at each concentration, and the extinction of organisms did not occur within the
concentration range of the microcosm test. The time series of community metabolism
also exhibited nearly the same trajectory as in the control system, and the ratio of
respiration volume to production volume (P/R ratio) after the 10th day from the start of
the culture also approached 1. From these results, β-HCH was not estimated to affect
this system in the concentration range examined (Sugiura 1992).
7.4.10 γ-Hexachlorocyclohexane (γ-HCH)
The effect of γ-Hexachlorocyclohexane (γ-HCH) was investigated by Dr. Sugiura.
At the start of the microcosm culture (day 0), γ-HCH was adjusted to 0.01, 0.1, 0.5,
1.0, and 5.0 mg/L and added to the system. As in the case of β-HCH, the numbers of
Cyclidium glaucoma, Philodina erythrophthalma, and Lecane sp. were higher in the
early stage of transition at concentrations of 0.01, 0.1, and 0.5 mg/L when compared
with the control system. However, as the transition progressed, the control system
population was approached in all of the addition systems. The change over time in
community metabolism also exhibited almost the same trajectory as in the control
system. From this result, it was assumed that γ-HCH does not affect this system in
the concentration range examined (Sugiura 1992).
7.4.11 Dichlorodiphenyltrichloroethane (DDT)
The effect of Dichlorodiphenyltrichloroethane (DDT) was investigated by
Dr. Sugiura. At the start of the microcosm culture (day 0), DDT was adjusted to
0.01, 0.05, 0.1, and 0.5 mg/L and added to the system. The addition of DDT did not
affect the population density of the constituent organisms, nor did it appear as a
change in the time series of the community metabolism relative to the control system
until the addition of 0.5 mg/L (Sugiura 1992).
7.4.12 λ-Cyhalothrin
λ-Cyhalothrin is a synthetic pyrethroid insecticide. It acts on the central and peripheral nervous systems and acts to inhibit neurotransmission. On the 16th day after the
start of the microcosm culture, λ-Cyhalothrin was adjusted to 1 ng/L and 10 ng/L and
added to the system. As a result of performing a one-way ANOVA on the production
and respiration, which are functional parameters, it was determined that there was no
7 Example Assessments of the Microcosm N-System
103
concentration range of the microcosm test. The time series of community metabolism
also exhibited nearly the same trajectory as in the control system, and the ratio of
respiration volume to production volume (P/R ratio) after the 10th day from the start of
the culture also approached 1. From these results, β-HCH was not estimated to affect
this system in the concentration range examined (Sugiura 1992).
7.4.10 γ-Hexachlorocyclohexane (γ-HCH)
The effect of γ-Hexachlorocyclohexane (γ-HCH) was investigated by Dr. Sugiura.
At the start of the microcosm culture (day 0), γ-HCH was adjusted to 0.01, 0.1, 0.5,
1.0, and 5.0 mg/L and added to the system. As in the case of β-HCH, the numbers of
Cyclidium glaucoma, Philodina erythrophthalma, and Lecane sp. were higher in the
early stage of transition at concentrations of 0.01, 0.1, and 0.5 mg/L when compared
with the control system. However, as the transition progressed, the control system
population was approached in all of the addition systems. The change over time in
community metabolism also exhibited almost the same trajectory as in the control
system. From this result, it was assumed that γ-HCH does not affect this system in
the concentration range examined (Sugiura 1992).
7.4.11 Dichlorodiphenyltrichloroethane (DDT)
The effect of Dichlorodiphenyltrichloroethane (DDT) was investigated by
Dr. Sugiura. At the start of the microcosm culture (day 0), DDT was adjusted to
0.01, 0.05, 0.1, and 0.5 mg/L and added to the system. The addition of DDT did not
affect the population density of the constituent organisms, nor did it appear as a
change in the time series of the community metabolism relative to the control system
until the addition of 0.5 mg/L (Sugiura 1992).
7.4.12 λ-Cyhalothrin
λ-Cyhalothrin is a synthetic pyrethroid insecticide. It acts on the central and peripheral nervous systems and acts to inhibit neurotransmission. On the 16th day after the
start of the microcosm culture, λ-Cyhalothrin was adjusted to 1 ng/L and 10 ng/L and
added to the system. As a result of performing a one-way ANOVA on the production
and respiration, which are functional parameters, it was determined that there was no
7 Example Assessments of the Microcosm N-System
103