九州大学 研究者情報
論文一覧
奈良岡 浩(ならおか ひろし) データ更新日:2021.06.16

教授 /  理学研究院 地球惑星科学部門 太陽惑星系物質科学


原著論文
1. Muneishi, K., Naraoka, Interactions between organic compounds and olivine under aqueous conditions: A potential role for organic distribution in carbonaceous chondrites., Meteoritics and Planetary Science, doi: 10.1111/maps.13614, 56, 195-205, 2021.02.
2. Oba, Y., Takano, Y., Naraoka, H., Furukawa, Y., Glavin, D. P., Dworkin, J. P. and Tachibana, S., Extraterrestrial hexamethylenetetramine in meteorites-a precursor of prebiotic chemistry in the inner solar system. , Nature Communications, doi.org/10.1038/s41467-020-20038-x, 11, 6243 (8pp), 2020.08, TBD.
3. H. Nakano, N. Hirakawa, Y. Matsubara, S. Yamashita, T. Okuchi, K. Asahina, R. Tanaka, N. Suzuki, H. Naraoka, Y. Takano, S. Tachibana, T. Hama, Y. Oba, Y. Kimura, N. Watanabe N. and A. Kouchi, Precometary organic matter: A hidden reservoir of water inside the snow line., Scientific Reports, doi.org/10.1038/s41598-020-64815-6, 10, 7755, 2020.05.
4. A. Furusho, T. Akita, M. Mita, H. Naraoka, K. Hamase, Three-dimensional high-performance liquid chromatographic analysis of chiral amino acids in carbonaceous chondrites., Journal of Chromatography A, doi.org/10.1016/j.chroma.2020.461255, 1625, 461255 (8pp), 2020.05.
5. Shunsuke Horai, Noriaki Yamauchi, Hiroshi Naraoka, Simultaneous total analysis of core and polar membrane lipids in archaea by high-performance liquid chromatography/high-resolution mass spectrometry coupled with heated electrospray ionization, Rapid Communications in Mass Spectrometry, 10.1002/rcm.8506, 33, 20, 1571-1577, 2019.10, [URL], Rationale: Archaea have characteristic membrane lipids including diether and/or tetraether isoprenoidal core lipids with various polar head groups. Since the polar group is removed soon after the end of archaeal activity, the occurrences of core and polar lipids are regarded as dead and active signals, respectively. The core and polar lipids have generally been analyzed separately using atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI), respectively, coupled with mass spectrometry. Methods: In this study, simultaneous analyses of core and polar archaeal lipids have been examined using heated electrospray ionization (HESI) by high-performance liquid chromatography/high-resolution mass spectrometry (HPLC/HRMS). Results: Both core and intact polar lipids can be analyzed simultaneously by HESI with good sensitivity (sub ng to 100 ng) and separation using a semi-bore diol column by normal-phase chromatography. The core lipids eluted firstly to separate archeaol, then glycerol dibiphytanyl glycerol tetraethers (GDGTs), followed by the polar lipids with glycosides and glycophosphates. The relative GDGT composition is identical between HESI and APCI methods. Conclusions: The simultaneous analysis has the benefit of minimizing sample amount and elution solvent as well as preparation work. The method can also be applied to a compound class fractionation for compound-specific carbon and hydrogen isotope analysis..
6. Hiroshi Naraoka, Minako Hashiguchi, Yu Sato, Kenji Hamase, New applications of high-resolution analytical methods to study trace organic compounds in extraterrestrial materials, Life, 10.3390/life9030062, 9, 3, 2019.09, [URL], Organic compounds are present as complex mixtures in extraterrestrial materials including meteorites, which may have played important roles in the origin of life on the primitive Earth. However, the distribution and formation mechanisms of meteoritic organic compounds are not well understood, because conventional analytical methods have limited resolution and sensitivity to resolve their molecular complexity. In this study, advanced instrumental development and analyses are proposed in order to study the trace organic compounds of extraterrestrial materials: (1) a clean room environment to avoid organic contamination during analysis; (2) high-mass-resolution analysis (up to ~150,000 m/⊿m) coupled with high-performance liquid chromatography (HPLC) in order to determine the elemental composition using exact mass for inferring the chemical structure; (3) superior chromatographic separation using a two-dimensional system in order to determine the structural and optical isomers of amino acids; and (4) in situ organic compound analysis and molecular imaging of the sample surface. This approach revealed a higher complexity of organic compounds with a heterogeneous distribution in meteorites. These new methods can be applied to study the chemical evolution of meteoritic organic compounds as well as the molecular occurrence in very-low-mass extraterrestrial materials such as asteroid-returned samples..
7. Yasuhiro Oba, Yoshinori Takano, Hiroshi Naraoka, Naoki Watanabe, Akira Kouchi, Nucleobase synthesis in interstellar ices, Nature Communications, doi.org/10.1038/s41467-019-12404-1, 10, 2019.09.
8. Jasmine Hertzog, Hiroshi Naraoka, Philippe Schmitt-Kopplin, Profiling murchison soluble organic matter for new organic compounds with APPI- and ESI-FT-ICR MS, Life, 10.3390/life9020048, 9, 2, 2019.06, [URL], The investigation of the abundant organic matter in primitive meteorite such as carbonaceous chondrites is of major interest in the field of origin of life. In this study, the soluble organic fraction of the Murchison meteorite was analyzed by atmospheric pressure photoionization (APPI) and electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), in both detection modes. Such an approach ensured that we obtained an extensive description of the organic matter of the CM2 meteorite. Indeed, while in total close to 16,000 unique features were assigned, only 4% are common to all analyses, illustrating the complementarity of both the detection modes and the ionization sources. ESI FT-ICR MS analysis, in negative-ion mode, ensured to observe specifically CHOS and CHNOS species, whereas the positive-ion mode is more dedicated to the detection of CHNO and CHN species. Moreover, new organomagnesium components were observed in (+) ESI. Eventually, (+) APPI FT-ICR MS analysis was a preferred method for the detection of less polar or nonpolar species such as polycyclic aromatic hydrocarbons but also heteroatom aromatic species composing the organic matter of Murchison..
9. Masayuki Uesugi, Motoo Ito, Hikaru Yabuta, Hiroshi Naraoka, Fumio Kitajima, Yoshinori Takano, Hajime Mita, Yoko Kebukawa, Aiko Nakato, Yuzuru Karouji, Further characterization of carbonaceous materials in Hayabusa-returned samples to understand their origin, Meteoritics and Planetary Science, 10.1111/maps.13236, 54, 3, 638-666, 2019.03, [URL], Carbonaceous materials in the sample catcher of the Hayabusa spacecraft were assigned as category 3 particles. We investigated the category 3 particles with a suite of in situ microanalytical methods. Possible contaminants collected from the cleanrooms of the spacecraft assembly and extraterrestrial sample curation center (ESCuC) were also analyzed in the same manner as category 3 particles for comparison. Our data were integrated with those of the preliminary examination team for category 3 particles. Possible origins for the category 3 particles include contamination before and after the operation of the Hayabusa spacecraft..
10. H. Naraoka, M. Hashiguchi, Distinct distribution of soluble N-heterocyclic compounds between CM and CR chondrites, Geochemical Journal, doi:10.2343/geochemj.2.0546, 53, 33-40, 2019.01.
11. M. Hashiguchi, H. Naraoka, High-mass resolution molecular imaging of organic compounds on the surface of Murchison meteorite, Meteorites and Planetary Science, doi: 10.1111/maps.13211, 54, 452-468, 2019.01.
