著者

Toshitaka Gamo Harue Masuda Toshiro Yamanaka Kei Okamura Junichiro Ishibashi Eiichiro Nakayama Hajime Obata Kiminori Shitashima Yoshiro Nishio Hiroshi Hasumoto Masaharu Watanabe Kyohiko Mitsuzawa Nobukazu Seama Urumu Tsunogai Fumitaka Kouzuma Yuji Sano

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.38, no.6, pp.527-534, 2004-12-20 (Released:2008-04-08)

参考文献数

31

被引用文献数

12 32

---

This paper reports a series of studies leading to the discovery of a submarine hydrothermal field (called Nakayama Field) at an arc seamount (12°43′N, 143°32′E) in the southernmost part of the Mariana Trough, western Pacific Ocean. We first detected hydrothermal plumes characterized by water column anomalies of temperature, light transmission, Mn, Fe, Al, O2, CH4, and δ13C of CH4 above the summit caldera of the seamount. Then deep-tow camera surveys confirmed the existence of hydrothermal activity inside the caldera, and an ROV dive finally discovered white smoker-type fluid venting associated with vent fauna. A high concentration of aluminum in the plume and white smoker-type emissions imply acidic hydrothermal activity similar to that observed at the DESMOS Caldera in the eastern Manus Basin, Papua New Guinea. Anomalously low δ13C (CH4) of −38‰ of a vent fluid sample compared to other arc hydrothermal systems along the Izu-Bonin and Mariana Arcs suggests an incorporation of biogenic methane based on a subsurface microbial ecosystem.

著者

Tomohiro Toki Kiichiro Kawamura Urumu Tsunogai Toshitaka Gamo

出版者

Japan Agency for Marine-Earth Science and Technology

雑誌

JAMSTEC Report of Research and Development (ISSN:18801153)

巻号頁・発行日

vol.25, pp.1-12, 2017-09-01 (Released:2017-09-28)

参考文献数

39

---

We describe in detail the pore water chemistry in the sediments below a white mat around a bunch of bananas at a water depth of 2,200 m in the Tenryu Submarine Canyon. We infer the metabolism of microbes in the sediments around the bananas based on the chemical and isotopic compositions of the pore water. On the basis of the relation between ammonia and total carbonate (ΣCO2) concentrations in the pore water, we identified that an excess ΣCO2 was distributed around the bananas that cannot be explained by the decomposition of organic matter derived from marine organisms, indicating that the bananas decomposed to generate the excess ΣCO2. We conclude that the bananas built a local organic-rich environment, stimulating the activity of organotrophic bacteria.

著者

SHINSUKE KAWAGUCCI KOTARO SHIRAI TEFANG FAITH LAN NAOTO TAKAHATA URUMU TSUNOGAI YUJI SANO TOSHITAKA GAMO

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.44, no.6, pp.507-518, 2010-12-20 (Released:2013-03-23)

参考文献数

60

被引用文献数

14 35

---

Hydrothermal plumes above the HAKUREI and JADE sites, two high-temperature hydrothermal vent sites in the Izena Cauldron at the mid-Okinawa Trough, were investigated in order to gain a preliminary understanding of gas geochemical characteristics at underlying hydrothermal vent sites. Three geochemical tracers, H2, CH4 and δ3He, covary with each other above the HAKUREI site but only CH4 and δ3He are correlated above the JADE site. The carbon isotope ratio of methane within the Izena Cauldron can be accounted by a combination of the fluid dilution by ambient seawater and microbial consumption with the kinetic carbon isotope effect (KIE) of 1.007. An estimated endmember δ13C value of -32‰ in the HAKUREI fluid was obtained. Both the plumes above the HAKUREI and JADE sites showed C1/C2 ratios between 103∼104. Only the bottom water around the HAKUREI site showed significant N2O excess with isotopically light δ15N and δ18O, suggesting N2O input from microbial activity in the sediment. A linear correlation between H2 and CH4 in the HAKUREI plume gives a H2/CH4 ratio of the HAKUREI fluid of more than 0.022. The estimated H2/CH4 ratio in the HAKUREI fluid is significantly higher than that of the JADE fluid, comparable with those of fluids venting at other sediment-related hydrothermal systems, and also comparable with those of thermogenic gases produced by hydrothermal sediment experiments. These facts suggest that fluid-sediment interaction during fluid upwelling appears to modify gas geochemical characteristics at the HAKUREI site but have little influence at the JADE site. This study demonstrates the availability of the Izena Cauldron hydrothermal field and the HAKUREI and JADE sites as a natural laboratory for investigating the fluid-sediment interaction during fluid upwelling.

著者

Hui Lan Urumu Tsunogai Fumiko Nakagawa Masanori Ito Ryo Shingubara Yuko Miyoshi Shuichi Hara

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

pp.GJ23005, (Released:2023-02-10)

被引用文献数

1

---

To clarify the sources and fate of CH4 enriched in coastal seawaters, we determined the distribution of both the concentrations and dual stable isotope compositions (δ13C and δ2H) of dissolved CH4 in the bays of Ise and Mikawa in Japan during five sampling campaigns from 2013 to 2020, together with those in the major inflows of the Kiso, Nagara, and Yahagi Rivers. Excess CH4 were found in the surface layer of Ise Bay, and their δ13C and δ2H values were close to those of CH4 enriched in the major inflows, but deviated from those of CH4 in the sedimentary layer at the bottom of Ise Bay. The oxidation rates of CH4 in the water columns were negligibly small during the incubation experiments. In conclusion, the excess CH4 in the surface layer of Ise Bay was derived from the inflows. The CH4 enrichment in the freshwater sediments of the inflows showing up to four orders of magnitude higher CH4 concentrations than those in the sediments of Ise Bay supported this conclusion. Similar results were obtained in Mikawa Bay. The total emission flux of CH4 from the estuary area of Ise Bay was larger than the influx of CH4 into Ise Bay via the inflows, suggesting that the CH4 dissolved in the inflows was emitted into the atmosphere immediately after inflowing into the bay water.

著者

WEN HSINYI Naoto Takahata Akizumi Ishida Kentaro Tanaka Yama Tomonaga Takanori Kagoshima Kotaro Shirai Jun-Ichiro Ishibashi Hisayoshi Yokose Urumu Tsunogai Yuji Sano

出版者

日本地球化学会

雑誌

日本地球化学会年会要旨集

巻号頁・発行日

vol.61, 2014

---

The aim of this study is to get information of gas geochemical characteristics at hydrothermal vent sites in the adjacent region of Tokara Islands by using helium isotopes and methane concentration and its stable carbon isotope ratio to estimate the 3He flux and understand the mechanism of carbon cycling.