Natural Factors Affecting the Chemical Composition of Water in the Catchment of Wołosatka Stream (High Bieszczady Mts.)

Abstract

The aim of this study was to identify the natural factors determining spatial differences in spring water chemistry in the flysch Carpathians using the Wołosatka catchment (High Bieszczady Mountains, SE Poland) as an example. A Principal Component Analysis (PCA) was used to find the regularity in the variance of common and biogenic ion concentrations among the surveyed springs. The PCA identified three factors that altogether explain 85 % of the variance. The first factor explained 51 % of the variance and was best correlated with concentration of Ca²⁺, Mg²⁺ and HCO₃ ⁻. Generally, the fundamental factor shaping the ions concentration is the lithology of aquifer. The second factor, correlated mainly with the concentration of SO₄ ²⁻ and Cl⁻, seems to explain the variation in water chemistry resulting from varying elevation of springs. The elevation controls climate conditions and plant communities in the alimentation area. Generally, higher concentrations of sulfates are characteristic of the upper part of the catchment, while the highest concentrations of chlorides are characteristic of springs located on the valley floors. The third factor, reflecting mainly the concentration of nitrates, seems to be related to the role of shallow groundwater circulation in the alimentation of springs after rainfall events.