Faculty Profiles - MINAMI, Masayo

Papers - MINAMI, Masayo

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Radiocarbon age and racemization reaction of amino acids extracted from a Naumann's molar fossil

Minami Masayo, Muranaka Yasushi, Nakamura Toshio

Abstracts of Annual Meeting of the Geochemical Society of Japan Vol. 50 ( 0 ) page： 31 - 31 2003

Application of Sr isotope to an assessment of geoenvironmental impact

Asahara Yoshihiro, Ishiguro Hiroko, Tanaka Tsuyoshi, Yamamoto Koshi, Mimura Koichi, Minami Masayo, Yoshida Hidekazu, Yogo Setsuo

Abstracts of Annual Meeting of the Geochemical Society of Japan Vol. 50 ( 0 ) page： 63 - 63 2003

Publisher：GEOCHEMICAL SOCIETY OF JAPAN

陸域の金属元素の主なリザーバは岩石圏にあり、風化、侵食により土砂や溶存態に形を変え、河川、沿海、外洋へと移動、拡散していく。現代においては、人為的な森林伐採や丘陵地開発による侵食の加速、人間活動による金属物質の放出もある。これらの様々な要因が複合的に絡まり河川水や海水、堆積物の元素組成が決まっているが、その要因をひとつひとつ紐解くにはその起源の情報を与えてくれる同位体は有力な指標である。本講演では、愛知県北東部地域から採取された150の河川堆積物試料と15の基盤岩岩石試料中の微量金属元素ストロンチウムの同位体比から得られる地圏環境情報について報告する。

DOI： 10.14862/geochemproc.50.0.63.0

CiNii Research

Geochemical map of Aichi Prefecture -Minor elements-

Tanaka Tsuyoshi, Yamamoto Koshi, Minami Masayo, Mimura Koichi, Asahara Yoshihiro, Yoshida Hidekazu, Yogo Setsuo, Inayoshi Masami

Abstracts of Annual Meeting of the Geochemical Society of Japan Vol. 50 ( 0 ) page： 62 - 62 2003

Publisher：GEOCHEMICAL SOCIETY OF JAPAN

Geochemical map is a useful tool for geoenvironmental assessment. 27 minor elements were examined for 1500 stream sediment of Aichi Prefecture, Japan. Most of the elemental distribution patterns are considered as an effect of basement geology. Some of the high Fe distribution ,however, are correlated with golf cource. Gold and arsenic distribution seems be a result of geothermal activities.

DOI： 10.14862/geochemproc.50.0.62.0

CiNii Research

Geochemical map of aichi Prefecture - Major elements -

Yamamoto Koshi, Tanaka Tsuyoshi, Minami Masayo, Mimura Koichi, Asahara Yoshihiro, Yoshida Hidekazu, Yogo Setsuo, Inayoshi Masami

Abstracts of Annual Meeting of the Geochemical Society of Japan Vol. 50 ( 0 ) page： 61 - 61 2003

Language：Japanese Publisher：GEOCHEMICAL SOCIETY OF JAPAN

Geochemical and Cosmochemical Laboratory, Nagoya University, has started a geochemical mapping in 1994, in order to make a geo-environmental assessment of Aichi Prefecture, central part of Japan.The analyses suggest that the stream sediments from areas with sedimentary rock basement are more enriched in SiO2 than those from areas with granitic basement. This SiO2 enrichment can be ascribed to the wide distribution of siliceous sedimentary rocks such as bedded cherts in their hinterland, the Mino Terrane. Samples from the area in the granitic basement are characterized by enrichment of Na, K, and Ca. The relative abundance of these elements, however, differs in the respective granitic bodies. This difference reflects the difference of abundance and chemical composition of plagioclase and potassium feldspar in stream sediments. Therefore, the major elements examined here reflect natural geo-environment and geochemical map may be useful as a supporting data for geological mapping.

