R/V Natsushima cruise report

NT13-23 21st – 26th November, 2013

Iheya North Field and Yoron holeOkinawa 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 UniversityNational 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 cruise, a variety of sensors for conductivity, temperature, DO, pH (a glass type and an ISFET type), ORP, turbidity, and in situ ATP analyzer were united as a prototype “integrated Environmental Parameter Archiver (iEPA)” and it was operated for a hydrothermal plume mapping and survey at the Yoron Knoll area. In addition to the operation of the in situ biogeochemical sensors, a manganese sedimentation test piece was deployed in Yoron Knoll, and a multi-channel seawater sampling device was deployed together with a syringe seawater sampling system.

3.2 In-situ measurements

During this cruise, several different payloads were mounted on Hyper-Dolphin (HPD). These can be grouped into sensors for real-time measurement, tools to facilitate sampling of both solids and liquids, and on-site experimental apparatus for electricity generation and to investigate manganese mineralization. During the dives the readings of the some of the sensors were monitored in the ROV control room by members of the research party, and several of the sensors used were operated as stand alone units.

3.2.1 ChemiCam ChemiCam is a chemical sensor developed to perform in situ, multi-element analysis of the composition of liquid and solids at depths of up to 3000m. The measurement technique is based on LIBS, which is a form of atomic emission spectroscopy that performs measurements on plasmas generated by focusing a high power pulse laser into the bulk liquid, or onto immersed solid targets. Two types of LIBS device were deployed during this cruise. ChemiCam D is a 3000m depth rated device that uses a direct optic that focuses the laser to generate plasmas directly in bulk seawater to measure its chemical composition. ChemiCam F is a 3000m depth rated device, principally designed to measure the composition of solids. The latter system uses a fibre optic probe that is attached to the ROV manipulator and can target specific regions of the seafloor for analysis. Both devices perform measurements at a sampling rate of 1Hz and the results of the obtain spectra can be observed in real-time in the ROV control

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room. The ChemiCam systems for the 2nd generation of ocean going LIBS devices, following the prototype I-SEA system that was deployed during NT12-07. The most significant difference between the ChemiCam and I-SEA systems is the use a long duration ns-pulse laser, which has been demonstrated to present significant advantages in the quality of spectral emissions that can be observed underwater and at high pressure. Figure 2 shows Hyper-Dolphin about to be deployed with ChemiCam F mounted in its payload skid. The fibre optic probe, more clearly visible in the image on the right, is attached to the ROV manipulator on a single axis linear stage. The probe is moved into the vicinity of the measurement target using the ROV manipulator, after which the laser is focused onto the target using the linear stage. Both systems are controlled using a PC via a single RS232 communication line on the ROV and the measured data can be monitored in real-time.

Figure 2 HPD about to be deployed with ChemiCam F (left)and a closer look at the focusing fibre optic probe (right)

3.2.2 Biogeochemical sensors for hydrothermal plume mapping

Integrated Environmental Parameter Archiver (iEPA) As a core element of the iEPA system, a CTD profiler (SBE19PlusV2, Sea-Bird

Electronics Inc.) with DO sensor (SBE63, Sea-Bird Electronics Inc.), turbidity sensor (Seapoint turbidity meter, Seapoint sensors Inc.), and pH/ORP sensor (SBE 27, Sea-Bird Electronics Inc.) was mounted on the payload basket of HPD (Figure 3). The CTD profiler was also integrated with an ISFET (Ion Sensitive Field Effect Transistor) pH sensor using a flexible vinyl hose line. The water inlet of the CTD profiler was elongated using a vinyl hose and the inlet was fixed at the front of the payload skid near the SBE 27 pH/ORP sensor and the turbidity sensor. The sample inlet of IISA-ATP (Described in 3.2.3) was also bundled with the inlet hose of the CTD. The CTD was operated as a standalone device with a 0.5s sampling interval during deployment.

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Figure 3 CTD profiler with ISFET pH sensor

IISA-ATP – in situ microbial ATP analyzer IISA (Integrated In Situ Analyzer) –ATP is a prototype CFA (continuous flow analysis) device for automated ATP quantification. It has a microfluidic device as its core CFA element for luciferin-luciferase based ATP assay. The microfluidic device and all of pumping elements are stored in a pressure compensated container. A PMT (Photo Multiplier Tube) and its control electronics are enclosed in a cylindrical pressure vessel. IISA-ATP is controlled using a PC via a RS232 communication line of HPD and the

measured data can be monitored in real-time.

