233
Fig. 2 (continued)
and
lE lw v
= ¢ ¢
r ,
(8.3)
where C p is specific heat, l is latent heat of vaporization, and E is the amount of
water evaporated.
The air–sediment CO 2 flux in intertidal and subtidal areas and the air–water CO 2
flux were measured by the chamber technique. In intertidal and subtidal areas,
atmospheric CO 2 or aqueous CO 2 above the sediment are exchanged directly at the
sediment surface by biological processes such as CO 2 absorption by photosynthesis
of microphytobenthos or CO 2 emission by respiration of benthic animals and
decomposition of organic matter. Therefore, the air–sediment and water–sediment
CO 2 fluxes were measured by using a dark chamber and a light chamber. Net primary production (NPP), sedimentary respiration, and gross primary production
(GPP) at the interface of the sediment were calculated by using Eqs. 8.4, 8.5 and
8.6:
NPP =
-
×
+
C
C
t
V
A
L
t t
L
t
L
L
D
D
(8.4)
Sedimentary respiration =
-
×
+
C
C
t
V
A
D
t t
D
t
D
D
D
D
(8.5)
8 CO 2 Flux in Tidal Flats and Salt Marshes