Changes in Concentrations of Monovalent Basic Cations in the Water of the Čaradice Stream / Zmeny Koncentrácií Jednomocných Bázických Katiónov vo vode Vodného toku Čaradický Potok

In the years 2005-2010, the changes in concentrations of monovalent basic cations in the Čaradice Stream were evaluated depending on the time and place of sampling in its longitudinal profile. Results show that the average concentration of Na⁺ in the whole period was 14.75 mg. dm^-3. Its share in the total amount of monovalent basic cations of Na⁺ and K⁺ in the whole reference period was 76.32%. The mass ratio of Na⁺ : K⁺ in the whole period was 3.34 : 1. Depending on the time of sampling, the lowest average sodium concentrations of the whole period were recorded in the spring season with the minimum average in March. The highest average concentration of the whole reference period was recorded in September. Depending on the sampling site, the minimum average concentration was recorded in a forest ecosystem and an ecosystem of permanent grassland, and the maximum average concentration in the village Kozarovce. Using the analysis of variance, we detected a statistically significant effect of all three qualitative factors (year, month and place of sampling) on the change of concentration. According to the Regulation of the Government of the Slovak Republic No. 269/2010 Coll., the 90^th percentile values of this indicator are lower than the recommended value. The average concentration of potassium in the whole reference period was 4.54 mg. dm^-3. The share of K+ in the total amount of monovalent basic cations in the whole period reached 23.68%. The lowest average concentrations of the whole period were usually found in the spring season, with the minimum value in March. The maximum average concentration of the whole reference period was recorded in July. Similarly to Na⁺, the lowest average concentration of K⁺ was detected in a forest ecosystem and the highest one in the village Kozarovce. The effect of seasonality on the dynamics of Na⁺ and K⁺ concentrations during the period was not detected. Using the analysis of variance, we found a statistically significant effect of all three qualitative factors (year, month and place of sampling) on the change of concentration. In the Regulation of the Government of the Slovak Republic No. 269/2010 Coll., the recommended value for potassium is not specified. The discharge rate significantly affected the changes in concentrations of Na⁺ and K⁺ in the stream.