12. Yuki Isono, Shogo Tachibana, Hiroshi Naraoka, François Régis Orthous-Daunay, Laurette Piani, Yoko Kebukawa, Bulk chemical characteristics of soluble polar organic molecules formed through condensation of formaldehyde
Comparison with soluble organic molecules in Murchison meteorite, GEOCHEMICAL JOURNAL, 10.2343/geochemj.2.0551, 53, 1, 41-51, 2019.01, [URL], Carbonaceous chondrites contain up to 2 wt% organic carbon, which is present as acid and solvent insoluble solid organic matter (IOM) and solvent soluble organic matter (SOM). The extraterrestrial organic matter should record chemical processes occurred in different environments in the early history of the Solar System, and the role of parent body aqueous alteration in the synthesis or subsequent modification of IOM and SOM still requires accurate constraints. We conducted hydrothermal experiments to simulate the synthesis of organic molecules during aqueous alteration on small bodies. Bulk chemical characteristics of soluble organic matter synthesized from formaldehyde in aqueous solutions were studied to compare them with that of chondritic SOM. We found that the redox state of synthesized organic molecules depends on temperature; the molecules become richer in hydrogen at higher temperatures. This can be explained by a cross-disproportionation reaction between organic molecules and formic acid, which occurs as a side reaction of the aldol condensation and works more effectively at higher temperatures. Comparison of the bulk chemical characteristics between the synthesized molecules and SOM extracted from the Murchison meteorite with methanol shows that the soluble organic molecules in Murchison are more reduced than the synthesized molecules. Considering the temperature condition for aqueous alteration on the CM parent body that is lower than or equivalent to the experimental temperatures, the reduced nature of Murchison organic molecules requires a reducing environment for them to be formed during hydrothermal alteration or imply that processes other than hydrothermal alteration were responsible for their synthesis. In case of hydrothermal synthesis, reducing conditions might be established by the interaction between water and iron-bearing silicates or metals on the parent body..
13. François Régis Orthous-Daunay, Laurette Piani, Laurène Flandinet, Roland Thissen, Cédric Wolters, Véronique Vuitton, Olivier Poch, Frédéric Moynier, Iyo Sugawara, Hiroshi Naraoka, Shogo Tachibana, Ultraviolet-photon fingerprints on chondritic large organic molecules, GEOCHEMICAL JOURNAL, 10.2343/geochemj.2.0544, 53, 1, 21-32, 2019.01, [URL], The organic matter in carbonaceous chondrites is of two kinds: one is called Insoluble Organic Matter, made of extremely large molecules that cannot be named with the usual nomenclature; one can be extracted by laboratory solvents and analyzed as a molecular mixture. Both are of debated origin. Retracing their natural histories requires putting strong constraints on their possible place of birth and their life time in space environments. It cannot be excluded they were formed in an interstellar medium before accretion on the chondritic parent bodies. As ultraviolet rays are the most common in the star forming regions and during the accretion phase of solar system, we propose to test the resilience of the natural organic matter of the Murchison meteorite against photolysis. The meteoritical soluble molecules were extracted by maceration and artificially exposed to a La photon dose commensurate to the one expected in molecular clouds and disks. The gaseous photolysis products were analyzed on the fly whereas the solid state mixture was solubilized again after irradiation for Orbitrap High Resolution Mass Spectrometry monitoring. We found that ultraviolet photons do modify the molecular mixture, removing H
2
and small carbon bearing species, shifting the mass distribution toward lower masses and increasing the number of cycles and double bonds in the molecules structure. A noteworthy effect of the irradiation is its selective preservation of species with a double bond equivalent consistent with aromatic rings in their structure. This is explained by the higher stability of such compounds. As the pristine Murchison extract lacks those features, we estimate it has not undergone significant irradiation after its synthesis. The extract we used for experiment being water insoluble, we assume its reactivity in hydrothermal condition would have been limited and have had no effect on the irradiation fingerprints. As a result the soluble fraction of Murchison was whether formed where the UV photon flux was negligible or it has been accreted quickly and shielded from photolysis in a parent body..
14. H. Naraoka, M.Hashiguchi, In situ organic compound analysis on a meteorite surface by desorption electrospray ionization coupled with an Orbitrap mass spectrometer, RAPID COMMUNICATIONS IN MASS SPECTROMETRY, 10.1002/rcm.8121, 32, 959-964, 2018.05.
15. H. Naraoka, Y. Yamashita, M. Yamaguchi, F. R. Orthous-Daunay, Molecular evolution of N-containing cyclic compounds in the parent body of the Murchison meteorite, ACS Earth and Space Chemistry, 1, 540-550, 2017.08.
16. Y. Oba, Y. Takano, H. Naraoka, A. Kouchi, N. Watanabe, Deuterium fractionation upon the formation of hexamethylenetetramines through photochemical reactions of interstellar ice analogs containing deuterated methanol isotopologues, Astrophysical Journal, 10.3847/1538-4357/aa8ea5, 849, 122(9pp), 2017.06.
17. S. Fuchida, H. Naraoka, H. Masuda, Formation of diastereoisomeric piperazine-2,5-dione from DL-alanine in the presence of olivine and water, Origin Life Evol. Biosphe, 47, 83-92, 2017.05.
18. T. Koga, H. Naraoka, A new family of extraterrestrial amino acids in the Murchison meteorite, Scientific Reports, 10.1038/s41598-017-00693-9, 7, 636(8pp), 2017.05.
19. Naraoka, H., Aoki, D., Fukushima, K., Uesugi, M., Ito, M., Kitajima, F., Mita, H., Yabuta, H., Takano, Y., Yada, T., Ishibashi, Y., Karouji, Y., Okada, T. and Abe, M., ToF-SIMS analysis of carbonaceous particles in the sample catcher of the Hayabusa mission., Earth, Planets and Space, 10.1186/s40623-015-0224-0, 67, 67(9pp), 2015.05.
20. Yohei Yamashita, Hiroshi Naraoka, Two homologous sereis of alkylpyridines in the Murchison meteorite., Geochem. J., 48, 519-525, 2014.01.
21. Masanori Kaneko, Naraoka Hiroshi, Yoshinori Takano, Naohiko Ohkouchi, Distribution and isotopic signatures of archaeal lipid biomarkers associated with gas hydrate occurrences on the northern Cascadia Margin, Chemical Geology, 343, 76-84, 2013.03.
22. M. Igisu, K. Takai, Y. Ueno, M. Nishizawa, T. Nunoura, M. Hirai, 奈良岡 浩, 金子 雅紀, M. Shimojima, K. Hori, S. Nakashima, H. Ohta, S. Maruyama, Y. Isozaki, Domain-level identification and quantification of relative prokaryotic cell abundance in microbial communities by Micro-FTIR spectroscopy., 4, 42-49, 2012.10.
23. Sano Hiroyoshi, T. Wada, Naraoka Hiroshi, Late Permian to Early Triassic environmental changes in the Panthalassic Ocean: Record from the seamount-associated deep-marine siliceous rocks, central Japan., Palaeogeogra. Palaeoclimat. Palaeoecol., 363, 1-10, 2012.10.
24. P.J. Noble, H. Naraoka, S.R. Poulson, E. Fukui, Y. Jin and S. O’Connor, Paleohydrographic influences on Permian radiolarians in the Lamar limestone, Guadalupe Mountains, West Texas, elucidated by organic biomarkers and stable isotope geochemistry. , Palaios, 26, 180-186, 2011.04.
25. M. Kaneko, F. Kitajima and H. Naraoka, Stable hydrogen isotope measurement of archaeol ether-bound hydrocarbons. , Organic Geochemistry , 42, 166-172, 2011.01.
26. K. Hashizume, N. Takahata, H. Naraoka and Y. Sano, Extreme oxygen isotope anomaly with a solar origin detected in meteoritic organics., Nature Geoscience, 4, 165-168, 2011.01.
27. M. Kaneko, Y. Oba and H. Naraoka, Vertical carbon isotope change in acetate in a surface sediment from the northwestern Pacific Ocean. Res. Org. Geochem. 26, 73-79., Researches in Organic Geochemistry, 26, 73-79, 2010.12.
28. M. Kaneko, H. Shingai, J.W. Pohlman and H. Naraoka, Chemical and isotopic signature of bulk organic matter and hydrocarbon biomarkers within mid-slope accretionary sediments of the northern Cascadia margin gas hydrate system. , Marine Geology, 275, 166-177, 2010.06.
29. H. Naraoka, T. Uehara, S. Hanada, T. Kakegawa, δ13C- δD distribution of lipid biomarkers in a microbial mat from a hot spring in Miyagi Prefecture, NE Japan., Organic Geochemistry, doi:10.1016/j.orggeochem.2009.11.008 , 41, 398-403, 2010.04.
30. Y. Oba and H. Naraoka, Elemental and isotope behavior of macromolecular organic matter from CM chondrites during hydrous pyrolysis., Meteoritics Planet. Sci., 44, 943-953, 2009.10.
31. H. Naraoka, T. Naito, T. Yamanaka, U. Tsunogai and K. Fujikura, A multi-isotope study of deep-sea mussels at three different hydrothermal vent sites in the northwestern Pacific, Chemical Geology, 255巻 25-32ページ, 2008.09.