Figure 4 IISA-ATP in situ microbial ATP analyzer

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ISFET pH sensor with temperature logger ISFET pH sensors were bundled with standalone temperature sensor (SBE 56, Sea-Bird Electronics Inc.) for hydrothermal plume mapping and survey. The ISFET pH sensors were fixed on the port side of HPD.

Figure 5 ISFET pH sensors and temperature sensor

3.2.3 UV LED light

A 385nm UV-LED light was deployed during HPD#1600 to investigate the application of mineral and biological fluorescence as a tool to aid mapping of hydrothermal vent areas. The system emits about 15 W of light with a 30 degree opening angle. The system is focused onto the target using the ROV manipulator. Image data is recorded using HPDs imaging cameras (i.e. Hi-vision camera, CCD camera, SeaMax camera).

Figure 6 UV-LED light used to investigate bioflouresense in Galethied squat lobsters in the Iheya North Field

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3.3 Sampling and manipulation tools

3.3.1 Rotary blade A rotary blade was deployed during HPD#1601 to aid sampling and allow for sub-surface measurements of rock like hydrothermal deposits. The blade is used to make incisions into hard deposits to expose a fresh, sub-surface layer, which can then be measured by ChemiCam. The main hydraulic unit of the ROV supplies hydraulic pressure, and the flow can be controlled from the control room of the ROV. The specifications of the rotary blade are as shown in Table 3.

Table 3 Specifications of the rotary blade Hydraulic pressure 13.7MPa (2,000psi) Flow rate 20L/min Maximum rotation 1,500rpm Torque 30Nm Power 2.5kW Blade diameter 300mm

Figure 7 Rotary Blade being used for rock sampling during dive HPD#1601

Typically the rotary blade is clamped to the ROV manipulator during operation. However, since the nature of the operations during this cruise required one manipulator to operate ChemiCam F, the rotary blade could not be fixed to the remaining free manipulator. During operation, the system slipped in the ROV manipulator, and it is clear that modifications of the system are necessary in order to perform efficient sub-surface measurements.

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3.3.2 Rock breaker The rock breaker is a hydraulic vibration chisel with the specification given in Table 4. During HPD#1598, the rock breaker was used to recover the blocked C0014 vent hole in the Iheya North Field prior to the electricity generation experiments during HPD#1599.

Figure 8 Rock breaker inserted into the C0014 vent during HPD#1598

Table 4 Specifications of the Rock breakerHydraulic pressure 13.7MPa (2,000psi)

Flow rate 20L/min Vibration frequency 45Hz

Acceleration 11.4m/s2 Weight 10.6kg (in air) 8.6kg (in water)

Dimension 250x 200x 700mm

3.3.3 Seawater sampling using a syringe water sampler A seawater sampler using four aseptic plastic syringes with 100 ml of cylinder volume (Figure 9) were used during dive #1597 for onboard biochemical analyses. The collected samples were aseptically transferred to plastic tubes immediately after the ROV recovery and stored at 4˚C until onboard ATP, TIC, and pH analysis could be performed.

Figure 9 Seawater sampler using plastic syringes (Dive #1597)

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3.3.4 MINIMONE water sampler MINIMONE is an autonomous small volume parallel water sampler and is a miniature version of ANEMONE water sampler. A single unit can collect 24 samples of 10ml each. In this cruise, 3 sampling units (72 samples in total) were bundled together. The sampling interval was set to 3 min. The collected samples were transferred to glass vials immediately after recovery of the ROV recovery and stored at 4˚C until onboard analyses of TIC (total inorganic carbon), and pH could be performed.

Figure 10 MINIMONE water sampler

3.4 Energy generation 3.4.1 Thermal energy generation A deep sea power generation system that uses TEMs was tested during HPD#1599. The power generation system is composed of a power generator and a power management system. The hexagonal shape power generator, shown in Figure 11, is composed of six housing in which thermoelectric modules and related electric circuits are mounted. When the power generator is installed on top of a hydrothermal vent, the hot fluids will be injected into the system, and power will be generated by the TEMs by utilizing the temperature difference of hot fluids inside and cold seawater outside the system. The power management system uses the power generated to charge a 24V 17Ah lead-acid battery. The charging voltage, current and accumulated electricity are recorded continuously. A protection circuit is used to prevent overcharging the battery.

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Figure 11 Thermal energy generation system

3.4.2 Hydrothermal fluid battery A hydrothermal fluid fuel cell generator was developed for installation on a deep-sea hydrothermal vent. This system consists of an anode, a cathode, and a control unit in a pressure resistant housing, which are connected by underwater cables. The system generates electricity by exposing the anode to vent fluids, while the cathode is exposed to seawater. The system was installed together with the thermal energy generation unit on the artificial hydrothermal vent C0014 using the ROV manipulators.

