Abstract
The spatial distribution of nitrate concentrations in streamwater was investigated in forested watersheds within the northeastern peripheral area of the Kanto plain to evaluate anthropogenic influences on streamwater chemistry. The study area was divided into the Yasato area, located 65-80 km from Metropolitan Tokyo, and the Shirosato area, at a distance of 100-120 km. Mean nitrate concentrations in the Yasato area were significantly higher than those in the Shirosato area, with the spatial distribution of nitrate concentrations showing a decreasing tendency with increasing distance from Metropolitan Tokyo. Although the atmospheric input of inorganic nitrogen by precipitation at open sites in the Yasato area was similar to that in the Shirosato area, the input by throughfall in the Yasato area was double that in the Shirosato area. This data suggests the difference in input is due to different atmospheric dry deposition in the two areas, resulting in the variation in nitrate concentration in streamwater in forested watersheds.