32. Y. Oba and H. Naraoka, Carbon and hydrogen isotope fractionation of low-molecular-weight organic compounds during ultraviolet degradation., Organic Geochemistry, 39巻、501-509ページ, 2008.02.
33. Y. Chikaraishi and H. Naraoka, δ13C and δD relationships among three n-alkyl compound classes (n-alkanoic acid, n-alkane and n-alkanol) of terrestrial higher plants., Organic Geochemistry, 38巻、198-215ページ, 2007.08.
34. Y. Oba and H. Naraoka, Carbon and hydrogen isotope fractionation of acetic acid during degradation by ultraviolet light., Geochemical Journal, 41巻、103-110ページ, 2007.04.
35. Y. Oba and H. Naraoka, Site-specific carbon isotope analysis of aromatic carboxylic acids by elemental analysis/pyrolysis/isotope ratio mass spectrometry. , Rapid Commun. Mass Spec., 20巻、3649-3653ページ, 2006.10.
36. Y. Oba and H. Naraoka, Carbon isotopic composition of acetic acid generated by hydrous pyrolysis of macromolecular organic matter from the Murchison meteorite. , Meteoritics Planet. Sci., 41巻、1175-1181ページ, 2006.10.
37. Y. Chikaraishi and H. Naraoka, Compound-specific δ13C- δD analysis of lipid molecules in a plant-soil system., Chem. Geol., 218巻、117-133ページ, 2006.04.
38. S. R. Poulson and H. Naraoka, Carbon isotope fractionation during degradation of benzene, trichloroethene, and tetrachloroethene under ultraviolet light., Geochem. J., 40巻、291-296ページ, 2006.02.
39. H. Ohmoto, Y. Watanabe, K. E. Yamaguchi, H. Naraoka, M. Haruna, T. Kakegawa, K.-I. Hayashi and Y. Kato, Chemical and biological evolution of early Earth: Constraints from banded iron formations., The Geological Society of America Memoir, 198巻、291-331ページ, 2006.01.
40. Y. Chikaraishi, Y. Yamada and H. Naraoka, Carbon and hydrogen isotopic compositions of sterols from riverine and marine sediments., Limnology and Oceanography, 50巻、1763-1770ページ, 2005.08.
41. H. Yabuta, H. Naraoka, K. Sakanishi and H. Kawashima, Solid-state 13C NMR characterization of insoluble organic matter from Antarctic CM2 chondrites: Evaluation of the meteoritic alteration level, Meteoritics and Planetary Science, 40巻、779-787ページ, 2005.08.
42. Y. Chikaraishi and H. Naraoka, δ13C and δD identification of sources of lipid biomarkers in sediments of Lake Haruna (Japan), Geochim. Cosmochim. Acta, 69巻、3285-3297ページ, 2005.07.
43. H. Naraoka, H. Mita, M. Komiya, S. Yoneda, H. Kojima and A. Shimoyama, A chemical sequence of macromolecular organic matter in the CM chondrites, Meteoritics and Planetary Science, 39巻、401-406ページ, 2004.12.
44. Tomoaki Okuda, Hideshige Takada, Hiroshi Naraoka, Thermodynamic behavior of stable carbon isotopic compositions of individual polycyclic aromatic hydrocarbons derived from automobiles, Polycyclic Aromatic Compounds, 10.1080/10406630308060, 23, 2, 219-236, 2003.06, [URL], Concentrations, molecular compositions, and compound-specific stable carbon isotopic compositions (δ13C) of polycyclic aromatic hydrocarbons (PAHs) in gasoline exhaust particles (GEPs) and diesel exhaust particles (DEPs) were investigated in this study. δ13C of PAHs in GEPs ranged from -13.3‰ to -26.8‰, and that in DEPs ranged from -21.7‰ to -26.3‰. The interspecies δ13C variations in each sample were 5.3 ± 2.2‰ in GEPs and 2.6 ± 1.3‰ in DEPs. PAHs in GEPs show larger interspecies δ13C variation than those in DEPs; hence, a degree of carbon isotopic fractionation during the conversion from fuel to PAH seems to be larger in gasoline engines than that in diesel engines. Pyrene series PAHs, which consist of only hexagonal rings, in almost all GEP samples show strong negative correlation between the H/C ratio and δ13C whereas fluoranthene series PAHs, which contain a pentagonal ring, show less systematic isotopic behavior in GEP samples. A kinetic isotope effect in thermal cracking of organic macromolecules may be minor for PAH formation in vehicle engines. We suggest that the isotopic trend of pyrene series in GEPs can be explained by a thermodynamic isotope effect, and that disturbance from isotopic equilibrium may cause a weak correlation between the isotopic behavior and the H/C ratio among the interspecies PAHs..
45. A. Sarkar, H. Yoshioka, M. Ebihara, Hiroshi Naraoka, Geochemical and organic carbon isotope studies across the continental Permo-Triassic boundary of Raniganj Basin, eastern India, Palaeogeography, Palaeoclimatology, Palaeoecology, 10.1016/S0031-0182(02)00636-3, 191, 1, 1-14, 2003.02, [URL], Organic carbon isotope and geochemical changes across a continental interior Permo-Triassic boundary section from the Raniganj Basin, India, indicate a ∼9% drop in organic carbon δ13C in the Early Triassic and synchroneity of this event throughout the Pangea. The study demands a common causative mechanism for the perturbation of the global carbon reservoir and not a combination of multiple causes. A global sea-level fall and oxidation of marine gas hydrates possibly increased the 12CO2 input in the ocean-atmosphere system which caused a climatic shift from humid to warm semi-arid type and consequent extinction of land plants. Simultaneous increase in erosion from near-barren lands, change in the erosional base level and provenance deposited the boundary sandstone with positive europium anomaly and debris flow type matrix rich conglomerate. No extraterrestrial source, therefore, is needed to explain this Eu anomaly. The response of the terrestrial plant community to this perturbation of the carbon reservoir was, however, sluggish and the δ13C drop took place slowly, being maximal in the Early Triassic only..
46. Yoshito Chikaraishi, Hiroshi Naraoka, Compound-specific δD-δ13C analyses of n-alkanes extracted from terrestrial and aquatic plants, Phytochemistry, 10.1016/S0031-9422(02)00749-5, 63, 3, 361-371, 2003.01, [URL], Stable hydrogen and carbon isotopic compositions of individual n-alkanes were determined for various terrestrial plants (33 samples including 27 species) and aquatic plants (six species) in natural environments from Japan and Thailand. In C3 plants, n-alkanes extracted from angiosperms have a δD value of -152 ± 26‰ (relative to Standard Mean Ocean Water [SMOW]) and δ13C value of -36.1 ± 2.7‰ (relative to Peedde Belemnite [PDB]), and those from gymnosperms have a δD value of -149 ± 16‰ and δ13C value of -31.6 ± 1.7‰. Angiosperms have n-alkanes depleted in 13C relative to gymnosperms. n-Alkanes from C4 plants have a δD value of -171 ± 12‰ and δ13C value of -20.5 ± 2.1‰, being a little depleted in D and much enriched in 13C compared to C3 plants. n-Alkanes of CAM plants are a little depleted in D and vary widely in δ13C relative to those of C3 and C4 plants. In aquatic plants, n-alkanes from freshwater plants have a δD value of -187 ± 16‰ and δ13C value of -25.3 ± 1.9‰, and those from seaweeds have a δD value of -155 ± 34‰ and δ13C value of -22.8 ± 1.0‰. All n-alkanes from various plant classes are more depleted in D and 13C relative to environmental water and bulk tissue, respectively. In addition, the hydrogen and carbon isotopic fractionations during n-alkane synthesis are distinctive for these various plant classes. While C3 plants have smaller isotopic fractionations in both D and 13C, seaweed has larger isotopic fractionations..
