206ῌ῎ +,  st u+ vwxy, z{|' +3  2  0   +3  +,  .  Radioactivity of Sulfurous Sinter Depositfrom Tamagawa Hot SpringTakashi SAITO+, Takeyasu YAMAGATA, and Hisao NAGAI+The Institute of Natural Sciences, Nihon UniversityGraduate School of Integrated Basic Sciences, Nihon UniversityDepartment of Chemistry, College of Humanities and Sciences, Nihon University,

AbstractRadioactivities of several sulfurous sinter deposits from Tamagawa Hot Spring,Akita Prefecture, were investigated. Radioactivity of radium isotopes and the progenywas observed by nondestructive gamma-ray spectrometry. The activity ratio of ,,2Ra/,,0Ra tended to be lower, and that of ,,2Th/ ,,0Ra higher for the sample taken at a longerdinstance from the spring source, respectively. The micro crystals of hokutolite wereobserved by SEM-EDS in the residue of the sulfurous sinter deposit from which sulferwas removed.
On the assumption that the radioactivity source of sulfurous sinter deposit is derivedby the micro crystals of hokutolite, the formation age of the hokutolite and ,,2Ra/ ,,0Raactivity ratio of the hokutolite at the time of formation in Tamagawa hot spring wereestimated. The ,,2Ra/ ,,0Ra activity ratio of the micro hokutolite within the sulfuroussinter deposit agreed with the value of the sample taken from the surface of the knownage hokutolite.
Key words : Tamagawa hot spring, sulfurous sinter deposit, radioactivity, hokutolite,radium isotopes

῏῍!"#$%&'()*+,-. /0 123456789: /0;<=>?@ABCDEFGHIJKILM6NO:PQR STUVWXY  ,,0Ra, ,,2Ra 2Z[\]^2345_`abc: d: /012STUVWXY2345e ,,2Raῌ ,,0Ra f g]^hc);i=jk9:_ ,,2Thῌ ,,0Ra 2345eflm9: /0]^*+6nop=:qr.6 /1  ,**2 207 SEM-EDS  !" #$%&'()*+,- )#$%& ./01234 5674  89:;<3=$%&)89>?./01@ABC)D6E F GHD6I-./01@ABCJ 89:;KL$%&MNO,PQI-RS2TUVD6I-./01@ABC WXYZ[Z\ :   $%& ./01@AB+ῌ ῏ ῍ ῐ ῎]^_ `a$%J bc012./01)deVU4$%& fg-4hij(& Ba Pb SO. )ekl

V8974!

)L,-VU4 mng op+3-*

qr2st74./012J 0.uvw ,,0Ra xyz : +0** y {c01vw ,,2Ra xyz : /.1/ y ,,.Ra xyz : -.00 d <3=|}~01vw ,,-Ra xyz : ++.. d  . @AB)4) !-F2HI-VU4$%&@AB ,,0Ra4,,2274 23 $%&2J./01Ra )2st -,mng Saito , +30-,,0Ra,,2)I-4! )L,-VURa hvwW Fig. + 27 F Saitoand Nagai ,**1 J 89:;KL$%&MN./01@ABC ,,2Raῌ ,,0Ra )W67! HVU4 I,2 ,**/ J  O,4 $%&¡6 ¢3¢£) ¥F)¤U¦ )¤U! HVU4¦T! )L,-VU4 Saito , +30- J § ) 2st74#$%& Micro hokutolite 2Fig. + A part of decay chain of uranium and thorium series.

208    ,**0   ,,0Ra ,,2Ra  ,,2Th  !" : +.3+y #$%&'  ( &)*+*,-./*012*34ῌ5*6*789:;*34ῌ<=>?@(AB5&C DEFCGH+*'IJ 5*78K'LM$%789:;*0M5*34ῌ78KN'LM O (PQR*ST'JUVW῍'XYZ[\R]^ X _R`abcdefghij SEM-EDS 'klm,ῌ ῐ῍,ῌ+ ῏ ῒno ,**0 p 1 qrstuvwGHIJx?yz'{|x*C} no*IJ~*UC} Sinter A :  

U /* m C #ῌQ ~Sinter B : * RC T*#` ~Sinter C : * RC *#` ~&&C Sinter A IJIcx*'no Sinter B, C GHZ#IJx*'yz GH*noIJ~' Fig. , # Sinter A, B, C * C(¡) ,ῌ, ῐ῍ῑ῎no¢_,£¤'k¥<(  . g '¦§¤¨©ª£«*LM¬­®
 EURYSIS ¯«.°Z^±£²_³´µ¶¨·\¸C ,,0Ra ,,2Ra  ,,2Th *¹:;*±£Fig. ,Sampling localities of sulfurous sinter deposits from Tamagawa hot spring.

