AHW24-P01

Room:Convention Hall

Time:May 25 18:15-19:30

Stable isotopic ratio of atmospheric vapor in Hiratsuka, JapanTAKAGI, Kenta1∗ ; INOUE, Takayuki2 ; OOKI, Seigo2 ; OHBA, Takeshi2
1

Course of Chemistry, Graduate School of Science, Tokai University, 2 Course of Chemistry, School of Science, Tokai University

The origin of water vapor in atmosphere could be variable, for example, the water vapor at a specific point is transported froma distance or the vapor is generated from surface water near the specific point. If there is equilibrium between precipitation
and atmospheric vapor, the hydrogen and oxygen isotope ratios (δD and δ 18 O) of atmospheric vapor are plotted theoreticallyin meteoric water line. Recently, δD and δ 18 O of atmospheric vapor is used as a tracer for atmospheric water cycle, because
the water vapor is much ubiquitous than precipitation (Tsunakawa and Yamanaka, 2005). However, Japan has various waterresources. From this aspect, δD and δ 18 O of atmospheric vapor could be disturbed by several factors such as seasonal variationand difference vapor source of supply (Hiyama et al, 2008). In this study, we investigated the seasonal isotopic variation ofatmospheric vapor and precipitation. Then, we also examined surface water on ground and transpiration from leaves of plants,
as the candidates of atmospheric vapor sources.
Precipitation and atmospheric vapor were collected on the roof of a No.17 building at Shonan campus, Tokai University fromMay 2013 to Dec. 2014. Precipitation samples were collected based on the method described by Negrel et al. (2011) andYoshimura (2002). The duration of collection varied from hours to days. Precipitation samples were percolated through 0.2 µm
filter, and kept into a 100 ml low-density polyethylene bottle. Atmospheric vapor samples were collected by the cryogenic trap
cooled with ethanol-dry ice mixture (Tsunakawa and Yamanaka, 2005). The total number of precipitation and atmospheric vapor
samples were 142 and 90, respectively. The atmospheric vapor may be supplied by surface water on ground and transpirationfrom leaves of plants, therefore surface water samples were collected on 4 points (pond or river) near a No.17 building from Apr.
to Dec. 2014. Transpiration samples were collected at 6 points near a No.17 building from Aug. to Dec. 2014 by polyethylene
bag which covers leaves and twig over 1-4 days. Surface water and transpiration samples were percolated through 0.2 µm filter,and kept into a low-density polyethylene bottle. The total number of surface water samples was 6 in each points and the total
number of transpiration samples were 16. δD and δ 18 O of samples were measured by a Cavity Ring-Down Spectrometer analyzer(model L2120-i from PICARRO). Some data of rain water, which were sampled several times in a day, were processed to be theweighted average value.
Precipitation showed wide variations in δD and δ 18 O from -124.7 to +9.1 ‰ and -16.6 to -0.6 ‰, respectively. Atmosphericvapor also showed wide variations from -223.5 to -82.2 ‰ and -31.2 to -11.6 ‰, respectively. The δD-δ 18 O relationship ofprecipitation and atmospheric vapor were regressed by δD=8.5δ 18 O+17.4 (R2 =0.95) and δD=6.6δ 18 O-2.6 (R2 =0.92), respectively. The d-excess values (d=δD-8δ 18 O) of precipitation has a variation from -0.7 to 31.4 ‰. The d-excess of atmosphericvapor shows a definite seasonal trend within the range between 5.6 and 35.7 ‰. The isotopic compositions of atmospheric vapor
almost agreed to the calculated value from precipitation assuming isotopic equilibrium with the exception in May 2014, wherea significant difference between the observed and the calculated isotopic ratios. Such a composition seemed to be generated by
the completely evaporated vapor originating in precipitation (= bulk vapor). In Jun. 2014, the d-excess of atmospheric vapor wasdeviated from the seasonal variation. Such a deviation can be caused by the addition of evaporated vapor from local surface water.
The δD-δ 18 O plots of all sample suggested that atmospheric vapor was mainly composed by three kinds of vapor, namely, thevapor equilibrated with precipitation, the bulk vapor and the vapor evaporated from the local surface water near the observation
point.
Keywords: Precipitation, Atmospheric vapor, Stable isotope

