CO5-1

Size Distribution and Concentration Change of Antimony in the
Atmospheric Aerosols at Sakai, Osaka

N.Ito, A.Mizohata , R Okumura1 and Y Iimura1

5.00E-4
4.50E-4

Sb 120214-0221

4.00E-4

Radiation Research Center, Osaka Prefecture University,
1Research Reactor Institute, Kyoto University

3.50E-4
3.00E-4
2.50E-4
2.00E-4
1.50E-4
1.00E-4
5.00E-5
0.00E+0

Particle size range(μm)

Fig.1 Size distribution of Sb in aerosols collected at
Sakai,0214-0221 in 2012.

average and standard deviation, 2.8 ±1.9 ng/m3 ,min=0.5
ng/m3 , max=24 ng/m3. This value indicate that mean
inhalation of Sb per day is about 0.06 mg.
Monthly changes(mean, sdev., min.,max.) of daily
concentration are shown Fig.3 . Months in highconcentration are Jan.(3.4ng/m3), Oct.(3.5ng/m3), Nov.
(3.6ng/m3) and lowest on May(2.0ng/m3). Maximum
concentration of daily change in 2007 were observed on
September 30th. On this day we observed highconcentration in bromine(Br), suggesting the source offume in high concentration might be waste burning ofplastic that contain flame-proofing compound.
120
100

Frequency

60
40
20
0
<1

Dec 11-18 0.57

3.3

5

0

D50:Central diameter TC:Total Concentration

Month in 2007

From the result of concentration change in dailycollected(in 2007) samples we have obtained
concentration frequency distribution(Fig.2), showing
mostly frequent in range, 1-3ng/m3. And we have got theFig.3 Monthly changeof Sb in aerosols
collected at Sakai, 2007.

27018- 83 -

Dec

2.3

Nov

0.67

Oct

Oct 9-16

10

Sep

1.2

Jul

0.69

Aug

Aug 7-14

Jun

1.3

Max

Apr

0.64

6<=

15

May

Jun 5-12

5<= <6

Min

Feb

1.7

0.68

4<= <5

Mean
20

Jan

Apr 3-10

3<= <425

Concentration(μg/m3)

1.7

2<= <3

Fig.2 Frequency distribution for daily concentrationsof Sb in arosols collected at Sakai,2007.

D50(μm) TC(ng/m3)

Feb 14-21 0.94

1<= <2Concentration range(μg/m3)

Table 1 Central diameter and total concentration of Sbcollected by 9 particle size separation at Sakai in 2012.
Period(2012)

Sb in 2007

80

Mar

Antimony is a metal element, of which symbol Sb;
atomic number 51;atomic weight 121.76;melting point
630.5℃. It is used in alloys with lead in battery plates
and flame-proofing compound. Antimony(Sb) is toxic bysmall amount (100mg) into body. As it exist naturally inthe soil we get it as food contamination from which Sb isabsorbed into the body by 0.002-1.mg per day. Also theairborne particulate matter, aerosol in the atmosphere
contain antimony as the fume from burning of the waste
matter. This suggest that the daily inhaling of Sb fromambient atmosphere could influence our health. To
estimate the effect of Sb to our health ,here we report thesize distribution and the concentration( mean andvariation) and monthly concentration change.
The analyzed samples are size-separated aerosols andnon size-separated aerosol. The size-separated samples
have been collected with 9-size particle size ranges in 1
weak sampling period. The non size-separated samples
have been collected daily on membrane filter in 24h
sampling period. The sampler of both samples are locatedat Osaka Prefecture University, at Sakai.
The element of the samples were analyzed by neutron
activation analysis using KUR. The Analysis condition
for Sb are , Irradiation : 2 hours in Pn2 1MW, detectionof gamma ray : 124Sb 1661kev.
From the analyzed results the size distribution of Sb in
atmospheric aerosol can been seen as mostly
concentration distribute in very fine range , <0.43μm(Fig.1). The central diameter and concentrations ofsamples collected in 2012 are described on table 1.