Figure 12 Hydrothermal fluid fuel cell setup deployed during HPD#1599

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4. ROV dives A total of 5 dives were performed with the ROV over 3 days. A 4th day of dives was originally planned, but operations on the final day were cancelled could due to bad weather conditions. The first dive, HPD#1597 was carried out under proposal 2. The remaining dives were carried out under proposal 1. However, in both cases the payload space was shared between the two proposals to maximize the use of the available dive time.

4.1 HPD #1597 HPD dive #1597 was conducted at the western area of the Yoron hole. During the dive, the CTD and chemical sensor (pH, ORP and H2S) was continuously operated to detect physiochemical anomalies for hydrothermal plume survey. IISA-ATP was also deployed to estimate microbial biomass in situ. The MINIMONE water sampler was continuously operated to collect a series of water samples at 3 minute intervals. ChemiCam D was also deployed during this dive. HPD was dived to the bottom of the southern slope of a seamount and ascended up the slope to the north while making observations of the seafloor, as shown in the route track in Figure 13. Cracks with black or dark-brown sedimentation were observed (Figure 14), temperature measurement (Figure 15) and water sampling using the syringe water sampler and the Niskin water sampler were performed in these areas. Small pieces of rock (or sediment) were collected using the ROV manipulators. Two of Mn sedimentation test pieces (H1597-1 (Figure 16) and H1597-2) were placed nearby one of the crack, and will be recovered at a later date. Following the operations near the cracks, HPD moved to the east of the slope and climbed one of the seamount for hydrothermal activity survey with continuous chemical measurement and water sampling. Some of the cracks discovered were colonized by polychaetes (Figure 17).

Figure 13 ROV dive track during HPD#1597

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Figure 14 Black or dark brown cracks Figure 15 Temperature measurement

Figure 16 Mn sedimentation test piece Figure 17 Polychaetes colony

4.2 HPD #1598 Dive site: Iheya North Field Start Point: 27-47.428N 126-54.090E End Point: 27-47.420N, 126-54.037E

The purpose of this half-day dive was to recover the activity of the artificial hydrothermal vent (C0014G guide base) in preparation for hydrothermal energy generation experiments that followed this dive, and also perform LIBS measurements of seawater composition. Activity of the C0014G was previously recovered during NT12-27 using a heavy duty drilling system in October 2012. The drill hole had gradually became blocked after its initial installation in 2010. Just one year on from NT12-27, the hole had become blocked by hydrothermal deposits again. During this dive, a compact rock breaker was used to recover the drill hole (see Figure 8). Recovery of the drill hole took just 15 minutes after which vigorous venting was again observed. It can be concluded from this that the rock breaker is an efficient tool for this purpose. During the dive, ChemiCAM D was also mounted on HPD, and successful LIBS measurement of seawater composition were performed at depth of about 1050m. Additionally, LIBS measurement of rock samples were also performed by mounting a test piece on a linear stage that could bring the sample to the focal point of the laser.

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Figure 18 ROV dive track for HPD#1598

Figure 19 Activity of C0014 before and after recovery with the rock breaker

Table 5 Event log for HPD#1598Time Depth(m) Remark 08:22 Dive start 09:18 1048 Reach the seafloor 09:27 1056 Recovery of C0014G using the rock

breaker. Measurement of seawater composition using ChemiCam D

09:31 Measurements of sample test pieces with ChemiCam D

09:42 1055 End of dive

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4.3 HPD #1599

Dive site: Iheya North Field Start Point: 27-47.401N, 126-54.054E End Point: 27-47.417N, 126-54.027E

The purpose of this half-day dive was to perform energy generation experiments and perform LIBS measurements of seawater composition. The energy-generating devices were mounted on the ROV sample basket. The thermal generator and fuel cell were attached to each other and successfully installed on the mounting bracket of the C0014G guide base. Energy generation was performed for almost 2 hours. During this period, LIBS measurement of seawater composition were performed using ChemiCam D near the C0013E and C0016B guide bases and the NBC mound. After performing seawater chemical mapping experiments, the ROV returned to the C0014G guide base to recover the energy generation devices.

Figure 20 ROV dive track for HPD#1599

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Figure 21 Energy generation devices mounted on the C0014G vent.

