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Takahashi, Shinya*; Inoue, Takanobu*; Tsushima, Koji*; Sakioka, Masamichi*; Matsunaga, Takeshi
Kankyo Kogaku Kenkyu Rombunshu, 46, p.565 - 572, 2009/00
This study analyzed the changes of water quality during rain events at Ijira river, a mountain stream in Gifu Prefecture, by measured the major ion concentration, pH, electric conductivity, discharge, and hydrograph separation using deuterium isotope ratio of the water. During rain events, where the discharge is increase, almost all of the major ion concentration, pH and electric conductivity were decreased. We also found that the correlation of the changes of pH and the changes of electric conductivity with precipitation were negative. The result of hydrograph separation shows that the ratio of surface runoff for discharge is increased with an increased of the precipitation, and also increased in the high precipitation. It was shown that the major factor of the changes of water quality in this study site is the contribution of surface runoff.
Tsuzuki, Katsunori; Matsunaga, Takeshi; Inoue, Takanobu*
JAEA-Research 2008-008, 31 Pages, 2008/03
JAEA-Research-2008-008.pdf:3.68MB
The discharge of nitrate nitrogen from a forested catchment was analyzed using a distributed rainfall-runoff model. Observation in rainfall events were carried out in November, 2006 in the Ijira River. The distributed rainfall-runoff model carried out runoff simulation of ground water and rain water at the catchment. The model was verified by observed flow rate, and the hydrogen isotopic ratio of rain water and river water. The nitrate ion concentration in river water was shown as a function of the residence time of discharge water in the catchment calculated by the model. As a result, it was estimated that the nitric-acid ion in the river water was transported by the lateral flow of the rain water at the subsurface and the up-flow of ground water. Moreover, it was estimated that the residence time of the soil moisture influenced the discharge of nitrate nitrogen. This study was suggested that dynamic behavior of water in catchment was important when considering the balance of nitrate nitrogen in catchment.
Matsunaga, Takeshi; Tsuzuki, Katsunori; Yanase, Nobuyuki; Hanzawa, Yukiko; Naganawa, Hirochika; Inoue, Takanobu*; Yamada, Toshiro*; Miyata, Akifumi*
Proceedings of International Symposium on Environmental Modeling and Radioecology, p.243 - 246, 2007/03
The aim of this work is to obtain a fundamental scheme of stream discharge of inorganic toxic materials derived from Characteristics of the stream discharge of metallic elements were investigated in two forested catchments in the Oda River and the Ijira River watersheds. Precipitations, stream water and soil water samples were collected in raining events and were analyzed for inorganic elements, dissolved organic carbon and isotopic abundance of deuterium. Results revealed an accelerated discharge of specific metals of Cu, Sb and Cr and all the studied REE in dissolved form. This feature was commonly found in the two catchments. The specific metals are strongly suspected to be of anthropogenic origin. An analysis of hydrological discharge, using chemical and isotopic tracers, suggested that the increased discharge of the metals originate from their deposits on the ground surface and/or instantaneous resuspension of stream sediment. Contrary, REE discharge was tightly coupled with that of dissolved humic substances.
Tsuzuki, Katsunori; Matsunaga, Takeshi; Inoue, Takanobu*; Miyata, Akifumi*; Yamada, Toshiro*
no journal, ,
no abstracts in English
Tsuzuki, Katsunori; Matsunaga, Takeshi; Inoue, Takanobu*; Yamada, Toshiro*
no journal, ,
no abstracts in English
Tsuzuki, Katsunori; Matsunaga, Takeshi; Nagai, Haruyasu; Inoue, Takanobu*; Takahashi, Shinya*
no journal, ,
no abstracts in English