title: Identification of the chemical form of sulfur compounds in the Japanese pink coral (Corallium elatius) skeleton using μ-XRF/XAS speciation mapping.
abstract: The distributions and chemical forms of sulfur compounds in the skeleton of Japanese pink coral (Corallium elatius) were investigated using X-ray spectroscopic techniques combined with micro-focused soft X-ray radiation. Microscopic X-ray fluorescence/soft X-ray photoabsorption (μ-XRF/XAS) speciation mapping clarified that sulfate is the primary species in the coral skeleton, with minor amounts of organic sulfur, whereas both sulfate and organic sulfur coexist in coenenchyme. Analysis of the post-edge region of the XAS spectra confirmed that sulfate ions in the coral skeleton are mainly in the form of gypsum-like inorganic sulfate substituting for the carbonate ions in the calcite skeleton. The sulfate concentration was negatively correlated with the magnesium concentration and positively correlated with that of phosphorus. Speciation mapping of sulfate in the coral skeleton showed clear fluctuations with sulfate concentrations being higher at dark bands, whereas the small amount of organic sulfur had unclear dark/bright bands. These results suggest that the little organic sulfur that is present is contained in the organic matter embedded in the biocrystal of coral skeleton.
authors.affiliation: Japan Synchrotron Radiation Research Institute/SPring-8, 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan. Electronic address: tamenori@spring8.or.jp.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Tamenori
authors.affiliation: Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka, Kanagawa 237-0061, Japan.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Yoshimura
authors.affiliation: Institute of Science and Engineering, Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192, Japan.
authors.forename: Nguyen Trong
authors.initials: NT
authors.lastname: Luan
authors.affiliation: Institute of Science and Engineering, Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hasegawa
authors.affiliation: Geological Survey of Japan, National Institute of Advance Industrial Science and Technology, Tsukuba Central 7, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8567, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Suzuki
authors.affiliation: Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan.
authors.forename: Hodaka
authors.initials: H
authors.lastname: Kawahata
authors.affiliation: Faculty of Geo-environmental Science, Rissho University, Magechi, Kumagaya, Saitama 360-0194, Japan.
authors.forename: Nozomu
authors.initials: N
authors.lastname: Iwasaki
mesh_terms: D060105:Animal Shells / Q000737:chemistry*; D000818:Animals; D037421:Anthozoa / Q000737:chemistry*; D004577:Electron Probe Microanalysis; D005453:Fluorescence; D007564:Japan; D008274:Magnesium / Q000032:analysis; D013058:Mass Spectrometry; D056951:Photoelectron Spectroscopy; D013457:Sulfur Compounds / Q000032:analysis*
chemical_list: D013457:Sulfur Compounds; D008274:Magnesium
keywords: Biological carbonate mineral; Chemical mapping; Microscopic X-ray fluorescence; Soft X-ray photoabsorption; Sulfur speciation