日本地球惑星科学連合2018年大会

講演情報

[JJ] ポスター発表

セッション記号 M (領域外・複数領域) » M-IS ジョイント

[M-IS17] ガスハイドレートと地球環境・資源科学

2018年5月22日(火) 10:45 〜 12:15 ポスター会場 (幕張メッセ国際展示場 7ホール)

コンビーナ:戸丸 仁(千葉大学理学部地球科学科)、八久保 晶弘(北見工業大学)、谷 篤史(神戸大学 大学院人間発達環境学研究科、共同)、後藤 秀作(産業技術総合研究所地圏資源環境研究部門)

[MIS17-P10] サハリン沖海底堆積物中のガスハイドレート埋没コアの同位体ガスならびに微生物組成解析

*須川 和生1八久保 晶弘1坂上 寛敏1南 尚嗣1山下 聡1高橋 信夫1庄子 仁1Jin Young2Baranov Boris3Obzhirov Anatoly4小西 正朗1 (1.北見工業大学、2.韓国極地研究所、3.ロシア科学アカデミーP.P.シルチョフ海洋研究所、4.ロシア科学アカデミー極東支部V.I.イリチョフ太平洋海洋学研究所)

Gas hydrates (GH) are crystalline water-based solids including hydrocarbons under high pressure and low temperature. Methane as the major gases of GH are considered to generate from organic matters buried under the benthic sediments by theological clacking reactions and / or by methanogenesis. Isotope compositions of methane are considered to record the gas-generating manner, because microbes selectively metabolitze 12C, in the field of geochemistry. In addition, microbial compositions of the GH sediments have been often studied all over the world. However, combination study by both isotopic gas and microbial diversities analyses is insufficient to understand the gas-generating behavior. In this study, using microbial and isotopic analyses, we examined a unique GH-burying core; obtained in the western Sakhalin slope off Sakhalin Island during Japan-Russia-Korea joint projects (SSGH projects).

The GH-gas confirmed as thermogenic gas on the basis of Barnard plots, and including higher H2S and ethane than the other cores using principal component analysis of gas compositions. According to DNA-based microbial composition analysis, the Archaea abundance reduced along with the sediment depth. Under 20 cmbsf, MBG-B, MBG-D and Woesearchaeota (DHVEG-6) were dominated in Archaea. No methanogen was detected. Heterotrophic Chloroflexi and Candidate Atribacteria were major bacteria at a depth of 100 to 260 cm. It had been reported that Atribacteria decompose organic matters and generate ethanol and acids, by single cell genomics and metagenomics strategies. Since the low-molecules can be metabolized by methanogens, the Atribacteria-dominated bacteria composition may exhibit the possibility of methanogens, but methanogen was not detected. Low resolution of cloning-based DNA analysis might interrupt to detect methanogen. We, therefore, attempt to perform amplicon sequencing by Illumina the next generation sequencer.