47. T. Watanabe, Hiroshi Naraoka, M. Nishimura, M. Kinoshita, T. Kawai, Glacial-interglacial changes in organic carbon, nitrogen and sulfur accumulation in Lake Baikal sediment over the past 250 kyr, GEOCHEMICAL JOURNAL, 10.2343/geochemj.37.493, 37, 4, 493-502, 2003.01, [URL], The waters of modern Lake Baikal circulate well and maintain oxic conditions for the entire lake in spite of its great depth. Past oxic/anoxic conditions in the water column are not known. Because reconstruction of paleo-redox conditions involved with climate changes provides information on dynamics of lake water circulation and biological activity, high-resolution analyses of total organic carbon (TOC), total nitrogen (TN) and total sulfur (TS) concentrations, and gamma ray density (GRD) were carried out using 492 sediment samples over the past 250 kyr (every other 1 cm from the 10 m core Ver98-1 St.5 taken from the Academician Ridge at 325 m water depth). Fifteen events of high TS/TOC ratio (>0.2 atomic) are observed; these are much larger than TS/TOC ratio of typical freshwater sediment (0.001-0.070) and also normal oxic marine sediments (0.13 in average). The sulfur occurs as pyrite by X-ray diffraction (XRD) analysis, probably being produced by sulfate-reducing bacteria (SRB). Such high TS/TOC ratios indicate high SRB activity in the lake and a high input of sulfate to the lake. A high TS/TOC layer often accompanies a decrease of TOC/TN ratio to ca. 5 (atomic). In particular, during a rapid cooling such as the Younger Dryas event, the TOC/TN ratio decreases steeply from 10.4 to 7.8 just prior to the increase of TS/TOC ratio from 0.02 to 0.55. Because the low TOC/TN ratio suggests low terrestrial organic matter contribution to the lake, saline water inflow from rivers could diminish to result in decreased water circulation in the lake. The rapid cooling event may restrict deep-water ventilation and create less oxic conditions in Lake Baikal..
48. Tomoaki Okuda, Hidetoshi Kumata, Hiroshi Naraoka, Hideshige Takada, Origin of atmospheric polycyclic aromatic hydrocarbons (PAHs) in Chinese cities solved by compound-specific stable carbon isotopic analyses, Organic Geochemistry, 10.1016/S0146-6380(02)00180-8, 33, 12, 1737-1745, 2002.12, [URL], We report measurement of molecular and carbon isotopic compositions of atmospheric polycyclic aromatic hydrocarbons (PAHs) in three Chinese cities, Beijing, Chongqing, and Hangzhou. Precision of δ13C measurement by GC/C/ IRMS ranged from 0.4 to 0.7‰, and accuracy ranged from 0.0 to 0.4‰. δ13C of atmospheric PAHs ranged from -22.9 to -27.2‰ for Chongqing, from -24.2 to -26.8‰ for Hangzhou, from -21.1 to -26.1‰ for Beijing summer and from -22.5 to -25.7‰ for Beijing winter. Atmospheric PAHs of both Chongqing and Hangzhou become more depleted in 13C with increasing PAH molecular weight. On the other hand, atmospheric PAHs in Beijing become more enriched in 13C with increasing PAH molecular weight. The difference of isotopic signature between "Beijing" and "Chongqing + Hangzhou" is statistically significant (t-test, P < 0.05). The isotopic trends of PAHs in Chongqing and Hangzhou are similar to that obtained from fluidized-bed coal combustion particles, whereas the isotopic trend of PAHs in Beijing air is similar to that obtained from automotive exhaust particles. According to this observation, it appears that automotive exhausts significantly affect PAH loading to Beijing air and that coal combustion is the main cause of PAH existence in Chongqing and Hangzhou air. While the isotopic signatures can classify the three Chinese cities into two groups, the molecular profiles do not show a clear trend among them. This can be explained by the following description: carbon isotopic signatures of PAHs are expected to have source- and/or combustion field-specific values and patterns mainly, whereas molecular compositions of PAHs depend on various factors such as source material, burning temperature, air/fuel ratio, and environmental alteration during transport..
49. Simon R. Poulson, Hiroshi Naraoka, Carbon isotope fractionation during permanganate oxidation of chlorinated ethylenes (cDCE, TCE, PCE), Environmental Science and Technology, 10.1021/es0205380, 36, 15, 3270-3274, 2002.08, [URL], Permanganate oxidation of chlorinated ethylenes is an attractive technique to effect remediation of these important groundwater contaminants. Stable carbon isotope fractionation associated with permanganate oxidation of trichloroethylene (TCE), tetrachloroethylene (PCE), and cis-1,2-dichloroethylene (cDCE) has been measured, to study the possibility of applying stable carbon isotope analysis as a technique to assess the efficacy of remediation implemented by permanganate oxidation. Average carbon isotope fractionation factors of αTCE = 0.9786, αPCE = 0.9830, and αcDCE = 0.9789 were obtained, although the fractionation factor for PCE may be interpreted to change from a value of 0.9779-0.9871 during the course of the reaction. The fractionation factors for all three compounds are quite similar, in contrast to the variation of fractionation factors vs degree of chlorination observed for other degradative processes, such as microbial dechlorination. This may be due to a common rate-determining step for permanganate oxidation of all three compounds studied. The large fractionation factors and the relative lack of dependence of the fractionation factors upon other environmental factors (e.g. oxidation rate, presence of multiple contaminants, incomplete oxidation, presence of chloride in solution) indicate that monitoring δ13C values of chlorinated ethylenes during oxidation with permanganate may be a sensitive, and potentially quantitative, technique to investigate the extent of degradation..
50. Tomoaki Okuda, Hidetoshi Kumata, Hiroshi Naraoka, Ryoshi Ishiwatari, Hideshige Takada, Vertical distributions and δ13C isotopic compositions of PAHs in Chidorigafuchi Moat sediment, Japan, Organic Geochemistry, 10.1016/S0146-6380(02)00031-1, 33, 7, 843-848, 2002.08, [URL], Compound-specific carbon isotope analysis and molecular composition analysis were performed on polycyclic aromatic hydrocarbons (PAHs) extracted from a dated 50 cm sediment core from the Chidorigafuchi Moat, Japan. δ13C values ranged from -23.0 to -26.9‰ for individual PAHs, and ranged from -24.0 to -25.5‰ for the weighted average of PAHs at different core depths. Whilst total PAH concentrations showed a distinct maximum at around the year 1960, δ13C values did not show a statistically significant feature in the corresponding section of the core. Indeed, there was little correlation (r2=0.12, P=0.19) between ΣPAH and δ13C throughout the core. PAHs in surface sediment (ca 0-8 cm) were characterised by a significantly higher benzo(ghi)perylene to indeno(1,2,3-cd)pyrene ratio (t-test, P<0.025) and heavier δ13C values (P<0.015) than lower sections in the core. This suggests that PAHs sedimented after 1990 were more strongly influenced by PAHs fromautomotive exhausts. This preliminary study suggests that a two-dimensional analysis of both the molecular and isotopic compositions of PAHs may be useful in obtaining a more detailed source identification of organic pollutants in environmental samples..
51. Tomoaki Okuda, Hidetoshi Kumata, Mohamad Pauzi Zakaria, Hiroshi Naraoka, Ryoshi Ishiwatari, Hideshige Takada, Source identification of Malaysian atmospheric polycyclic aromatic hydrocarbons nearby forest fires using molecular and isotopic compositions, Atmospheric Environment, 10.1016/S1352-2310(01)00506-4, 36, 4, 611-618, 2002.02, [URL], We report measurements of molecular and carbon isotopic compositions of Malaysian atmospheric polycyclic aromatic hydrocarbons (PAHs) in smoke haze from the 1997 Indonesian forest fire. Comparison of the carbon isotopic compositions (δ13C) of individual PAHs from the smoke haze, with those from other PAHs sources (soot collected from gasoline and diesel vehicle muffler, woodburning smoke), enables us to discriminate among the diverse sources of atmospheric PAHs. Soot PAHs extracted from gasoline and diesel vehicles show heavy isotopic signatures with a large inter-species δ13C variation from -12.9‰ to -26.6‰, compared to soot PAHs extracted from woodburning smoke which are isotopically light, and have a small inter-species δ13C variation from -26.8‰ to -31.6‰. Values from -17.7‰ to -27.9‰ were obtained for the corresponding PAHs extracted from the smoke haze, indicating that they are derived mainly from automotive exhaust. Molecular and isotopic compositions of PAHs extracted from smoke haze were similar to those extracted from non-haze aerosol. Quantitative estimation shows that woodburning contribution to Malaysian atmospheric PAHs ranges from 25% to 35% with no relation to haze intensity, while automotive contribution ranges from 65% to 75%. These results suggest that the major contributor of PAHs in Malaysian air is automotive exhaust whether smoke haze is observed or not..
