MTT44-01

Room:102B

Time:May 26 15:15-15:30

Detection of low isotopic ratio of iron in anthropogenic aerosols and evaluation of its
contribution to the ocean
KURISU, Minako1∗ ; IIZUKA, Tsuyoshi1 ; MIYAHARA, Aya2 ; YAMAKAWA, Yoshiaki1 ; MIYAMOTO, Chihiro1 ;SAKATA, Kohei2 ; SAKAGUCHI, Aya3 ; TAKAHASHI, Yoshio1
1

Graduate School of Science, The University of Tokyo, 2 Graduate School of Science, Hiroshima University, 3 Faculty of Pureand Applied Sciences, University of Tsukuba

Productivity of phytoplankton affects global carbon cycle, and may also affect the climate. Iron (Fe) is an essential element
for phytoplankton, but its solubility is low and much of it is removed as Fe (III) hydroxide. Therefore, it has been reported
that phytoplankton growth in the High Nutrient-Low Chlorophyll (HNLC) regions is limited by Fe concentration (Martin and
Fitzwater, 1988). Aerosols are important sources of Fe species to the surface seawater. They are classified into anthropogenic andnatural ones. Particle sizes of anthropogenic aerosols are generally smaller than those of natural ones because of their different
formation processes (Whitby, 1977). Previous studies have shown that high soluble Fe species were included in anthropogenic
aerosols (e.g., Takahashi et al., 2013). In terms of Fe isotope composition, Mead et al. (2013) compared Fe isotopic compositions
between course aerosols (› 2.5 µm) and fine ones (‹ 2.5 µm) and suggested that the Fe isotopic composition of finer aerosols(anthropogenic source; δ 56 Fe = -0.10 ‰) is lighter than that of coarse aerosols (natural source; δ 56 Fe = 0.08 ‰). However, it
is possible that the separation of the aerosols at the particle size of 2.5 µm cannot fully separate the two sources. The purposeof this study, therefore, was to detect anthropogenic aerosols and measure their Fe iron isotopic compositions. Size-fractioned
aerosol samples were collected at Higashi-Hiroshima City using a cascade impactor (particle sizes: › 10.2 µm, 4.2 ∼ 10.2 µm,
2.1 ∼ 4.2 µm, 1.3 ∼ 2.1 µm, 0.69 ∼ 1.3 µm, 0.39 ∼ 0.69 µm, ‹ 0.39 µm), which could specify the isotopic compositions ofanthropogenic Fe. Iron isotopic compositions of bulk aerosols and soluble aerosols for simulated rain water were measured using
multi-collector inductivity-coupled plasma mass spectrometry (MC-ICP-MS; Neptune Plus, Thermo Scientific). The chemical
species were also identified by employing Fe K-edge X-ray absorption fine structure (XAFS) spectroscopy and their solubility
for seawater was evaluated by leaching experiments. As a result, Fe isotopic compositions (δ 56 Fe) of larger particles werearound +0.25 ‰, whereas smaller particles showed lower isotopic composition (-0.5 ∼ -2 ‰). In addition, smaller particles ofsoluble component for simulated rain water showed much lower δ 56 Fe values (δ 56 = -3.9 ‰) than bulk particles, suggestingthat anthropogenic Fe has much lower isotopic compositions. The value was the lowest among other environmental samples
reported so far. This means that the large isotopic fractionation of anthropogenic aerosols occurs when Fe species evaporate.
δ 56 Fe value of the remaining materials after the water-extraction experiment was calculated using the values of bulk Fe andsoluble Fe, and it was revealed to be similar to that of earth’s crust (+0.25 ‰). This means that the anthropogenic Fe in aerosol iscompletely soluble and has very low δ 56 Fe. It has been suggested that Fe in aerosol contributed significantly to the supply of Fein surface seawater. When considering Fe isotopic budget for surface seawater using the value measured in this study as a δ 56 Feof anthropogenic aerosol (-3.9 ‰), it is suggested that aerosols is main source of Fe dissolved in the surface seawater.
Keywords: iron isotopic composition, aerosol, anthropogenic iron

