Effect of water stage and tree stand composition on spatiotemporal differentiation of spring water chemistry draining Carpathian flysch slopes (Gorce Mts)

Abstract

The purpose of this study was to identify the factors affecting spring water chemistry in different tree stands and to measure the influence of water stage on the physicochemical parameters of spring waters in a small Carpathian catchment. Water samples were collected three times per year at various stages of the water: after the spring thaw, after a period of heavy rain and after a dry period in 2011 and 2012. Water samples were left in the laboratory to reach room temperature (19-20°C) and analyzed for EC (reference T=25°C) and pH. After filtration through 0.45μm PTFE syringe filters, the water samples were analyzed by means of ion chromatography using a DIONEX ICS 5000 unit. The following ions were analyzed: Ca²⁺, Mg²⁺, Na⁺, K⁺, HCO₃^-, SO₄^2-, Cl^-, and NO₃^-. Multivariate analysis (PCA) allowed the identification of two factors of spring water chemistry: factor 1, water stage and factor 2 tree stand composition. Seasonal variation of spring water chemistry showed that, higher pH values and mineralization as well as higher concentrations of Ca²⁺ and Mg²⁺ were measured during low water stage periods while lower EC and pH values were noted after spring snowmelt and rainfall, when higher concentrations of NO₃^- and SO₄^2- were also found. Higher concentrations of Ca²⁺ and Mg²⁺ and higher pH of spring waters located in beech-fir stands and in those mixed with a large proportion of beech as well as a lower concentration of Ca²⁺, Mg²⁺ and HCO₃^-, pH, conductivity and mineralization of these spring waters, in which the alimentation areas were covered by upper subalpine spruce stands were noted.

Keywords: Carpathians; Nitrogen deposition; Springs; Water chemistry.