7.15.2 Acid Rain
To assess the effect of acid rain on ecosystems, an HCl addition investigation was
conducted by Dr. Sugiura. The microcosm was cultured with the addition of HCl at
concentrations of 10 μmol, 20 μmol, 35 μmol, 75 μmol, 100 μmol, and 200 μmol at
the start of cultivation (day 0) to investigate the effects of acid rain on ecosystems.
The pH values were 5.40, 4.92, 4.45, 3.78, 3.60, and 3.15. Except for the
10–35 μmol of HCl addition systems, the time series of the P/R ratio exhibited
different behaviors between the addition and control systems. Some species of
microorganisms in the microcosm went extinct with 100 μmol of added HCl. The
difference in the time series of the P/R ratio from the control system increased
according to the increase in the amount of HCl added until the 75 μmol concentration
was reached. Changes in the P/R ratio over time without the extinction of microorganisms was considered to be caused by changes in the biological interactions and
balance with the addition of HCl. The fact that microorganisms in the microcosm
N-system could resist changes in pH is considered to result from its biodiversity and
suggests that it is useful as a model of natural ecosystems (Sugiura 1993).
Literature Cited
Beyers RJ. The metabolism of twelve aquatic laboratory microecosystem. Ecol Monogr.
1963;33:281–306.
Kurihara Y. Studies of succession in a microcosm, science report of Tohoku University, 4th Ser.
(Biology), No.37, 1978a. p. 151–60.
Kurihara Y. Studies of the interaction in a microcosm, science report of Tohoku University, 4th Ser.
(Biology), No.37, 1978b. p. 161–77.
158
K. Murakami et al.
To assess the effect of acid rain on ecosystems, an HCl addition investigation was
conducted by Dr. Sugiura. The microcosm was cultured with the addition of HCl at
concentrations of 10 μmol, 20 μmol, 35 μmol, 75 μmol, 100 μmol, and 200 μmol at
the start of cultivation (day 0) to investigate the effects of acid rain on ecosystems.
The pH values were 5.40, 4.92, 4.45, 3.78, 3.60, and 3.15. Except for the
10–35 μmol of HCl addition systems, the time series of the P/R ratio exhibited
different behaviors between the addition and control systems. Some species of
microorganisms in the microcosm went extinct with 100 μmol of added HCl. The
difference in the time series of the P/R ratio from the control system increased
according to the increase in the amount of HCl added until the 75 μmol concentration
was reached. Changes in the P/R ratio over time without the extinction of microorganisms was considered to be caused by changes in the biological interactions and
balance with the addition of HCl. The fact that microorganisms in the microcosm
N-system could resist changes in pH is considered to result from its biodiversity and
suggests that it is useful as a model of natural ecosystems (Sugiura 1993).
Literature Cited
Beyers RJ. The metabolism of twelve aquatic laboratory microecosystem. Ecol Monogr.
1963;33:281–306.
Kurihara Y. Studies of succession in a microcosm, science report of Tohoku University, 4th Ser.
(Biology), No.37, 1978a. p. 151–60.
Kurihara Y. Studies of the interaction in a microcosm, science report of Tohoku University, 4th Ser.
(Biology), No.37, 1978b. p. 161–77.
158
K. Murakami et al.