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Effect of trial impoundment on downstream macroinvertebrate community during construction of a large dam

Asaeda T., Zaman T., Takahashi Y.

Polish Journal of Ecology

2013

Vol. 61, nr 4

787--796

The dam construction has substantial impacts on the downstream environment even from the beginning of construction stages. The stage of impounding water is supposed to have the largest effects on the downstream environment. Monthly observation was carried out during the trial impoundment of a large concrete dam, including water temperature, organic matter fluxes, epilithic chlorophyll a, and macroinvertebrate communities both at the upstream and the downstream water of the impoundment. Both before and after the impoundment, the epilithic chlorophyll a contents and fine particulate organic matter (FPOM) fluxes variations were insignificant. As the impoundment volume increased the downstream water temperature substantially increased in comparison to upstream water temperature. Coarse particulate organic matter (CPOM) fluxes (gDW/10min) in the downstream became lower than that of the upstream even with one day of retention period. Chironomidae, Stenopsychidae, Simuliidae, Tipulidae and Hydropsychidae substantially enhanced immediately after the impoundment started, whereas, Taeniopterygidae and Chloroperlidae were declined. It was evident that the trial impoundment has a substantial effect on the downstream biota even from the low volume of water.

Electrooxidative Conversion of Dibenzoylbenzene Dihydrazones into the Coreesponding Bis-Diazo Compounds and Bis-Dimethyl Acetals

Okimoto M., Numata K., Takahashi Y.

Polish Journal of Chemistry

2005

Vol. 79 / nr 9

1477-1482

Several dibenzoylbenzene dihydrazones were electrochemically oxidized into the corresponding bis-dimethyl acetals in a methanolic solution containing sodium methoxide and catalytic amount of KI. During electrolysis, the anolyte exhibited a characteristic deep purple, which strongly suggested that formation of a diazo compound as an intermediate. Interestingly, some of the diazo compounds could be isolated directly from the anolyte