Development of Technology for Application of a Closed Experimental System to Carbon
Transfer Studies
Susumu NOZOE, Sho-ichi TSUGA, Osamu KOMATSUBARA,
Yasuhiro TAKO, Yuji NAKAMURA
Department of Environmental Simulation
Abstract
In order to verify dynamic models for estimation of 14C transfer from the atmosphere to edible andinedible parts of 7 crops, an experiment to examine validity of the model calculation after continuous
enhancement of atmospheric 13C/12C ratio during different stage in the growing period is planned for 2009.
Then in FY2008, preliminary experiments were conducted to establish methods for obtaining appropriate
values of atmospheric δ13C and for controlling its temporal fluctuation which will be used in the 2009 study.
It was found that the overall range of spatial variation was approximately 2‰ and a point representative of
the atmosphere in the plant cultivation chamber was identified. It was also confirmed that δ13C of thechamber atmosphere was stable (the range of fluctuation was within 1‰) during almost the whole lighting
period.
To reconstruct realistic carbon metabolism models of humans and ruminants, experimental data
concerning carbon mass flow are also necessary. It was confirmed that the amount of carbon in excrement
could be accurately measured using a closed waste processing system. Necessary conditions for obtaining
appropriate data about the daily cumulative respiratory CO2 amount using the animal holding and humanhabitation module under [CO2] control were also obtained.
0-2

Monitoring
point 2

with crop
The windward sidewith crop

Exit13

Plant
Plant
Plant
cultivation cultivation cultivation
bed B
bed A
bed C-4
δ C (‰)

Monitoring
point 1

Plant
Plant
Plant
cultivation cultivation cultivation
bed Ebed D
bed F
without
without
withoutcropcropcrop-6-8-10

with crop-12

The leeward side-14
PCB-A

PCB-B

with crop
Monitoring
point 1

Monitoring
point 2Fig. 1 The arrangement of measuring points (denoted byclosed circles) in a plant chamber illuminated byartificial lighting, in which plants of orchard
grass were grown on 3 of all 6 plant cultivation
beds, in a test for evaluation of spatial difference
in atmospheric δ13C values.

PCB-C

PCB-D

PCB-E

PCB-F

without crop

Monitoring
pointFig. 2 An example of spatial variation in δ13C of CO2 in
the atmosphere of a plant cultivation chamber, inwhich plants of orchard grass were grown on 3 ofall 6 plant cultivation beds (n=3). Open, closed,vertically-striped,
andhorizontally-stripedcolumns denote δ13C values for middle level
between ceiling and top of plant canopy, middle
level in the canopy, “monitoring points 1” and“2” shown in Fig. 1, respectively. PCB: plantcultivation bed.

0Dark period-2Light period-413δ C (‰)-6-8-10-12-14-16-18
21:00 23:00 01:00 03:00 05:00 07:00 09:00 11:00 13:00 15:00 17:00 19:00 21:00

Time of day

Fig. 3 An example of temporal fluctuation ofatmospheric δ13C value in a plant cultivationchamber illuminated by artificial lighting, inwhich plants of potato were grown.

10Obtained CO2 (mol)

864
200

2

4

68

10Carbon in raw material (mol)Fig. 4 The correlation between amount of carbon
contained in raw material (human feces) and that in
CO2 obtained during carbonization and incineration
processing.

-1600

Human stay200

Human stay400

Human stay

CO2 concentration (μ L L )CO2 separation

800

CO2 separation

1000

CO2 separation

1200

0
2008/12/15 0:00

2008/12/16 0:00

2008/12/17 0:00

2008/12/18 0:00

Date and time (Y/M/D h:m)

Fig. 5 An example of result of CO2 concentration controlof the animal holding and human habitation module
atmosphere, in which an adult man stayedintermittently (8 hours/day × 3 days).