The paper presents the influence of two factors: geology and meteorological conditions on the differentiation and the seasonal variability of the head waters chemism in the Olczyski Stream catchment in the Tatra Mts. During field work basic physico-chemical properties of water and the springs discharge were measured using the volumetric method. In the hydro-chemical laboratory of the IGiGP UJ were marked the ion concentration: Ca2+, Mg2+, Na+, K+, NH4+, Li+, HCO3-, SO42-, Cl-, NO3-, NO2-, F-, Br- (DIONEX ISC-2010). The total hardness (To), carbonate (Tw), not carbonate (Tnw) mineralization (M) and concentrations H+ were calculated. The characterized physico-chemical properties were analysed both for the passive (I–III, X–XII) and active (IV–IX) periods of the year. Water of the investigated sources is low alkaline, normal, soft and sweet. According to Mainzer’s efficiency classification the Eliasz springs belong to class V, while that No. 3 to class VI (Pazdro 1977). According to the Szczukariew-Prikłoński classification these waters belongs to the HCO3–Ca–Mg type (Maciaszczyk 1987). Minimum average values of ion concentrations were found during the active period, maximum – during the passive one; however these values in both the periods are similar. The research showed the occurrence of spatial differentiation and seasonal variability of water physico-chemical properties of the investigated springs. In the spatial differentiation of these properties appeared the influence of geology of the springs alimony area. In turn, the seasonal variability of physico-chemical properties derives from meteorological conditions before and during fieldwork. The highest concentrations of most ions occurred during autumn and winter low waters, while the lowest ones during high waters caused be snow melting and rainfall. Similar results were by A. Wolanin and M. Żelazny (2010), which allows to state that the studied springs are characterized with a typical reaction to atmospheric conditions.
