<原著論文>

源流と河口の環境−鳥取県加勢蛇川を事例として

苗村 晶彦^*1，齋藤 圭^*2，奥田 知明^*3，小寺 浩二^*4

^*1戸板女子短期大学総合教養センター，〒105-0014 東京都港区芝 2-21-17
^*2京都大学大学院理学研究科，〒874-0903 大分県別府市野口原 3088-176
^*3慶應義塾大学理工学部, 〒223-8522 神奈川県横浜市港北区日吉 3-14-1
^*4法政大学文学部, 〒102-8160 東京都千代田区富士見 2-17-1

Influence of environment on river water quality from head to mouth: A case study of the Kasechi River basin, Tottori

Akihiko NAEMURA^*1, Kei SAITOH^*2, Tomoaki OKUDA^*3 and Koji KODERA^*4

^*1Department of General Studies and Liberal Arts, Toita Women’s College, 2-21-17 Shiba, Minato-ku, Tokyo 105-0014, Japan
^*2Graduate School of Science, Kyoto University, 3088-176 Noguchibaru, Beppu, Oita 874-0903, Japan
^*3Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan
^*4Faculty of Letters, Hosei University, 2-17-1 Fujimi, Chiyoda-ku, Tokyo 102-8160, Japan

Abstract

Surface ozone concentrations and river water quality within the Kasechi River basin are analyzed, considering land use and vegetation. The samples are from Daisen Falls and the Kasechi Bridge, located upstream and downstream of the river, respectively. The ozone concentration at Yonago, located upstream of the river, indicates transboundary pollution from the Asian continent since the value, 32.9 ppb, is 1.2 times higher than the simultaneous observation at Tokyo Tower. The nitrate concentrations at Daisen Falls are substantially low, while it is known to be associated with ozone production. These results imply the effects of nitrogen fertilization on beech as forest covers 68 percent of the catchment area of the Kasechi Bridge. The river water hardness increases downstream from 21.9 mg/L at the waterfall to 37.5 mg/L at the bridge on the coast. It is essential to consider the influence of watershed characteristics covering mountains, rivers, and oceans for land-use planning. Therefore, we need continuous monitoring of matrices showing the comprehensive environmental state.

Key Words : Transboundary pollution, ozone, Mt. Daisen, Kasechi River basin, beech forest

(Received January 28, 2021. Accepted March 12, 2021)