Bull. Volcanol. Soc. Japan
Vol. 48 (2003) No. 1, pp. 27῍33

ArticleMercury Concentrations in Fumarolic Gas Condensates and
Mercury Chemical Forms in Fumarolic Gases
ῌCase Study on Satsuma῍Iwojima Volcanoῌ
Hayao S6@6BDID῎, Shun-ichi FJ?>I6῎, Takashi TDB>N6HJ῎ and Katsuro AC6O6L6῎(Received, April 10, 2001; Accepted November 30, 2002)
The mercury concentrations in fumarolic gas condensates collected from volcanic areas in Hokkaido,
Miyazaki, and Kagoshima Prefectures, Japan, were investigated. Mercury concentrations ranged from 0.12 to 135
mglῌ1 in 44 collected samples. It was found that there was a positive correlation between mercury and chloride
concentrations in fumarolic gas condensates collected from Satsuma῍Iwojima Volcano, Kagoshima Prefecture. It
was considered that the mercury in fumarolic gas was discharged in the form of mercury (I or II) chloride.
However, the results from mercury chemical equilibrium calculations for the vapor in fumarolic gases indicatedthat mercury was discharged mainly in the form of metallic mercury vapor.

1. Introduction
Particular attention is devoted to the study ofgeothermal ﬂuids, fumarolic gases and geothermal
waters on conducting a geothermal survey. Mercury
is a highly volatile element in its both elemental andcompound forms and its presence in fumarolic gases
can be directly linked to volcanic activity. Hence,
mercury in volcanic gases can convey information
about nature of magmatic gases. The estimates of
volcanic mercury ﬂux have previously been done bysome investigators (Cadle, 1980; Unni et al., 1978;
Phelan et al., 1982; Anderson, 1975) from Mount St.
Helens, giving a range for mercury ﬂux from 3 to 900
Mg/yr. Several studies have been carried out inJapanese volcanoes and geothermal areas in order toestimate the volcanogenic mercury contribution to
the atmosphere.
Noda (1983) has previously reported concentrations of mercury in fumarolic gas condensates fromvolcanic areas in Japan. Fukuzaki et al. (1983)
reported mercury emissions in fumaroles, Minamijigokudani, Mt. Myoko. Nakagawa (1984; 1985)
estimated the background levels of mercury in theatmosphere of the geothermal areas of Japan. The
fumarolic gases analyzed by Noda (1983) and Nakagawa (1984; 1985) were of low temperature 100῍ or
῎ Department of Earth and Environmental Sciences,
Faculty of Science, Kagoshima University, 1῍21῍35
Korimoto, Kagoshima-shi, Kagoshima 890῍0065,
Japan.
Corresponding author: Hayao Sakamoto
e-mail: sakam@sci.kagoshima-u.ac.jp

less. However, they have not reported on the mercury in high-temperature fumarolic gases.
The objective of the present study is to determine
the mercury concentrations in fumarolic condensatesfrom some Japanese volcanoes in which we collected
the fumarolic gas by chance, and also to elucidate thechemical forms of the mercury in the fumarolic gas
discharges. To this end, the concentrations of mercury and chloride in fumarolic gas condensates were
determined. And the relationships between thevolatile constituents in these condensates were investigated with particular attention on Satsuma῍
Iwojima Volcano. The overall fumarolic contribution of mercury to the atmosphere from all Japanese
volcanoes will be reported in the future paper.
2. Sample Collection and Analytical Methods
Prior to the sampling, the gas collector and bottles
used for sampling were immersed in 3 M nitric acidfor two weeks and thoroughly washed with ultrapure water in order to avoid mercury contaminationfrom the sampling equipment. The sampling equipment used in the collection is shown schematically in
Fig. 1. The fumarolic gas condensate samples werecollected by inserting a quartz or teﬂon tube into
fumarole. The fumarolic gas enters through the tube
and condensed into an externally cooled ice water
condenser attached to the tube. The tube tip was
ﬁlled with quartz wool to prevent contamination ofsolid particles from fumarole. A mini suction pump
was attached at the end of the condenser in order tosuck non-condensable gases. In the case of fumarolicgas condensates collected from Satsuma῍Iwojima

