulfide ion and the absorption band of -** /** nm which participates in yellow color were found in UV-Vis absorption spectra of the green colored hot spring waters. A lot of peaks of HSx were observed in the ESI-MS measurement of the green colored hot spring water of Kumanoyu. This x was mainly 1, in addition, there were 0, 2 and +*. It was confirmed that, these hot spring waters contain polysulfide ions S x. The various size fine particles of calcium carbonate and sulfur were found in the hot spring waters of the Kumanoyu and Kunimi by scanning electron microscope observations. From these results, it is concluded that the above hypothesis can be supported as for the green coloration mechanism. Key words : green colored spring water, polysulfide ion, Rayleigh scattering, ESI-MS, UV-Vis absorption spectrum, Kumanoyu hot spring, Kunimi hot spring,1. 2/+*,, + Department of Chemistry, Faculty of Science, Toho University, Miyama,, +, Funabashi-shi,,1. 2/+*, Japan. + + 119

UV-Vis ESI-MS ph ORP Eh-pH HS UV-Vis,-* nm -** /** nm ESI-MS HSx x 1 0 2 +*, Sx : ESI-MS, UV-Vis + Ohsawa et al.,,**3, Fe - Ohsawa et al.,,**,,**-,,,**-, Fe UV-Vis ESI-MS 120

0*,*+*,,+ Fig. + Cl HCO- +31+ Fig.,, 0,.,.,** L, 1, L,**/ 3,0,1,**1 +*,,,-,**/ +* +* ESI-MS,**2 + +*,, CS-+** Ohsawa et al.,**, CIE +3-+ XYZ Yxy CIE+3-+ XYZ R G B Y x y - x, y *.-+*+ *.-+0, x, y nm SOLAX XC-+** A l-1* 12* nm, -,*** cd 3*,- CUSTOM CT-/** ph ph HM-,* P ORP, ph HM-+. P EC, CM-+. P,, Na K Ca Mg Cl SO DIONEX QIC IONCHROM ANALYZER,.,,, - -,+* H SiO U- Cu Fe ICP-AES SEIKO SPS-*** ICP 121

Fig. + A location map of Kunimi hot spring in Iwate Prefecture and a photograph of the open-air bath of Kunimi hot spring. Fig., A location map of Kumanoyu hot spring in Nagano Prefecture and a photograph of the open-air bath of Kumanoyu hot spring.,. 122

0*,*+* ph, 3,, * 0, -,, SO- SO.,, Sx HS x+ 2S S H, 2 x,,, S0 S/ S.,, S- S,, - 3, ESI-MS Sx x Kleinjan et al.,,**/ Gun et al.,**. HS O HS ESI-MS Cold-ESI JMS-T+** S ESI-MS mz SO,.+ UV-Vis + cm U--,+*,** /** nm,., ESI-MS Steudel,,**- Kleinjan et al.,,**-,/., Ohsawa et al.,**, *+*. *./. mm *+*. *./. mm +,. mm,**- 123

*.*- *.*. mm,**-,/+ CaCO -,, Ca CO- CaCO- Ksp Saturation Index SI SI log Ca CO,, - Ksp,, ph CO- Ca SI,/, SEM *+. mm JSM-/2** LV - -+ Table + 02 cm /3 cm : /** /// nm, : /// /1* nm Fig. -, Table + The data of hue wavelength (WL) of Kunimi and Kumanoyu hot spring waters. Sampling location Sampling date WL/nm -, ph, Kunimi-open air,0-oct-*/ /0+ Kunimi-indoor+,0-Oct-*/ //1 ph, ORP Table, Kunimi-indoor, Kunimi-open air Kunimi-open air,0-oct-*/,,-oct-*1,--oct-*1 //- /03 /0- ph, Kunimi-indoor- Kunimi-indoor. Kumanoyu-open air,--oct-*1,--oct-*1 +* -Oct-*/ /0, /0- /0, ORP Kumanoyu-indoor +* -Oct-*/ /1, 124

