- 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
- M. Lutfi FIRDAUS Ikka FITRIANI Santhy WYANTUTI Yeni W. HARTATI Renat KHAYDAROV Jason A. MCALISTER Hajime OBATA Toshitaka GAMO
- 出版者
- The Japan Society for Analytical Chemistry
- 雑誌
- Analytical Sciences (ISSN:09106340)
- 巻号頁・発行日
- vol.33, no.7, pp.831-837, 2017-07-10 (Released:2017-07-10)
- 参考文献数
- 60
- 被引用文献数
- 2 95
Novel green-chemistry synthesis of silver nanoparticles (AgNPs) is introduced as a low-cost, rapid and easy-to-use analytical method for mercury ion detection. Aqueous fruit extract of water apple (Syzygium aqueum) was used for the first time as bioreductant to synthesize stable AgNPs. The prepared AgNPs have a yellowish-brown color with a surface plasmon resonance peak at 420 nm. The addition of Hg(II) ions then changes the AgNPs color to colorless. The color change was in proportion to the concentration of Hg(II) ions. The presence of other metal ions in the system was also evaluated. The proposed method shows good selectivity and sensitivity towards Hg(II) ions. Using UV-visible spectrophotometry, the detection limit of the developed method was 8.5 × 10−7 M. The proposed method has been successfully applied for determination of Hg(II) ions in tap and lake water samples with precision better than 5%.