Environmental and anthropogenic determinants of water chemistry in the Carpathians

The most important natural and anthropogenic factors affecting stream water and groundwater chemistry in the Carpathians were identified mainly on the basis of hydrochemical case studies from numerous small headwater Carpathian catchments. The most important natural factor determining water chemistry in the Carpathians is geology. In areas formed of poorly soluble granite and gneiss rocks (crystalline portion of the Tatra Mountains), the total dissolved solids (TDS) and concentration of main cations and anions are many times lower than that in areas formed of highly soluble carbonate rocks (sedimentary portion of the Tatra Mountains, Pieniny Mountains) and also clastic rocks forming so-called Carpathian flysch (Beskidy Mountains, Carpathian Foothills). Stream water and spring water chemistry in the Carpathians change primarily due to hydrologic factors—changes in discharge. As discharge increases, TDS declines and the concentrations of most main ions also decline, while the concentration of K+, NO3−, and PO43− increases. Elevation and geographic location of springs and streams in given climate zone and vegetation zone are additional natural factors affecting water chemistry, and this is particularly true of SO42− and Cl− concentration as well as pH. Anthropogenic factors affecting water chemistry in the Carpathians include acid rain, deforestation, agriculture, and tourist-generated wastewater. The effects of acid rain are felt in the form of low concentrations of main cations in stream and spring water in the western part of the Carpathians. This region was affected by very high acidic sulfur and nitrogen deposition in the second half of the twentieth century. Deforestation in the Carpathians impacts mainly spruce monocultures declining due to acid rain, strong winds, and bark beetle infestation, and is the main cause of increasing NO3− concentrations in stream water and spring water. Agricultural land use does not threaten stream water and groundwater due to low usage of mineral fertilizer. Threats that do exist are associated with unregulated releases of wastewater in rural areas. Wastewater generated by tourists is a major threat to stream water quality in areas with a high environmental value that are highly popular with tourists. Tourist lodges release wastewater into Carpathian streams leading to excess nitrogen and phosphorus concentration in stream water.