234
GPP
,
=
-
×
æ
è
ç
ö
ø
÷ -
-
×
æ
è
ç
ö
ø
÷
+
+
C
C
t
V
A
C
C
t
V
A
D
t t
D
t
D
D
L
t t
L
t
L
L
D
D
D
D
(8.6)
where Δt is the measurement time interval; C L and C D are the CO 2 concentrations
inside light and dark chambers, respectively; C
t
and C
t  +  Δt
are the CO 2
(a)
(b)
Japan
Osaka Bay
N
Subtidal area
West
Saltmarsh
Intertidal area
0 m
50 m
100 m
North salt
marsh
West
Saltmarsh
South salt
marsh
Station 2
Station 1
Station 3
microalgae algae
benthos
H.W.L
L.W.L
Seawater exchange
pipe
Intertidal area
Subtidal area
sediment
organic matter
phytoplankton
plankton
Light chamber
Dark chamber
Air-sediment CO 2 flux
CO2 meter
Air-water CO 2 flux
Float
Water-sediment CO 2 flux
Light chamber
Dark chamber
CO2 meter
PTFE tube
Fig. 8.3 Location and instrumentation of the Osaka bird sanctuary field site. (a) Measurement
sites of CO 2 fluxes (Station 1, air–sediment CO 2 flux; Station 2, air–water CO 2 flux; Station 3,
water–sediment CO 2 flux), (b) Schematic diagram of the CO 2 flux measurements in the field site.
H.W.L., high water level; L.W.L., low water level
S. Otani and T. Endo