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MTT44-02

Room:102B

Time:May 26 15:30-15:45

The evaluation for ion trajectory and transmittance of Laser Ionization MAss nanoScope(LIMAS)TONOTANI, Azusa1∗ ; BAJO, Ken-ichi1 ; YURIMOTO, Hisayoshi1
1Department of Natural History Sciences, Graduate School of Science, Hokkaido University

In analyses of interstellar materials in meteorites, target material sizes are generally smaller than 100 nm. Therefore, analyticalmethod with high sensitivity and a high mass resolution is required for sub-microscale in-situ analysis.
We have developed a tunnel ionization time of flight sputtered neutral mass spectrometer: LIMAS. This apparatus mainly
consists of a focused ion beam system (Ga-FIB), a femtosecond (fs) laser system and a MULti-TUrn time-of-flight Mass spectrometer II (MULTUM II) (Ebata et al., 2012).
The fs laser is used for tunnel ionization of neutral particles that are sputtered by the Ga-FIB beam. Because the energy densityof the fs laser is more than 2 x 1015 W/cm2 , all of elements can be ionized.
Based on the ion optics of MULTUM II, time of flight of the ion can be infinitely extended to get high mass resolution.
In this study, we operated voltages of einzel lenses and deflectors in an ion injection optics based on the result of an ion optics
simulation using SIMION. A parameter setting of MULTUM II was based on (Okumura., 2005). As a result, we evaluated mass
resolving power and the transmittance of fs laser induced ions in the MULTUM II.
Sample surface was kept on ground state, and the acceleration voltage was fixed at -4 kV. The voltages of the ion injection
optics and MULTUM II were floated on -4 kV. Then, post-ionized positive ions were injected into MULTUM II. The ion injection optics consists of three stage injection and acceleration lens, two einzel lenses, and two sets of two direction deflectors. The
˜30% of ions were injected into MULTUM II from the result of the ion simulation. We operated parameters in the ion injection
optics for an ion was focused on a cycle starting focal point in MULTUM II. Focal point in ion injection optics of ion trajectory
moves to sample position side to become a large aperture angle by the high electrode voltage of injection lenses. The focal point
in MULTUM II was determined by the aperture angle and voltage of the einzel lenses.
The above eight parameters were changed and adjusted based on the result of the ion simulation. Toroidal fields in MULTUM
II were optimized by operating electrical potential valance among the fields.
After the optimize of the electrode voltages, we obtained the mass resolving power of more than 27,000 (24 Mg+ , numberof cycle: 100 cycles in MULTUM II) without laser (SIMS mode), and of more than 40000 (24 Mg+ , number of cycle: 100
cycles) with laser (SNMS mode). The ion transmittance in MULTUM II was evaluated. Relationships of the ion transmittanceof MULTUM II with the number of cycles are as follows. Assuming that the ion intensity of linear mode (from sample surface
to the detector) is 100%, the ion transmittances at 20 cycles are 28% and 5% for SIMS and SNMS modes, respectively. The
transmittances of 100 cycles are 26% and 2% for SIMS and SNMS modes, respectively. The decreasing of the intensity can be
explained by two factors. One is that the half of the injected ions cannot meet a condition of the ion trajectory of MULTUM II.
Another is ion collision with residual gas molecules in MULTUM II.
Keywords: TOF-MS, SNMS, fs-laser

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MTT44-03

Room:102B

Time:May 26 15:45-16:00

A current status of high precision in situ isotopic analysis by SIMS in JAMSTEC andperspectives for future researches
USHIKUBO, Takayuki1∗ ; ITO, Motoo1 ; TOMIOKA, Naotaka1 ; SHIMIZU, Kenji1 ; ISHIKAWA, Tsuyoshi11