28

Hayao S6@6BDID, Shun-ichi FJ?>I6, Takashi TDB>N6HJ and Katsuro AC6O6L6

Fig. 1. Schematic diagram of collection equipment.
A: Fumarole, B: Quartz wool, C: Quartz or
teﬂon tube, D: Condenser, E: Cooling ice water,
F: Suction pump

volcano, 78% to 88% of total mercury was collectedby this sampling method. These condensates were
preserved in polypropylene containers. Analyses
were carried out in less than 2 weeks after the
sampling.
Mercury analyses were conducted by the dithizone
extraction method using chloroform (Kamada andSakamoto, 1979) and also by measuring mercury
vaporized by reduction using tin (II) chloride atwhich the mercury was concentrated with a porous
gold collector (Sakamoto and Kamada, 1981; Sakamoto et al., 1988) followed by atomic absorption
spectrometry. The mercury vapor that evolved fromthe collector upon heating was analyzed by cold
vapor atomic absorption spectrometry. The mercury
was analyzed using a Nippon Instruments Co. Mercury System S-1 and a Shimadzu-MA AtomicAbsorption Spectrophotometer. The detection limitof mercury concentration (based on S/N῎2) of theatomic vapor produced by reduction was found to beapproximately 0.4 ngl῍1. In order to conﬁrm thereproducibility of the analysis, standard samples containing 15.0 ngl῍1 of mercury were analyzed ﬁvetimes repeatedly. The average value and relative
standard deviation were found to be 2.95 and 1.37%,
respectively (Sakamoto et al., 1997).
The chloride analyses were done by the Vollhard
method and by colorimetry using thiocyanic acidmercury (Utsumi, 1952). Both methods were applied after the hydrosulﬁde ions and sulﬁte ions wereoxidized to sulfate ions using hydrogen peroxide.
3. Results and Discussion
3ῌ1 Sampling locations and analytical results
Sampling locations of fumarolic condensate samples are shown in Fig. 2. The location numbers,

Fig. 2. Map of sampling locations of fumarolicgases condensates.
1, 2: Meakandake, 3: Asahidake, 4, 5: Tokachidake, 6ῌ8: Usuzan, 9, 10: Tarumaesan, 11ῌ16:
Ebino, 17ῌ19: Kirishima, 20ῌ23: Yamagawa,24ῌ44: SatsumaῌIwojima

sampling localities and the results of mercury concentration analyses are shown in Table 1, together
with fumarolic outlet temperature, pH, and chloride
concentrations.
The mercury concentrations in fumarolic gas condensates, based on 44 samples collected during theperiod 1973ῌ2000, range from 0.12 to 135 mgl῍1.
The found values are at the level which are almost
equal to the values by Nakagawa (1984; 1985) andFukuzaki et al. (1983). The previous measurementsof mercury in geothermal waters from several volcanic areas in Japan (Sakamoto et al., 1988) showed
concentrations from 0.0026 to 0.0898 mgl῍1, suggesting that the concentration of mercury in fumarolicMercury Concentrations in Fumarolic Gas Condensates and Mercury Chemical Forms in Fumarolic Gases

29

Table 1. Mercury concentrations, outlet temperature, pH and chloride ion concentrations in fumarolic gas condensates.
No.