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AHW24-P02

Room:Convention Hall

Time:May 25 18:15-19:30

Characteristics of water quality in groundwater near the coastal area at northern part ofFukushima Prefecture
YABUSAKI, Shiho1∗
1

Faculty of Symbiotic Systems Science, Fukushima University

The coastal area at northern part of Fukushima Prefecture suffered big damage by a tsunami generated in 11 March, 2011. Thegroundwater around these areas was affected by the tsunami. These areas were greatly affected by the accident of the nuclear
power plant, and the radioactive contamination of a plant, soil and farm products became serious problem. It is important to makeclear the groundwater flow in these areas because of considering the solution to the serious problem. The objective in this study
is to uncover the groundwater flow system and residence time of spring water and groundwater in the coastal area at northernpart of Fukushima Prefecture.
As a result of field survey, EC values of spring water and groundwater were under 30 mS/m in most sites. Almost site shows
lower than 7 of pH values, however, in several sites show higher than 7.5 of pH. The water temperature is from 13 to 18 degree
Celsius in almost site, but some site shows the lower than 12 degree Celsius. So, it is considered that the groundwater andspring water which show lower than 12 degree Celsius were recharged in the relative high altitude area. Water quality of shallow
groundwater is Ca-HCO3 type, but that of spring water and deep groundwater is Na-HCO3 type. Since the SiO2 concentrationof these spring water and deep groundwater is relatively high, it is expected that the residence time of these water are relativelylong.
The δ 18 O values show from -10 to -6 ‰ and δD values show from -65 to -35 ‰. The altitude effect in this area is -0.16 ‰/100
m of δ 18 O and -0.6 ‰/100 m of δD.
In future, we will analyze the 3 H, CFCs and SF6 , and will consider the residence time and groundwater flow system.
Keywords: Minamisoma City, Soma City, Namie City, water quality, stable isotopes, recharge area

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AHW24-P03

Room:Convention Hall

Time:May 25 18:15-19:30

Effects of mountainous water recharge to groundwater quality of alluvial fan
NAKAMURA, Takashi1∗ ; NISHIDA, Kei1 ; KAZAMA, Futaba1
1ICRE, University of Yamanashi

In this study, the hydrogen and oxygen stable isotopes (dD and d18O) and chemical compositions of environmental water wereemployed to identify the effects of mountainous water recharge for groundwater quality on alluvial fan.
The study area is Midaigawa alluvial fan, located in western Kofu basin on central Japan, which is formed by Raised-bed River
discharged from the mountain watershed.
The groundwater samples were collected from 25 deep wells (100˜300m) in June-2010, Novenber-2011 and Novenber-2012.
Those wells were located on Midaigawa alluvial fan and adjacent mountain. Four End-member mixing analysis using isotope
value and chemical compositions revealed spatial variation in the contribution ratios for various groundwater sources. This
presentation focused on groundwater recharge from mountain area to alluvial fan. It also found the relationship between contributions of mountainous water on groundwater and chemical composition.
Acknowledgment
This study was supported by the Kurita water and environment Foundation (No.14B063).
Keywords: Groundwater recharge, Alluvial fan, Isotopes, End-member mixing analysis, Mountainous water resource

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AHW24-P04

Room:Convention Hall

Time:May 25 18:15-19:30

Change of rainfall runoff processes with the erosion of the volcano body: a case study ofMt. Ontake
ASAI, Kazuyoshi1∗ ; TSUJIMURA, Maki2
1Geo-science laboratory, 2 University of Tsukuba

To clalify the change of rainfall-runoff processes with the erosion, long-term monitoring of stream-runoff and EC were conducted on two basins in Mt. Ontake.
Keywords: rainfall-runoff, Mt. Ontake, erosion, hydrograph separation, direct runoff, recharge rate

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AHW24-P05

Room:Convention Hall

Time:May 25 18:15-19:30

Helium isotopes in groundwaters from the middle and lower reaches of the Tone River,Japan.
MORIKAWA, Noritoshi1∗ ; YASUHARA, Masaya1 ; NAKAMA, Atsuko1 ; INAMURA, Akihiko1 ;TAKAHASHI, Masaaki11

