7.10.5 Mn
The addition concentration of Mn was adjusted to 0.1, 0.25, 0.5, 1.0, and 5.0 mg/L,
and it was added on the 16th day of the stable state into the microcosm. The
endpoints were abundance (structural parameter) and the concentration of DO
(functional parameter), and the population was measured using an optical microscope and counted from the start of culturing on days 0, 2, 4, 7, 14, 16, 18, 20,
23, and 30; it was evaluated from the results of B 16–30 (days 16–30), which was the
ratio of abundance and population density (N 30 ) on the 30th day. The DO concentration was measured continuously from the 16th day, and the P/R ratio was
calculated from the amounts of production (P) and respiration (R).
An evaluation of the risk of Mn on the structural parameter was conducted by
comparison with the behavior of microorganisms in the control system 14 days after
the addition of Mn. It was clear that the protozoan, Cyclidium glaucoma, was greatly
affected at a concentration of 1.0 mg/L of Mn from the behaviors of representative
species in the microcosm (Fig. 7.26). In other words, it was shown in the multispecies system that the influence varied according to microbial species. In N 30 , the
microbial community was divided into two groups, species that increased in abundance (microalgae) and those that decreased in abundance (microanimals). These
groups were divided into two as N 30 in B 16–30 . Using the functional parameter,
evaluation of the Mn risk was conducted in comparison with the behavior of the P/R
ratio in the control system 14 days after the addition of Mn. An influence was
observed at a concentration of 1.0 mg/L of Mn, especially in the respiration amount,
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
Toxicant added
(t=0)
Toxicant
added
(t>0)
POTENTIAL
VARIABLE
O
g
m
(
n
o
i
t
c
u
d
o
r
P
2 /day)
Respiration (mgO 2 /day)
Al 3+
0.6 mg/L
1.25 mg/L
5.0 mg/L
0.3 mg/L
Possibility of
transition
with system
collapse
Image of
transition
Fig. 7.25 Time course of P/R ratio in Al-added microcosm N-system
116
K. Murakami et al.
The addition concentration of Mn was adjusted to 0.1, 0.25, 0.5, 1.0, and 5.0 mg/L,
and it was added on the 16th day of the stable state into the microcosm. The
endpoints were abundance (structural parameter) and the concentration of DO
(functional parameter), and the population was measured using an optical microscope and counted from the start of culturing on days 0, 2, 4, 7, 14, 16, 18, 20,
23, and 30; it was evaluated from the results of B 16–30 (days 16–30), which was the
ratio of abundance and population density (N 30 ) on the 30th day. The DO concentration was measured continuously from the 16th day, and the P/R ratio was
calculated from the amounts of production (P) and respiration (R).
An evaluation of the risk of Mn on the structural parameter was conducted by
comparison with the behavior of microorganisms in the control system 14 days after
the addition of Mn. It was clear that the protozoan, Cyclidium glaucoma, was greatly
affected at a concentration of 1.0 mg/L of Mn from the behaviors of representative
species in the microcosm (Fig. 7.26). In other words, it was shown in the multispecies system that the influence varied according to microbial species. In N 30 , the
microbial community was divided into two groups, species that increased in abundance (microalgae) and those that decreased in abundance (microanimals). These
groups were divided into two as N 30 in B 16–30 . Using the functional parameter,
evaluation of the Mn risk was conducted in comparison with the behavior of the P/R
ratio in the control system 14 days after the addition of Mn. An influence was
observed at a concentration of 1.0 mg/L of Mn, especially in the respiration amount,
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
Toxicant added
(t=0)
Toxicant
added
(t>0)
POTENTIAL
VARIABLE
O
g
m
(
n
o
i
t
c
u
d
o
r
P
2 /day)
Respiration (mgO 2 /day)
Al 3+
0.6 mg/L
1.25 mg/L
5.0 mg/L
0.3 mg/L
Possibility of
transition
with system
collapse
Image of
transition
Fig. 7.25 Time course of P/R ratio in Al-added microcosm N-system
116
K. Murakami et al.