Sampling location

Date

Temp. ῏pH

Hg mgl῍1 Cl῍ mgl῍1

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44

Meakandake 1st fumarole (Hokkaido)
Meakandake 1st fumarole (Hokkaido)
Asahidake (Hokkaido)
Tokachidake 62 fumarole (Hokkaido)
Tokachidake 62-1 fumarole (Hokkaido)
Usuzan 1 fumarole (Hokkaido)
Usuzan 1 fumarole (Hokkaido)
Usuzan 1 fumarole (Hokkaido)
Tarumaesan B fumarole (Hokkaido)
Tarumaesan B fumarole (Hokkaido)
Ebino Shiratoriiwoyama (Miyazaki Pref.)Ebino Shiratoriiwoyama (Miyazaki Pref.)Ebino Shiratoriiwoyama (Miyazaki Pref.)Ebino Shiratoriiwoyama (Miyazaki Pref.)Ebino Shiratoriiwoyama (Miyazaki Pref.)Ebino Shiratoriiwoyama (Miyazaki Pref.)Kiirishima Iwodani (Kagoshima Pref.)Kiirishima Iwodani (Kagoshima Pref.)Kiirishima Iwodani (Kagoshima Pref.)Yamagawa Unagi (Kagoshima Pref.)Yamagawa Unagi (Kagoshima Pref.)Yamagawa Fushime (Kagoshima Pref.)Yamagawa Fushime (Kagoshima Pref.)SatsumaῌIwojima Kamanokuchi (Kagoshima Pref.)SatsumaῌIwojima Nakanoe (Kagoshima Pref.)SatsumaῌIwojima Nakanoeshita (Kagoshima Pref.)SatsumaῌIwojima Arayama (Kagoshima Pref.)SatsumaῌIwojima Arayama (Kagoshima Pref.)SatsumaῌIwojima Arayama (Kagoshima Pref.)SatsumaῌIwojima Kuromoe (Kagoshima Pref.)SatsumaῌIwojima Kuromoe (Kagoshima Pref.)SatsumaῌIwojima Kuromoe (Kagoshima Pref.)SatsumaῌIwojima Kuromoe (Kagoshima Pref.)SatsumaῌIwojima Kuromoeshita (Kagoshima Pref.)SatsumaῌIwojima Kuromoe (Kagoshima Pref.)SatsumaῌIwojima Kuromoechuudan (Kagoshima Pref.)SatsumaῌIwojima Oukabeshita (Kagoshima Pref.)SatsumaῌIwojima Oukabeshita (Kagoshima Pref.)SatsumaῌIwojima Ouhati (Kagoshima Pref.)SatsumaῌIwojima Ouhati (Kagoshima Pref.)SatsumaῌIwojima (Kagoshima Pref.) No. 1
SatsumaῌIwojima (Kagoshima Pref.) No. 2
SatsumaῌIwojima (Kagoshima Pref.) No. 3
SatsumaῌIwojima (Kagoshima Pref.) No. 4

Aug. 24. ’88
Aug. 27. ’89
Aug. 22. ’88
Aug. 23. ’88
Aug. 25. ’89
Jun. 27. ’85
Aug. 18. ’88
Aug. 22. ’89
Nov. 13. ’88
Aug. 24. ’89
Aug. 19. ’73
Nov. 19. ’88
Feb. 15. ’95
Oct. 19. ’95
Nov. 19. ’95
Oct. 07. ’00
Oct. 19. ’95
Nov. 19. ’95
Oct. 07. ’00
Aug. 17. ’95
Oct. 04. ’00
Jun. 21. ’94
Oct. 04. ’00
Aug. 22. ’73
Aug. 24. ’73
Aug. 23. ’73
Aug. 23. ’73
Aug. 22. ’88
Aug. 22. ’88
Aug. 25. ’73
Aug. 25. ’73
Aug. 24. ’88
Aug. 24. ’88
Oct. 23. ’90
Oct. 23. ’90
Oct. 24. ’90
Aug. 24. ’73
Aug. 24. ’73
Oct. 20. ’90
Oct. 22. ’90
Oct. 19. ’00
Oct. 19. ’00
Oct. 21. ’00
Oct. 21. ’00

163
256
137
450
328
648
579
557
168
210
245
96
105
97.1
96.4
96.6
97.2
97.2
98.1
101
99.0
105
99.7
235
465
109
850
189
783
710
108
105
705
216
702
110
224
138
876
872
105
112
818
267

0.60
0.80
1.28
0.59
0.65
1.40
1.59
1.62
1.28
1.24
3.00
3.20
2.26
3.27
3.14
4.13
5.30
5.33
4.07
2.81
3.91
5.30
6.59
0.70
0.72
0.62
0.70
0.76
0.84
0.69
0.72
0.55
0.85
0.66
0.73
0.66
0.68
0.65
0.53
0.66
0.75
0.75
0.73
0.62

47.8
71.9
4.2
30.7
73.2
19.5
2.9
13.8
60.9
57.0
0.90a)
0.60
0.30
0.58
0.44
0.15
2.28
1.43
0.69
0.24
0.21
0.34
0.33
0.80a)
1.8a)
135a)
5.0a)
46.2
3.2
0.62a)
0.71a)
96.8
4.8
1.0
1.0
0.12
0.62a)
0.53a)
1.2
1.8
0.20
0.20
1.70
2.70

a)