Geological Survey of Japan, AIST

There exist three regions in the Kanto plain, central Japan, whose groundwater is characterized by a high Cl− concentration:(1) floodplains and deluvial uplands along the lower reaches of the Tone rivers (Ibaraki and Chiba Prefectures), (2) south-east
parts of the Gunma Prefecture along the middle reaches of the Tone rivers, (3) central parts of the Kanto plain, south east of theArea (2).
The high-chloride groundwaters from the central parts of the Kanto plain are characterized by the following features; (a)helium isotopic ratios (3 He/4 He) are relatively homogeneous with an end member of 0.8-1.1 x 10−6 , (b) helium-4 concentration
show positive correlation with chloride concentration (Morikawa et al., 2006). Morikawa et al (2014a) investigated the noble
gases in the deeper groundwaters (hot springs) in the central parts of the Kanto plain and the high-chloride groundwaters fromsouth-east parts of the Gunma Prefecture to elucidate the origin of water and chrolide component. Low 3 He/4 He ratios in thehot springs indicate that there is almost no interconnectivity between the high chloride groundwater and hot spring water aroundthese regions. In contrast, both 3 He/4 He ratio and correlative 4 He and Cl− concentration in the high-chrolide groundwatersfrom south-east parts of the Gunma Prefecture are similar to those in the groundwaters in the central part of the Kanto Plain.
They suggest that these groundwaters and their constituents are closely related to each other in their origin. Although there isno hydrogeological connectivity, groundwaters from some part of the lower reaches of the Tone river also show similar helium
isotopic ratios (3 He/4 He) and positive 4 He-Cl correlation (Morikawa et al., 2014b).
In this study, we further conducted complementary investigation for the groundwaters between the region of middle reach andlower one of the Tone River. Low Cl− with low 4 He groundwaters exist in this region. Combined with previous and presentresults, the groundwaters along the Tone River implies a mixture of young meteoric water and high chloride saline water bearing
with high 4 He which seems to be stagnant nature.
References: Morikawa et al. (2006) JPGU 2006, H121-004, Morikawa et al. (2014a) JPGU 2014, AHW25-12, Morikawa etal. (2014b) JAHS 2014, P18.

Keywords: Helium, Groundwater, Tone River, Kanto Plain, Chloride Ion, Noble Gas

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AHW24-P06

Room:Convention Hall

Time:May 25 18:15-19:30

Visualization of the deep-seated fluid ascending along the fault
NISHIYAMA, Nariaki1∗ ; TANAKA, Kazuhiro1 ; SUZUKI, Koichi2
1Yamaguchi University, 2 Central Research Institute of Electric Power Industry

1. Introduction
It is known that deep-seated fluid is highly saline water and includes gas. In addition, it is thought that fluid rises from thedeep part under the ground. Therefore it is thought that the deep-seated fluid has a big influence on environment of deep partgroundwater.
It is known that the groundwater mix deep-seated fluid derived from the slab, based on the result of geochemical analysis
at the inland from Northeast Yamaguchi to Southwest Shimane (Murakami and Tanaka, 2009). The most of these fluids spout
out at the surface of the ground. However, the fluid erupted from only the flowing borehole in Tokusa basin, Yamaguchi. Wecannot identify the deep-seated fluid if we don’t play drilling operation. Therefore, we cannot identify the fluid if we play field
investigation. And, distribution and flow of the deep-seated fluid is not known in underground.
I used the CSAMT method in this study in Tokusa Basin and tried visualization of the distribution of the deep-seated fluid
underlying underground.
2. Geological setting
The bedrock consisted of Late Cretaceous welded tuff and rhyolitic lava of Abu group in Tokusa Basin. Sediments of theQuaternary period cover the bedrock in the basin. Based on the result of gravity survey, thickness of the sediments are up toabout 200 m. The point of the fluid spout out from the borehole is three places in total and is distributed along Tokusa-Jifuku
fault dislocation estimated by NE-SW direction.
3. Results
Groundwater from the borehole : Electric conductivity of the groundwater is higher than general groundwater (211 mS/m,426mS/m and 1,310 mS/m). Water quality type are NaCl type or NaHCO3 type. Though the groundwater is an inland, it ishighly saline water.
The surface groundwater : Electric conductivity of the groundwater varied considerably ranging from 5.80 to 22.8 mS/m.
The water quality type of most surface groundwater is CaSO4 type. However, the groundwater of the north side of the fault tends
to be slightly higher Na+ and Cl- than the groundwater of the south side of the fault. Based on the result of groundwater level
survey, the surface groundwater flows to the river of the northwest direction across the fault from the southeastern direction.
Distribution of resistivity : Fig-1B shows the resistivity profile line X-X’. As a result, H1 was a high resistivity zone morethan 1,000 ?m and caught distribution of the bedrock. And, L1 and L2 were low resistivity zone less than 100 ?m and 30 ?m.
These low resistivity zone is the area where the deep-seated fluid gets mixed with.
4. Discussion
The area of L1 where low resistivity is distributed in Fig.1B is known that distribution Tokusa-Jifuku fault and the highly
saline groundwater is identified in the direct top. As a result, L1 that low resistivity zone catches the rise of the deep-seated fluid
along the fault. It is thought that the deep-seated fluid ascending along the fault penetrates in sediment, because low resistivity
zone L2 distributes the north side of the fault and the shallow groundwater of the NaCl type distributes. Namely, the deep-seatedfluid ascending Tokusa-Jifuku fault (L1) mixes the shallow groundwater in sediments, but the flow is regulated by the shallow
groundwater system which flows from the south of the Tokusa Basin to the north (L2). The plural ratio resistivity distribution
across Tokusa-Jifuku fault shows similar tendency to Fig.1B. Therefore, the deep-seated fluid distributes not only the place where
the fluid spouts out from the borehole but also in the range of at least 1.5km along the fault in the underground of the Tokusa
Basin.
When the fluid spouts out from the borehole in the place where the sediments distributes, it is necessary to considerate that thefluid may be widely distributed along fracture zone such as faults in the underground.

