VÝVOJ PŮD NA OPUŠTĚNÝCH HALDÁCH PO TĚŽBĚ POLYMETALICKÝCH RUD NA HAVLÍČSKOBRODSKU

Abstract

Old slags situated in the areas of former exploitation of polymetallic ore mineralization are places where initial steps of soil evolution in specific conditions can be investigated. Two soil profi les of different age have been studied in the Utín (2nd half of 13th century to 1st half of the 14th century) and Dlouhá Ves (60’s of 20th century) localities. Soil samples of fine fraction were studied including vertical distribution of selected elements (Fe, Pb, As, Ag, Cu; AAS) in context to other soil parameters including loss on ignition (LOI), sequential extraction analysis (SEA), soil exchangeable acidity (pH/KCl), mass specific (χ) and frequency dependent (χFD) magnetic susceptibility. There were higher concentration of Pb (up to 4,700 ppm), Cu and Ag (both up to 100 ppm) in the Utín soils observed mostly in upper part of the soil profile. Arsenic contamination occurs in entire soil profile with average concentration about 3,000 ppm. In the Dlouhá Ves soils, the higher concentrations of Ag, Cu (about 500 ppm) and As (near 13,000 ppm; 70 cm) occur rather in bottom horizons of soil profile. Noticeable positive correlations of LOI vs. Pb (r = 0.96), Cu (r = 0.90), Fe (r = 0.87), Ag (r = 0.94) together with SEA values from Utín soils indicate that studied elements have in fraction bound to organic matter and sulphides have a tendency to be bound rather to organic compounds. This is the main difference between the two localities because the studied elements in Dlouhá Ves soils have in the same fraction tendency to be bound just to sulphides. In addition to presupposed higher pedogenesis degree in distinctly older Utín soils, the difference between two soil profiles is acidobazic conditions in Dlouhá Ves soil profile, in which the pH/KCl is very low. Decomposition of organic matter is also slower in this environment. The lower degree of pedogenesis in Dlouhá Ves is also supported by in average lower values of frequency dependent magnetic susceptibility (χFD = 1–5 %).