DOI： 10.14862/geochemproc.50.0.61.0

CiNii Research

J-GLOBAL

Presence of evolved continental crust in Archean Pilbara craton, Western Australia: Evidence from Re-Os isotopic systematics of 3.4Gyr cherts

Suzuki K, Shimizu F, Okamoto M, Hattori Y, Minami M, Shimoda G, Tatsumi Y, Adachi M

GEOCHIMICA ET COSMOCHIMICA ACTA Vol. 66 ( 15A ) page： A755 - A755 2002.8

Isotope diluted neutron activation analysis (ID-NAA) for quantitative analysis of PGEs and Re

Tanaka T, Senda R, Shibata S, Minami M, Tanimizu M

GEOCHIMICA ET COSMOCHIMICA ACTA Vol. 66 ( 15A ) page： A763 - A763 2002.8

Preliminary results of 2000-fourth international radiocarbon intercomparison : international blind test of <14>^C measurement

Nakamura Toshio, Oda Hirotaka, Niu Etsuko, Ikeda Akiko, Minami Masayo, Takahashi Hiroshi, Ohta Tomoko

Summaries of Researches using AMS at Nagoya University ( 13 ) page： 29 - 40 2002.3

Publisher：Nagoya University

A Tandetron accelerator mass spectrometer (Tandetron-I AMS system), an apparatus dedicated to high sensitivity radiocarbon (^<14>C) measurements, manufactured by General Ionex Corporation, USA, has been used since 1983 to measure the ^<14>C concentrations of environmental samples as well as ^<14>C dates of geological and archaeological materials, at the Center for Chronological Research (CCR), Nagoya University. In the meanwhile, a so-called second generation AMS ^<14>C apparatus (Tandetron-II AMS system) manufactured by High Voltage Engineering Europe, BV, the Netherlands has been installed successfully at CCR in 1997. Though we had experienced a lot of difficulties with the Tandetron-II just two years after its installation, we were able to start ^<14>C measurements with the machine in acceptable precision since the end of 1999. The ^<14>C measurement error (one sigma error)of the Tandetron-II is around ±20 - ±40 years, which is clearly smaller than that of the Tandetron-I (around ±50 - ±90 years). In addition, the reproducibility tests of ^<14>C measurements for the IAEA C1- C8 ^<14>C standards suggest that accuracy of ^<14>C measurement can be as good as around 0.5% We participated the Forth International Radiocarbon Intercomparison (FIRI) program started in 1999,after its set up at the time of the 15^<th> International Radiocarbon Conference at the University of Groningen, the Netherlands, in 1997. In the FIRI program, 10 samples of different materials were distributed to 92 ^<14>C laboratories of three different ^<14>C detection methods (25 AMS labs., 18 GPC labs. and 49 LSC labs.) from 37 different countries. Our AMS group of Nagoya University is one of the 25 AMS labs. The FIRI results have been reported preliminarily at the Edinburgh workshop on March 2001. We can also get the results by the web site of Radiocarbon (www. radiocarbon. org). We briefly summarize the report in relation with our own results, which are consistent with the mean values of ^<14>C results reported from 25 AMS labs.

DOI： 10.18999/sumrua.13.29

Determination of the condition in decalcification for fossil bones

Minami Masayo, Nakamura Toshio

Summaries of Researches using AMS at Nagoya University ( 13 ) page： 177 - 185 2002.3

Publisher：Nagoya University

To investigate the best HCl concentration used for decalcification of a fossil bone without loss of bone organic fractions, various concentrations of 0.4M, 0.6M, 0.8M, 1.0M and 1.2M HCl were examined to analyze carbon, nitrogen and radiocarbon isotopes. The bone used in the experiment is a fossil fragment collected from the Awazu submarine archeological site, Shiga. The yield of insoluble decalcified fractions does not change in the range from 0.4M to 1.0M HCl, and it decreases on 1.2M HCl. The result suggests that a part of bone organic fractions departs from the decalcified fractions by treatment of higher HCl concentration. The ^<14>C age for gelatin collagens does not change on any concentrations of 0.4M, 0.6M, 0.8M and 1.2M HCl, and could be reliable because the XAD-2 treated hydrolysate fraction shows the same ^<14>C age. Therefore, 0.4M is the best concentration of HCl to efficiently decalcify the fossil fragment in this study. The fossil bone used in this study is well-preserved, and the above best condition of decalcification does not apply to another poorly-preserved fossil bones. It could be, however, suitable to decalcify and fossil bone with 0.4M HCl in a cellulose tube.

