Japan Geoscience Union Meeting 2015

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Symbol A (Atmospheric and Hydrospheric Sciences) » A-HW Hydrology & Water Environment

[A-HW27] Water and material transport and cycle in watersheds: from headwater to coastal area

Sun. May 24, 2015 11:00 AM - 12:45 PM 301B (3F)

Convener:*Shinji Nakaya(Department of Civil Engineering, Faculty of Engineering, Shinshu University), Mitsuyo Saito(Graduate School of Environmental and Life Science, Okayama University), Shin-ichi Onodera(Graduate School of Integrated and Arts Sciences, Hiroshima University), Kazuhisa Chikita(Department of Natural History Sciences, Faculty of Science, Hokkaido University), Tomohisa Irino(Faculty of Environmental Earth Science, Hokkaido University), Masahiro Kobayashi(Forestry and Forest Products Research Institute), Seiko Yoshikawa(Narional Institute for Agro-Environmental Sciences), Noboru Okuda(Research Institute for Humanity and Nature), Chair:Noboru Okuda(Research Institute for Humanity and Nature)

11:30 AM - 11:45 AM

[AHW27-10] Dissolved organic nitrogen dynamics in forested watersheds with different nitrogen inputs

*Masahiro KOBAYASHI1, Yuko ITOH1, Yoshiki SHINOMIYA2 (1.Frestry and Forest Products Research Institute, 2.Tohoku Research Center, Frestry and Forest Products Research Institute)

Keywords:Forest, dissolved organic nitrogen, flux, discharge

Increasing atmospheric nitrogen deposition often causes nitrogen saturation in forest ecosystems around Kanto plain in Japan. To clarify the mechanism of nitrogen saturation, we have observed the dissolved nitrogen of bulk precipitation, throughfall, litter leachate, soil water, and stream water in Katsura experimental forest (KEF) with low nitrogen deposition and Tsukuba experimental forest (TEF) with high nitrogen deposition. In the present study, we focused on the flux and discharge of dissolved organic nitrogen (DON) in the studied forest ecosystems. The seasonal variation of the ratio of DON to the total dissolved nitrogen (TDN) was observed for the litter leachate both in KEF and TEF. The DON/TDN ratios for litter leachate, stream water were lower in TEF than in KEF. It may be caused by the high rate of mineralization in TEF with excessive nitrogen.