 /1  ,**2





209

Table + Target nuclides and the measurement progenies and gamma-rayenergy for gamma-ray spectrometryTarget nuclide

Half lifeRaRa,,2Th+0** y/41/ y+43+ y,,0,,2Measurementdaughter nuclide

Half life

Gamma-rayenergy (keV)

PbAc,+,Pb,042 m04+/ h+*40 h-/,3++,-3,+.
,,2Table , Concentrations and activity ratios of Ra and Th in sulfurous sinter deposit from Tamagawa hot springConcentration (Bq/g)

Activity ratio

SampleRaRa,,0Sinter A,,2Th

Ra/ ,,0Ra,,2,,2,,2Th/ ,,0Ra*432*4*,,+4.*4,+422*4*+,+43*4/+43,*4*.

Sinter B

No. +No. ,No. No. .

+4*,*4*,*412*4*,*411*4*,*413*4*,+34,*4,+-42*4,+-4-*4++-4-*4+042-*4*,04+2*4*,/43/*4*,/421*4*,+243*4.
+143*4.
+14,*4.
+043*4.

041-*4++1430*4+1141**4+014.1*4+/

Sinter C

No. +No. ,No. No. .

*4.0*4*+*4.3*4*+*4.1*4*+*4..*4*+

14*0*4*314-2*4*114*1*4*104,,*4*1.4*,*4*,.4/.*4*+.4+/*4*+-413*4*++/4,*4.
+.43*4+/4**4+/4+*4-2401*4,34+3*4+02413*4+/240/*4+0  !

"#$%&'() *+,-. /012,$3'. !456789: Table + $;<(SEM-EDS 3=>!&?+* g Sinter B  - molῌL+NaOH @AB ,** mL $C

D&C EFGHIJKL Na,SX MNOP&FQRS.T UVWX$0YZ[WXῌ\].^3'. _=>$`abc defghigj6789:Wkl X Wmnopqrstuvw xystz{ JSM-0-3*LA 3' C|s} ,* kV ~=>/01NWWm . ,,0Ra ,,2Ra /01 ,,2Th -ῌ ῎῍+!

 Table , $;<( . 45I8 Sinter A  Fig. - $. @ $? K5!IJKL/01 &'(_! ,**/ $0YO&'( Table , ! Fig. (Y? $? ,,0Ra ,,2Ra /01 ,,2Th ! 

-O&'' _?  ,**0 !^&'( .X($ ' ,,2Raῌ ,,0Ra $¤.¥¦&=>$/'&©?

¡¢ ,,2Thῌ ,,0Ra ,,2Ra *+0Y"#$%&''_!ªd.1 D¬ ,,2Ra ?®¯&?£C. ,,2Th *+§¨ ,,2Ra- ,,2Th «"#=>? ¬¨ o.T$­?¡¢ ,,2Th ?°8±²³´&?£C¥(?210Fig. -#$%

Typical gamma-ray spectra of a sulfurous sinter deposit from Tamagawa hot spring.

 &'()*+ +2,!- ,,0  Fig. .  Figure .  !" ,,2Ac  ,,2Ra ./012*344567
,+,Pb  ,,2Th

:; Table , ./089<0&'()*= <><$ ?@AB,!-CDEFGHI:% JKL$0MNOPGQRST UVWX YZ[\ ,,0 Ra]^_]^_,+.

`abcdPb 0 e

f6g : -.2, d 1h:ijk,,,Rn Saito ,**, 0 OPlmSUV ,,0Ra nopqrstu ,+.Pb`abcd4vw WXUV+5 ,,,Rn xUVz{:|} ~,,0Ray<!55 v4 :;  JKL,;:5 ,,0 Ra +ijk,,,

Rn xOPGQRSUV+|}k,?x%  ?v$ &'WXcd<4 `ak *312&'cd<4 ,,,Rn |}   Table -  MN,,0Rax no:; !"$%&'0&'¡0 ,,,Rn 0¢4Fig. . A part of gamma-ray spectrum of a sulfuroussinter deposit from Tamagawa hot spring (SinterA).
Storage times for +2 and ,,0 days are represented by a solid line and a dotted line, respectively.