6,240
2,200
1,450
3,510
2,380
3,000
973
744
3,230
3,300
567
0.8
7.5
1.0
1.4
1.2
21.5
32.6
5.4
0.7
0.2
0.8
0.1
16,60012,20030,10012,80020,20014,10014,00013,90019,80018,40016,50014,40020,40015,10017,40013,30013,40012,40015,10013,47016,500Dithizone chloroform extraction

gas condensates was about 1,000 times higher thanthat in geothermal waters. This is supported by thefact that mercury fractionates more readily into thevapor phase, and hence occurs in greater abundancein fumarolic gases.
3ῌ2 Correlation between various constituents
Table 2a shows the correlation coe$cients of fum-arolic outlet temperature, pH, and the concentrations of mercury and chloride ions among the completed data set of 23 samples from various fumaroles
in Japan, excluding the data from SatsumaῌIwojima.
Among those variables, signiﬁcant positive correlation is found only between mercury and chloride (r῎ῌ0.75), whereas, negative correlation is found be-30

Hayao S6@6BDID, Shun-ichi FJ?>I6, Takashi TDB>N6HJ and Katsuro AC6O6L6Table 2. Correlation coe$cients between temperature, pH, mercury and chloride ion concentrations in fumaloric gas condensates.
a)

all fumaloric gas condensate samples excluding
SatsumaῌIwojima.
T

pH

Hg

Cl῍

T
pH

῍0.56

Hg

0.23

῍0.67

Cl῍

0.38

῍0.73

0.75

(n῎23)b)

fumaloric gas condensate of SatsumaῌIwojima.
T

pH

Hg

Cl῍

T
pH

0.18

Hg

῍0.34

῍0.38

῍

῍0.48

῍0.23

Cl

Fig. 3. Relationship between mercury and chloride
ion concentrations in fumarolic gas condensates.
ῐ: Hokkaido
῏: Ebino, Kirishima
ῑ: Yamagawa
ῒ: SatsumaῌIwojima

0.82(n῎21)

tween pH and chloride (r῎῍0.73), and pH-mercury (r῎῍0.67). Table 2b shows the correlation
coe$cients of among the completed fumarolic data
set of 21 samples obtained from SatsumaῌIwojima.
A signiﬁcantly high correlation (r῎ῌ0.82) is also
found between mercury and chloride ions as shownin Fig. 3, however correlations for other variable
pairs as between mercury and temperature are notsigniﬁcant.
The positive correlation may be explained by thefollowing assumptions; 1) The mercury in the fumarolic gas is discharged in the form of mercury chloride(HgCl2 or Hg2Cl2) or 2) There is only one source ofvolatile components, and the dilution of mercury as
well as other components is occurring on the way
from the source to the vents of SatsumaῌIwojima.
However, the former possibility from the chemical
equilibrium calculation has been denied as describedin section 3ῌ4. Our data indicate that higher concentration of mercury was observed in the condensate oflower temperature fumarolic vents and in more
acidic chloride-rich condensates. The fact suggeststhat the dissolution of metallic mercury occurs easilyin acidic chloride-rich conditions.
The mercury emission route is not simply one.
However, mercury in the fumarole region may occur
independently from chloride, in the form of metallic
mercury vapor from fumarole (Braman and Johnson, 1974; Sakamoto et al., 1989).

Fig. 4. Relationship between pH and mercury concentrations in fumarolic gas condensates.
ῐ: Hokkaido
῏: Ebino, Kirishima
ῑ: Yamagawa
ῒ: SatsumaῌIwojima

3ῌ3

Relationships between mercury, pH andtemperature
A negative relationship between mercury and pH
in the fumarolic condensates is shown in Fig. 4. Thisobservation indicates that mercury concentration
was high in the samples with low pH, particularly inthose excluding SatsumaῌIwojima.

Mercury Concentrations in Fumarolic Gas Condensates and Mercury Chemical Forms in Fumarolic Gases