CO5-2

Characteristics of Synthetic Calcite Thermoluminescence Studied for
Paleoenvironmental Reconstruction of East Asia

N. Hasebe, K. Miura1 and M. Ogata1
Institute of Nature and Environmental Technology, Kanazawa University
1
Graduate School of Natural Science and Technology,
Kanazawa University
INTRODUCTION: Luminescence dating observes thenatural accumulated radiation damage caused by radioisotopes such as U and Th as the form of glow after stimulation by heating or lightening. Thermally stimulated
luminescence from calcite shows strong red emission.
However, thermoluminescence dating of calcite is lesspopular because of some unknown problems; e.g., sensitivity change of calcite occurred through repeated heatingof samples, possible anomalous fading, difference incharacteristics of luminescence response against different
kinds of radiation (e.g., gamma-ray, beta-ray, alpha-ray,and X-ray). When thermoluminescence characteristics
of calcites are examined using natural occurring calcite,
their response to the various radiations depends on minor
chemistry (Fe, Mg, Mn and Sr). In this study, calcites

RESULTS: Calcite/quart ratios in dose estimate byluminescence were different among samples. However,ratios by beta-ray and by gamma- rays are more or lessconcordant (Fig. 1). When Calcite/quartz ratios by
gamma dose is plotted against Mn concentration, theyshow negative correlation (Fig. 2). Thermoluminescence characteristics of calcite is controlled by the Mn
impurity. Therefore, measurement of Mn concentration isinevitable for calcite thermoluminescence dating.

with controlled impurity concentrations were synthesized and analyzed to evaluate relationship between multiple impurity concentration and thermoluminescence properties quantitatively, together
with natural calcites.
EXPERIMENTS: Calcite were synthesized from sodium carbonate (>99.8wt%) and calcium chloride (>95wt%). Iron (II) chloride (>99.0-102.0 wt%), magnesium
chloride (>98.0wt%), and manganese chloride (>99.0wt%) were added at different levels to produce calciteswith different amount of impurity. Chemical compositionof resultant calcite were measured by LA-ICP-MS, andthe results were reported in KURRI progress report 2014.
Gamma irradiation was carried out at the 60Co gamma
irradiation facility at Kyoto University Research Reactor.
Alpha and beta ray irradiations were carried out withdisc-type 241Am and 90Sr source, respectively. Given
doses by Gamma and beta irradiation were estimated byquartz irradiated together with synthesized calcite. A
given dose by alpha irradiation was estimated by alphatrack counting. Then luminescence emission from calcite was measured by the luminescence reader MOSL-22,
and dose was estimated by the external x-ray source,
whose dose rate is calibrated as 0.1 Gy/sec with quartz.
This measured dose on calcite was compared to the givendose on quartz, and the ratio (calcite/quartz) was calculated for each irradiation (gamma, beta). Results on alphairradiation will be reported later.

27024- 84 -

Fig. 1. Relationship between calcite/quartz ratios
by beta and gamma irradiation.

Fig. 2. Calcite/quartz ratios by gamma irradiation
are plotted against Mn concentration.

CO5-3

Study of Earth and Planetary Matters by Thermoluminescence

Okayama University of Science
INTRODUCTION: Induced TL (thermoluminescence),
the response of a luminescent phosphor to a laboratory
dose of radiation, reflects the mineralogy and structure of
the phosphor, and provides valuable information on themetamorphic and thermal history of meteorites. Thermal
metamorphism causes the production of feldspar, themajor TL phosphor in ordinary chondrites, by the devitrification of feldspathic mesostasis. TL sensitivity normalized by Dhajala chondrite was measured at around 150 oCor 80 oC in the induced TL intensity. Primitive chondritesof petrologic subtype ≦ 3.4 with coefficient of varia-tions ( as a percentage of the mean) over 50%, of
fayalite in the olivine have low TL sensitivities under 0.1.
The TL sensitivity was usually used to determine petrologic subtype of unequilibrated ordinary chondrites [1].
On the other hand, the TL sensitivity decreases 10-foldafter shock-loading to 25-32 GPa [2], and terrestrial
weathering makes the TL sensitivity decrease 16-fold at
maximum in Antarctic chondrites [3]. Then these secondary altered chondrites were reported to have low TL
sensitivities, equivalent to primitive chondrites [4]. Until
now, the induced TL of ordinary chondrites has beenmeasured above room temperature. Last fiscal year, wepreliminarily measured low temperature TL from liquid
nitrogen temperature of twenty-one Asuka ordinarychondrites under 0.1 in TL sensitivities. This time wemeasured low temperature TL of additive two Asuka ordinary chondrites, A881397 (LL3.3) and A881236 (remarkably shocked). Also this time, we also measured
induced TL of unshocked and artificially shocked terrestrial feldspars, Minas Genas albite, Shiga albite and Niigata plagioclase, to investigate the shock effects. This
year, there is no request from NIPR to determine subtype
because samples, judged to be unequilibrated, became alittle. Then we didn’t try to measure new chondrites.