DOI： 10.18999/sumrua.13.177

Sr isotope ratios of sediments in southern Lake Biwa

Minami Masayo, Oda Hirotaka, Kojima Sadao, Yokota Kiichiro, Nakamura Toshio

Summaries of Researches using AMS at Nagoya University ( 13 ) page： 71 - 81 2002.3

Publisher：Nagoya University

A sediment core in the southern Lake Biwa was analyzed for ^<210>Pb, ^<137>Cs and Sr isotope ratio. The sedimentation rate of the lake sediments assumed by ^<210>Pb is about 3mm/y. 137Cs, a fallout product from atmospheric nuclear weapon tests, shows maximum activity at 9.5cm depth. Maximum fallout of ^<137>Cs to water and land occurred during 1963-1964,and the sedimentation rate assumed by ^<137>Cs is also about 3mm/y. The sedimentation rate of 3mm/y, however, could be untrue because surface sediments are disturbed and mixed by physical turbulence. Sr isotope ratios of the lake sediments radically change from 0.7185 to 0.7198,and Sr concentrations also radically change from 73ppm to 64ppm at near 10cm depth. Therefore, the following causes are expected : 1) Sr system has changed by artificially environment pollution since near 1960,and 2) surface sediments are disturbed and mixed by physical turbulence. In the case of 2), the profiles of ^<210>Pb and ^<137>Cs lead to mixing process except sedimentation process. The profiles of other nuclides such as ^<14>C and ^<90>Sr would help better understanding of the behavior of lake sediments. It is necessary to analyze another sediment cores of southern and northern Lake Biwa.

DOI： 10.18999/sumrua.13.71

Isotope diluted neutron activation analysis (ID-NAA) for quantitative analysis of PGEs and Re

Tanaka Tsuyoshi, Senda Ryouko, Shibata Sinnosuke, Minami Masayo, Tanimizu Masaharu

Abstracts of Annual Meeting of the Geochemical Society of Japan Vol. 49 ( 0 ) page： 209 - 209 2002

Strontium isotope ratio of sediments from Lake Biwa

Minami Masayo, Oda Hirotaka, Kozima Sadao, Yokota Kiichiro, Nakamura Toshio

Abstracts of Annual Meeting of the Geochemical Society of Japan Vol. 49 ( 0 ) page： 187 - 187 2002

Carbon, nitrogen and strontium isotope compositions of fossil bones from the bottom of lake or sea

Minami Masayo, Nakamura Toshio

Abstracts of Annual Meeting of the Geochemical Society of Japan Vol. 49 ( 0 ) page： 142 - 142 2002

AMS <14>^C ages of deer and human bones collected from British Columbia

Minami Masayo, Chisholm Brian, Muto Hiroo, Nakamura Toshio

Summaries of Researches using AMS at Nagoya University ( 12 ) page： 169 - 179 2001.3

Publisher：Nagoya University

We measured ^<14>C ages, carbon and nitrogen stable isotopic ratios of gelatin-collagens extracted from deer and human bones at British Columbia, Canada. The deer bone samples, samples #1〜#3,come from a site in the interior of British Columbia, designated as DhRa-02 site. The human bone samples, samples #4〜#6,are from the Pender Canal site, on North Pender Island, British Columbia. In general, reliable ^<14>C ages, carbon and nitrogen stable isotopic ratios can be obtained for collagens extracted from fossil bones, provided that the collagens have been preserved well from weathering in nature. Experimental yields of gelatin-collagens were higher than 0.7%, except for sample #1 with 0.25%. For sample #1,we tried to extract amino acid fractions by hydrolyzation and XAD-2 treatment and to measure its ^<14>C age. The age is the same as that of gelatin-collagen, about 1200 yrBP. Samples #1 and #2 are situated stratigraphically above a volvcanic ash, identified as Mazama tephra ca 6800 yrBP, and have post-ash dates, 1260 and 3010 yrBP, respectively. Sample #3 shows 3820 yrBP, younger than the age of Mazama tephra, though #3 comes from a pre-ash layer. Samples #4〜#6 have relatively high gelatin yields of 6〜9%, and show the ^<14>C ages of 3120〜3550 yrBP. The CO_2 yields from the gelatin-collagens of samples #1〜#6 are over 41%, consistent with the value of 40〜50% for gelatin-collagen extracted from fresh bones. Thus, the ^<14>C ages, carbon and nitrogen stable isotopic ratios obtained for the gelatin-collagens seem to be reliable. The deer bone samples #1〜#3 demonstrate δ^<13>C value of 〜-21‰ and δ^<15>N value of +5〜+8‰, which are the values of C3 millets. On the other hand, the human bone samples #4〜#6 show relatively high δ^<13>C value of -13‰ and δ^<15>N value of +18‰. It is thought that they ate marine products such as fishes and shellfishes, with δ^<13>C value of -15〜-20‰ and δ^<15>N value of +15〜+20‰, when they were alive. The high δ^<13>C and δ^<15>N values for the human bones are caused by the food resources.

