| Budget Amount *help |
¥3,900,000 (Direct Cost: ¥3,900,000)
Fiscal Year 2000: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1999: ¥3,400,000 (Direct Cost: ¥3,400,000)
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| Research Abstract |
Hokkaido, the land blessed with nature has many oligotrophic lakes. The state of such lakes is changing by development of the area. This report means to show how human activities effect on water of Lake Kuttara and Mashu, the representative ologotrophic lake of Hokakido. Especially we analyzed the behavior of nutrients of the lakes. Besides that, we proposed the way to manage water flow into the lakes to keep them natural depending on the data.
In 1999, we investigated the actual conditions of lake water quality and rivers flowing into lake, and in 2000, we made more precise water quality research on lake Kuttara. And we also studied load-production mechanism of nutrients and other pollution matters and management of catchments area to keep oligotrophic lakes in desirable state.
【Results】(1999)We grasped general water quality of Lake Kuttara and Lake Mashu by our survey.. After the collection of data in the past, we could make clear the trend of water quality of Lake Kuttara. As Chlorotec(water quality monitoring instrument), which we purchased in 1999, did not work well, we made some improvements and at the end of the year, we could make use of it.(2000)We researched on Lake Kuttara for 7times, from May to October, and on Lake Mashu, once in August with Ministry of Environment. Especially on Lake Kuttara, we made the research in rainy season in August successively. We took water samples from 9 layers, at the deepest, 146m. From the research, we saw nitrate-nitrogen increases a little recently but transparency did not change so much. As the concentration of nitrate nitrogen is more than in Lake Mashu, it is necessary to manage the catchments area. And from the chlorophyll range in Lake Kuttara, we could find the new concepts about the movement of algae(phytoplankton).
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