1400

TL Intensity (cps)

1200
1000

A881397 (LL3.3)
A881236 (H)

800
600
400
200
0
-200 -150 -100

-50

0

50

100

150

200

250

300

350

Temperature (oC)Fig.1. induced TL glow curves of A881397 (LL3.3) and aremarkable shocked chondrite of A881236 (H).

RESULTS: Fig.1 shows TL glow curves of a primitive
ordinary chondrite of A881397 (LL3.3) and remarkableshocked chondrite of A881236 (H). There were also two
peaks around -120 and -80oC lower than room temperature. However, we could not find the qualitative tendency
in induced TL glow curves in all twenty-three chondrites.
Induced TL of terrestrial feldspars, Minas Genas albite,
Shiga albite and Niigata plagioclase, showed very highintensity. Shocked samples showed relatively less intensity than unshocked samples. However, we unfortunately
couldn't find clear difference in the induced TL glow
curves between the unshocked and shocked terrestrial
feldspars. Fig.2 shows induced TL glow curves of unshocked and artificially shocked Shiga albite.

1400000
Unshocked

1200000

TL Intensity (cps)

K. Ninagawa, Y. Arima, R. Kenemaru and H. Nishido

Shocked1000000
8000006000004000002000000-200 -150 -100

-50

0

50

100

150

200

250

300

350

Temperature (oC)Fig.2. Induced TL of unshocked and artificially shocked
Shiga albite.
ACKNOWLEGEMENTS: Over twenty years, wehave measured induced TL of 407 Antarctic unequilibrated ordinary chondrites, Yamato 242 chondrites (LL3:30, L3: 113, H3: 99), Asuka 163 chondrites (LL3: 39, L3:
48, H3: 76) and ALH 2 chondrites (L2:, 2), which TL
analysis has been requested from NIPR, under the Visiting Researcher’s Program of the Research Reactor Institute, Kyoto University We have found 50 samples to beprimitive chondrite under ≦3.4 in them. This time wefinished to apply to this program. We would like to thankto not only staffs in the Research Reactor Institute, who
has supported us, but also all staffs in the Research Reactor Institute, Kyoto University.
REFERENCES:[1] Sears et al., Proceedings of Lunar and Planetary Science 21 (1991) 493-512.
[2] Hartmetz et al., Proc. 17th Lunar Planet. Sci. Conf. (J.
Geophysical Research), 91, (1986) E263-E274.
[3] Benoit and Sears, J. Ge-ophys. Res., 104, (1999)
14159-14168.
[4] K. Ninagawa et al., Antarctic Meteorite Research, 15(2002) 114-121.

