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

据报道，即使在上游有森林流域的地区，通河的氮浓度也超过1 mg/l。因此，在Yubiso河，音川的支流之一，在其流域和Nikagi河的降雨量的溪流水的氮浓度进行了分析，调查优先洗脱和氮饱和的效果。Yubiso河流域氮的年湿沉降量为12.1kgN/ha/y。Yubiso河流域氮素年径流量为12.5kgN/y。研究结果表明，同江流域上游水体氮素饱和现象仍在持续。

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.