Contents of nutrients and arsenic in litterfall and surface humus in mature nudal beech stands subjected to different emission-immission loads

The aim of the paper was to compare the litterfall and surface humus (Oo) quality in nudal beech stands with different emission-immission load from the Al smelter Žiar nad Hronom. The study was carried out in the Kremnické vrchy Mts (control stand, 18 km from the emission source) and the Štiavnické vrchy Mts (stressed stand, 1.5 km from the emission source), both in Central Slovakia. The contents of arsenic and nutrients (Ca_t, Mg_t, K_t, Na_t), with exception of calcium in the beech litterfall from the stressed stand were markedly higher (by 4.3%, 23.9%, 2.1% and 87.9%, respectively) compared to the samples taken from the control plot. On the contrary, the surface humus samples (with the exception of Na in the necrotic Oon subhorizon) from control plot were richer in nutrients. However, significant differences (p < 0.01) between the plots were observed for Ca content in the litterfall as well as in the surface humus. The concentrations of As in Oo samples from the stressed stand mainly increased with the organic horizon depth (mg kg^-1): necrotic Oon 1.10 < fermentation Oof 3.1 < humification Ooh 55.6. The results showed, that As amounts detected in subhorizon Ooh and in beech litterfall from the stressed stand were higher than the limit values, thus indicating that the environment of the Žiar territory is exposed to persistent negative impacts of industrial activities.