27046- 85 -

CO5-4

Possible Removal of Tritium by Reaction of Magnesia and Water with Tritium

H. Hashizume, A. Uehara1, S. Fukutani1, F. Fujii and T.
An-do
Carbon composites group, National Institute for Materials Science
1
Research Reactor Institute, Kyoto University
INTRODUCTION: Characteristics of tritium water(HTO) are almost the same as water (H2O) and deuterium
water (D2O or HDO). The slight difference of the characteristics (e.g. the boiling temperature and electrolysisetc) have been used to fraction three waters. It was recently reported that manganese oxide adsorbed T+ [1].
However, it is still difficult to fraction the three waters.
Magnesium is one of the main elements composed of theearth. Magnesium oxide (MgO) easily reacts with watermolecules and magnesium hydroxide (Mg(OH)2) is produced, immediately. Additionally, if MgO is placed in
the air, MgO will react with water molecules and become
Mg(OH)2 [2]. The mineral name of Mg(OH)2 is brucite.
Brucite is produced by weathering of a mafic rock withother clay minerals on the earth’s surface. Mg(OH)2
was dehydrated at about 300 °C [3]. Recently, there aresome reports about the dehydration of Mg(OD)2 by the
X-ray or the neutron diffraction with the heating system.
The temperature of the dehydration was about 330 °C [4,5]. Although the temperature is not certain, the dehydration temperature of Mg(OD)2 was higher than that ofMg(OH)2. When MgO reacts with HTO, the reaction
rate and dehydration temperature of Mg(OT)2 might bedifferent from those of Mg(OH)2.
We investigated that the reaction rate of Mg(OT)2 is different from that of Mg(OH)2, as a first step.
EXPERIMENTS: We used MgO (light and heavy) to
be on the market. MgO (light) and (heavy) means a fineparticle and a coarse particle, respectively. We prepared
six glass bottles with stopper. In every three bottles, 1 gof MgO (light) and 2g of MgO (heavy) were put, respectively and 10 cm-3 of water with HTO was added insix bottles. These bottles are left for about 1, 4 or 24 h.
After the purpose reaction time, suspension was filteredby 0.2 µm of a disposable filter. We diluted 0.1 cm-3 ofsupernatant by 20 cm-3 of the liquid scintillator. The
tritium concentration of each sample was measured by ascintillation detector (Packard, Liquid Scintillation Analyzer).
RESULTS: When the tritium concentration of supernatant is smaller than that of the initial solution, moreamount of HTO reacts with MgO than that of H2O. If
the tritium concentration of supernatant is larger than thatof the initial solution, H2O will be preferred to HTO in
the reaction with MgO. In the case of the similar tritium
concentration of the initial solution and supernatant, almost the same amounts of HTO and H2O react withMgO.
The tritium concentration of supernatant is shown in Table 1. For MgO (light), the tritium concentration decreased for 1 and 4 h after MgO contacted with waterwith HTO. The removal ratio was about 5.1%. After
24 h, the tritium concentration of supernatant was almost
the same as that of the initial solution. The removal
ratio was about 1.5 %. If MgO contacts with water with
HTO for a few hours, the reaction of HTO with MgOmight be quicker than that of H2O. MgO might reactwith slightly more HTO than H2O in water for 4 h. After the synthesis of brucite, the exchange reaction would
occur between T+ or H+ in brucite and H+ or T+ in water.
The exchange reaction might achieve the equilibrium for
24 h. The tritium concentration of supernatant after 24h might be similar to that of the initial solution
For MgO (heavy), we used 2g of MgO, because it was
expected that the reaction of MgO and water with HTO
would be slow. After 4 h contact, the tritium concentration of supernatant was a smaller than that of the initialsolution. The ratio of 2.4 % of T+ decreased from thesolution. This removal ratio was smaller than that ofMgO (light). Since MgO (heavy) is a coarse particle,
MgO (heavy) would not sufficiently react with waterwith HTO. The removal ratio of MgO (heavy) would besmaller than that of MgO (light). In 24 h, the removal
ratio was about 1.9 %. The tritium concentration ofsupernatant in MgO (heavy) and the initial solution isalmost the same in the case of MgO (light). Probably,
T+ or H+ in brucite will be exchanged for H+ or T+ in water.
Table 1 Change of the tritium concentration in supernatant by the contact time of MgO and water with tritium.
MgO(light) MgO(light) MgO(light)
time (h)1424concentration (Bq) 522066
522440541768
removal ratio (%)
5.12
5.05
1.54
MgO (heavy) MgO (heavy) initialtime (h)424concentration (Bq) 533224
539834550232
removal ratio (%)
3.09
1.89
REFERENCES:[1] H. Koyanaka & H. Miyatake, Separation. Sci. Tech.,
50, (2015) 2142-2146.
[2] H. Hashizume, J. Soc. Inor. Mater. Jp., 19, (2012)247-252.
[3] I. Halikia & A. Economacou, Int. CHem. Kinet. 25,(1993) 609-631.
[4] H. Xu et al. Phys. Chem. Miner., 40, (2013) 799-810.
[5] T. Nagai et al., Ann. Meeting Miner. Sco. Jpn. (2012)
3.

