6.2 Calculation of Respiration and Production Volumes
in the Microcosm N-System
6.2.1 Outline
The amount of respiration (R) and total amount of production (P) are calculated from
the DO concentration between 312 and 336 h after the addition of a test material to
the microcosm N-system. Generally, the amount of respiration (R), net amount of
production (Pn), and total amount of production (P) can be calculated from an
increment (ΔDO) of the DO concentration by the following expressions:
ΔDO D=L ¼ total increment of the DO in the L=D photoperiod
ð6:1Þ
R ¼ À2 Â ΔDO D
ð6:2Þ
Pn ¼ ΔDO L
ð6:3Þ
P ¼ Pn þ 1=2 R
ð6:4Þ
There is an exchange of oxygen with the atmosphere regardless of biological
activity, as calculated by the dissolution rate of oxygen (δDO), described in Sect. 4.
2.4. Therefore, it is necessary to revise expressions (6.2) and (6.3) as (6.6) and (6.7),
respectively.
δDO D=L ¼ total so lubility from the atmosphere to culture medium for an L=D photoperiod
ð6:5Þ
R ¼ À2 Â ΔDO D À δDO D
ð
Þ
ð 6:6Þ
Pn ¼ ΔDO L À δDO L
ð6:7Þ
P ¼ Pn þ 1=2 R
P ¼ Pn þ 1=2 R:
ð6:4Þ
6.2.2 Calculation
The methods for calculating ΔDO D and ΔDO L and δDO D and δDO L in MS Excel
are shown in Figs. 6.1 and 6.2, respectively. Figure 6.1 shows a numerical formula to
input into each cell, and Fig. 6.2 shows the calculation results. Additionally,
although the δDO, which was calculated in Sect. 4.2.4, was À0.00239 (x À 8.26)
mg/L/min, these data were measured in 1-hour increments and became À0.00239
(x À 8.26) Â 60 ¼ À0.1434 (x À 8.26) mg/L/h. From Fig. 6.3, it can be seen that
6 Estimation Using the Microcosm N-System
49