『Abstract
　Fluxes of major ions in rainfall (RF), throughfall plus stemflow (TF + SF), and stream water (SW) were measured for five water years in a small catchment of a Japanese cedar forest near the Sea of Japan. The fluxes of most ions in RF and in TF + SF, including the non-sea-salt constituents, increased from late autumn to midwinter owing to the seasonal westerly wind. The concentrations of most ions in SW showed no obvious seasonal trend during the study period, whereas NO3^- concentrations were lowest in summer, with a small seasonality. The Ca²⁺ and Mg²⁺ outputs in SW were approximately 3.7 and 1.8 times the TF + SF inputs of these cations, respectively. The large net outputs of base cations in the catchment may indicate a decrease in the soil's acid-neutralizing capacity. Annual dissolved inorganic nitrogen inputs in RF and in TF + SF were 17.7 and 17.9 kg N ha^-1 year^-1, respectively, which exceeded previously published thresholds in Europe and the U.S.(i.e., the values at which these inputs increased NO3^- levels in SW) and equaled the highest level of nitrogen deposition previously reported in Japan. The NO3^- concentrations in SW were relatively high even in summer. During high-precipitation events, NO3^- concentrations in SW increased with increasing water discharge, and the pH decreased simultaneously during several events. Nitrogen deposition may contribute to the high NO3^- concentrations in SW and the temporary acidification that occurred during the rain events.

Keywords: Acidification; Atmospheric deposition; Catchment; Input-output budget; Nitrogen saturation; Stream water』

1. Introduction
2. Methods
　2.1. Study site
　2.2. Field sampling
　2.3. Chemical analysis
　2.4. Data analysis
3. Results
　3.1. Seasonal trends in fluxes
　3.2. Fluxes during heavy rain events
　3.3. Annual fluxes
4. Discussion
　4.1. Seasonality of fluxes
　4.2. Input-Output budgets
　4.3. Possible N saturation
5. Conclusion
Acknowledgments
References