TERRAPUB Journal of Oceanography

Journal of Oceanography, Vol. 54 (No. 3), pp. 241-246, 1998

A New, Automatic Hydrothermal Fluid Sampler Using a Shape-Memory Alloy

Takeshi Naganuma1,2, Masanori Kyo2, Tatsuhiko Ueki3, Kazuhiko Takeda4 and Jun-ichiro Ishibashi5

1Faculty of Applied Biological Science, Hiroshima University, 1-4-4 Kagamiyama, Higashi-hiroshima 739-8528, Japan
2Deep Sea Technology Department, Japan Marine Science and Technology Center, 2-15 Natsushima-cho, Yokosuka 237-0061, Japan
3Furukawa Electric Co., Ltd., Yokohama R&D Laboratories, 2-4-3 Okano, Nishi-ku, Yokohama 220-0073, Japan
4Faculty of Integrated Arts and Sciences, Hiroshima University, 1-7-1 Kagamiyama, Higashi-hiroshima 739-8521, Japan
5Laboratory for Earthquake Chemistry, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan

(Received 20 September 1997; in revised form 5 January 1998; accepted 16 January 1998)

Abstract: A new hydrothermal fluid sampler has been developed to provide more maneuverability in underwater operation. The sampler characteristically employs a shape-memory alloy, which senses high temperature and actuates the suction mechanism. A shape-memory alloy is also used to switch the intake valve of the sampler, the intention being to avoid mis-sampling when the inlet is in low temperature water. Prototype samplers were designed to collect the fluids hotter than 80°C. Test sampling was performed at hydrothermal vents (1372-1374 m deep) in the submarine volcano, Suiyo Seamount, Izu-Bonin Arc, northwestern Pacific. Observed fluid temperature was between 138 and 298°C, while the ambient seawater temperature was 3.1°C. Each prototype collected about 100 ml fluid as designed. The magnesium concentration in the samples indicated a seawater content of 47.5-90.8%, which indicates the entrainment of ambient seawater. Microscopic observation revealed the occurrence of microorganisms in the sample fluids at a population density of 105 to 106 cells ml-1, which is 2-3 orders of magnitude higher than those in seawater at that depth. The use of the newly developed fluid sampler will greatly facilitate the collection of vent-associated microorganisms, which are of potential biological and biotechnological interest.

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