DOI： 10.18999/sumrua.12.169

Carbon-14 terrestrial ages of Antarctic meteorites with a Tandetron AMS at Nagoya University

Minami Masayo, Nakamura Toshio

Summaries of Researches using AMS at Nagoya University ( 12 ) page： 134 - 145 2001.3

Publisher：Nagoya University

Terrestrial age of meteorites gives us important informaion to estimate the terrestrial history of the meteorites. With the advent of AMS, the required sample mass of meteorite for measurement has been reduced as small as 0.1g. As a result, many more ^<14>C measurements have been performed intensively by the Toronto AMS group, Canada, the Arizona AMS group, USA, and so on. In Japan, AMS ^<14>C measurements of meteorites have been scarcely performed, to our regret. We have constructed a system to extract carbon from meteorites using a vacuum-tight RF melting method in order to study ^<14>C activities in meteorites, in a similar method used by the Arizona group. A meteorite powder sample mixed with pure iron chips is combusted in a RF furnace (Leco HF-10) in the presence of purified carbon-free oxygen in a closed vacuum-tight glass line system. The sample gases evolved are passed through MnO_2 and Pt/CuO traps, and then the CO_2 is separated in a liq.N_2 trap, by pumping out oxygen completely. The amount of ^<14>CO_2 is determined by a pressure transducer in a certain volume and diluted with a known amount of ^<14>C-free CO_2. The total CO_2 is graphitized by reducing with hydrogen in a Fe-powder catalyst and the produced graphite is measured of its ^<14>C concentration with a Tandetron accelerator mass spectrometer at the Center for Chronological Research, Nagoya University. Terrestrial ^<14>C ages of two Antarctic meteorites, Y-75102 from the Yamato icefield, ALH-77294 and ALH-77262 from the Allan Hills icefield, were determined. The age of Y-75102 is estimated 4.0±1.0 ka, the age of ALH-77294 is 19.5±1.2 ka, and the age of ALH-77262 is 28.5±0.9 ka. The ^<14>C ages on the meteorites roughly agree with the literature value. However, the results of the small-counter method (Fireman, 1983; Fireman and Norris, 1981) tend to be oldest, the results of the AMS method by Jull et al. (1984,1989b, 1998) are youngest, and our results of the AMS method are intermediate. The difference would be caused by analytical uncertainties, contamination in samples, incomplete fusion of samples and back-ground value in the extraction system. Y-74190,Y-75097 and Y-75108,which are thought to have fallen at the same time as Y-75102,gave similar ages of 〜4 ka, though Y-74190 gave a slightly younger age of 2.8 ka. These four chondrites might have fallen at the same time. Further studies are needed to improve analytical technique : reducing back-ground value of the extraction system and complete combustion of meteorites by such as longer heating time in RF furnace and use of much more combustion accelerator. It is indispensable to measure saturated ^<14>C activity of recently fallen meteorites with our extraction system. Furthermore, shielding or depth corrections are needed for ^<14>C terrestrial age determination of a meteorite sample if the meteoroid was very large or very small. We intend to obtan the other radioisotope data such as ^<10>Be to estimate the shielding effect. By normalizing the saturated activity of ^<14>C to that of ^<10>Be in a meteorite, more correct terrestrial age for the meteorite could be obtained.

DOI： 10.18999/sumrua.12.134

Measurement of IAEA <14>^C standard materials with the 2nd Tandetron AMS machine at Nagoya University : estimates of precision and accuracy

Nakamura Toshio, Oda Hirotaka, Niu Etsuko, Ikeda Akiko, Minami Masayo, Takahashi Hiroshi, Ohta Tomoko

Summaries of Researches using AMS at Nagoya University ( 12 ) page： 35 - 43 2001.3

Publisher：Nagoya University

A Tandetron accelerator mass spectrometer, an apparatus dedicated to high sensitivity radiocarbon (^<14>C) measurements, manufactured by General Ionex Corporation, USA, has been used since 1983 to measure the ^<14>C concentrations of environmental samples as well as ^<14>C dates of geological and archaeological materials, at the Center for Chronological Research (CCR), Nagoya University. A so-called second generation AMS ^<14>C apparatus manufactured by High Voltage Engineering Europe, BV, the Netherlands has been installed at CCR in 1997 and has been tested of its performance on ^<14>C measurements. The authors present here a brief review of the present performance and status of the Tandetron-I and Tandetron-II AMS systems. The ^<14>C measurement error (one sigma error) of the Tandetron-II is around +/-20-+/-40 years, which is clearly smaller than that of the Tandetron-I (around+/-50-+/-90 years). In addition, the reproducibility tests of ^<14>C measurements for the IAEA C1-C8 ^<14>C standards suggests that accuracy of ^<14>C measurement can be as good as around 0.5%.