Kochi Institute for Core Sample Research, JAMSTEC

Secondary Ion Mass Spectrometry (SIMS) has a unique capability of isotopic and elemental measurements for micrometerscale distributions in region-of-interests in variety of samples. With this unique capability, researches with SIMS brought out
new evidence for understanding of processes occurred under extreme environment (e.g., Earth’s earliest crust formation, reactions in Earth’s deep interior, and high temperature processes in the solar nebula) and processes caused by biological/biochemical
activities (e.g., biomineralization, metabolic functions of microorganisms).
While SIMS is a destructive technique, required amount of sample with SIMS analyses is very small (e.g., for oxygen twoisotope analysis, less than 1ng with a pit of ˜10 micrometer in size and ˜1 micrometer in depth) [e.g. 1,2]. SIMS analysis with asmaller beam and improvement of efficiency of analysis are highly required for multilateral analyses of the same sample.
A large geometry and ultra-high sensitivity magnetic sector SIMS with multiple detectors (CAMECA IMS 1280-HR) was
installed in the Kochi Institute for Core Sample Research, JAMSTEC in early 2014. The Kochi’s latest generation IMS 1280-HR
has a capability to perform in-situ stable isotope analyses with sub-permil (down to +/-0.2 permil, 2SD) precision and accuracy
for samples of a few to tens micrometer in size [1,3].
Here, we will present preliminary results of oxygen two-isotope (18 O/16 O) measurements in selected minerals using two Faraday cup detectors in multi-detection, and the Pb three-isotope (206 Pb/207 Pb/208 Pb) measurements in several standard materials
using an axial electron multiplier detector with mono-collection. The achieved spot-to-spot reproducibility for 18 O/16 O is ˜+/0.3 permil (2 SD) with a ˜10 micrometer spot for silicates and carbonates. The achieved precision and spatial resolution arepromising to explore seasonal variations of precipitation recorded in speleothems [e.g., 4]. The spot-to-spot reproducibility for
Pb three-isotopes is ˜+/-7 permil with a ˜20 micrometer spot for USGS BCR-2G standard glass ([Pb]=11ppm). Developed Pb
isotopic measurements can be applied to researches for glass inclusions entrapped in minerals, which elucidate heterogeneityof the Earth’s mantle [e.g., 5]. In the future work, we will use multiple electron multipliers to detect three Pb isotope signals
simultaneously. This may provide better precision with a smaller spatial scale (˜10 micrometer).
In addition to the development of high precision and high spatial resolution analysis with SIMS, we are planning to build
a coordinated analytical system which provides information of microstructure and elemental/isotopic distributions for smallerscale samples, such as a piece of asteroid which will be returned by the JAXA Hayabusa-2 mission in 2020 and samples of theultra-deep drilling by Chikyu.
[1] Valley J. W. and Kita N. T. (2009) In Mineralogical Association of Canada Short Course 41 (M. Fayek Eds), pp.19-63.
[2] Page F. Z., Ushikubo T., Kita N. T., Riciputi L. R., and Valley J. W. (2007) American Mineralogist, 92, 1772-1775.
[3] Ushikubo T. (2010) Planetary People (Journal of the Japanese Society for Planetary Sciences), 19, 287-294 (in Japanese).
[4] Orland I. J., Bar-Matthews M., Ayalon A., Matthews A., Kozdon R., Ushikubo T., Valley J. W. (2012) Geochimica et
Cosmochimica Acta, 89, 240-255.
[5] Saal A. E., Hart S. R., Shimizu N., Hauri E. H., and Layne G. D. (1998) Science, 282, 1481-1484.

Keywords: high precision in situ isotopic analysis, ion microprobe, SIMS, oxygen isotope, lead isotope

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MTT44-04

Room:102B

Time:May 26 16:30-16:45

How to build a habitable planet for geochemists in Japan ?
TSUNOGAI, Urumu1∗
1

Graduate School of Environmental Studies, Nagoya University
In this talk, I would like to present the methods to build a habitable planet for geochemists in Japan.

Keywords: The Geochemical Society of Japan, JpGU, Sampling method, Education

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MTT44-05

Room:102B

Time:May 26 16:45-17:00

Is it representative of the Earth? -Necessity of ultrahigh-speed massive analysis in petrology-

KOGISO, Tetsu1∗
1

HES, Kyoto Univ.

