December 2, 2015

Electrical measurement plan
Central Research Institute of Electric Power Industry

1. Aims
The aims of this measurement are to monitor time variation of electrical potential and to estimate the undergroundelectrical resistivity structure without CO2 around the previous CO2 released point.
2. Method
Three cables with electrodes are set on the seafloor as shown figure 1 and figure 2. Each cable has ten electrodes
at one side with five meters interval on the seafloor and ten conductors connected to a data logger at the otherside on the ground.
Time variation of electrical potential differences between measurement electrodes and a reference point (selfpotential) are recorded continuously to a data logger.
Electrical resistivity under the seafloor is evaluated by charging electricity between each measurement electrodes
and an electrode at a far field and measuring electrical potential induced by the charged electricity at eachmeasurement electrodes referred to a reference point.
3. Procedure1) The three cables will be set on
the seafloor before May 23, 2016
by SAMS.
2) A data acquisition system and areference point will be set up in
the morning of May 23, 2016.
3) Self-potential data will berecorded continuously from theafternoon of May 23 to themorning of May 27, 2016.
4)

TheelectricalFigure 1 Electrical measurement points on the seafloor (Plan view)

resistivity

measurement will be conducted in
the afternoon of May 27, 2016.
5) The data acquisition andresistivity

measurement

equipment will be removed after
the resistivity measurement.
6) The cables will be removed anddisposed

aftertheresistivity

measurement by SAMS.

Figure 2 Electrical monitoring concept (Vertical cross section view)

Monitoring of leaked CO2 after the QICS experimentKiminori Shitashima
International Institute for Carbon-Neutral Energy ResearchKyushu UniversityObservation
1. pH, pCO2, ORP in seawater• Bottom installed sensor around the leakage point• Water column (vertical) observation with micro-CTD around the leakage point
2. pH in sediment• In-situ pH in sediment of 50~80cm deep from seafloor*We gave up drilling for deep layer (2~3m) monitoring by using a portable excavator
3. Seismic observation (towing) using SBP and SSS

Space for preparation/setting of observation• Desk (1.5mW x 1mD) for sensor• Floor space (2m x 2m) for towing boat

December 2, 2015

Sampling and chemical analyses of pore water and sediments
AIST
1. Introduction
Sampling and chemical analyses pore water and sediment at Ardmuckinish Bay addresses two unsettled issues
from QICS: (1) the fate of the released CO2 potentially remaining in the subsurface sediments, and (2) themechanism behind the rapid recovery of pore water parameters to pre-release levels. To trace the injected CO2,
carbonate content of the sediment will be compared between the area close to the CO2 release point and theunaffected reference site. Time series in situ monitoring of pore water chemistry in the subsurface sediments will
be conducted in order to investigate pore water dynamics. To characterize pore water behaviour more precisely,
we will conduct a tracer test. For collection of pore water from various depths, a custom-made pore water
extractor as well as ready-made samplers.
2. Method
Approach (1): quantification of the injected CO2 remaining in the subsurface sediments.
Pore water sampling and analysis (Exp. 1): Pore water samples will be collected from two locations of theQICS experiment (QZ1: above the CO2-release diffuser, and QZ4: the reference site, 450 m away from QZ1) in
Ardmucknish Bay (locations shown in Fig.1). A commercially available ready-made pore water samplers with 5mm in diameter (Fig. 2) will be used for sampling of shallow layer at the depths up to 50 cm or 100 cm ofsediments, depending on the results of a preliminary test. For deeper sediments at the depths up to 1.5 m, we willuse custom-made pore water extractor with 2.5 cm in diameter (Fig. 2). The extractor is equipped with a sharptip, a filter protected with a perforated stainless steel cover and a connecter for a syringe. Installation of thesamplers and collecting samples by suction will be preliminary tested by divers from the National Facility for
Scientific Diving at SAMS. At each location and depth, sampling will be carried out with three replicates. The
arrangement plan of the samplers installed to sediments is shown in Fig. 3. The collected pore waters andoverlying seawater will be analysed for nutrients and carbonate species including pH, DIC and δ13C-DIC.
Sediment sampling and analysis (Exp. 2): Sediments will be collected using the SAMS mega-corer. The porewaters will be extracted through pre-drilled holes in the core barrel wall by inserting Rhizon pore water samplers.
The sediments will then be sliced into 2.5 cm sections, freeze-dried and analysed for inorganic carbon contentsand δ13C. Some samples will be sent to Japan and analysed for δ13C-DIC and δ13C-carbonates.
Approach (2): investigation of physically forced behaviour of pore water.
Serial monitoring of pore water chemistry (Exp. 3): The commercially available ready-made pore waterextractors will be installed at the depths from 5 cm to 1 m of sediments as above at QZ1 and CZ (Fig. 1). The
arrangement plan of the samplers is same as above (Fig. 3). CZ will be set close to the coastline where seawater
constituents are strongly affected by freshwater, as they are above the halocline and thus have different salinity.
CZ will be located at the distance by walking from the beach.
The pore waters will be collected from the extractor at high, ebb, low and flood tides. The samples will beanalysed for salinity, density, nutrients, anions, pH, DIC and δ13C-DIC.
Tracer test (Exp. 4): Six sets of the commercially available ready-made pore water extractors are installed at

depth of 10 cm, 20 cm, 30 cm and 50 cm at QZ1 as the arrangement plan shown in Fig. 4. The conservative
tracers (bromide and/or fluorescein dye) will be spiked into 20 cm depth of sediment through one of the extractors.
At intervals of 2 hours, pore water samples will be collected from the extractors and analysed for the tracer.
DateStationPlanProcedures

23rdQZ1

Exp.4

Tracer test system setting

QZ1

Exp.1&3

Pore water sampler setting

QZ1

Exp.4

Tracer injection

QZ4

Exp.1

Pore water sampler setting

QZ1

Exp.4

Tracer sampling (Day-0)

QZ1

Exp.4

Tracer sampling (Day-1)

QZ1

Exp.2

Mega-corer sampling

QZ4

Exp.2

Mega-corer sampling

QZ4

Exp.1

Pore water sampling and sampler removal

CZ

Exp.3

Pore water sampler setting (moved from QZ4)

QZ1

Exp.4

Tracer sampling (Day-2)

QZ1

Exp.1&3

Serial sampling (3~4 times) and sampler removal

CZ

Exp.3

Serial sampling (3~4 times) and sampler removal

26th

QZ1

Exp.4Tracer sampling (Day-3)

27th

QZ1

Exp.4

Tracer sampling (Day-4) and sampler removal

24th

25th

3. Requirements for space and equipment
Laboratory space: 1.8 m (W) x 0.7 m (D)Procedures

Equipment required

Pore water sample processing
Nutrient analysis

Autoanalyzer

pH measurement
Density measurement
Sample fixation with HgCl2

HgCl2 solution

Sediment sample freeze-dry

Freeze-dryer

Tracer preparation

Tracer reagent

Tracer measurement

Spectro-fluorometer

Floor space (warehouse): 2 m x 2 m
Procedures

Equipment required

Pore water extractor setting
Mega corer sample preparation

Mega corer and apparatus for

Pore water samplingsubsampling

Sediment cutting5 cm
20 cm
50 cm
100 cmFig. 3. Schematic view of pore water extraction strategy (left) and arrangement planon sediments (right).

A cluster of samplers(Enlarged view)

10 cm
20 cm
30 cm
50 cm

Fig. 4. Arrangement plan of samplers on sediments
for the tracer test.