Distribution of sulphur and heavy metals in forest floor humus of the Czech Republic

Forest humus, which has a large cation binding capacity (up to 550 meq/100 g), and provides relatively very stable bindings with elements and their compounds, can effectively adsorb elements from atmospheric deposition and retain them over a long period. In order to test the monitoring potential of using forest humus to retain the recent and long-term accumulated loads of 14 elements (Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mo, Ni, Pb, S, V, and Zn), samples of coniferous forest floor humus (H or O-h horizon) were collected over an area of 78 864 km(2) using a 20 x 20 km scale grid of sampling points overlaid on the entire territory of the Czech Republic (CZ). Data from 192 points and the distribution of the concentrations of individual elements in forest floor humus are presented here. The extent of relatively very high loading covers 18% of CZ and includes the following four hot spots: an area in the western part of central Bohemia, northwestern Bohemia in the lignite coal mining area, the cross-border area in the Sudeten mountains in northern Bohemia, and the black coal mining area and industrial centre in northern Moravia. Relatively high, moderate and low loads of the elements were observed in 42, 30, and 28%, respectively, of CZ. Coniferous forest floor humus is evenly spread in the Central European territory and has proved to be a suitable and sensitive indicator of long-term relative atmospheric deposition loads.