Earth and planetary sciences target at very large-scale subjects, such as the evolution of the Earth and the Solar system, but weusually treat very small samples taken from the Earth and the outer space. This means that we have to read various phenomena of
the spatial scale order-of-magnitude larger than the samples we can have. In petrology, we usually use rock samples smaller thanpalm size. In addition, it’s difficult to take rock samples from the whole globe like those of the ocean and atmosphere, because
we have to take rocks from underground. In other words, petrologists is forced to understand large-scale phenomena using datafrom a limited number of rocks taken from limited areas. Therefore, we always have to question ourselves “are those samples
representative of things and phenomena we want to know about?”
I have been interested in the behavior of platinum-group elements in the mantle, which would provide us with a key to understand the early-Earth differentiation and subsequent chemical evolution of the Earth’s interior. Platinum-group elements in
mantle peridotites are concentrated in base-metal sulfides (BMS) and platinum-group minerals (PGM). So it is very important toreveal the stability and genesis of BMS and PGM in order to understand the behavior of platinum-group elements in the mantle.
Because BMS and PGM are very small both in size and amount, it has been quite difficult to describe the occurrence of them inperidotites. Recent developments in small-scale analyses, such as FE-SEM, laser-abrasion ICP-MS and synchrotron micro XRF,
enable us to analyze BMS and PGM in submicrometer scale, and we are getting to know the occurrence and genesis of BMS and
PGM in peridotites. However, we can still analyze only limited number of BMS and PGM in small portions of a sample becauseof their smallness in size and amount, and therefore we don’t know whether the BMS and PGM we observe are representativeof the sample they are included in, not to mention of the Earth’s mantle. Even if we get able to analyze much smaller-size
minerals, it is uncertain whether we can know better about BMS and PGM in the mantle. What we want to know is the behaviorof platinum-group elements in the mantle, not genesis of them in a particular sample.
Then, what should we do? It’s not to advance the methods for small-scale analyses with much higher precision, but to develop
methods for analyzing a large number of samples in limited time. In other words, we need “ultrahigh-speed” analysis of rocksamples. We don’t need to care so much about precision and accuracy, because, at least in the case of platinum-group elements,
concentration data even with +/- 100% precision would tell us much about geochemistry of platinum-group elements. The way
petrologists and geochemists must go is not only to higher precision and accuracy, but also to ultrahigh speed.
Keywords: small-scale analysis, wide-area analysis, massive analysis, mantle, heterogeneity

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MTT44-06

Room:102B

Time:May 26 17:00-17:15

Studies of the Earth’s Interior and Geochemistry
IWAMORI, Hikaru1∗
1

Japan Agency for Marine-Earth Science and Technology, 2 Tokyo Institute of Technology

In this presentation, I would like to discuss the following points, in terms of the relationship between studies of the Earth’s
interior and geochemistry, referring to several examples from the combined studies. First, geochemistry concerns both geoscienceand chemistry. How we balance the two does matter for both geochemists and the others. Second, how we relate mechanisms andprocesses of an elemental scale to global scale-phenomena requires some concrete methods which lie often outside geochemistry.
An approach bridging the two scales may play an important role. Third, since the Earth (and the planetary) system is highly
complex, there is no doubt that combining information available from all geoscience fields (including geochemistry) is crucial.
As an example, ‘Geofluid Map‘ in the crust and mantle is discussed.

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MTT44-07

Room:102B

Time:May 26 17:15-17:30

We are always on the frontier!
YURIMOTO, Hisayoshi1∗
1

Hokkaido University

Oxygen isotope anomaly in the solar system was found from a meteorite by Clayton et al. (1973). The origin is still unknown
and it is principally unsolved although we can infer it precisely. More interesting puzzle for the oxygen isotope anomaly thanthe origin may be the anomalous distribution among minerals and within a mineral in a Ca-Al-rich inclusion (CAI). CAIs are theoldest rock in the solar system, and are largely mm to cm in size. The CAIs formed in the solar nebula by crystallization fromliquid droplet or from surrounding hot gas. However, nobody has been succeeded to describe how to establish heterogeneous
oxygen isotope anomaly in a CAI according to known chemical reactions so far because the oxygen isotopic distribution isapparently inconsistent with phase relation and crystal growth in the chemical system of CAIs. This is mysterious because
the chemical system of CAIs seems to be much simple comparing with terrestrial rocks. In this talk, I show an attempt toclarify this mystery predicts that oxygen isotope anomaly distributes globally but changes the degree systematically on all solar
system objects including outer planets. The global change of oxygen isotope anomaly in the solar system should involve isotope
anomalies of hydrogen and nitrogen. The attempt also predicts that isotope anomalies of these three elements are universallyobserved in exoplanetary systems, which degrees may be an indicator for habitability. These predictions can be proved bydevelopment of planetary explorations and astronomical observations, which are parts of cosmochemistry, even if the origin of
the oxygen isotope anomaly in the solar system is principally an unsolved issue.
References:
Yurimoto, H. (2014) That’s One Thing, This Is Something Else! Kakenhi NEWS 2014, vol. 2, 7.
http://www.jsps.go.jp/j-grantsinaid/29 essay/no63.html
http://www.jsps.go.jp/english/e-grants/kakenhi essay/grants11 63.html
Yurimoto, H. (2009) Anatomy of Protosolar System. JGL 5 (3), 8-9.
http://www2.jpgu.org/publication/jgl/JGL-Vol5-3.pdf
Yurimoto, H. (2006) Preface. Yuseijin 15, 43.
https://www.wakusei.jp/book/pp/2006/2006-2-01/2006-2-01.pdf

