久慈川流域の水質

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1) We have conducted an investigation into the water quality of the basin of Kuji River, especially, into the relation between the main stream and its tributary streams. 2) In the main stream, the electric conduction is 33.0〜238.0μυ/cm. It is high value in Kunose with a large population (238.0μυ/cm), but is lower value in Shikanomata forestry road Bridge (33.0μυ/cm) and Takachihara Bridge (71.8μυ/cm) with a small population. In the tributary streams, the electric conduction is 51.5〜388.0μυ/cm. It is low value in Yamatsuri River (51.5μυ/cm), but it is high in Taki River (229.0μυ/cm) and Asa River with a large population (388.0μυ/cm). 3) In the main stream of Kuji River, the contents of the dissolved oxygen is 6.4〜12.8ppm. It is 12.8ppm at Nakanosawa in the upper stream, 7.7ppm at Shimo-Ogawa Bridge in the middle reaches, and 6.4ppm at Kami Bridge in the lower reaches. In the tributary streams, it is 6.5〜10.9ppm. High contents is seen in Tanakura Machiya Bridge with a large population and in Umakoshi Bridge over a clear stream. 4) The contents of Cl^- is 1.4ppm at Shikanomata Bridge near the source of the stream, 3.0ppm at Shimo-Ogawa Bridge in the middle course, and 32.0ppm at Kami Bridge in the lower reaches. In the tributary stream, the contents of Cl^- is 10.0ppm in a clear stream, Yamaturi River with a small population, 12.0ppm in Oda River, 65.0ppm at Genji Bridge in Hitachi-Ota City, and 80.0ppm at Okamachi Bridge. High contents can be seen in the area with a large population. 5) The contents of Na^+ is 2.8ppm at Shikanomata forestry road Bridge, 5.7ppm at Shimo-Ogawa Bridge in the middle courses, and 9.5ppm at Kami Bridge in the lower reaches. The contents increase as we go down the stream. 6) The contents of Ca^<2+> and Mg^<2+> do not show the great differences between those of our research spots. 7) The result of the pack test gives some indication of water pollution in Genji River, but in general, it gives good figures. 8) The loads of Ca^<2+>, Mg^<2+>, Na^+, Cl^- increase as we go down the stream. On some particular points of the tributary streams in the area with a large population, concentrated loads can be observed. 9) The electric conduction is apt to increase every years from the investigations in summer for the last twelve years. The contents of Cl^-, Na^+ and dissolved oxygen show the unpredictable fluctuation. 10) We can see local symptoms of water pollution, but generally, the water analysis shows good result in the main and tributary streams.
茨城キリスト教大学の論文
2002-12-25

久慈川流域の水質

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