MIRAI MR05-01 Primary Production

 Primary Production Data during MR05-01 cruise were obtained by the following methods :
- Simulated in-situ incubation method (SIS)
 Water sampling, incubation, and devices and tracers for analysis for each method
are outlined below.
For further information, please see Cruise Report.

  Simulated in-situ incubation (SIS) Outline figure
1)  Vertical sampling : Niskin
2)  Surface sampling :  Bucket
3)  Sampling layer :    8
4)  Tracer :            NaH¹³CO₃
5)  Incubation period : 24hours
6)  Filtration :        Whatman GF/F filter was used at dark place.
7)  Preservation :      Filters were kept to freeze at -20degC and dried
                           in the oven at 45degC.
8)  Preservation period of frozen filter paper : within 30 days
9)  Analysis place :    MIRAI
10) Analysis device :   CN mass spectrometer (see section 3 and 4 for detail)
11) Analysis method :   Dumas method, Mass spectrometry

 CN mass spectrometer system equipped with R/V Mirai can measure stable isotope
ratios of ¹³C and ¹⁵N comprised in liquid, solid, and gas states of
biological or biogenic samples, simultaneously and continuously.
This system consists of two devices, preprocessing equipment “ROBOPLEP-SL” and
stable isotope ratio mass spectrometer “EUROPA20-20”.

(1) ROBOPLEP-SL
A tin capsule containing the sample falls into the combustion tube and is
converted in the presence of oxygen to CO₂, N₂, NO_x and H₂O.
An elemental copper stage reduces NO_x, a MgClO₄ trap removes water vapour,
a switchable Carbosorb trap can be used to remove CO₂ (for ¹⁵N only analyses)
and a GC column separates CO₂ from N₂ (allowing dual isotope analysis).
And then, it is introduced into the “EUROPA20-20”.

(2) EUROPA20-20
CO₂ and N₂ are collided with thermion and ionized in the high vacuum ion source.
When the generated ions are accelerated by constant voltage and pass through
the analysis tube, differences in mass (m) and electric charge (z) of isotope
ions make the different orbits by the magnetic field in the analysis tube.
Thus, isotopes can be separated by the displacement of the orbits.
These signals are converted into the frequency at the detector, and transmitted
to control PC. Blank and drift corrections are conducted on the control software.

see flow diagram. MR05-01_pp_ANCA-SL PDF file

(1) ROBOPLEP-SL
Manufacturer : SerCon Ltd. (former PDZ Europa Ltd.)
Instruments :  ANCA-SL ROBOPREP-SL
S/N :          17001-051
Sample Range Solids/Liquids : 10 to 1000 µgN, 10 to 1000 µgC.
Autosampler :  60 position pneumatic autosampler that takes (standard) capsules with up to 47mm in diameter.

(2) EUROPA 20-20
Manufacturer : SerCon Ltd. (former PDZ Europa Ltd.)
Instruments :  ANCA-SL EUROPA 20-20
S/N :          9007-075
Analyzer and Analysis tube : 120° extended geometry with an 11 cm radius magnetic sector
Resolution :   m/Δm=95 (N₂) 10% valley definition
Sensitivity :  Inside Vacuum level is 4×10^-6mbar in an atmosphere of helium
                20 nmol CO₂
                15 nmol N₂
Abundance Sensitivity : Inside Vacuum level is 4×10^-6mbar in an atmosphere of helium
                30 ppm for CO₂ at 4×10^-6mbar in continuous flow mode.
                5 ppm for N₂ at 4×10^-6mbar in continuous flow mode.

(3) Precision
All specifications are for n=5 samples.
It is a natural amount and five time standard deviation of the analysis as for amount 100 µg of the sample.
                ¹³C (0.2 ‰)
                ¹⁵N (0.5 ‰)

(4) Data processing
Device control and processing soft : ANCA ver.3.5 (former PDZ Europa Ltd.)
Fully compatible with Windows 3.1 or Windows 95.

(5) Reference material
The third-order reference materials whose data values were decided by the second reference materials
(IAEA-N-1, IAEA-N-2, and IAEA-CH-6) dealt in International Atomic Energy Agency (IAEA) were used.