The Evaluation of the Concentration of Bivalent Basic Cations in Surface Water of the National Nature Reserve Čičov Oxbow

During the years 2013–2014, the concentrations of bivalent basic cations Ca²⁺ and Mg²⁺ were evaluated in the water of the Čičov tributary, which belongs to the National Nature Reserve of the basin of the river Danube. On the basis of the results obtained, it can be stated that the average concentration of calcium for the whole reference period was 59.63 mg.dm⁻³. Minimum average concentration depending on the time of sampling was found in November (48.42 mg.dm⁻³) and maximum in July (70.73 mg.dm⁻³). We assume that this above average concentrations in the summer could be due to the lower surface of the water due to higher evaporation. Depending on the places of sampling points, the lowest average concentration (58.10 mg.dm⁻³) for the whole reference period was at the mouth of the Čilizian brook and the top (60.32 mg.dm⁻³) in the first side shoulder. The analysis of variance detected highly statistically significant effect of the year and month of collection on changes in the concentration of calcium. The average concentration of magnesium for the whole reference period was 14.54 mg.dm⁻³. As for the time of collection, the highest average concentrations for the entire observation period were found during the summer, with the maximum average concentration in July (16.94 mg.dm⁻³) and minimum in February (10.81 mg.dm⁻³). The lowest average magnesium concentration for the entire reference period, regarding to the sampling points, was measured in the north-eastern part of the nature reserve (14.28 mg.dm⁻³) and the highest one at the mouth of the Čilizian brook into the National Nature Reserve (14.72 mg.dm⁻³).