Ammonium sulfate is commonly applied on the snow surface of ski runs to maintain the snow condition for the Alpine events. The applied ammonium sulfate possibly causes acidification of soil, deterioration of vegetation and so on. However, discharge processes of the applied ammonium sulfate from snowpack are still unknown. In this study, the discharge characteristics of applied ammonium sulfate were investigated by collecting snow meltwater through a lysimeter (1m²) and measured pH, conductivity, NH₄⁺ concentration, SO₄^2- concentration and δ¹⁸O. The applied ammonium sulfate was discharged from the snowpack with little change in quality. In contrast, the snow meltwater was acidified a little bit because of nitrification after application. The applied ammonium sulfate was not absorbed into the snow particles but adsorbed on the surface of the snow particles. Most of ammonium sulfate was thus immediately discharged with snow meltwater. Flow of water in snowpack and the daily variation of snow meltwater quality were affected by the application of ammonium sulfate, because ammonium sulfate lowers the snow temperature and keeps the freezing condition.

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The relationship between groundwater quality and landuse was examined on a regional scale for Nobeyama district, Nagano Prefecture which is a large-scale agricultural zone and has a lot of dairy farms in the region. NO_3-N, SO₄^2-, Ca²⁺ and Mg²⁺ of high concentrations were detected in areas where agricultural activity was high. The concentration of groundwater composition of shallow wells was higher than that of spring water. In particular, high concentrations of NO_3-N and SO₄^2- were detected in shallow wells. These show that the effect of human activities for the shallow-well water is stronger than that for the spring water. Many strong correlations were found between the groundwater compositions of the shallow wells, whereas not so many in the spring waters. This suggest that the shallow groundwater quality rapidly reacts to the human impact in limited region. The hexadiagram show that the groundwater has much larger NO_3-N and Ca²⁺ concentrations than the groundwater of the non-polluted control site. The present results indicate that not only NO_3-N, Cl^-, Ca²⁺ and Mg²⁺ but also SO₄^2- could be groundwater composition indicators in an agricultural region like Nobeyama district.

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