This suggests that acidic gas components and metallic mercury were mutually dissolved in condensates depending on acidity. The negative correlation
between mercury concentration and pH is especially
supporting in the light of the work by Varekamp andBuseck (1986) who showed that mercury is very
soluble as mercury chloride complexes in oxidizing
chloride rich solutions. Hence, our data indicatethat more mercury was detected in more acidic chloride-ions-rich condensates from lower temperature
vents. Fig.5 shows the relationship between mercury concentration and outlet temperature. Mercury
concentration decreases with increasing temperature
as shown in Fig. 5. This fact may be due to thesampling procedure inadequacy that mercury might
have been released as metallic mercury vapor in hightemperature fumarolic gas. Hence, low mercury
concentration was detected in the high temperaturecondensates.
3ῌ4 Chemical forms of mercury in fumarolicgases
The mercury tends to be rich in fumarolic condensates with high chloride ion collected from Satsumaῌ
Iwojima Volcano. Mercury may be discharged infumarolic gases in the form of metallic mercury
vapor, and partly of mercury(I or II) chloride. Krauskopf (1957) calculated the composition of volcanic gases and the vapor pressures of various materials
at 600ῐ in order to explain the concentration of
metallic elements in mineral deposits. The author
reported that the vapor pressures of metallic elements and its chlorides are high. The present authors examined the chemical form of mercury involcanic gases by calculating the stability of various
species of mercury and mercury compounds basedon the typical conditions of fumarolic gas discharge.
It is suggested that the following reaction between
mercury and hydrogen chloride may occur:
Hg (g)ῌ2 HCl (g)῏HgCl2 (g)ῌH2 (g) (1)1
Hg (g)ῌHCl (g)῏HgCl (g)ῌ H2 (g)(2)2
The equilibrium constant of reaction (1) can be
expressed with the partial pressure of each component in the reaction:
KP1῏

PHgCl2 PH2PHg P[HCl]2

where KP1 is the pressure at equilibrium constant,and PHgCl2, PH2, PHg and P[HCl]2 are the partial pressures. KP1 is also deﬁned as:
ln KP1῏῍DG/RT
where DG is the change in Gibbs free energy, R is thegas constant, and T is the temperature of the fumarole.
It is considered for fumarolic gas to be in chemical

31

Fig. 5. Relationship between temperature and mercury concentrations in fumarolic gas condensates.
ῒ: Hokkaido
ῑ: Ebino, Kirishima
ΐ: Yamagawa
῕: SatsumaῌIwojima

equilibrium when it was discharged from magma(Shinohara et al., 1993; Ohba, 1997).
The fumarolic gases of SatsumaῌIwojima can also
be assumed to be in chemical equilibrium at 1,000 K(Matsuo et al., 1974). Then, ln KP1 can be estimatedto be ῍12.79 (KP1῏2.8῎10῍6) based on data from
JANAF Thermochemical Tables by Stull and Prophet (1971). Using this value of KP1 and the concentration of H2 and HCl gas (H2: 0.12%, HCl: 0.71%) of
the volcanic gases of SatsumaῌIwojima reported by
Matsuo et al. (1974), the fumarolic temperature isreasonably estimated as 932 K (659ῐ). Therefore,
the analytical data of Matsuo is assumed there being
in the equilibrium state based on reaction (1), and so
relative ratio of PHgCl2/PHg has been calculated to be
1.2῎10῍4. This result suggests that under this condition the relative amount of elemental Hg is very
high compared to that of HgCl2. The ratio of PHgCl/
PHg for reaction (2) has been calculated in a similarmanner, found to be 2.8῎10῍2 in fumarole of SatsumaῌIwojima, which also indicates that the vapor
pressure of Hg is higher than that of HgCl (PHg῔
PHgCl). The equilibrium constant of reaction 1) and2) decreases with low temperature. Therefore, it canbe seen that mercury does not exist as mercury (I,II) chloride, but rather occurs in the form of metallic
mercury vapor in the volcanic gases of Satsumaῌ
Iwojima.
The volcanic gases have local features on the

