148
5.6.4 Carbon Storage in Sediment at Osaka Nanko Bird
Sanctuary
Table 5.7 shows the carbon storage in sediment of 1 m depth estimated from the data
reported here. The SOC concentration was calculated under the assumption that
vertical distribution of R-SOC followed Eq. (5.12) from 0 to 5  cm depth and
remained constant from 5 to 100 cm depth. The average concentration of R-SOC for
the top 1 m was 0.35 mg C g-dry
−1
in the aerobic (intertidal) area and 3.65 mg C
g-dry
−1
in the anaerobic (subtidal) area. The carbon storage was 14.7 t C in the aerobic zone and 37.1  t C in the anaerobic zone, such that total carbon storage was
estimated to be 51.8 t C at the bird sanctuary site.
5.7 Summary
In this chapter, we estimated the carbon flows and stocks of bivalves, phytoplankton, and sediments in a tidal flat and salt marsh of a eutrophic area. Figure  5.13
illustrates the estimated carbon stock and flow in this study. The secondary carbon
production including calcification was 159 g C m
−2
 year
−1
for bivalves and NEP was
Secondary Production: 159 g C m -2 year -1
(including calcification)
Stock: 0.95 t C ha -1
sediment
Sediment (Anaerobic area)
Stock : 5.13 t C ha -1
• 2-23%: Degradable organic carbon
• 77-98%: Residual organic carbon
bivalve
phytoplankton
NEP: 118.3 g C m -2 year -1
Stock: 0.0017 t C ha -1
Sediment (Aerobic area)
Stock: 0.49 t C ha -1
• 23-54%: Degradable organic carbon
• 46-77%: Residual organic carbon
Fig. 5.13 Summary of carbon stocks and flows of the tidal flat ecosystem in this study
Table 5.7 Carbon stock in the upper 1 m of sediment at the Osaka Nanko bird sanctuary
Site
Area of seafloor
(m
2 )
Sedimentary carbon concentration
(mg C g-dry
−1
)
Carbon stock (t C)
Aerobic area 30,040
0.35
14.7
Anaerobic
area
7225
3.65
37.1
Total
51.8
T. Endo and S. Otani