52. Y. Chikaraishi, Hiroshi Naraoka, Organic hydrogen-carbon isotope signatures of terrestrial higher plants during biosynthesis for distinctive photosynthetic pathways, GEOCHEMICAL JOURNAL, 10.2343/geochemj.35.451, 35, 6, 451-458, 2001.01, [URL], Stable isotopic compositions of organic hydrogen (δD) have positive correlations (r2 > 0.95) with those of carbon (δ13C) among several compound fractions of terrestrial plant leaves possessing distinctive photosynthetic pathways (C3, C4 and CAM). The δD/δ13C slopes of C3 plants vary from ∼25 to 42, which are larger than those of C4 plants (11 to 12). CAM plants have intermediate δD/δ13C slopes (∼17 to 20) between C3 and C4 plants. Using a δD-δ13C diagram, photosynthetic metabolisms are clearly discriminated, even though they sometimes cannot be distinguished from each other only by carbon isotopes. Relative to bulk organic matter, hydrogen and carbon of lipid fraction are more depleted in 13C than those of pigment fraction, respectively. Furthermore, δD values of lipid and pigment fractions relative to bulk organic hydrogen have negative correlations with δ13C values of corresponding fractions among the three photosynthetic pathways. This isotopic covariance among each fraction may be attributable to kinetically-controlled molecular biosyntheses using similar enzymes but with different isotope fractionations. Or the intermediate molecules for the biosyntheses have isotopically different pools in hydrogen and carbon..
53. Hiroshi Naraoka, Akira Shimoyama, Kaoru Harada, Isotopic evidence from an Antarctic carbonaceous chondrite for two reaction pathways of extraterrestrial PAH formation, Earth and Planetary Science Letters, 10.1016/S0012-821X(00)00316-2, 184, 1, 1-7, 2000.12, [URL], Polycyclic aromatic hydrocarbons (PAHs) are one of the most ubiquitous organic compounds in the universe. PAHs are sometimes used as a molecular marker for biological activity, however, they are also formed by abiogenic processes. Carbon isotopic compositions of individual PAHs have important clues to clarify their origins and formation mechanisms for the better understanding in organic cosmogeochemistry of PAHs. In the Asuka-881458 carbonaceous chondrite which was recovered from Antarctica in 1989, more than 70 PAHs were identified from naphthalene to benzo(ghi)perylene, where fluoranthene and pyrene are the most abundant. Carbon isotopic compositions of individual PAHs range from -26 to 8% (relative to PDB). More condensed PAHs are more depleted in 13C as the H/C ratio decreases. The carbon isotope distribution of PAHs containing more than three rings is similar to that from the Murchison meteorite, but clearly different from that of the terrestial PAHs. The isotope distribution suggests that the PAHs in carbonaceous chondrites are formed under kinetic control rather than by thermodynamic equilibrium. In particular, two reaction pathways ('pyrene series' and 'flouranthene series') can be distinguished assuming kinetic control. The relatively large isotopic fractionation could occur during cyclization and/or carbon addition in the interstellar or meteorite parent body environment..
54. Hiroshi Naraoka, Ryoshi Ishiwatari, Molecular and isotopic abundances of long-chain n-fatty acids in open marine sediments of the western North Pacific, Chemical Geology, 10.1016/S0009-2541(99)00159-X, 165, 1-2, 23-36, 2000.04, [URL], Molecular abundance and compound-specific carbon isotope ratios of long-chain n-fatty acids (LCFAs) ranging from C20 to C30 are reported for open marine sediments of the western North Pacific. A positive correlation (r2 = 0.94) is observed between total organic carbon (TOC) and LCFA concentrations, although the TOC concentrations varied from 0.34 to 2.62 (wt.% in dry sediment). The relatively uniform ratio of LCFAs to TOC (0.74 ± 0.12 mg/gC) is similar to that of the central Pacific reported by Ohkouchi et al. [Ohkouchi, N., Kawamura, K., Kawahata, H., Taira, A., 1997. Latitudinal distributions of terrestrial biomarkers in the sediments from the Central Pacific. Geochim. Cosmochim. Acta 61, 1911-1918] and in a core sample from the tropical central Pacific by Prahl et al. [Prahl, F.G., Muehlhausen, L.A., Lyle, M., 1989. An organic geochemical assessment of oceanographic conditions at MANOP site C over the past 26,000 years. Paleoceanography 4, 495-510]. On the other hand, LCFA concentrations in riverine and estuarine sediments are apparently higher than in open marine sediments. Carbon isotopic compositions of individual LCFAs in open marine sediments are similar (-26 ± 1‰ for n-C24 and n-C26), being more enriched in 13C than bay and riverine sediments by up to 6‰. Terrestrial C3 higher plants commonly have a δ13C value of ~ -26‰ in bulk organic carbon, and because lipid components including fatty acids are known to be depleted in 13C by several per mil compared to bulk organic matter, this study indicates that the open marine sedimentary LCFAs are not derived from normal terrestrial C3 higher plants. Rather, the isotopic composition is consistent with a mixed source of C4 and C3 terrestrial higher plants, and/or marine organisms. Low carbon preference index (CPI) values of the LCFAs, and the isotopic difference between the northern and southern samples suggest that the LCFAs of this study are likely to be related to marine primary productivity, even though LCFAs have often been used to infer a terrestrial higher plant input to marine sediments. (C) 2000 Elsevier Science B.V. All rights reserved..
55. David Brincat, Keita Yamada, Ryoshi Ishiwatari, Hitoshi Uemura, Hiroshi Naraoka, Molecular-isotopic stratigraphy of long-chain n-alkanes in Lake Baikal Holocene and glacial age sediments, Organic Geochemistry, 10.1016/S0146-6380(99)00164-3, 31, 4, 287-294, 2000.04, [URL], The molecular distribution and the carbon-isotopic composition (δ13C) of n-alkanes extracted from a Lake Baikal core spanning the last 20 kyr of sediment accumulation have been investigated. A terrestrial origin has been inferred for the odd carbon-numbered long-chain (> C27) n-alkanes, on the basis of the observed high CPI27-33 values (range: 8.7-10.8) typical of n-alkanes derived from leaf waxes of higher plants. A shift in the abundance of n-C27 alkane relative to n-C31 homologue is observed across the late Pleistocene glacial-Holocene interglacial climate change, perhaps indicative of the climate-induced vegetational change previously deduced from palynological analyses. Compound-specific isotope analyses indicate remarkably uniform δ13C values in the range of -31.0 to -33.5‰ for the leaf-wax C27-C33 n-alkanes in the entire cored sequence. Such an isotopic compositional range is characteristic for n-alkanes biosynthesized by plants utilizing the C3 photosynthetic pathway. Our data suggest that the observed 13C-enrichment in the bulk organic matter in the glacial age sediments, relative to δ13C values of total organic carbon in the Holocene section, is therefore unlikely to be attributed to an expansion of C4-type vegetation in the Baikal watershed during the late Pleistocene glacial interval. (C) 2000 Elsevier Science Ltd..
56. K. Matsumoto, K. Yamada, Hiroshi Naraoka, R. Ishiwatari, Carbon isotopic composition of sterols in geochemical samples, Geochemical Journal, 10.2343/geochemj.34.429, 34, 6, 429-438, 2000.01, [URL], Carbon isotopic composition of sterols in marine Holocene sediments, marine sinking particles, tree leaves, and soils were determined. δ13C values of algae-derived sterols such as 24-methylcholesta-5, 22-dien-3β-o1 and dinosterol in the marine sediments range from -22.1 to -25.2‰, while those of 24-ethylcholest-5-en-3β-ol (24-ethylcholesterol) range from -22.6 to -24.3‰. We conclude that 24-ethylcholesterol in the marine sediments derives from marine algae, because their δ13C values are markedly different from those of the leaves of C3 (∼-29‰) and C4 (-14‰) plants and similar to those of the algal sterols..
