Influence of air-contaminants transported from metropolitan area on nitrogen saturation phenomenon in the upper stream of Tone river.

有报道称，即使在上游有森林的流域，Tone河的氮浓度也在1mg/1以上。因此，本文分析了Tone河支流之一的Yubiso河的溪水氮浓度及其流域和Nikagi河的降雨量，探讨了优先洗脱和氮饱和度的影响。育碧索河流域年氮湿沉降量为12.1kgN/ha/y。育碧索河流域年氮径流量为12.5kgN/y。结果表明，Tone河流域上游氮饱和正在进行中。

It has been reported that the nitrogen concentration at Tone River was more than 1mg/1 even in the upper stream area with a forested watershed. Therefore, the nitrogen concentration of the stream-water at the Yubiso river, one of the tributaries of Tone River, and rain fall on its watershed and Nikagi river were analyzed to investigate the effect of preferential elution and nitrogen saturation. The annual wet deposition of nitrogen to Yubiso river watershed were 12.1kgN/ha/y. The annual nitrogen runoff of Yubiso river watershed were 12.5kgN/y. It was suggested that nitrogen saturation on the upper stream at Tone river watershed was on going.