r/v natsushima cruise report nt13-23 survey at the yoron knoll area. in addition to the operation of

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  • R/V Natsushima cruise report

    NT13-23 21st – 26th November, 2013

    Iheya North Field and Yoron hole Okinawa trough

    Chief Scientist: Blair Thornton (Institute of Industrial Science, The University of Tokyo)

    in collaboration with:

    Japan Agency for Marin-Earth Science and Technology (JAMSTEC) Center for Advanced Marine Core Research, Kochi University

    International Institute for Carbon-Neutral Energy Research, Kyushu University National Maritime Research Institute

  • Preface

    This report describes the dives of the ROV Hyper-Dolphin between 21st and 16th November, 2013 at the Okinawa trough, during the NT13-23 cruise of the R/V Natsushima.

    The NT13-23 cruise was conducted based on two separate proposals; #KS13-08 “Investigation and field testing of in situ chemical sensing methods using light matter interactions”, proposed by Blair Thornton of the University of Tokyo, and #JS13-35 “Optimization of methodology for hydrothermal plume mapping and survey using multiple in situ chemical sensors”, proposed by Tatsuhiro Fukuba of JAMSTEC.

    The main objectives of the cruise were as follows; to investigate the application of laser-induced plasmas as a mechanism to perform in situ multi-element analysis of both liquids and solids at sea, and to optimize survey methods using multiple high spatiotemporal resolution in situ physicochemical/biochemical sensors.

    A total of five dives were performed with Hyper-Dolphin over three days. Successful multi-element analysis of both liquids and solids was achieved at depths of over 1000m. Integrated biogeochemical sensor measurements were made. In addition, energy generation experiments were successfully performed at an artificial hydrothermal vent in the Iheya North Field, and several novel sampling tools were successfully operated during the dives.

    December 2013 Blair Thornton (NT13-23 Chief Scientist)

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  • Notice on use

    This cruise report is a preliminary document prepared at the end of the cruise. Its content may be changed/corrected without notice and this document may not be corrected even if errors in its content are found. Data presented is shown only to demonstrate the principle of the techniques applied, and data may be raw, uncalibrated or unprocessed. Regarding the use of information contained within this report, please contact the chief scientist at blair@iis.u-tokyo.ac.jp for up to date details. Users of data or results contained within this report are requested to submit their results to the Data Management Group of JAMSTEC.

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  • Contents

    1. Cruise information 5 2. Cruise Log 2.1 Survey area and time schedule 5 2.2 Research party 6

    3. Instrumentation and methods 3.1 Objectives 7 3.2 In-situ measurements 3.2.1 ChemiCam 8 3.2.2 Biogeochemical sensors for hydrothermal plume mapping 9 3.2.3 UV LED light 11

    3.3 Sampling and manipulation tools 3.3.1 Rotary blade 12 3.3.2 Rock breaker 13 3.3.3 Seawater sampling using a syringe water sampler 13 3.3.4 MINIMONE water sampler 14

    3.4 Energy generation 3.4.1 Thermal energy generation 14 3.4.2 Hydrothermal fluid battery 15

    4. ROV operation 4.1 HPD #1597 16 4.2 HPD #1598 17 4.3 HPD #1599 19 4.4 HPD #1600 21 4.5 HPD #1601 22

    5. Sample list 23 6. Preliminary results 6.1 In-situ multi-element chemical analysis 24 6.2 Optimization of methodology for hydrothermal plume 25

    mapping and survey using multiple in situ chemical sensors 6.3 UV LED light 25 6.4 Energy generation 26

    7. Summary and Future Plans 27

    Acknowledgements 28

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  • 1. Cruise information

    Cruise number: NT13-23 Research vessel: R/V Natsushima Title of cruise: Hyper-Dolphin research dive, Deep-sea research, FY2013 Chief scientist: Blair Thornton, Institute of Industrial Science,

    The University of Tokyo Representative of Science Party: Thornton, Blair [The University of Tokyo]

    Tatsuhiro Fukuba [JAMSTEC] Proposal titles: Investigation and field testing of in situ chemical sensing

    methods using light matter interactions, #KS13-08 proposed by Blair Thornton of the University of Tokyo Optimization of methodology for hydrothermal plume mapping and survey using multiple in situ chemical sensors, #JS13-35 proposed by Tatsuhiro Fukuba of JAMSTEC

    Cruise period: November 21 to 26, 2013 (Okinawa, Japan) Survey site: Iheya North Field, Yoron Hole

    2. Cruise Log 2.1 Survey area and time schedule

    A total of 5 dives, HPD#1597 to HPD#1601, were performed over 3 days at the Yoron hole and Iheya North Field in the Okinawa trough. The research areas are shown in Figure 1. An additional day of operation was cancelled due to bad weather conditions. Table 1 shows the time schedule of the cruise.