 /1  ,**2

211

Table - Time after source preparaion and ,,2Ra/ ,,0Ra activity ratio of sulfurous sinterdeposits from Tamagawa hot spring sulfurous sinterSample

Time after sourcepreparation (day)Sinter A+,*3,+4-,.*,+40*./,+4-,.*,-4,*.0

Sinter B+,*/+34/+42+240*4.

+34/+42,*4**4.

Sinter C+,*2+/42+4/+/4**4.

+/42+4/+04+*4/

Ra/ ,,0Ra activity ratio,,2Ra/ ,,0Ra activity ratio*),,2*) Corrected for decay ! ,,,Rn "#$%&'()*+,- ./012345 ,,2 Raῌ ,,0 Ra 678+9,6-

:, ;< ,,,Rn "=>(?@ABCDEF5 ,,2 Ra ῌ ,,0 RaῑGH)*I,JK6LM

5NOPQ+RS FG,6-:, )E) Table - !RFG,NT!U῏VWX)* + YZ/012345,,2,** YZ- .
Raῌ ,,0 Ra [\]6^_`ab-cd)*eO ,,0 Ra EFfgh, ,,,Rn "./01"i;G<jk !ῌ;l*I* ῑGH)*I9ImVn)*I, mop!qrst uvwxy-6,,,

Rn "CDEFῑHh,z{Plate + SEM image of residual solid material in thesulfurous sinter deposit from Tamagawa hotspring.

6|}I )*~OTm"Q,.ῌ ῍῎!6 ,,0Ra ,,2Ra eN ,,2Th ")*I," F H8G*I,"+,,2Th 6 ,,26 ./01ERa EFfg)< -:,FG,m-  EF῍V)*FG<ῌkV SEM-EDS VI*op)< op8G<V Plate + !nh Plate + !n)< SEM !6 +* mm Z mm x῎"op8G< Saito +30-  ,**- 6῍ k!67")*I,mVv¡)*I,- ῌk  : - U῏ x῎ : + U῏ ¢g££¤V¥I ¦V Table . !§¨< ¢g£6©Viª῍«¬>01- x῎¢g£6­«®¯°-:, ±²F +33+  Takano and Watanuki +31, !N,¢g££¤¦6 BaO )* .1ῌ0+ῌ PbO )* +.1ῌ+.ῌ -:, Table - !§¨< Ba eN Pb i³ῐV«®k!´µh,G¶G /. ῌ /0ῌ +. ῌ +0ῌ 9O ·v]±²F +33+ ; Takano and Watanuki, +31, cd)<- u¸¹!*op8G< +* mm212

Table . Chemical composition of residual solid materials of sulfurous sinter deposits from Tamagawa hot springElement

Crystal +Crystal ,Crystal -Amorphousmaterial

OSi
SSrBaPb,.4,ND,/4+ND,-4.
ND+-4+*4+*.34*+-40++43*4*,/*4+,41+,41ND/343-043*41ND.241+/4,,40ND

Unit : w/w῍, ND : not detected!"#$%$% Micro hokutolite &'()*+,-(./012345-67601245-(8)9:32'; SEM-EDS &<=>-? SiO, @:+

ABC,DEF&G(8:H>7#H3IJK()G2L;M5-(NOPQRS&'; <=>-67?

,Th  ,,2Ra C,TUVWXY?Z&'(,,22L;M5-? ,,0Ra-,,2Ra [\] ,,2Th ^_`[\]WUabcd2\(C,`EF&G(8:H>7)eK() 01IJfg[\]IJhiPQRSjklDmRaῌ ,,0Ra no(p)3&G(,,2Okubo and Sakanoue +31/ +..++* y 3qr67(p)st67(3+*D *.++ Bqῌg ) +ῌ+** uv&';,,2Ra  ,-,Th :Ra D3 +. Bqῌg )G ,-,Th ,,0wxy& ,,0Ra \; ,,2Ra D3z{|7?owxy2[76 Th C,}~>-( Ra EF&G()*+6\7 012O,-,,,2ABZ45-67(& p-,AB245-(#RPZ*+,-(3 w27? *./῎+.* Bqῌg 01 . g 2 +* ppm RP4AB3 + g 6Z,,0Ra  -῍ C@7 ?36 + , eJK()*+6\7 5? PQRS[\]RS3AB&8)9:767@7p) Saito and Nagai ,**1 2\;st>-67(?o - eZJK(+῎- e3J;)*+,-(& 01IJfg[\]IJhiPQRSjklDm ,,2Raῌ ,,0Ra \26no(p)3&G( 3IJ6C,h t day IJh t *  ,,2RaYh Ra,,2Th D ARa, ATh,,,2Ra,,,2Th D ARaῌ*, AThῌ*, 01,,2Th  ¡¢ lRa, lTh )K() £,,2¤ ¡¥¦C,uv§3J;ARaARaῌ*ῌelRatῌAThlThῌARaῌ*ῌelRatelTht AThῌ*ῌelThtlThlRa῍῍ §2[76 3IJ?hi& ,,2Th qr@7)e67(& AThῌ** &'; ῍ §¨©ª , «¬­&G( ARa, ATh ®&'; lRa, lTh ¢&'(& p-,ῌ §) ῍ §2g t 276¯°)uv±;)@( /1  ,**2