DOI： 10.18999/sumrua.12.35

The procedure and accuracy of INAA for geological materials by new γ-ray counting and data processing system at Radioisotope Center in Nagoya University

SHIBATA Shin-nosuke, TANAKA Tsuyoshi, MINAMI Masayo, SENDA Ryoko, TAKEBE Masamichi, KACHI Takuya, KONDO Masashi, ODA Shuhei, HAYASHI Takamasa, NISHIZAWA Kunihide, KOJIMA Hisashi

Bulletin of the Nagoya University Museum ( 17 ) page： 15 - 32 2001

Publisher：Nagoya University

A new gamma-ray counting and data processing system for non-destructive neutron activation analysis has been set up in Radioisotope Center in Nagoya University. The system carry out gamma-ray counting, sample change and data processing automatically, and is able to keep us away from parts of complicated operations in INAA. In this study, we have arranged simple analytical procedure that makes practical works easier than previous. The concrete flow is described from the preparation of powder rock samples to gamma-ray counting and data processing by the new INAA system. Then it is run over that the analyses used two Geological Survey of Japan rock reference samples JB-1a and JG-1a in order to evaluate how the new analytical procedure give any speediness and accuracy for analyses of geological materials. Two United States Geological Survey reference samples BCR-1 and G-2 used as the standard respectively. Twenty two elements for JB-1a and 25 elements for JG-1a were analyzed, the uncertainty are <5% for Na, Sc, Fe, Co, La, Ce, Sm, Eu, Yb, Lu, Hf, Ta and Th, and of <10% for Cr, Zn, Cs, Ba, Nd, Tb and U. This system will enable us to analyze more than 1500 geologic samples per year.

DOI： 10.18999/bulnum.017.03

Contributions of anthropogenic and biogenic CO_2 to the atmosphere at an urban forest in winter season and their diurnal variations of vertical profiles

Takahashi Hiroshi A, Konohira Eiichi, Hiyama Tetsuya, Minami Masayo, Takahashi Atsuhiro, Oguri Hideyuki, Nakamura Toshio

Summaries of Researches using AMS at Nagoya University ( 11 ) page： 88 - 99 2000.3

Publisher：Nagoya University

Diurnal variations of carbon isotopic compositions (Δ^<14>C and δ^<13>C) of atmospheric CO_2 as well as concentration in an urban area on 9 February, 1999 were measured. The carbon isotopic approach in the present study discriminated quantitative contributions from the several CO_2 sources, i.e., background, anthropogenic and biogenic components, in the urban atmosphere. The diurnal variations in vertical profiles in anthropogenic and biogenic components within the forest were estimated, and their contributions were ranged from 1.3 to 15.8% and from 1.6 to 7.8%, respectively. There was a little variation vertically at each time in the respective components, whereas anthropogenic CO_2 fluctuated largely according to the total atmospheric CO_2 variation. On the other hand, the biogenic CO_2 concentration remained relatively constant throughout the day. With regard to the vertical profiles, the biogenic contribution increases from the top to the floor of the forest with smooth gradient, while the anthropogenic contribution shows the mirror image profile against biogenic one. Both of them showed the large gradual change especially during the night.

DOI： 10.18999/sumrua.11.88

The <14>^C AMS facility of the Nagoya University : achievements and present status of the Tandetron-I

Nakamura Toshio, Oda Hirotaka, Ikeda Akiko, Niu Etsuko, Minami Masayo, Yoshioka Shigeo, Ohta Tomoko, Takahashi Hiroshi, Adachi Mamoru

Summaries of Researches using AMS at Nagoya University ( 11 ) page： 38 - 50 2000.3

Publisher：Nagoya University

A Tandetron accelerator mass spectrometer, an apparatus dedicated to high sensitivity radiocarbon (^<14>C) measurements, manufactured by General Ionex Corporation, USA, has been used since 1983 to measure the ^<14>C concentrations of environmental samples as well as ^<14>C dates of geological and archaeological materials, at the Dating and Materials Research Center, Nagoya University. The authors present here a brief review of the present performance and some archaeological and geological applications of the Tandetron-I AMS, as well as a brief introduction to application field of ^<10>Be measurements. After the second AMS machine goes into routine operation, the main purpose of the Tandetron-I AMS will be shifted towards ^<10>Be measurements. Some hardware and software tools are in preparation now for the ^<10>Be measurements.