57. Yu Liu, Hiroshi Naraoka, Ken Ichiro Hayashi, Hiroshi Ohmoto, Laser microprobe technique for stable carbon isotope analyses of organic carbon in sedimentary rocks, GEOCHEMICAL JOURNAL, 10.2343/geochemj.34.195, 34, 3, 195-205, 2000.01, [URL], A technique for analyzing stable carbon isotope composition of organic carbon using a Nd-YAG laser microprobe system has been developed. Analyses were performed on graphite rod and silica-graphite discs made from mixtures of silica glass and graphite powders with a weight ratio as SiO2/C = 3/2. The sample was ablated by the laser and simultaneously combusted by laser ablation with excess O2 to produce CO2. Replicate analyses on the two types of standards under O2-atmospheric condition (8-20 torr) are reproducible to ±0.1‰ (1 σ) for δ13C, which is in agreement with accepted precision by the conventional method. In order to examine the matrix effect by other silicate minerals in natural samples during laser ablation, the silica-graphite disc samples were also combusted by laser ablation without excess O2 to produce CO2. In this case, the amounts of CO2 produced were far smaller (<1 %) than those of CO2 produced with excess O2 and the δ13C values range from -18.9 to -7.5‰. Considering the mass balance, we conclude that the matrix effects of silica or other silicates on the δ13C analyses of organic carbon can be ignored because it only result in a little positive shift (<0.2‰) in δ13C values. Application of the laser microprobe technique on δ13C analyses of organic carbon to five late Archean black shale samples (Jeerinah Formation, Hamersley Basin, Western Australia) gives δ13C values that are reproducible to ±0.1-0.3‰, and the mean δ13C values range from -37.2 to -39.1‰ which are very close to the δ13C values of the kerogens extracted from these shales. The analytical results demonstrate that the laser microprobe technique developed in this study is effective for the in situ isotope analyses of organic carbon in sedimentary rocks with a good precision of ±0.1‰..
58. Hiroshi Naraoka, Keita Yamada, Ryoshi Ishiwatari, Recent sedimentary hopanoids in the northwestern Pacific alongside the Japanese Islands - Their concentrations and carbon isotopic compositions, Organic Geochemistry, 10.1016/S0146-6380(00)00112-1, 31, 10, 1023-1029, 2000.01, [URL], Two hopanoids, 17β(H),21β(H)-hop-22(29)-ene (diploptene) and 17β(H),21β(H)-bishomohopanoic acid (ββC32-HA), are the most abundant among the pentacyclic triterpenoids found in Recent sediments of the Pacific Ocean alongside the Japanese Islands. The concentration of diploptene normalized to organic carbon content is higher in sediments where C37 polyunsaturated alkene (a biomarker of Haptophytes) is in high concentration, suggesting that the diploptene may be associated with the accumulation of marine organic matter. In open marine settings, δ13C values of ββC32-HA range from -23.8 to -19.4 parts per thousand (relative to PDB), being enriched in 13C relative to diploptene (-31.6 to -26.3 parts per thousand) by 5-9 parts per thousand. The isotopic difference indicates the presence of at least partially different sources for the two hopanoids. While diploptene is derived from cyanobacteria and chemotrophic bacteria in the water column or sediment, bishomohopanoic acid may be produced mainly by heterotrophs in the sediment using marine organic matter. In contrast, the δ13C values of the two hopanoids from river and bay sediments are similar (approximately -31 to -29 parts per thousand), indicating a common source derived from soil components (terrestrial plants or bacteria in soils)..
59. R. Ishiwatari, K. Yamada, K. Matsumoto, M. Houtatsu, Hiroshi Naraoka, Organic molecular and carbon isotopic records of the Japan Sea over the past 30 kyr, Paleoceanography, 10.1029/1998PA900014, 14, 2, 260-270, 1999.04, [URL], The organic and isotopic geochemical study of two sediment cores (KH-79-3, L-3, and KH-79-3, C-3) from the Oki Ridge in the Japan Sea has revealed that total organic carbon (TOC) mass accumulation rates are extremely high in the 12-11 ka (calendar age) interval and TOC in the sections in the 24-17 ka interval is depleted in 13C by 3.5‰ relative to Holocene sediments. Alkenone sea surface temperature (SST) shows a decrease from 18°to 14°C from 17.5 to 11.6 ka and a sharp increase from 14°to 19°C from 11.6 to 11.1 ka. The SST changes are associated with the inflow of cold seawater with the vertical water mixing and the inflow of warm Tsushima Current into the Japan Sea. The δ13C values for both 24-methylcholesta-5,22-dien-3β-ol (diatom marker) and dinosterol (dinoflagellate marker), are at their minimum from 24 to 17 ka, while those for long-chain alkenones are not. The theoretical considerations on δ13C for biomarkers suggest low photosynthetic carbon demand of diatoms and dinoflagellates from 24 to 17 ka..
60. Hiroshi Naraoka, Akira Shimoyama, Kaoru Harada, Molecular distribution of monocarboxylic acids in Asuka carbonaceous chondrites from Antarctica, Origins of Life and Evolution of the Biosphere, 10.1023/A:1006547127028, 29, 2, 187-201, 1999.03, [URL], Molecular distribution of low-molecular-weight monocarboxylic acids was studied in three CM2 Asuka carbonaceous chondrites (A-881280, A-881334 and A-881458), which were recovered from Antarctica by the 29th Japanese Antarctic Research Expedition in 1988. GC and GC/MS analyses identified more than 30 monocarboxylic acids in A-881458, including aliphatic and aromatic acids with various structural isomers. Isomeric phenolic compounds were also identified. The aliphatic carboxylic acids have straight-chain structures having 2 to 12 carbon atoms (C2 to C12), and branched-chain structures (C4 to C9). The quantities of straight-chain acids decrease logarithmically with increasing carbon number. At the same carbon number, a straight-chain isomer is always predominant compared to branched-chain isomers. All of the 14 possible C4, C5 and C6 aliphatic monocarboxylic acids (not including optical isomers) have been identified, although all the isomers were not reported in Murchison and Y-791198 meteorites. Of the 17 possible isomeric C7 acids, at least 14 isomers were tentatively identified by mass spectra (EI and CI mode). At C8 or above, peaks of branched-chain isomers become obscure, probably due to the large number of isomers and small concentrations. Branched-chain monocarboxylic acids over C6 have never been reported in Murchison. Although occurrence of aliphatic acids are similar between A-881458 and Murchison at C4, C5 and C6 acids, a major difference is that A-881458 as well as Y-791198 have straight-chain predominance among isomers in contrast to Murchison being branched-chain predominant. In the case of isomeric aromatic compounds such as toluic acids and cresols, m-toluic acid and p-cresol are more abundant among their isomers, respectively. The molecular distribution may not reflect thermodynamic equilibrium but rather a kinetically controlled process for their formation mechanism. The other two CM2 chondrites (A-881280 and A-881334) were depleted in carboxylic acids in spite of similar carbon contents. The depletion is not due to weathering on ice, because the degrees of weathering are small and similar among the three chondrites. Probably those latter two chondrites may have been subjected to aqueous alteration or metamorphism on their meteorite parent bodies..
61. Hiroshi Naraoka, Ryoshi Ishiwatari, Carbon isotopic compositions of individual long-chain n-fatty acids and n-alkanes in sediments from river to open ocean
Multiple origins for their occurrence, GEOCHEMICAL JOURNAL, 10.2343/geochemj.33.215, 33, 4, 215-235, 1999.01, [URL], Stable carbon isotopic compositions of individual n-fatty acids and n-alkanes were determined in six sediments from the Ohtsuchi River to the Pacific Ocean at north Honshu Island, Japan. Long-chain n-fatty acids (LCFAs) ranging from C20 to C30 and long-chain n-alkanes (LCALs) ranging from C23 to C33 have large isotopic variations from -35 to -25‰ and -35 to 29‰, respectively, although the molecular distributions of LCFAs and LCALs are almost identical in all analyzed samples. LCFAs are more depleted in 13C than total organic carbon (TOC) by about 5 to 12‰. The δ13C values are relatively similar between n-C20 and n-C26, and gradually decrease with increasing molecular weight to n-C30 by 3 to 5‰. Each n-fatty acid component shows a systematic enrichment in 13C from river to open ocean by up to 6‰ (from -32.5 to -26‰ for n-C26), and a similar isotopic composition in the open ocean (~-26‰ for n-C26). LCALs are also more depleted in 13C than TOC by about 6 to 12‰. The δ13C values gradually decrease from n-C19 to n-C31 by up to 6‰, then increase for >n-C31. Abundant LCALs, such as n-C29 and n-C31, show a systematic enrichment in 13C from river to open ocean by up to 3‰ (from -34.6 to -31.9‰ for n-C31), and a similar isotopic composition in the open ocean (~-31.5‰ for n-C31). On the other hand, C35 n-alkane has a relatively uniform isotopic composition (~-29‰) for all sediments. Such isotopic variations exhibit good correlations with δ13C(TOC) (-26.4 to -20.4‰) and C/N ratio (12 to 7 by atom) variations as well as amount of sedimentary cutin- and lignin-derived organic compounds of terrestrial higher plant origin. The isotopic distributions can be explained by a two-component mixture model involving isotopically different terrestrial and marine LCFAs and LCALs as endmember components. Although LCFAs (>n-C20) and LCALs (>n-C23) in marine sediments have been previously presumed to be derived from terrestrial higher plants, the results presented here may indicate that some of the LCFAs and LCALs in marine sediments are actually originated in the marine environment. Compound-specific isotope signature is important for evaluating the sources, as well as transport and mixing processes for the LCFAs and LCALs in a terrestrial-marine system..
