| Budget Amount *help |
¥3,820,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥420,000)
Fiscal Year 2007: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Fiscal Year 2006: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Research Abstract |
The effect of combined metals pollution such as Ca, Mg, Zn and Al on survival of Nitzschia palea (NIES-487), typical diatom found in Japanese rivers, was studied in batch experiments to assess river ecosystem. The experiments were conducted under the condition of pH 6, 25℃, continuous irradiation of 4000 lx and several times of stirring in a day. The concentrations of chlorophyll a were monitored during the experiments.
It was shown that the addition of Ca or Mg mitigated the inhibition of polymerized Al to the survival of Nitzschia palea. However, their concentrations in Japanese rivers were lower than those in the experiments. Then, it was concluded that mitigation of Ca or Mg was not significant.
Zn less than 100μg/L did not affect the survival of Nitzschia palea. At 30μg/L of Zn, which is the concentration of not affecting its survival, coexistent polymerized Al inhibited the survival of Nitzschia palea under low concentrations. However, combined effect of Zn and polymerized Al did not show the inhibition under high polymerized Al concentrations because of its high inhibition effect.
From these results, it was concluded that combined metals pollution of Zn and polymerized Al inhibited the algal survival even under neutral pH condition and 30μg/L of Zn, which is the upper limit of Japan water quality standard. It should be noted that Al eluted from soils or discharged from mines and industrial works has the possibility of affecting adverse effect on river ecosystem.
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