DOI： 10.18999/sumrua.11.38

An attempt to measure carbon-14 terrestrial ages of Antarctic meteorites with a Tandetron AMS at Nagoya University

Minami Masayo, Nakamura Toshio

Summaries of Researches using AMS at Nagoya University ( 11 ) page： 100 - 112 2000.3

Publisher：Nagoya University

Terrestrial age of meteorites gives us important information to estimate the terrestrial history of the meteorites. With the advent of AMS, the required sample mass of meteorite for measurement has been reduced as small as 0.1g. As a result, many more ^<14>C measurements have been performed intensively by the Toronto AMS group, Canada, the Arizona AMS group, USA, and so on. In Japan, AMS ^<14>C measurements of meteorites have been scarcely performed, to our regret. We are now at the early stage of the program for studying ^<14>C activities in meteorites, and constructing a system to extract ^<14>C from meteorites, in a similar method used by the Arizona group. A meteorite powder sample mixed with pure iron chips is combusted in a RF furnace (Leco HF-10) in the presence of purified carbon-free oxygen in a closed vacuum-tight glass line system. The sample gases evolved are passed through MnO_2 and Pt/CuO traps, and then the CO_2 is separated in a liq.N_2 trap, by pumping out oxygen completely. The amount of ^<14>CO_2 is determined by a pressure transducer in a certain volume and diluted with a known amount of ^<14>C^free CO_2. The total CO_2 is graphitized by reducing with hydrogen in a Fe-powder catalyst and the produced graphite is measured of its ^<14>C concentration with a Tandetron accelerator mass spectrometer at the Dating and Materials Research Center, Nagoya University. Extraction yields of CO_2 using the above method which employs RF melting of steel standards of known carbon content were about 90%. The new extraction procedure gave higher extraction yields and older ^<14>C ages than those using the old extraction method. Carbon yields of two Antarctic meteorites (Y-75102 and ALH-77294), however, were significantly low, and the carbon-14 terrestrial ages for the meteorites were different from the reported values. The results might be caused by imperfect combustions of the meteorites and high blanks from the crucible with iron chips alone. Further studies are needed to improve analytical techniques.

DOI： 10.18999/sumrua.11.100

Carbon and nitrogen isotope fractionations of collagen by chemical treatment : mainly by XAD-2 treatment

Minami Masayo

Summaries of Researches using AMS at Nagoya University ( 11 ) page： 231 - 238 2000.3

Publisher：Nagoya University

XAD-2 rasin is considered a good material to separate quantiatively polar amino acids from less polar fulvic and humic acids, which are predominant sources of error in ^<14>C and stable isotope analysis on collagen of fossil bone. To evaluate if XAD-2 treatment affects carbon and nitrogen isotope values, Minami (1999) measured δ^<13>C and δ^<15>N on several extracted fractions of collagens from modern bovine Achilles heel tendons made of Sigma Chemical and Nacalai Tesque. There were about +1.0‰ difference in δ^<13>C and about -0.1‰ in δ^<15>N between hydrolyzed collagen and XAD-treated collagen hydrolysates from modern collagen standards. On the other hand, the carbon and nitrogen isotope fractionations were about -0.6‰ and +0.3‰ in δ^<15>N, respectively, on animal fossil bones collected from collected from the Awazu submarine archeological site in this study. The C/N ratios, δ^<13>C and δ^<15>N values of extracted fractions : decalcified, hydrolyzed and XAD-treated hydrolysate fractions, vary as chemical extraction proceeded. The change of the isotope values, which differ between fossils and modern collagens, might be caused by purification of collagen, decomposition of a part of collagen, and combined changes in amino acid composition in collagen. The XAD-treatment affected amino acid compositions on both fossils and modern collagen standards. Since there was no difference in both δ^<13>C and δ^<15>N values by XAD-2 treatment on amino acid standards (Minami, 1999), the isotope fractionation with XAD-2 resin on the collagens can not be due to the total isotope variation of individual amino acids, but be due to the change of amino acid compositions. We need to further study the effect of chemical treatment with HCl on carbon and nitrogen isotope ratios of collagen with XAD-2 resin.

DOI： 10.18999/sumrua.11.231

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Papers - MINAMI, Masayo