抄録
Many streams of Kureha Hill, Toyama, Japan, have high nitrate concentration throughout the year. This nitrate leaching into the streams is believed to be the result of nitrogen saturation because the nitrogen budget shows excess loss of nitrate to the stream water over the nitrogen deposition on the forested watersheds.
We examined variations of nitrate and other components in detail of Hyakumakidani, one of the streams on Kureha Hill, in order to investigate the effects of nitrogen saturation on the water chemistry.
Two first tributaries of the Hyakumakidani stream were investigated for their discharges and major ions. Clear relationships were found between the nitrate concentration and the discharge, while the chloride concentration remained constant throughout the year for both the tributaries. A reverse relationship between nitrate and sulfate was also found for both the tributaries, however, the absolute concentrations of these ions were quite different. A denitrification process involved with pyrite was a possible explanation of the reverse relation, however, no conclusive evidences have not been obtained from the laboratory experiments.