0*,*+* : -/+ mv, : +/0 mv :,-/ mv, :, mv,**1 EC Fe Cu ppb Table - Fig. - Examples of calorimetric data shown on the xy-chromaticity diagram established by Commision Internationale d Eclairage (CIE) in +3-+. The boxed color photographs were taken in,**1. Photograph (A) was taken in indoor bath tab -, photograph (B) in open-air bath tab at the time of the fine sky and photograph (C) in open-air bath tab at the time of the cloudy sky. -- ph Eh-pH Pourbaix Diagram Eh-pH Krauskopf, +301 ph ORP Fig.. HS,, SO, - Sx Table. Table, The water chemistry of Kunimi and Kumanoyu hot spring waters. Sampling location Sampling Water Temp. ph ORP EC Alk + + date mv Sm meql Content/mg L +,,, Na K Ca Mg Cl SO. H, SiO- Kunimi-source Kunimi-open air Kunimi-indoor+ Kunimi-indoor, Kunimi-source Kunimi-open air Kunimi-indoor- Kunimi-indoor. Kumanoyu-source Kumanoyu-open air Kumanoyu-indoor,1-Oct-*/,0-Oct-*/,0-Oct-*/,0-Oct-*/,--Oct-*1,,-Oct-*1,,-Oct-*1,,-Oct-*1 +* -Oct-*/ +* -Oct-*/ +* -Oct-*/ /+40./40.,4. -34/.,4..14,.14. -141.142.*41..4+ 043+ 14,, 14+3 14+2 14,- 1413 1403 14/* 14,2 14.1 14., -/+ -/, -/3 -/3 -., -03 --1-0- -12-00 -2+ *4.1+ *4.-. *4.0- *4.0- *4./- *4.*- *4.,0 *4.,. *4+.* *4+,3 *4+,2.+4- -04, -342-241 -24, -/4* -141-04. 04/* /412 /421 3*3 20+ 3*3 3-/ 2/0 2,- 2-3 3,1 +*- 3340 304/ -+40,24, -+4. -/4/,24+,14-,04.,043 /4*0 /4-+ /4,. +,2 ++* +*. +*/ +,* 214. +,0 +,* +1- +12 +10 2.41 1+4+ 1343 1241 1-42 1/4/ 1043 104,,*4+ +240 +243,*/ +3-,*-,*+,/3,/,,/.,/0 1,43 2.4, 0.40,-1,,-,-/,-+,01,3-,0+,30,10 --+ -/1 +-/ 3,4-334, 334/ 2-4- 2*4* 2,42 2+4/ ++2 +*/ +*1 125

HS,-* nm Ellis and Golding +3/3 HS UV Fig. 0 HS,-* nm --+ UV-Vis + UV Fig. /,-* nm +30- +30-,/* nm, Table - The data of total Fe and Cu contents of Kunimi and Kumanoyu hot spring waters. Sampling location Sampling date Fe /ppm Cu /ppm Kunimi-source,1-Oct-*/ *4.0 *4*- Kunimi-open air,0-oct-*/ *4-- *4*- Kunimi-indoor+,0-Oct-*/ *4-1 *4*. Kunimi-indoor,,0-Oct-*/ *4.. *4*- Kunimi-source Kunimi-open air Kunimi-indoor- Kunimi-indoor.,,-Oct-*1,,-Oct-*1,--Oct-*1,--Oct-*1 *4+1 *4+* *4+0 *4*- *4*, *4*, *4*, *4*, Kumanoyu-source +* -Oct-*/ *4**- *4**+ Kumanoyu-open air +* -Oct-*/ *4**. *4**, Kumanoyu-indoor +* -Oct-*/ *4**- *4**, Fig.. The figure which plotted the data measured at the source of Kunimi (,**1) and Kumanoyu hot spring (,**/) on the ORP-pH diagram created by Krauskoph ( +301). Table. The data of H, S, HS content and Saturation Index (SI) for CaCO- of Kunimi and Kumanoyu hot spring waters. + + Sampling location Sampling date H, S/mgL HS /mgl SI (CaCO-) Kumanoyu-source Kumanoyu-open air Kumanoyu-indoor Kunimi-source,1-Oct-*/ /,41 1+42 *41+3 Kunimi-open air,0-oct-*/,/4+ 0,41 *42/+ Kunimi-indoor+,0-Oct-*/,/4+ //4+ *412- Kunimi-indoor,,0-Oct-*/,34. /343 *41,1 Kunimi-source,--Oct-*1-04/ 224* *43*/ Kunimi-open air,,-oct-*1 34.1 124- +4,2 Kunimi-indoor-,,-Oct-*1 34-+ 1*42 +4-1 Kunimi-indoor.,,-Oct-*1 +14/ 1+43 +4+. +* -Oct-*/ 04,/ +24/ *4.-* +* -Oct-*/ 34-3 -24+ *4/*1 +* -Oct-*/ 242- -.4* *4.21 126

0*,*+* Fig. / Absorption spectrum of the water colored in green after having left the water of source of Kumanoyu hot spring for a few days. HS Fig. 0 HS S O SO,,, -. +30- -** /** nm UV-Vis Fig. 1 Fig. 2,-* nm HS + Fig. 0 Change of absorption spectrum of the water colored in green after having left the water of source of Kunimi hot spring for a few days.,) and -) are the spectra of the water after having left it more for / and +/ days, respectively. + Fig. 1 Change of absorption spectrum of the water made by conduction H, S into the distilled water.,) and -) are the spectra of the water after having left it more for ++ and +0 days, respectively. 127

