2004 年 41 巻 p. 97-104
Dissolved nitrogen concentration of bulk precipitation and stream water were investigated on the Kabura river watershed (Western part of Gunma Pref.) and the Oze-numa lake. Also dissolved nitrogen concentration of stream (upper end of each river) around the Echigo Mountains including Fukushima, Niigata and Gunma Pref. were analyzed. NOx-N concentration showed most high value on the Kabura river watershed, and rather high value on the Tone river. In Niigata Prefectural side of Echigo Mountains, nitrogen concentration of the stream water lowered in 1/2 and in Fukushima side of that nitrogen concentration decreased to 1/5 level.
Rather high concentration of inorganic nitrogen on the upper stream of Tone River is thought to be derived from the air contaminants which comes flying from the metropolitan area with the sea wind in summer.