27053

- 86 -

CO5-5 Application of Neutron Activation Analysis to Micro Gram Scale of Solid Samples
S. Sekimoto, N. Shirai1and M. Ebihara1
Research Reactor Institute, Kyoto University
1
Graduate School of Science, Tokyo Metropolitan University

INTRODUCTION: Instrumental neutron activation
analysis (INAA) is often used in cosmochemistry, where
meteorites are the objects for INAA. Chondritic meteorites (chondrites) and iron meteorites contain relatively highcontents of Co and Ir compared with those in the earth
crust. As Co and Ir have high sensitivity in INAA, they canbe good markers for the identification of such
extraterrestrial materials. In NAA of chondrites, a few tens
mg of specimen is commonly used. For such a case, a few
hundred μg kg-1 of Ir and a few hundred mg kg-1 of Co canbe reliably determined. When an extremely small size(e.g., micro gram) of samples such as micrometeor-ites
recovered on the Earth surface and tiny particles re-turned
from extraterrestrial asteroids are to be analyzed by INAA,
the conventional INAA procedure used for a few tens mg
is not suitable. For such tiny samples, neu-tron irradiation
with high neutron flux and long irradia-tion time (namely,
high neutron dose) is required. Re-cently we havepresented the INAA procedure for micro gram scale ofsolid samples [1]. In this report, the degree of increase in
isotopic abundance induced by neutron irradiation is
described in detail.
RESULTS: As INAA is a nondestructive method of elemental analysis, the same sample once subjected to INAA
can be reused for different analytical purposes. For such acase, effects caused by neutron irradiation are of concern.
Major concerns are the induced radioactivity and the increase in isotopic abundance including the production of
long-lived radioactive nuclides. Scientifically, the lattercase is important by far and, therefore, is considered here.
In order to make the evaluation of degree of the increase in
isotopic abundance meaningful, used are the data from theexperiment [2], where 1.66 mg of a tiny grain from theasteroid Itokawa was irradiated by neutrons under thecondition (19 h-irradiation, th: 8.2 × 1013 n cm-2 s-1, f:
3.9 × 1013 n cm-2 s-1, and 5MW-operation). Assuming theelemental composition of bulk LL chondrite [3] for thisgrain, the number of produced nuclides with neutron irradiation was calculated based on the Monte-Calro simulation code (MVP 2.0) [4] and the reaction cross section
data (JENDL-4.0) [5]. Both stable and unstable (radioactive) nuclides could be produced and the result is summarized in Table 1. In calculation, the position of control rod,
temperature of the reactor core, and the combustion rateof nuclear fuel were all taken into consideration, because
the neutron irradiation of the experiment [2] was performed near the reactor core and, therefore, these factors

27058

- 87-

affect the neutron energy spectrum. The produced nuclides in Table 1 are grouped into stable nuclides (21Ne,
22
Ne and 38Ar) and long-lived radioactive nuclides (36Cl,
26
Al and 10Be). These nuclides are typical cosmogenic
nuclides and radionuclides produced by nuclear reactions
triggered by cosmic rays and commonly detected in extraterrestrial materials like meteorites.
In Table 1, the calculated values are compared withnumbers of corresponding nuclides observed in extraterrestrial samples. For stable nuclides (of noble gases),measured values for a different Itokawa grain are given
for comparison [6]. It is well acknowledged that noble
gases are extremely sensitive in mass spectrometry. As
seen in Table 1, calculated values and measured values in
the Itokawa grain are mostly comparable for all threenuclides. For long-lived radionuclides, concentrations in
the Gold Basin L4 chondrite (a shower sample,
UA-1188) [7] are given for comparison in Table 1. These
data were obtained by accelerator mass spectrometry. The
measured values are smaller or much smaller than thecalculated values, with the difference varying by an order
to six orders of magnitude. Evidently the reuse of neutron-irradiated samples should not be allowed for noble
gas mass spectrometry and accelerator mass spectrometry
for the study on noble gas nuclides and long-lived radioactive nuclides, respectively.
Table 1 Production of some cosmogenic nuclides from1.66 g of LL chondrite by neutron-induced reaction in
INAAa
Targetnuclides
24

