The purpose of the study was to determine the role of land use, seasonality, and hydrometeorological conditions on the relationship between stream water potassium (K⁺) concentration and discharge during different types of floods—short- and long-duration rainfall floods as well as snowmelt floods on frozen and thawed soils. The research was conducted in small catchments (agricultural, woodland, mixed-use) in the Carpathian Foothills (Poland). In the woodland catchment, lower K⁺ concentrations were noted for each given specific runoff value for summer rainfall floods versus snowmelt floods (seasonal effect). In the agricultural and mixed-use catchments, the opposite was true due to their greater ability to flush K⁺ out of the soil in the summer. In the stream draining woodland catchment, higher K⁺ concentrations occurred during the rising limb than during the falling limb of the hydrograph (clockwise hysteresis) for all flood types, except for snowmelt floods with the ground not frozen. In the agricultural catchment, clockwise hystereses were produced for short- and long-duration rainfall floods caused by high-intensity, high-volume rainfall, while anticlockwise hystereses were produced for short- and long-duration rainfall floods caused by low-intensity, low-volume rainfall as well as during snowmelt floods with the soil frozen and not frozen. In the mixed-use catchment, the hysteresis direction was also affected by different lag times for water reaching stream channels from areas with different land use. K⁺ hystereses for the woodland catchment were more narrow than those for the agricultural and mixed-use catchments due to a smaller pool of K⁺ in the woodland catchment. In all streams, the widest hystereses were produced for rainfall floods preceded by a long period without rainfall.

The purpose of the study was to examine the storage and transport ofions through snowpack, soils, and stream water in an acid‐sensitive alpine catchment (Tatra Mountains, Poland) during snowmelt and rain‐on‐snow events. Samples of snowpack layers, near‐surface soil horizons, and stream water were collected in the winter and snowmelt seasons of 2019. A laboratory experiment was conducted to determine the effect of temperature on the rate of soil nitrogen mineralization and nitrification. Our study has shown that snowpack is an important source ofions in the catchment. As the snow melts, the release ofions from snowpack occurs. A gradual and slow melting of snow starts even before the first snowmelt‐induced increase in stream discharge.ions eluted from available snowpack are temporarily stored in soil, which is shown by a large increase in the concentration of water‐solublein the soil at that time.ions are washed out of soils and supplied to streams during the first snowmelt event. This is demonstrated by a large increase in the stream waterconcentration, termed an “pulse.” Theion is a key acid anion responsible for the acidification of the studied stream during snowmelt season, as thepulse coincides with a decrease in bicarbonate alkalinity. Our field research and laboratory experiment have shown a minor role of mineralization and nitrification inproduction in soils in the winter andpulse formation in stream water during the early stages of the snowmelt season.