32

Hayao S6@6BDID, Shun-ichi FJ?>I6, Takashi TDB>N6HJ and Katsuro AC6O6L6chemical composition. Therefore, there is a di#erence at the mercury concentration because the acidity of the fumaloric gas condensate is di#erent.
The discharge of hydrogen sulﬁde and steam
occurs in addition to the discharge of hydrogenchloride in fumarolic gases. These gases react withmercury, and the most probable chemical form isthought to be mercury (II) sulﬁde or mercury (II)oxide. Then, [HgS]/[Hg] and [HgO]/[Hg] hasbeen calculated to be 6.2῍10ῌ5 and 1.4῍10ῌ8, respectively in fumarole [T῎1,000K, H2O῎983 (l/m3, H2῎0.9 (l/m3), H2S῎1.4 (l/m3)] of Satsumaῌ
Iwojima, based on KT values at arbitrary temperature by Symonds and Reed (1993), where KT is theequilibrium constant, at the temperature, T, and[Hg], [HgS] and [HgO] are concentration of gas
species.
Mercury is transported as the elemental gas, which
is at least ﬁve orders of magnitude more abundant
than the main subordinate species, including HgS,
HgCl2, HgO, HgCl, HgBr2, and HgH (Symonds andReed, 1993). We previously reported that inorganic(HgO, HgS, HgCl2, HgI2) and organic mercury(CH3HgCl, C2H5HgCl) compounds could be completely vaporized by heating and mercury only exist
as metallic mercury vapor at temperatures over
550῏ (Sakamoto et al., 1991). Hence, metallic
mercury vapor is the main species of mercury in the
fumarolic gases of SatsumaῌIwojima.
4. Conclusions
The concentrations of mercury in fumarolic condensates collected from Hokkaido, Miyazaki, andKagoshima Prefectures in Japan were investigated.
The results can be summarized as follows:
1) The concentrations of mercury in fumaroliccondensates ranged from 0.12 to 135 mglῌ1 in 44
samples.
2) A positive correlation was found between
mercury and chloride concentrations in fumarolic gas condensates.
3) A negative correlation was observed between
pH and mercury concentrations in condensates,suggesting that acidic gas components and metallic mercury were both dissolved in more
acidic chloride-rich condensates.
4) The possibility that mercury (I or II) chloride
exists in volcanic gases from SatsumaῌIwojima
volcano was rejected.
5) Chemical equilibrium calculations for SatsumaῌIwojima suggested that mercury in fumarolic gases was discharged as metallic mercury
vapor into the atmosphere from fumaroles.

Acknowledgements
The authors wish to express their thanks to Dr.
Takejiro Ozawa (previous professor of Saitama University) and Dr. Minoru Yoshida (previous professor of Tokyo Institute of Technology) for theirhelpful advices.
Thanks are also due to our many colleagues withwhom we have discussed the problems of analyticalmethods.
References
Anderson, A. T. (1975) Some basaltic and andesitic gases.
Rev. Geophys, Space Phys., 13, 37ῌ55.
Braman, R. S. and Johnson, D. L. (1974) Selective absorption tubes and emission technique for determination ofambient forms of mercury in air. Environ. Sci. Technol.,8, 996ῌ1003.
Cadle, R. D. (1980) A comparison of volcanic with otherﬂuxes of atmospheric trace gas constituents. Rev. Geophys. Space Phys., 18, 746ῌ752.
Fukuzaki, N., Tominaga, Y., Kifun, I., Tamura, R., Maruyama, T., Shinoda, Y. and Horii, K. (1983) Mercury
emission from Minamijigokudani, Mt. Myoko accompanied with fumarolic activity and its inﬂuence. Chikyuu Kagaku, 17, 10ῌ15 (in Japanese).
Kamada, M. and Sakamoto, H. (1979) Determination of
cadmium, copper, lead, zinc and mercury in fresh water,
sea water, sediment and vegetable. Spec. Pro. Res. Det.
Con. Envir. Poll., 1, 156ῌ160.
Krauskopf, K. B. (1957) The heavy metal content of magmatic vapor at 600῏. Econ. Geol., 52, 786ῌ807.
Matsuo, S., Suzuoki, T., Kusakabe, M., Wada, H. andSuzuki, M. (1974) Isotopic and chemical compositions of
volcanic gases from SatsumaῌIwojima, Japan. Geochem.
J., 8, 165ῌ173.
Nakagawa, R. (1984) Amounts of mercury discharged toatmosphere from fumaroles and hot spring gases in geothermal areas. Nippon Kagaku Kaishi, 709ῌ715 (in Japanese).
Nakagawa, R. (1985) Amonts of mercury discharged toatmosphere from fumaroles in geothermal areas of Hokkaido. Nippon Kagaku Kaishi, 703ῌ708 (in Japanese).
Noda, T. (1983) Geochemical prospecting method using
mercury as indicator. Geothermal Energy, 8, 229ῌ244 (inJapanese).
Ohba, T. (1997) Chemical equilibrium in high temperature
volcanic gas. Chikyu Kagaku, 31, 99ῌ110 (in Japanese).
Phelan, J. M., Finnegan, D. L., Ballantin, D. S., Zoller, W.
H., Hart, M. A. and Moyers, J. L. (1982) Airborne
aerosol measurements in the quiescent plume of mountSt. Helens: September, 1980. Geophys, Res. Lett., 9, 1093ῌ
1096.
Sakamoto, H. and Kamada, M. (1981) Determination ofultratrace amounts of mercury in environmental samples.
Nippon Kagaku Kaishi, 32ῌ38 (in Japanese).
Sakamoto, H., Kamada, M. and Yonehara, N. (1988) The
contents and distributions of arsenic, antimony, and mercury in geothermal waters. Bull. Chem. Soc. Jpn., 61,
3471ῌ3477.