Mg
Mg
37
Cl

25

35

Cl
K
27
Al
13
C
39

a

Number of
Number of
Produced
nuclidesnuclides(original)
Stable nuclides (noble gas)-production
21
Ne
1.58 × 108
1.15 × 107
(n,)
22
7
Ne
5.21 × 10
3.49 × 108
(n,)
38
6
Ar
7.97 × 10
1.78 × 107(n,), Radioactive nuclides-production
36
Cl
2.53 × 109
9.06 × 102
(n,)
36
Cl
3.24 × 107
9.06 × 102
(n,)
26
5
(n,2n)
Al
1.30 × 10
3.73 × 103
104Be3.03 × 10
2.07 × 103(n,)Reaction

Produced
nuclidesSee text for detail.

REFERENCES:[1] S. Sekimoto et al., J Radioanal Nucl Chem, 307(2016) 1757-1764.
[2] M. Ebihara et al., Science, 333 (2011) 1119-1121.
[3] J.T. Wasson and G.W. Kallemeyn, Phil Trans R Soc A.
325 (1988) 535-544.
[4] Y. Nagaya et al., JAERI Report, 1348 (2005)1-388.
[5] K. Shibata et al., J Nucl Sci Technol, 48 (2011)1-30.
[6] K. Nagao et al., Science, 333 (2011) 1128-1131.
[7] K.C. Welten et al., Meteorit Planet Sci, 38 (2003)
157-173.

CO5-6

Chemical Variations of Miller Range 07710 (L4) Collected in the Ice atMiller Range, Antarctica

N. Shirai, S. Sekimoto1 and M. Ebihara
Department of Chemistry, Tokyo Metropolitan University
1
Research Reactor Institute, Kyoto University
INTRODUCTION: Most of meteorites are currently
collected from cold and hot deserts. As these meteorites
may have resided on the Earth’s surface, they have experienced variable degree of terrestrial weathering. Terrestrial weathering obscures petrographic and chemical features, leading to misclassification and misunderstandingof geochemistry and cosmochemistry of these meteorites.
In addition, misinterpretations probably result from sampling effect [e.g., 1] A large data set for chondrites wereobtained by using 250-300 mg of sample [e.g., 2]. This
amount of sample is not enough to obtain representative
chemical compositions [1]. Therefore, we examine howterrestrial weathering and sampling problem affectchemical classification by using Miller Range (MIL)
07710 (L4) which was collected in the ice at Miller
Range, Antarctica.
EXPERIMENTS: Eight different aliquots were takenfrom MIL 07710 and carefully ground in an agate mortar.
Eight powder samples were analyzed by using INAA and
IPAA at the Kyoto University Research Reactor Institute(KURRI). Neutron irradiations were successively perfomred two times (10 s and 4 hrs irradiations). For IPAA,
we used a linear electron accelerator at KURRI. Electrons
were accelerated by the linear accelerator to about 20
MeV.
RESULTS: Twenty seven elements could be determinedby using both INAA and IPAA. MIL 07710 was grouped
into L4 based on petrological and mineralogical studies[3]. The homogeneity of chemical compositions wasfound to be less than 10% (1σ; n=8) for most lithophileelements analyzed, In contrast, the heterogeneity exceeding 10% was found in siderophile (Co, Ni, Os, Ir and Au)
and chalcophile elements (Se). This observed heterogeneity is considered to be due to sampling problem and/or
terrestrail weathering. We investigated how this heterogeneity affect chemical classification of this meteorites.
Fe/Mn and Fe/(Fe+Mg) ratios of eight different aliquotsof this meteorite are plotted in Fig. 1. As seen in Fig. 1,
two samples weighing about 1 g fall within the field of L,
while Fe/Mn and Fe/(Fe+Mg) ratios for other samples
with having less than 0.6 g fall in the ranges of L and LL.
Eight samples display a positive correlation between
Fe/Mn and Fe/(Fe+Mg) ratios. Such a trend can be explained by different modal abundances of metal and/or
terrestrial weathering of metal. Jarosewich [4] comparedmajor element abundances of fall meteorites with thoseof find meteorites from Antarctica and found that total Fe
contents of Antarctic H chondrites are lower than those offall H chondrites, but that total Fe contents of Antarctic L