Figure 22 Close up of ChemiCam D with a visible plasma seen in the right image

Table 6 Event log for HPD#1599Time Depth(m) Remark 12:13 Dive start 13:24 1042 Reach the seafloor 13:37 1056 Install the power-generating devices on a

hydrothermal vent 13:53 Start the measurement of seawater composition 14:21 1025 Pass over the C0013E guide base 14:43 991 Pass over the C0016B guide base 15:25 1055 Recover the power-generating devices 16:01 1059 End of dive

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4.4 HPD #1600

Dive site: Iheya North Field Landing Point: 27-47.377N 126-53.876E Leaving Point: 27-47.453N 126-53.795E

The main objective of this dive was to perform sampling and make bio-fluorescent observations using the UV-LED light. The UV-LED light was used to illuminate Galetheids and deep-sea shrimp. Sampling of hydrothermal sulfide deposits and seawater was also performed.

Figure 23 ROV dive track for HPD#1600

Figure 24 Illumination of Galetheids using the UV LED light

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Table 7 Event log for HPD#1599Time Depth(m) Remark 8:34 Dive start 10:28 1033 Niskin (red) bottle seawater sampling 10:29 1035 Reach the seafloor 10:56 990 Illuminate crustaceans with UV-LED light 11:24 995 Rock sampling 11:27 971 Niskin (green) bottle seawater sampling 11:39 971 End of dive

4.5 HPD#1601

Diving site: Iheya North Field Landing Point: 27-47.380N 126-53.853E Leaving Point: 27-47.462N 126-53.795E

During this mission, LIBS measurements of solids were performed using ChemiCam F. The fibre probe was placed near test piece samples and also near the seafloor using the ROV manipulator, and the linear stage was used to focus the laser on the targets. Successful LIBS measurements were achieved and high resolution spectral data was obtained at depths of over 1000m. Measurements were also made of the hydrothermal deposits that block C0013 to determine their chemical composition. The rotary blade was also deployed using the ROV to make incisions into hydrothermal deposits.

Figure 25 ROV dive track for HPD#1601

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Figure 26 Measurement of hydrothermal deposits blocking the C0013 vent and deposits at the base of the NBC mound using ChemiCam F

Table 8 Event log for HPD#1601 Time Depth(m) Remark 14:16 Dive start 14:24 LIBS measurements of test pieces using

ChemiCam F 14:55 1026 Reach the seafloor 15:09 1030 LIBS measurements of deposits inside

C0013 15:35 995 Rock sampling 15:58 994 Niskin(green) bottle seawater sampling 16:06 997 Measurements of hydrothermal deposits

at the base of NBC mound 16:23 996 End of dive

5. Sample list

Table 9 Rock samples obtained during NT13-23

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6. Preliminary results 6.1 In-situ multi-element chemical analysis

ChemiCam D was successfully operated to measure the chemical composition of seawater during HPD#1597,1598,1599. Successful measurements of solid test pieces were also made during HPD#1597 and HPD#1598 using ChemiCam D by bringing samples to the focal point of the laser using a linear stage. Measurements of solids were also performed using ChemiCam F during HPD#1601. The preliminary data demonstrates in situ multi element analysis of both solids and liquids using LIBS at over 1000m depth. It is to the knowledge of our group, the first time LIBS has been applied in the field at such depths. Detailed processing of the data obtained during this cruise will be performed in the near future.

6.2 Optimization of methodology for hydrothermal plume mapping and survey using multiple in situ chemical sensors

During HPD #1597, all of the physiochemical sensors and water samplers were successfully operated. Cracks with black to dark brown deposits were distributed on the south face of the seamount. Though, there was no visible hot water emission or simmering, a weak (1 to 2 ˚C) temperature anomaly was observed through temperature measurement. Biogeochemical sensors shown no apparent anomalies during the dive #1597 except for ORP and ATP. Lower ORP value were measured on the seafloor with cracks. It implies invisible supply or diffusion of reduced matters from the cracks. ATP data also showed lower value than the other place the crack. It may correspond to the absence of fine sediment around the cracks. These data will be analyzed in detail soon. As a result of onboard ATP analysis using desktop apparatus, the ATP contents of four water samples were successfully measured. The ATP concentrations were between 10 to 100 pM.

6.3 UV LED light

Bio-fluorescence observations were carried out near the NBC mound in the Iheya North field (depth 990 m). The Galetheid, Goemon-koshiori-ebi, showed blue-white fluorescence in their main body and green fluorescence in the bristles on their claws. The deep sea shrimp, Ohara-ebi showed weak red fluorescence. Deep-sea mussels, Shinkai-hibari-gai, showed green-yellow fluorescence at the edge of their shells. Color image processing and auto-count algorithms will be considered to process the data in near future.

