Leaching of ions from a forested Typic Udipsamment by acidified throughfall, Denmark

Abstract

Amounts were determined of aluminium, sodium, calcium, magnesium, potassium, iron, manganese, zinc, nickel, cadmium, ammonium, nitrate, sulphate and chloride leached from soil columns by either natural or acidified throughfall. The columns were collected from an acidic Typic Udipsamment under spruce forest. Some columns were replaced in their original sites for study, whereas others were studied in the laboratory. Comparisons were also made with results of a parallel study using ceramic cups for extracting water from soils. In the laboratory experiments even a slight decrease in the applied throughfall pH (from pH 3.6 to 3.3) induced a significant increase in the leaching of Mn and Cd. Further decreasing the pH of the throughfall to 2.8 increased the leaching of most elements. In comparison with the results obtained using ceramic cups, the technique of using soil column lysimeters implied increased nitrification and mineralization in the soil both in the laboratory and in the field. Dissolution of aluminium was in all cases the dominant buffering process. Sulphate accumulation was also an important buffering process, but only in the laboratory experiments.