and LL chondrites cannot be distinguished from those offall L and LL chondrites. Therefore, terrestrial weathering could not explain such a positive correlation seen in
Fig. 1. Fe/Mn and Fe/(Fe+Mg) ratios for mixtures ofmetal and olivine, and metal and low-Ca pyroxene were
calculated, and the calculated results are shown in Fig.1.
Different modal abundances of metal can explaine observed positive correlation among eight samples. It is
concluded that metal is heterogenous distributed in sample weight less than 0.6 g.

Figure 1. Fe/Mn vs. Fe/(Fe+Mg) diagram for ordinary chondrites.
Solid and dash lines represent mixing between metal [7] and low
Ca-pyroxene [8], and metal [7] and olivine [8]. The proportional contributions of metal are shown as percentages among the mixing lines.
Parentheses in sample position represent homogenized mass.

Siderophile element abundances are also useful forclassification of ordinary chondrites [2]. Siderophile element abundances for most MIL 07710 samples analyzed
in this study do not fall within the any range of ordinarychondrites. It is well known that sulfide and metal are
more susceptible to terrestrial weathering than silicate [5]and that some Antarctic chondrites show fractionatedabundance patterns for chalcophile and siderophile elements [6]. Therefore, observed scattering of siderophileelement are attributed to terrestrial weathering.
REFERENCES:[1] J. R. Haas and L. A. Haskin, Meteoritics, 26 (1991)
13-26.
[2] G. W. Kallemeyn et al., GCA, 53 (1989) 2747-2767.
[3] Antarctic Meteorite NewsLetter 33 (2), September
2010.
[4] E. Jarosewich, Meteoritics, 25 (1990) 323-337.
[5] J. L. Gooding, GCA, 50 (1986) 2215-2223.
[6] H. Huber et al., GCA, 70 (2006) 4019-4037.
[7] P. Kong and M. Ebihara, GCA, 61 (1997) 2317-2329.
[8] T. L. Dunn et al., Meteoritics & Planet. Sci., 45(2010) 135-156.

27061- 88 -

A study on Evaluation of Radioactive Cesium Behavior in Fukushima

INTRODUCTION:
After the Fukushima Nuclear Power Plant (FNPP) accident in March of 2011, radioactive cesium 137 (137Cs)
was deposited over a large area in eastern Japan. Most of
the 137Cs remained in environmental soils and sediments,
because of its 30-year physical half-life and strong adsorptive properties. A portion of the 137Cs within thesesoils and sediments was transported downstream withsuspended solids (SS). Additional sites affected by 137Cs
appeared downstream of the contaminated watershed(Sato et al., 2013), and most 137Cs had been accumulatedin Ogaki dam, along with suspended matter which originated from the watershed soils (Kitamura et al., 2014).
The purpose of this research was to quantitatively evaluate the form and distribution of 137Cs in watershed soils
and river/lake waters. Based on the measurement results,
the factors facilitating the determination of the solid-phase 137Cs concentration were discussed.
SURVEY and EXPERIMENT METHODS:
We collected samples from the Natsui River Basin(750 km2), located 40 km away from FNPP. The Natsui
River is the water resource for the 160,000 people living
in Iwaki city．River and lake waters, surface soils, andsediments were sampled using buckets, stainless shovels,
and Ekman-berge sediment samplers, respectively. Surface soils from a depth range of 0-5 cm were mixed andcombined from five point samples into a single sample.
The collected soil samples were desiccated by a freeze
dryer(FD-81), and were then divided by particle size using sieves (2000, 850, 425, 250, 106, 75 and 25 μm) after
removing particles over 2 mm in diameter. Measurementsof 137Cs and organic carbon content (NC-22F) were carried out for the separated particles. Water samples (20 L)
were separated into SS residue and filtrate through filtration, using a 1 μm glass fiber filter (GF/B). The 137Cs
contained in the filtrate was concentrated into a disk
(Empore TM Cesium Rad Disk) by forcible filtration.
Afterwards, the 137Cs in SS residues within the filters andin the disks were measured by a Ge semiconductor detector (GC4020/3020, CANBERRA).
RESULTS and DISCUSSIONS:
It was previously reported that 137Cs in soils were dependent on the specific surface area of the soil particles(He and Walling, 1995). In order to analyze the adsorption characteristics of 137Cs in soils, the 137Cs (logarithm
value) in each particle size category was plotted against
representative particle size (logarithm value). A regression line slope of S=0 indicates that the 137Cs was independent of particle size, while S =-1 indicates that the soil
137
Cs was dependent on the specific surface area of all

