Research on mechanism of nitrogen saturation of forest soil with Nox of atmospheric origin

东江东西两侧山溪的硝态氮浓度有显著差异。结果表明，这一现象是由大都市地区NOx的区域分布引起的。本研究利用森林氮素循环模型模拟氮素向河流的淋失。在这个模型中，树木生长所需吸收的氮量与树木的碳量有关。仿真结果与实测值基本一致。然而，在一些地区，土壤中观测到的氮素含量与山溪中观测到的氮素浓度并不一致。并进行了实验室实验，找出了产生这种现象的原因。对反硝化细菌数量的差异进行了检验。然而，土壤中观测到的氮素浓度分布的形状与反硝化细菌数量之间没有发现相关性。为了解释土壤和河流中氮浓度的差异，还需要进一步的调查。

There is a remarkable difference in the density of Nitrate-nitrogen of the mountain stream in the east and west side of Tone River. It is suggested that this phenomena is caused by regional distribution of Nox of the metropolitan area origin. This research simulated leaching to the river of nitrogen by using the nitrogen cycle model of the forest. In this model, the absorbed amount of nitrogen necessary for the tree's growing up is related to the amount of the carbon of the tree. The result of the simulation was almost corresponding to the value of the measurement. However, there were some regions where the observed amount of nitrogen in the soil did not correspond to the observed concentration of nitrogen of the mountain stream. The laboratory experiments were done looking for the reason of this phenomena. The difference of the amount of the denitrification bacterium was checked. However, the correlation between the shape of the distribution of the observed concentration of nitrogen in the soil and the amount of denitrification bacterium was not found. The further investigation is necessary to explain the difference between nitrogen concentration of soil and stream.