Seasonal chemistry of pore water in hummocks and hollows in a poor mire in the southern Alps (Italy)

We compared the seasonal patterns of sodium, potassium, calcium, and magnesium concentrations, pH, and electrical conductivity in pore water in a nutrient-poor mire of the southern Alps to precipitation chemistry, water-table depth, and potential evapotranspiration, with the main objective to unravel differences between pore-water chemistry in hummock and hollow habitats. Sodium concentrations in mire water were primarily determined by precipitation inputs, with highest values in spring. Potassium concentrations were dependent on vegetation uptake, peaking before the growing season started, and showing lowest values in summer. Calcium and magnesium concentrations were highest in summer. Cation-exchange processes, evaporation, and humification affected the periodicity of bivalent cations. The pH decreased from spring to autumn, gradually in hollow water and more abruptly in hummock water. Electrical conductivity followed the bivalent cation concentration pattern both in hummocks and hollows.