6.5

Logarithm of 137Cs concentration (Bq/kg-dry soil)

College of Science and Engineering, Ritsumeikan University
1
Research Reactor Institute, Kyoto University
2
Graduate School of Science and Engineering,
Ritsumeikan University

particles. Regression line slopes from the forest soil samples ranged from -0.8 to -0.4. This suggests that the 137Cs
in forest soils tend to be relatively dependent on the specific surface area. Conversely, regression line slopes fromthe bottom sediment samples in dam and paddy soils
were almost zero. It was considered that the 137Cs wasequalized between different particle sizes, because thesoil particles were more frequently exposed to water.
137
Cs in each particle size, plotted against the organiccarbon content in the forest soil at upstream site (Fig. 2).
The result showed there was a strong correlation between
these variables, and that the 137Cs per organic carbon (i.e.,
regression slope) was relatively constant (2,500 Bq/g-organic carbon) regardless of the season. This value wasstrongly related to the 137Cs deposition, indicating that theorganic carbon was an essential qualitative factor influencing 137Cs.
Ratios of particulate 137Cs in water were about 90% in
upstream site, and about 20% in Kodama dam site, evenduring the normal river water stage. These results suggestthat SS, as a carrier substrate, had a significant impact on
the total 137Cs loading to the sea. Calculated Kd values(137Cs in SS residue divided by the 137Cs in filtrate) were
distributed from 0.066 to 62 ML/kg. Because there was
not enough time to dissolve from particulate 137Cs to dissolved one, the Kd was significantly higher than thosevalues of previous studies. These results indicate that the
behavior of 137Cs in the natural environment is dominatedby the movement of particles during floods, as well theiradsorption on organic matter particles.
site1: forest soil (August in 2014)
site1: forest soil (December in 2014)
site2: bottom sediment in dam (March in 2014)
site3: forest soil (August in 2014)
site4: paddy soil (March in 2014)

C ∝ r -0.58
R² = 0.95
5.5

C ∝ r -0.87
R² = 0.94

4.5

C ∝ r -0.40
R² = 0.94
C ∝ r -0.03
R² = 0.80

3.5

C ∝ r -0.16
R² = 0.93

2.5
1.5

2.0

2.5

3.0

Logarithm of representative particle size (μm)

Fig.1 Relationship between

137

Cs and the particle size

800,000

site1: forest soil (August in 2014)(Bq/kg-dry soil)

K. Sato, M. Ikegami1 and M. Morisada2

137Cs concentration

CO5-7

site1: forest soil (December in 2014)
600,000

y = 25,135 x - 64,260
R² = 0.94

400,000

200,000

0
0

10

20

30

Organic carbon content (%)

137

Fig.2 Relationship between Cs and the organic carbon
REFERENCES:[1]He, Q. et al., Journal of Environmental Radioactivity,
30/2(1995), 117-137.
[2]Kitamura, A. et al., Anthropocene 5(2014), 22-31.
[3]Sato, K. et al., J. JSCE, Ser. G (Environmental Research) 69/7(2013), II_175-III_186 (in Japanese).

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