The impact of acid rain on calcium and magnesium status in typical soils of the Wielkopolski National Park

The previous investigation of the chemical characteristics of precipitation within the Wielkopolski National Park has shown its high acidity which sometimes drops below pH 3.0. This paper deals with calcium and magnesium ion leaching by acid rain from typical soils of the area. Laboratory experiments were conducted on soil monoliths (15 cm in diameter, 50 cm high) with acid solutions of pH 3.0, pH 2.0 and a water control of pH 5.6. The sprinkling lasted 30 days, simulating a rainfall of 400 mm. The eluates were analysed every day. The soil properties and forms of calcium and magnesium were determined before and after treatment. The investigations show that quite large amounts of Ca2+ and Mg2+ can be leached from soil — in the very acid treatment (pH 2.0) leaching amounted to about 100 mg Ca2+ and 17 mg Mg2+ per kg of soil. The leaching of these elements was several times less in the pH 3.0 and 5.6 treatments. The differences in the dynamics of the process is shown on the leaching curves — their shapes are smooth when pH is 5.6 and 3.0, while a sharp peak is present at pH 2.0.