7.4.8 Methoxychlor
The effect of Methoxychlor was investigated by Dr. Sugiura. Methoxychlor was
added at the start of the microcosm culture (day 0), and the number of organisms and
amounts of respiration and production were continuously tracked. The m-NOEC of
Methoxychlor was estimated to be 0.2 mg/L (Sugiura 1992).
7.4.9 β-Hexachlorocyclohexane (β-HCH)
The effect of β-Hexachlorocyclohexane (β-HCH) was investigated by Dr. Sugiura.
β-Hexachlorocyclohexane was added at the start of the microcosm culture (day 0) and
was adjusted to 0.1, 0.3, 1.0, and 3.0 mg/L. When 0.1 mg/L of β-HCH was added, the
populations of Cyclidium glaucoma, Philodina erythrophthalma, and Lecane sp.
increased during the early transition, when compared to the control system. Similarly,
in the 1.0 mg/L addition system, the numbers of bacteria and Cyclidium glaucoma
were higher than those of the control system. Conversely, in the 3.0 mg/L addition
system, the populations of Philodina erythrophthalma, Lecane sp., and Chlorella sp.
were lower than those of the control system. However, as the transition progressed,
each species showed a tendency to approach the population size of the control system
a) control
b) 0.25mg/l
c) 0.5mg/l
d) 1.0mg/l
e) 2.5mg/l
f) 15mg/l
Respiration(mg O 2 /L)
Respiration(mg O 2 /L)
Respiration(mg O 2 /L)
Respiration(mg O 2 /L)
Respiration(mg O 2 /L)
Respiration(mg O 2 /L)
Production(mg O
2 /L)
Production(mg O
2 /L)
Production(mg O
2 /L)
Production(mg O
2 /L)
Production(mg O
2 /L)
Production(mg O
2 /L)
0
2
4
6
8
10
0 2 4 6 8 10
0
2
4
6
8
10
0 2 4 6 8 10
0
2
4
6
8
10
0 2 4 6 8 10
0
2
4
6
8
10
0 2 4 6 8 10
0
2
4
6
8
10
0 2 4 6 8 10
0
2
4
6
8
10
0 2 4 6 8 10
Fig. 7.20 Time course of P/R ratio in Dinotefuran-added microcosm N-system. (a) Control. (b)
0.25 mg/L. (c) 0.5 mg/L. (d) 1.0 mg/L. (e) 2.5 mg/L. (f) 15 mg/L
102
K. Murakami et al.