HR: 14:25h
AN: B32C-03    [PDF]
TI: Biological and hydrological controls of streamwater nitrate concentration in a forested catchment with a natural disturbance
AU: * Hobara, S
EM: hobara.satoru@nies.go.jp
AF: National Institute for Environmental Studies, Onogawa 16-2, Tsukuba, 305-8506 Japan
AU: Tokuchi, N
EM: tokuchi@kais.kyoto-u.ac.jp
AF: Kyoto University, Kitashirakawa-Oiwake-cho, Kyoto, 606-8502 Japan
AU: Ohte, N
EM: nobu@bluemoon.kais.kyoto-u.ac.jp
AF: Kyoto University, Kitashirakawa-Oiwake-cho, Kyoto, 606-8502 Japan
AU: Katsuyama, M
EM: katuyama@kais.kyoto-u.ac.jp
AF: Kyoto University, Kitashirakawa-Oiwake-cho, Kyoto, 606-8502 Japan
AU: Kawasaki, M
EM: kawasaki@kais.kyoto-u.ac.jp
AF: Kyoto University, Kitashirakawa-Oiwake-cho, Kyoto, 606-8502 Japan
AU: Kim, S
EM: sujin@kais.kyoto-u.ac.jp
AF: Kyoto University, Kitashirakawa-Oiwake-cho, Kyoto, 606-8502 Japan
AB: In Matsu-zawa catchment, central Japan, nitrate concentrations in stream water increased following a small-scale, natural disturbance involving an outbreak of pine wilt disease that affected approximately 25 per cent of the forested catchment. In order to clarify controls of nitrogen dynamics in the soil and its relationship with stream water nitrate, we investigated soil nitrogen transformations and soil water chemistry in disturbed and undisturbed, water-unsaturated and -saturated plots. The highest values for nitrification rate, nitrate concentration in soil solution, and nitrate exported from the root zone were observed for the disturbed plot. The rate of nitrification in surface soil of the disturbed plot increased dramatically compared to prior to the disturbance. Root zone leachate from the disturbed area showed gradually increasing groundwater nitrate concentrations in the temporarily saturated zone during lateral, matrix flow. The catchment_fs deep soils and associated hydrologic processes limited the degree of plant uptake of the nitrate generated in the disturbed area. It was inferred that the persistent high levels of nitrate observed in the stream water resulted largely from the stable high nitrate concentrations observed in the saturated groundwater of this catchment. Stream water nitrate loads discharged following the disturbance were more than ten times greater than prior to it.
DE: 0400 Biogeosciences
DE: 1800 HYDROLOGY
DE: 4805 Biogeochemical cycles (1615)
DE: 4845 Nutrients and nutrient cycling
DE: 9320 Asia
SC: Biogeosciences [B]
MN: 2003 Fall Meeting