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Figure 27 Bio fluorescence images before (left) and after processing (right)

Mineral fluorescence observations could not be carried out due to the limited time available for operation, but fluorescence observations of hydrothermal deposits sampled from the Iheya North Field (depth 995 m) were performed.

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6.4 Energy generation

The hydrothermal energy generation experiment was performed during HPD#1599. Both the thermal and fuel cell generators were latched onto each other and mounted onto the C0014 artificial vent using the ROV manipulators. The whole experiment lasted for 110minutes. Both energy generation systems successfully generated power for the duration of the experiment and temperature measurement data of the vent fluids indicated that they had an average temperature of 310oC. Preliminary data suggests that the thermal energy generation system generated a maximum of 60 Watts, and an average of 45 Watts during the experiment. The fuel cell also generated power for the duration of the experiment and the data obtained is currently being processed.

Figure 28 Configuration of artificial hydrothermal vent

Figure 29 Attachment of energy generator unit onto C0013 vent using the ROV manipulators

Figure 30 Configuration of the thermal (left) and fuel cell (right) components of the energy generation system

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One issue that must be resolved for future, long term deployment of such a system is deposition of polymetallic sulfides on the inner surface of generator unit as shown below.

Figure 31 Hydrothermal deposits on the inner surface of the thermal energy generator

7. Summary and Future Plans The major objectives of the two proposals on this joint cruise were successfully achieved.

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,

In situ, multi element analysis of both seawater and hydrothermal deposits were successfully achieved. Laboratory quality data was obtained from the two ChemiCam systems mounted on the ROV at depths of over 1050m, confirming laboratory experiments that demonstrated that hydrostatic pressures of a few tens of MPa have only a negligible affect on the quality of the spectra that can be measured. The improvements in the 2nd generation LIBS devices over the prototype system deployed in March 2012 are clear, both in terms of the fundamental measurement technique, i.e. the use of a long-pulse and reflection optic, together with a bundle fibre for observation of the plasmas, and operation of the device i.e. use of a controllable linear focusing stage. In our future work, we will process the data obtained during the cruise using various analytical methods, including Calibration-free LIBS and catalogue based matrix matching methods to quantify the data obtained. The results will be compared with the composition of samples obtained during this cruise, which will be quantified using standard analytical techniques such as ICP-AES. With regards to the in situ device, future work will focus on downsizing of the instrument, and we will continue to work on optimization of the operation of the device using various support tools. We also plan on extending the application of the system to soft sediments, which has been demonstrated in the laboratory by our group, and perform downhole measurements of both liquids and solids.

Bio-fluorescent images in the hydrothermal field were obtained using the UV-LED light. In the near future, auto-count image processing software with species identification and body count using fluorescent colors will be developed based on obtained data. Additionally, a Laser-Raman spectroscopy system is also currently being considered for in situ identification of hydrothermal deposits.

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With regard to the energy generation systems, the principle of combining different types of energy generation methods was successfully demonstrated in the field. The energy generation data will be analyzed together with the temperature measurements to determine the efficiency of the generator units. For the fuel cell, we expect to clarify the electrochemical reactions on the surface of electrodes during generation. The 110minute deployment also identified some key areas for improvement that should be addressed before the systems can be deployed for extended periods (i.e. several months to several year deployments).

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

During this cruise, biogeochemical sensors were integrated for improvement of hydrothermal plume mapping and survey methodology. Though the standalone ISFET pH sensors and IISA-ATP were integrated with the CTD profiler, the data was stored only on its own local memory or onboard PC. The output signal from the auxiliary sensors such as ISFET pH sensor and IISA-ATP must be transferred to the CTD profiler to realize a reliable iEPA system. Water samplers must be also integrated with iEPA to realize “integrated Environmental Parameter and sample archiver (iEPSA) system. These improvements will enable efficient in situ sensing and sampling operations using ROVs or AUVs for the purpose of novel resource survey.

Acknowledgements The research party would like to thank the crew members of the R/V Natsushima lead by Captain Hitoshi Tanaka, the members of the ROV HPD operation team lead by Yoshinari Ono, marine technician Toshimasa Nasu, and Yuta Yamamuro together with the staff of JAMSTEC and Nippon Marine Enterprise for their dedicated efforts which contributed greatly to the success of this cruise. This research is supported by MEXT (Ministry of Education, Science, & Culture) through “Program for the development of fundamental tools for the utilization of marine resources”.

Figure 32 NT13-23 research party together with the HPD team and crew members

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