+ Fig. 2 Change of absorption spectrum of the water made by conduction H, S into the water after dissolving elemental sulfur in distilled water.,) and -) are the spectra of the water after having left it more for / and +/ days, respectively. Fig. 3 ESI-MS spectra of water colored in green after having left the water of source of Kumanoyu hot spring for a few days., x,-*,/* nm HS -** /** nm -** /** nm UV-Vis S + Fig. / Fig. 0 -** -/* nm, Sx --, ESI-MS *.*,/ mm, ESI Sx H HSx x 1 0 2 +* Fig. 3 ESI-MS 128

0*,*+* ESI-MS 1, Steudel and Eckert,,**- Sx -. -.+ CaCO - Table. SI SI SI* CaCO CaCO X -., *+. mm Figs. +* +- Fig. +*, Fig. ++ Fig. +,, Fig. +- Fig. +* - - Fig. +* Examples of SEM photographs of the substance on Nuclepore menbrane filter (*+. mm pore size) after filtering of the Kunimi hot spring water. (A) : Indoor bath tab + (,**/) ( //* ), (B) : Source (,**/) ( +*,***), (C) : Indoor bath tab, (,**/) ( +1, ***) and (D) : Open-air bath tab (,**/) (-*,***). 129

Fig. ++ Examples of SEM photographs with point analyses by EDX of the substance on Nuclepore menbrane filter (*+. mm pore size) after having filtered the Kumanoyu hot spring water. (A) : Source (,**/) (,/,***) and (B) : Open-air bath (,**/) ( +,***). Fig. +, Example of SEM mapping image with point Fig. +- Example of SEM mapping image with point analyses by EDX of the substance on Nuclepore analyses by EDX of the substance on Nuclepore menbrane filter (*+. mm pore size) after having menbrane filter (*+. mm pore size) after having filtered the Kunimi hot spring water. filtered the Kumanoyu hot spring water. -/, S x 130

0*,*+* : /1* nm nm - L + +/. g ORP -/* mv ph 1 Fig. 2 2* nm : Fig. +. Calorimetric data shown on the xy-chro- maticity diagram established by Commision In- PZ B ternationale d Eclairage (CIE) in +3-+. Photographs are (A) : distilled water, (B) : the water C containing polysulfide ion and (C) : the water added CaCO - (average particle size2* nm) Fig. +. into (B). /1* nm /0+ nm -0 Oscillatoria spp.. + //- /1, nm 131

, ph, ORP, ORP - UV-Vis,-* nm -** /** nm. ESI-MS HS x 1 0 2 +* ESI-MS, Sx x / 0 nm /1* nm /0, nm HSS, Sx *+. mm, ESI : Ellis, A. J. and Golding, R. M. ( +3/3) : Spectrophotometric determination of the acid dissociation constants of hydrogen sulphide. J. Chem. Soc. Part +, +,1 +-*. Gun, J., Modestov, A. D., Kamyshny, Jr. A., Ryzkov, D., Gitis, V., Goifman, A., Lev, O., Hultsch, V., Grischek, T. and Worch, E. (,**.) : Electrospray ionization mass spectrometric analysis of aqueous polysulfide solutions. Microchem. Acta, +.0,,,3,-1. +31+ :, +0 3* 31. +30- : 132

0*,*+* 2- /+- /+2. Kleinjan, W.E., de Keizer, A. and Janssen, A. J.H. (,**-) : Biologically produced sulfur particles and polysulfide ions. Top. Curr. Chem.,-*, +01 +22. Kleinjan, W.E., de Keizer, A. and Janssen, A. J.H. (,**/) : Equilibrium of the reaction between dissolved sodium sulfide and biologically produced sulfur. Biointerfaces,.-,,,2,-1. Krauskopf, K.B. ( +301 ) : Introduction to Geochemistry, p.,1*, International ed., McGraw-Hill Book, New York : Kogakusha, Tokyo. Ohsawa, S., Kawamura, T., Takamatsu, N. and Yusa, Y. (,**,) : Rayleigh scattering by aqueous colloidal silica as a cause for the blue color of hydrothermal water. J. Volcanol. Geotherm. Res., ++-,.30*.,**- : /. 0. +/,.. ++*. Ohsawa, S., Saito, T., Yoshikawa, S., Mawatari, H., Yamada, M., Amita, K., Takamatsu, N., Sudo, Y. and Kagiyama, T. (,**3) : Color change of lake water at the active crater lake of Aso volcano, Yudamari, Japan : is it response to change in water quality induced by volcanic activity? Limnology, DOI +*. +**1 /s+*,*+-**3-*-*.- 0.,**- : Steudel, R. (,**-) : Inorganic polysulfides S and radical anions S. Top. Curr. Chem.,,-+, +,1 +/,. Steudel, R. and Eckert, B. (,**-) : Solid sulfur allotropes. Top. Curr. Chem.,-*, + 13., n n 133