Element analysis on Change and origin of streamwater chemistry

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Separation of the runoff components in hydrograph is one of the final targets in the hydrological science. From the hydrochemical point of view, this is equivalent to evaluating the origin of the materials involved in the river water. Regarding the runoff from the forested basin, the inner element cycle participates in determining the streamwater chemistry.To substantiate the link between the element cycle and the streamwater chemistry, the element content in the forest soil was examined in the Tsukuba Experimental forest, in addition to the experiments for the streamwater and soilwater chemistries. It proves that such nutrients as nitrogen and calcium are highly accumulated in the surface soil due to the recycle within the intrasystem during the long formative process of the forest, contrary to this, the materials nonrelated to the element cycle become lowered in the surface soil due to blending the organic substances. These element contents in soil make out the soilwater chemistry containing the different concentration in the individual solute, and the soilwater leaching gives to the chemical changes of the streamwater in two ways of Type I and Type II during the recession period of the storm runoff. It is concluded that the element cycle in the forest ecosystem plays a prominent role in the determination of the streamwater chemistry by the soilwater leaching.