Keywords: Deep-seated fluid, CSAMT method, Tokusa-Jifuku fault

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AHW24-P06

Room:Convention Hall

Time:May 25 18:15-19:30

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AHW24-P07

Room:Convention Hall

Time:May 25 18:15-19:30

Secular change of stable carbon isotopic ratio in groundwater samples during their storage
in laboratory
TAKAHASHI, Hiroshi1∗ ; HANDA, Hiroko1 ; MINAMI, Masayo2 ; ARAMAKI, Takafumi3 ; NAKAMURA, Toshio2
1

Geological Survey of Japan, AIST, 2 Center for Chronological Research, Nagoya University, 3 National Institute for Environmental Studies
Carbon isotope is a useful tracer in order to identify carbon sources and behavior in the fields of biogenic and geochemical
processes. However, the isotopic change during the storage in sample bottles until the measurement sometimes occurs owing
to carbon exchange between DIC and atmospheric CO2 , biogenic activity and/or carbonate mineral reactions (deposition anddissolution). The present study examined the secular change of carbon isotopic compositions, 13 C/12 C and 14 C/12 C, of DIC inwater samples.
The water samples examined are surface seawater (RICE-W01), hot spring water (RICE-W03: high salinity and high DIC,
W04: high salinity and low DIC), shallow groundwater (RICW-W05: low salinity and low DIC), deep groundwater (RICE-W06:
low salinity and low DIC), and RO water prepared by dissolving chemical regent (RICE-W07: low DIC, W08: high DIC). The
carbon isotopic measurements were carried out on the samples which storage periods ware 860 days for W01, 560 days for
W03-W06, and 480 days for W07 and W08.
Secular changes of δ 13 C ranged from -5.4 ‰ to -0.2 ‰. The large isotopic change might be caused by decomposition ofbiogenic carbon in water samples, since the Keeling Plot showed the biogenic features of δ 13 C of added carbon. The storage examination suggested that some water samples did not change the δ 13 C values widely for years. The biogenic activity is prevented
by regent addition to water samples. Commonly HgCl2 or NaN3 is used, but it is hard to use them for groundwater samples
because sampling filed is not situated in the chemical controlled site. The present study confirmed that isotopic change reduced
by NaOH instead of poisonous materials.
The materials of storage bottles are also influenced the secular isotopic change. The present study compared the δ 13 C valueand 14 C concentration among the glass, PAN plastic and PP plastic bottles. The δ 13 C value was relatively constant for all bottles,
while the 14 C concentration was clearly different. The contamination of modern carbon was detected for PP plastic bottle.
This work was supported by the Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research C (No.
26340017): Radiocarbon Intercomparison on Chemical Experiments, Water series (RICE-W).

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