Change in River Water Chemistry as Affected by the Confluence of Forest Drainage Water in Dairy Farming Area on Hokkaido Island, Northern Japan

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概要

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• We evaluated i) the difference in river water chemistry between a watershed mainly consisting of pasture and a watershed mainly consisting of forest, and ii) how the chemistry of river draining the pasture is influenced by that of the river draining the forest. We selected one river (designated as the T-river) draining the pasture (3,587 ha), and two rivers draining a forest (738 and 879 ha) in eastern Hokkaido, northern Japan. During higher river flow due to precipitation and thawing, the concentrations of NO_3^-, SO_4^<2->, K^+, Fe, and Al increased, suggesting the relative importance of the shallow soil layer as their source. On the other hand, Na^+, Mg^<2+>, Ca^<2+>, and Si decreased, suggesting the relative importance of the source in a deep soil layer. The concentrations of NO_3^-, Cl^-, SO_4^<2->, K^+, Na ^+, Mg^<2+>, Ca^<2+>, and Fe were higher in the T-river than in the forest drainage waters, suggesting the contribution of the excretion components from the milk cows. The Si concentration exhibited the opposite pattern. The concentrations of NO_3^-, Cl^-, SO_4^<2->, K^+, Na^+ , Mg^<2+>, Ca^<2+> (p < 0.001), and Fe (p < 0.05) in the T-river decreased after the confluence of the forest drainage waters, while Si concentration increased (p < 0.001). The reason for the change in river chemistry was the confluence of the forest drainage waters. These findings suggested the environmental role of the forest in the dilution of the polluted river.

• 一般社団法人日本森林学会の論文
• 2002-08-16

著者

• Mawatari Kazunori

  Kyoto University Forest Graduate School Of Agriculture Kyoto University

• Nakagawa Yasunori

  Laboratory of Forest Ecology, Division of Environmental Science and Technology, Graduate School of A

• Nakashima Tadashi

  Laboratory of Forest Information, Kyoto University Forest, Graduate School of Agriculture, Kyoto Uni

• Nakashima Tadashi

  Laboratory Of Forest Information Kyoto University Forest Graduate School Of Agriculture Kyoto Univer

• Nakagawa Yasunori

  Laboratory Of Forest Ecology Division Of Environmental Science And Technology Graduate School Of Agr

関連論文

• Change in River Water Chemistry as Affected by the Confluence of Forest Drainage Water in Dairy Farming Area on Hokkaido Island, Northern Japan

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