213

Table / Estimated formation age for hokutolite and ,,2Ra/ ,,0Ra activity ratios of the hokutolite at the time of formation in Tamagawa hot springSample

Formation age (day)Sinter A

Ra/ ,,0Ra activity ratio,,23++,,.0*.0Sinter B

No. +No. ,No. No. .

.*2.
/-+0/--0/,00,+40*4/,+4-*4/,*40*4/,*4+*4/

Sinter C

No. +No. ,No. No. .

1+3+*13121.221,.2+34-*40+34.*4.
+34,*4.
+34,*4/lRa-.-*+*.day+ lTh3.3-+*.day+῍ ῍t+/+*ῌ῎lnῌ῎+lTh+./*lThlRa

ATh ῏῏ῐday+./*ῌARaῐ῍῍  t  ῌ  !"#$ %&'()*+%&'  ,,2Ra ,-./0, 1234 Table / ARaῌ* 56, %&'()7!89:;<:, =>?@AB --.8 9/CDEFG()EHI%&'/JKLMNOB@K.PQ R:BNSTEN>,UVWXEN>, MHI%&'()*YZ[\]^_` ,,2Raῌ ,,0Ra 8 ,* aG.AK +30*῎+33* 7 ()E()7!bc%&'()d*YZ[\]^_` ,,2Raῌ ,,0Ra e ,,.0῎,..- Saito and Nagai, ,**1f>e.AB/ῌ ῐῑ8 g/CDEh ()iJKLMHI%&'jkEN>,.lm,0ῌ ῎ ῍ ῏ῌῌnoE pM,

Vqr.s8YZ[\uvwYZ[\xqr

/yDiotEῌ:z{|}E~:8 %&'.lm,H3/

ῌ/#N%&'jk.o#,. %&'()*+YZ[\]^_`/ ()7!bc%&': oi%&'()d*YZ[\]^_`.Eῌΐ

8JKLMHI%&',.lm,ῒ

K>>Aw

214

SEM-EDSῌ ! "#$%&'()*῎῍῏ῌ+,-. /012 345 ,**0 : 67 8 9:);<=>?@A ,  B /3 CDEFFGHI ,2.
Okubo, T. and Sakanoue, M. (+31/) : Radioactive Disequilibrium of Thorium Series Nuclides inHot Spring Deposits, Geochem. J., 3, ,,+ῌ,,0.
Saito, N., Sasaki, Y. and Sakai, H. (+30-) : Radiochemical Interpretation on the Formation ofHokutolite, In Geochemistry of the Tamagawa Hot Springs, +2,ῌ+32.
Saito, T., Ohta, T. and Sato, J. (,**,) : Determination of Radium Concentration in Hot SpringWater with Cation Exchange Resin, J. Balneol. Soc. Jpn., /,, -ῌ++.

J, K ,**/ : 67LMNO PQRS T DEUVWXYZ XY[G  .* ,*-ῌ,*1.
Saito, T. and Nagai, H. (,**1) : Estimation of Growth Rate of Hokutolite from Tamagawa HotSpring, Akita, Japan., J. Radioanal. Nucl. Chem., ,1,, ..-ῌ..0.

\ ]^_ `abc d 2e +33+ : fg:hMNO iPjk  .+ ,*3ῌ,+0.
\ ]^_ ,**/ : lmMNOn =>opqrs tu B /2 CDEFFGHI,-.

vwxy +3-* : zW{|}~MNOPpP} .03 /2ῌ3-.

Takano, B. and Watanuki, K. (+31,) : Strontium and calcium coprecipitation with lead-bearingbarite from hot spring water, Geochem. J., 0, +ῌ3.

`abc ,**- : MNOL*< Proc. SITH,**-, -/0ῌ-/1.