Mercury Concentrations in Fumarolic Gas Condensates and Mercury Chemical Forms in Fumarolic Gases
Sakamoto, H., Tomiyasu, T. and Yonehara, N. (1989)
Determination of ultratrace amounts of mercury in atmosphere and its distribution. Rep. Fac. Sci. Kagoshima
Univ. (Math., Phys. and Chem.), No. 22, 159῍169.
Sakamoto, H., Tomiyasu, T. and Yonehara, N. (1991)
Elimination of interference by iodide determination ofultratrace amounts of mercury by heating evaporationgold amalgamation-cold vapor AAS. Nippon Kagaku
Kaishi, 1632῍1637 (in Japanese).
Sakamoto, H., Taniyama, J. and Yonehara, N. (1997)
Determination of ultra-trace amounts of total mercury
by gold amalgamation-cold vapor AAS in geothermal
water samples by using ozone as pretreatment agent.
Anal. Sci., 13, 771῍775.
Shinohara, H., Giggenbach, W. F, Kazahaya, K. and Hedenquist, J. W. (1993) Geochemistry of volcanic gases
and hot springs of Satsuma῍Iwojima, Japan. Following
Matsuo, Geochem. J., 27, 271῍285.
Stull, D. R. and Prophet, H. (1971) JANAF Thermochemical Tables, NBS, 520, 561.

33

Symonds, R. B. and Reed, M. H. (1993) Calculation ofmulticomponent chemical equilibria in gas-solid-liquid
systems: calculation methods, thermochemical data, andapplications to studies of high-temperature volcanic gaseswith examples from Mount St. Helens. Am. J. Sci., 293,
758῍864.
Unni, C., Fitzgerald, W. F., Settle, D., Gill, G., Ray, B.,
Patterson, C. and Duce, R. (1978) The impact of volcanic emissions on the global atmospheric cycles of sulfur,
mercury and lead. EOS. Trans. Am. Geophys. Union, 59,1223.
Utsumi, S. (1952) A new colorimetric method for thedetermination of chloride using mercury (II) thiocyanate
and iron (III) ammonium sulfate. Nippon Kagaku
Zasshi, 73, 835῍841 (in Japanese).
Varekamp, J. C. and Buseck, P. R. (1986) Global mercury
ﬂux from volcanic and geothermal sources. Appl. Geochem., 1, 65῍73.
(Editorial handling Jun-ichiro Ishibashi)

噴気孔ガス凝縮水中の水銀含有量と噴気孔ガス中の水銀の化学形
ῌ薩摩硫黄島火山をケ῏ススタデイとしてῌ

坂元隼雄῎藤田俊一῎冨安卓滋῎穴澤活郎

日本の北海道ῌ 南九州の火山地帯の噴気孔から採取した噴気孔ガス凝縮水中の水銀濃度を測定した῍ これらの火山地帯には高温の噴気孔ガスの放出を伴いῌ 噴気孔ガスや凝縮水の採取が可能なものがある῍ 特にῌ 鹿児島県の薩摩硫黄島火山は噴気孔温度が 800῔ にも達するものがある῍ 同火山の噴気孔ガス凝縮水 21 試料中の水銀濃度は 0.12ῐ
135 mglΐ1 であった῍ またῌ 噴気孔ガス凝縮水中の水銀と塩化物イオン濃度の間には高い正の相関 ῑ相関係数 0.82ῒ があることが見つかった῍ このことはῌ 1) 噴気孔ガス中の水銀が塩化水銀の形で放出されている῍ 2) 揮発成分の源は単独でῌ 源からの距離に応じてガス中の水銀濃度が希釈を被っているなどῌ いくつかの可能性が考えられる῍ しかしῌ
熱力学的なデ῏タを用いた化学平衡の計算から噴気孔ガス中の水銀の化学形はῌ 1) の可能性は否定された῍ またῌ 噴
気孔温度との相関性がないことなどから水銀の放出ル῏トが単純に一つでないことが考えられる῍ 一方ῌ 噴気孔ガス
中の水銀は金属水銀蒸気の形で放出されていることが示唆された῍