62. Hiroshi Naraoka, Akira Shimoyama, Osamu Matsubaya, Kaoru Harada, Carbon isotopic compositions of Antarctic carbonaceous chondrites with relevance to the alteration and existence of organic matter, GEOCHEMICAL JOURNAL, 10.2343/geochemj.31.155, 31, 3, 155-168, 1997.01, [URL], Bulk carbon isotopic compositions of 26 Antarctic carbonaceous chondrites (33 specimens) are reported and discussed with relevance to the processes involved in their alteration and the existence of solvent-extractable organic matter. The δ13C values (relative to PDB) vary from -16.6 to +0.9‰. The average value (-6.2‰) is higher than that for non-Antarctic carbonaceous chondrites by -6‰. The difference may be explained by contamination of terrestrial organic carbon on non-Antarctic chondrites and/or different populations of parent bodies. Most Antarctic carbonaceous chondrites have an apparent trend ("a major sequence") that the δ13C value becomes higher with increasing carbon content. The trend is likely to be explained by a mixing model of two components; isotopically heavy and labile component (solvent-extractable organic matter and carbonate), and isotopically light and inert acid-insoluble component (kerogen-like matter). In addition, an unique group (altered specimens) is characterized by relatively high content and isotopically light carbon. For seven CM chondrites, δ13C values of residues after the hot H2O and HCl/HF treatment are also reported. Despite considerable isotopic variations of bulk carbon, the δ13C values of acid-insoluble residues may be classified into two groups: isotopically light (-15 to -13‰) and heavy (-9 to -7‰) ones. Most kerogen-like matters belong to the light group, which are isotopically similar to non-Antarctic kerogen-like matter. The altered specimens have isotopically light bulk carbon (-15‰), which is similar to those of their kerogen-like matter; they probably lost heavy components such as solvent-extractable organic matters (e.g., amino acid and carboxylic acid) and carbonates during aqueous alteration and thermal metamorphism on parent bodies. This is in accord with mineralogical and oxygen isotope studies. The presence of solvent-extractable organic matter is one of the important factors controlling bulk carbon isotopes in carbonaceous chondrites..
63. Yumiko Watanabe, Hiroshi Naraoka, David J. Wronkiewicz, Kent C. Condie, Hiroshi Ohmoto, Carbon, nitrogen, and sulfur geochemistry of Archean and Proterozoic shales from the Kaapvaal Craton, South Africa, Geochimica et Cosmochimica Acta, 10.1016/S0016-7037(97)00164-6, 61, 16, 3441-3459, 1997.01, [URL], The C, N, and S contents and δ13C and δ34S values were analyzed for 100 shale samples from ten formations, 3.0 to 2.1 Ga in age, in the central and eastern regions of the Kaapvaal Craton, South Africa. The Kaapvaal shales are characterized by generally low contents of organic C (range 0.06-2.79 wt%, average 0.47 wt%), N (range <0.01-0.09 wt%, average 0.1 wt%), and S (range <0.01-1.63 wt%, average 0.1 wt%). The low N/C (<0.005) and H/C (mostly ∼0.2) atomic ratios in kerogens from the shales indicated that the Kaapvaal shales lost considerable amounts of N, C, S, and H during diagenesis and regional metamorphism (up to the greenschist facies). From the theoretical relationships between the H/C ratios of kerogen and organic C contents of shales, the original C contents of the Archean and Proterozoic shales from the Kaapvaal Craton are estimated to be on average ∼2 wt%. These values are similar to the average organic C content of modern marine sediments. This suggests that the primary organic productivity and the preservation of organic matter in the ocean during the period of 3.0 to 2.1 Ga were similar to those in the Phanerozoic era, provided the flux of clastic sediments to the ocean was similar. This would also imply that the rate of O2 accumulation in the atmosphere-ocean system, which has equaled the burial rate of organic matter in sediments, has been the same since ∼3.0 Ga. The δ34S values of bulk-rock sulfides (mostly pyrite) range from +2.7 to +7.4‰ for seven sulflde-rich samples of ∼2.9 Ga to ∼2.6 Ga. These values are consistent with a suggestion by Ohmoto (1992) and Ohmoto et al. (1993) that most pyrite crystals in Archean shales were formed by bacterial reduction of seawater sulfate with δ34S values between +2 and +10‰, and that the Archean seawater was sulfate rich. Changes in the δ13Corg values during maturation of kerogen were evaluated with theoretical calculations from the experimental data of Peters et al. (1981) and Lewan (1983), and from the observations by Simoneit et al. (1981) on natural samples. These evaluations suggest that the magnitudes of δ13Corg increase are much less than those estimated by Hayes et al.(1983) and Des Marais et al. (1992), and only about 2 to 3‰ for the kerogens that decreased their H/C ratios from 1.5 to less than 0.3. Based on the relationships among sulfide-S contents, organic-C contents, and δ13Corg values, four different types of depositional environments are identified for the Archean and early Proterozoic shales in the Kaapvaal Craton: (I) euxinic marine basins, characterized by normal marine organisms with δ13Corg = -33 ± 3‰ ; (II) near-shore, oxic marine environment, characterized by normal marine organisms with δ13Corg = -31 ± 3‰; (III) hypersaline, low-sulfate lakes, characterized by organisms with δ13Corg = -26 ± 3‰; and (IV) euxinic, marine basins which supported the activity of methanogenic and methanotrophic bacteria and accumulated organic matter with δ13Corg = -43 ± 3‰. In contrast to the currently popular model positing a global anoxic ocean prior to ∼2.2 Ga (e.g., Des Marais et al, 1992; Hayes, 1994; Logan et al., 1995), this study suggests that the development of anoxic basins, which accumulated Group II and IV sediments, occurred only regionally and episodically during the period between 3.0 Ga and 2.1 Ga. This further suggests that the normal ocean has been oxic since at least ∼3.0 Ga. Diversifications of environments, as well as of biological species, had already occurred ∼3.0 Ga. The carbon isotope mass balance calculation suggests that the removal rates of organic C and carbonate C from the ocean and the weathering rates of organic C and carbonate C on the continents during the 3.0-2.1 Ga period were basically the same as those in the Phanerozoic era. This would have been possible only if the atmospheric PO2 level had been basically constant since at least 3.0 Ga. The results of this study, therefore, add to a growing list of evidence that the atmosphere has been oxic (i.e., PO2 >1%PAL) since at least 3.0 Ga. The list of evidence includes the sulfur isotope data on Archean sedimentary rocks (Ohmoto and Felder, 1987; Ohmoto et al., 1993), the Fe3+/Ti ratios of paleosols (Ohmoto, 1996), and the paragenesis of minerals in the "detrital" gold-uranium ores in pre-2.0 Ga quartz pebble beds that suggests nondetrital origins for uraninite and pyrite in these deposits (Baraicoat et al., 1997)..
64. Keita Yamada, Ryoshi Ishiwatari, Kohei Matsumoto, Hiroshi Naraoka, δ13C records of diploptene in the Japan Sea sediments over the past 25 kyr, GEOCHEMICAL JOURNAL, 10.2343/geochemj.31.315, 31, 5, 315-321, 1997.01, [URL], Stable carbon isotopic compositions were determined for diploptene in the sediment core KH-79-3, L-3 (core length: 235 cm) taken from the Oki Ridge in the southern part of the Japan Sea. Two major groups of diploptene with different δ13C values were recognized. The first group appears in the 0-130 cm section (present to 10 kyr B.P.) of the core, the δ13C values being -25.0 ± 0.7‰ on average. Diploptene in this section should have originated from cyanobacteria. The second group which is strongly depleted in 13C (-53.1 ± 5.3‰ on average), is observed in the 145-204 cm section (12-21 kyr B.P.). Diploptene in this section might have originated from methanotrophic bacteria. This indicates that an anoxic bottom water condition was developed during 12-21 kyr B.P. (the last glacial period), which was perhaps caused by the development of seawater stratification in the Japan Sea..