Keywords: Geochemistry, Frontiers

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MTT44-08

Room:102B

Time:May 26 17:30-17:45

My identity as a geochemist in mineral physics
KAGI, Hiroyuki1∗
1

Graduate School of Science, The University of Tokyo

In the long-standing progress of earth sciences, the interplay between seismology and high-pressure mineral physics greatly
contributed to understanding of deep earth. It is my understanding that scientists in these fields establish the communities andshare the observational data, large facilities and so on. In contrast, it seems to me that many of geochemists, including myself
in a sense, construct their own laboratories equipping state-of-the-art device. The difference in research style is noteworthy andmay give a clue to the breakthrough of traditional geochemistry.
One of my research interests is to investigate the structure and properties of hydrous materials which potentially exists in deep
earth. To achieve these research projects in Japan, I joined to a research consortium and we have constructed a new high-pressure
beamline at the spallation neutron source, J-PARC for deep-earth mineralogy. We have been studying structures of hydrous
materials and ices; recent progress will be introduced in my talk.
Recently, our attention is focused into chemical evolution of organic materials during planetary shock bombardment process generating high pressure and high temperature simultaneously. We try to understand temperature-induced reaction andpressure-induced reaction independently. Our recent study on pressure-induced reactions on organic compounds and insights
into evolution of organic materials will be introduced.

Keywords: high pressure, neutron diffraction, organic compounds

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MTT44-09

Room:102B

Time:May 26 17:45-18:00

Molecular Geochemistry as a Future Topic in Geochemistry
TAKAHASHI, Yoshio1∗1Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo

Professor V. M. Goldschmidt is a father of geochemistry. He wrote in 1954 that geochemistry is the study of the distribution and amounts
Based on this concept, he discussed (i) substitution of trace elements into major element within a certain crystal, (ii) reaction of
metal ions with the ligands in water in terms of ion potential (= z/r; z: charge; r: ionic radius), and (iii) classification of all theelements in the periodic table in terms of chemical bounding nature such as ionic, covalent, and metallic bonding. Using X-ray
emission spectroscopy, which was the state-of-the art method at that time, he determined abundances of trace elements in various
geochemical samples.
However, his discussion on the distribution of these elements on the basis of the properties of their atoms and ions could not
be proved by any methods, since it was difficult at that time to clarify the chemical species (bonding nature and structure) oftrace elements. At present, on the other hand, we can determine the neighboring atom and interatomic distance of trace elements in various samples by advanced speciation methods such as by X-ray absorption fine structure (XAFS) spectroscopy. As
shown in our recent studies, abundances and isotopic compositions of various elements in natural samples strongly depend on thechemical state of various elements in nature. This fact shows that we can predict behaviors and isotopic fractionation of various
elements based on physic-chemical properties. This field can be called as ”Molecular Geochemistry”. This field includes (i)identification of organic polymolecules in nature which can be used for the paleoenvironment reconstruction, (ii) isotopomers ofvarious molecules, and (iii) fundamental understanding of isotopic fractionation such as mass-independent fractioation. Thus, I
propose ”Molecular Geochemistry” as an important future topic of geochemistry, which cannot be conducted by researchers inother fields in earth and planetary sciences and must be conducted by Prof. Goldschmidt if he could use the methods to reveal
the atomic- and molecular-level information in geochemical samples.

Keywords: Molecular Geochemistry, Goldschmidt

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