太陽系科学研究系

田畑 陽久

タバタ ハルヒサ  (Haruhisa Tabata)

基本情報

所属
国立研究開発法人宇宙航空研究開発機構 宇宙科学研究所 宇宙航空プロジェクト研究員
学位
博士(理学)(2022年3月 東京大学)

研究者番号
70962372
ORCID ID
 https://orcid.org/0000-0002-5653-5982
J-GLOBAL ID
202301015883174793
researchmap会員ID
R000047023

研究キーワード

 3

論文

 5
  • Haruhisa Tabata, Yasuhito Sekine, Kazumi Ozaki
    Geochimica et Cosmochimica Acta 381 97-115 2024年9月15日  査読有り筆頭著者
    Mars has experienced drastic environmental evolution in terms of pH, redox, and desiccation. NASA's Curiosity rover discovered that the sediments of the Pahrump Hills member of the Murray formation in Gale Crater contained different redox states of Fe oxides. To interpret the observations, understanding the factors that control iron redox states within early Gale lakes on Mars is needed. Here, we present the results of a one-dimensional geochemical model of a closed-basin lake that considers the Fe(II) photo-oxidation reaction. Depending on the source of Fe(II) (groundwater vs. river flow), lake pH, advection rate, and atmospheric composition, we defined four types of chemical profiles in the lake; namely, Fe(II) dominated, Fe(III) dominated, carbonate precipitating, and redox-stratified profiles. The Fe(III) dominated profile corresponds to the end member case in which photo-oxidation effectively oxidizes the supplied Fe(II). The redox-stratified profile, interpreted as an intermediate condition between Fe(III) dominated profile and Fe(II) dominated profile, appears in broad parameter set when Fe(II) is supplied from the groundwater, typically with a low to moderate Fe(II) input flux at acidic to alkaline pH (pH 5–9) conditions; however, the low water flux due to the nature of the groundwater may be unable to explain the measured abundance of Fe oxides in the sediments. Another endmember case, the Fe(II) dominated profile, which would also be expected to generate mixed valence Fe oxides, occurs when the pH is acidic (pH 4–5); nevertheless, the acidic pH is inconsistent with the mineral assemblages of the sediments. Carbonate precipitating profiles were limited to the case in which Fe(II) is supplied by groundwater with high Fe input flux and alkaline pH of 8–9. These results may imply either the Fe(II) input flux was high enough for the redox-stratified case or Fe(II) photo-oxidation was suppressed by turbidity or by dusty/cloudy atmosphere, or possibly that Fe(II) oxides found in the Pahrump Hills member are, at least partly, of detrital origin. Although numerous other factors (ex., effect of lake depth, variable pH throughout the lake water, detailed chemical speciation) remain unconsidered, the diverse profiles in Fe redox resulting from Fe(II) photo-oxidation reaction sheds light on interpreting the variety and the evolution of redox condition on early Mars.
  • Yuichiro Cho, Yayoi N. Miura, Hikaru Hyuga, Kenta Shimokoshi, Kazuo Yoshioka, Hiroyuki Kurokawa, Hidenori Kumagai, Naoyoshi Iwata, Satoshi Kasahara, Haruhisa Tabata, Mari Aida, Yoshifumi Saito, Seiji Sugita
    The Planetary Science Journal 2024年8月1日  査読有り
  • TABATA Haruhisa, CHO Yuichiro, YOSHIOKA Kazuo, AIDA Mari, YOGATA Kasumi, HAYASHIDA Masato, KANDA Tsuyoshi, KAWAKAMI Yui, TOEDA Junya, SATO Shin-ichiro, IMAIZUMI Mitsuru
    JAXA Research and Development Report 23 2024年2月  査読有り筆頭著者
  • Shoki Mori, Yuichiro Cho, Haruhisa Tabata, Koki Yumoto, Ute Böttger, Maximilian Buder, Enrico Dietz, Till Hagelschuer, Heinz-Wilhelm Hübers, Shingo Kameda, Emanuel Kopp, Olga Prieto-Ballesteros, Fernando Rull, Conor Ryan, Susanne Schröder, Tomohiro Usui, Seiji Sugita
    Planetary and Space Science 240 105835-105835 2024年1月  査読有り
  • Haruhisa Tabata, Yasuhito Sekine, Yoshiki Kanzaki, Seiji Sugita
    GEOCHIMICA ET COSMOCHIMICA ACTA 299 35-51 2021年4月  査読有り筆頭著者
    Photo-oxidation of aqueous Fe(II) (Fe2+ and FeOH+) to Fe(III) (Fe3+) was likely involved in the formation of iron oxide deposits on early Mars and Earth. Previous studies have reported the photo-oxidation reaction rate (i.e., quantum yield, phi = the number of oxidized ferrous ions divided by the number of photons absorbed by ferrous ions) under acidic conditions (pH 0.4-3.0). However, the quantum yield has not been systematically investigated using chemical actinometry in the range of weakly acidic to neutral pH, where the photo-oxidation would have occurred on early Mars and Earth. We report quantum yields for the photo-oxidation of aqueous Fe(II) species over a pH range of 0.5-7.6 with Hg and Xe lamps (with and without optical filters) based on measured Fe(II) concentrations and photon fluxes. The quantum yield under continuous UV and visible light (>200 nm, Xe lamp) varies with pH: phi = 0.103 (+/- 0.005) + 2.17 (+/- 0.27) x [H+](0.5) at pH = 3.0-7.0. Our quantum yield is a few times higher than those reported by the previous studies that used a Hg lamp, indicating the wavelength dependence of the quantum yield. At higher pH (7.1-7.6), with a UV cutoff at <= 300 nm (filtered Xe lamp), photo-oxidation of Fe (II) is attributed to oxidation of FeOH+, with a quantum yield of 0.08 +/- 0.01. Based on these quantum yields, we estimated Fe (III) (hydro)oxide precipitation rates in the early Gale lakes on Mars, and in Archean oceans on Earth. Results suggest that photo -oxidation may account for the amounts of Fe(III) (hydro)oxides in Gale sediments, assuming aqueous Fe(II) was supplied to the lakes through upwelling groundwater. Photo-oxidation of Fe(II) in Archean oceans on Earth could have been several times more intense than previously thought. (C) 2021 Elsevier Ltd. All rights reserved.

担当経験のある科目(授業)

 1

共同研究・競争的資金等の研究課題

 2