65. Hiroshi Naraoka, Makiko Ohtake, Shigenori Maruyama, Hiroshi Ohmoto, Non-biogenic graphite in 3.8-Ga metamorphic rocks from the Isua district, Greenland, Chemical Geology, 10.1016/S0009-2541(96)00076-9, 133, 1-4, 251-260, 1996.11, [URL], A 3.8-Ga-old metamorphic rock that contains up to ∼ 5.5 wt% reduced carbon as graphite was found in the Isua district, Greenland. This rock exhibits a strong schistosity, comprises mostly talc, contains high MgO (28.0 wt%), Ni (553 ppm) and Cr (267 ppm) and low Al2O3 (2.13 wt%), and bears a high Fe2O3/FeO ratio (0.94). The original rock was probably a submarine ultramafic tuff. The carbon content and the δ13C value of the rock vary on a microscopic scale (a few mm3 scale) from 0.7 to 5.5 wt% and from -15 to -12‰, respectively. The second rock, a quartzite, contains 0.13 wt% C as reduced carbon with a δ13C value of -11.2‰. These δ13C values fall within the range -27 to -10‰ reported by previous investigators for graphite from the Isua district. The δ13C values of the Isua graphite have been interpreted by previous investigators (e.g., Schidlowski and Aharon, 1992) as metamorphic modification of organic matter with initial δ13C values of ∼ -30‰. An important implication of this model has been that the ∼ 3.8-Ga ocean already supported some biological activity. However, an examination of the carbon content vs. δ13C relationship of the graphite-bearing rocks from Isua has revealed that the δ13C value generally increases with increasing carbon contents: the rocks with δ13C values less than ∼ -20‰ contain extremely small amounts of carbon (< 0.01 wt%), while the rocks with carbon contents greater than ∼ 1 wt% have δ13C values around -12‰. Such relationships are not consistent with the previous model for the origin of graphite in Isua, but are consistent with a two-component mixing model in which a major component had δ13C values of ∼ -12‰ and a minor component ∼ -25‰. The minor component may be biogenic, but it is not certain whether it represents a remnant of Archean biological products or more recent ones. The mineralogical and elemental characteristics of the rocks of this study - a thermodynamic consideration of the temperature and composition of metamorphic fluids - and carbon isotope mass calculations suggest that the major component of graphite with δ13C values around -12‰ was formed by an inorganic, rather than by a biological process. The graphite appeared to have formed at temperatures between 700° and 400°C by one or both of the following two processes: (1) reactions between CO2 and CH4 (CO2 + CH4 → 2C + 2H2O) during cooling of fluids with a CO2/CH4 molar ratio of ∼ 1; and/or (2) reactions between the FeO component in the ultramafic rock with CO2-rich fluids (4"FeO" + CO2 → 2"Fe2O3" + C). The δ13CΣC values for the fluids for both (1) and (2) were probably between -12 and -5‰, suggesting that the carbon-bearing fluids could have been derived from the mantle..
66. Hiroshi Naraoka, Keita Yamada, Ryoshi Ishiwatari, Carbon isotopic difference of saturated long-chain n-fatty acids between a terrestrial and a marine sediment, GEOCHEMICAL JOURNAL, 10.2343/geochemj.29.189, 29, 3, 189-195, 1995.01, [URL], Stable carbon isotopic compositions of individual n-fatty acids ranging from C20 to C30 in a terrestrial (riverine) and a marine (pelagic) sediment were determined using gas chromatography/isotope ratio monitoring mass spectrometry (GC/IRMS). These fatty acids in a terrestrial sediment at the Ohtsuchi river in northern Honshu Island, Japan, showed δ13C values (from -35 to -32%o relative to PDB) lighter than that of the total organic carbon (TOC; -26,4‰) by about 6 to 9‰, The δl3C values from a marine sediment in the Pacific Ocean ca. 500 km off the coast of Honshu Island varied from -31 to -26‰, which were also lighter than that of the TOC (-20.5‰) by 6 to 9‰. The δ13C values of n-fatty acids ranging from C20to C30 in the marine sediment were heavier by about 5 to 6‰ than those at the corresponding carbon numbers in the terrestrial one. Isotopically, the marine n-fatty acids were clearly distinguished from the terrestrial ones. These results suggest that long-chain n-fatty acids in marine sediment were not derived from land higher plant but from marine organisms, although long-chain n-fatty acids (≥C20) in marine sediments have often been used to assess terrestrial material contribution to the ocean..
67. Akira Shimoyama, Hiroshi Naraoka, Masatoshi Komiya, Kaoru Harada, Analyses of carboxylic acids and hydrocarbons in Antarctic carbonaceous chondrites, Yamato-74662 and Yamato-793321, GEOCHEMICAL JOURNAL, 10.2343/geochemj.23.181, 23, 4, 181-193, 1989.01, [URL], Analyses of the Yamato-74662 carbonaceous chondrite (C2) showed the presence of carboxylic acids, and aliphatic and aromatic hydrocarbons with various structural isomers, while those of the Yamato-793321 chondrite (C2) did not. The amounts of these compounds in Yamato-74662 are similar to those reported in the Yamato-791198 chondrite (C2) but less than in the Murchison chondrite (C2), The presence of various structural isomers in carboxylic acids and aromatic hydrocarbons indicated an abiotic origin and therefore, that these compounds are indigenous to the chondrite. n-Alkanes and other homologs of aliphatic hydrocarbons were found. However, these aliphatics may not be indigenous, especially under the finding of pristane and phytane. A potential use of the relative amounts of 1-methylnaphthalene and 2-methylnaphthalene was proposed to deduce the extent of thermal alteration. The result was: Yamato-74662
68. Hiroshi Naraoka, Kaoru Harada, Stereochemistry of piperazine-2,5-dione formation by self-condensation of DL-amino acid esters, Journal of the Chemical Society, Perkin Transactions 1, 1557-1560, 1986.12, 'Racemic' piperazine-2,5-diones (diketopiperazines, dkps) have been synthesized by the self-condensation of DL-amino acid esters without solvent. It was found that 'racemic' dkps consisted of cis-and trans-isomers, and that cis-dkp was preferentially formed in the early stage of the self-condensation, the cis:trans ratios gradually decreasing with increasing reaction time. These results may be attributed to the difference in the rates of cyclization of two kinds of diastereoisomeric dipeptide esters, intermediates in the formation of dkps from DL-amino acid esters. It was further confirmed that the pre-cis-dipeptide ester, which formed cis-dkp, cyclized faster than the pre-trans-dipeptide ester in methanol. Differences in steric hindrance in the cyclization reaction of pre-cis- and pre-trans-isomers may be an important factor in the stereochemistry of self-condensation..
69. Kaoru Harada, Michiaki Takasaki, Hiroshi Naraoka, Shinya Nomoto, Formation of bioorganic compounds in aqueous solution induced by plasma, Origins of Life, 10.1007/BF00933646, 14, 1-4, 107-114, 1984.12, [URL], When plasma jet of Ar-arc plasma was blown into an aqueous solution containing organic compounds, oxidation reactions were induced in the solution. The plasma-induced reaction was a powerful oxidation which could convert a methyl to a carboxyl group and cleave a carbon-carbon bond without using any oxidizing reagent. This reaction could be regarded as a model for the solar plasma-induced reaction in the primitive hydrosphere..
70. Shinya Nomoto, Michiaki Takasaki, Hiroshi Naraoka, Kaoru Harada, Formation of bioorganic compounds in aqueous solution induced by flames, Origins of Life, 10.1007/BF00933648, 14, 1-4, 123-130, 1984.12, [URL], Flames of flammable gases, when blown against a surface of an aqueous solution of organic compounds, were found to induce oxidation as well as other reactions in the solution. This reaction would be regarded as a new model for formation of bioorganic molecules in the primitive hydrosphere exposed to some radical-containing atmosphere..

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