    Figure 1 Ship track during NT13-23 (left) and ROV dive sites (right)

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  • Table 1 Time schedule of NT13-23

    2.2 Research party Table 2 Research Party (* chief scientist)

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  • 3. Instrumentation and methods

    3.1 Objectives

    The main objectives of the cruise were as follows:

    Proposal 1: Investigate the application of laser-induced plasmas as a mechanism to perform in situ multi-element analysis of both liquids and solids at sea.

    Proposal 2: Optimize methodology for hydrothermal plume mapping and survey using multiple in situ chemical sensors.

    The main objective of Proposal 1 is to test the principle of using laser-induced plasmas as a mechanism to perform in situ analysis of the chemical composition of liquids and solids on the seafloor. A 3000m depth rated device called the ChemiCam has been developed under the ‘Program for the development of fundamental tools for the utilization of marine resources’ of the Japanese Ministry of Education. The device employs a technique known as laser-induced breakdown spectroscopy (LIBS), which is a form of atomic emission spectroscopy, that works by focusing a high power laser pulse onto a target. This creates a plume of excited material that emits light containing spectral lines that correspond to the atoms and ions that compose the plume. Since the laser-ablated materials from which the optical emissions occur are in the form of atoms and ions in a plume, elemental analysis of gases, liquids and solids immersed in a transparent liquid, such as water, should be possible. ChemiCam is the 2nd generation of ocean going LIBS devices, following the prototype I-SEA (In situ Seafloor Element Analyser) that was deployed during NT12-07 in Kagoshima in March 2012 by our group. The main difference between these two systems is the integration of a long ns-duration pulse laser in the ChemCam, which has been demonstrated to present significant advantages in the quality of spectral emissions that can be observed underwater and at high pressure. The system utilizes a reflection based focusing optic for generation of plasmas and observation of spectral information over a wide range of wavelengths. The system also uses a linear z-focusing stage and water jet to aid operation. In addition to field testing of ChemiCam in the Iheya North Field, a number of tools developed to sample and manipulate the seafloor, including a rock breaker and rotary blade, were deployed during this cruise. The main aim was to use these tools to enable sub-surface measurements of rock mounds using ChemiCam. In addition to field testing of ChemiCam, two systems were deployed to generate

    electrical power from artificial hydrothermal vents in the Iheya North Field. The first system uses thermo electric modules (TEMs) to generate electricity from the thermal energy potential of hydrothermal vents. An early prototype of the system, consisting of 4 TEMs was successfully deployed during NT12-08 in Kagoshima bay to generate about 1.7Watts. The second electricity generation system is a hydrothermal fluid-seawater fuel cell designed to generate electric power from the electrochemical potential between deep-sea hydrothermal vent fluids and the surrounding seawater. A prototype of this system was successfully demonstrated during NT12-27. However, the time over which electricity was generated lasted only 4 minutes, which was too short to

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  • estimate its practical use. In this cruise, the aim was to fix the fuel cell on a deep-sea hydrothermal vent for several hours or more. The data will be analyzed not only to determine the amount of power generated, but also study the physical and chemical characteristics of the hydrothermal fluid, such as its temperature and oxidation-reduction potential. Finally, a UV light was tested to investigate its application to measure fluorescence in hydrothermal deposits and vent organism, and use their characteristic fluorescent colours as a tool to map their distribution in hydrothermal fields. The objective of proposal 2 is to optimize the methodology for hydrothermal plume mapping and survey using multiple in situ biogeochemical sensors. Plume mapping and survey strategies must be optimized considering the increasing need for in situ physicochemical/biochemical sensing operation with higher spatiotemporal resolutions. For example, to realize detailed mapping of biogeochemical properties or anomalies in meter to centimeter scale with acceptable reliability, measurement and sampling of “identical” water sample is essential. One of the promising methods to achieve this is to connect all of the sensors in series with a pump system. In this crui