Journal of the Graduate School of Biosphere Science, Hiroshima University Volume 46
2007-12-20 発行

広島県太田川・八幡川に設けられた貯水池前後での水質の長期変動

Long-term Changes in Water Quality in and Upstream/Downstream of Reservoirs Constructed on the Ohta River and the Yahata River, Hiroshima
Ohkubo, Fumie
Date, Etsuji
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abstract
Long-term changes in water quality in and upstream/downstream of four reservoirs (Uokiri, Tarutoko, Tateiwa and Ohdomari reservoirs) were statistically investigated using an approximately 20 years monitoring data. Increasing trend of TN/TP in the reservoir water was commonly found in the four reservoirs. At Uokiri Reservoir where complete data set was available, it was clear that both nitrogen and phosphorus were significantly trapped in the reservoir. Furthermore, addition of nitrogen and phosphorus in the downstream due to human activity was also obvious. The amounts of trapped dissolved inorganic nitrogen (DIN) and phosphorus (DIP) at the Uokiri Reservoir were estimated to be 6.9 tNy-1 and 0.63 tPy-1. Assuming the same trapping mechanism is working at 15 reservoirs on the Ohta River, it is estimated that 30 % of DIN and 35 % of DIP which should be loaded to the estuary could be reduced by their trapping mechanisms.
subject
栄養塩
太田川
長期変動
貯水池
八幡川
long-term change
nutrient
Ohta River
reservoir
Yahata River
SelfDOI