Geoindicators enable us to assess the quality of the environment and to monitor anthropogenic impacts on different ecosystems. The results of geochemical studies of soils in the selected forest ecosystems of eastern Poland (performed during 1998–2003) indicated that the organic fermentative-humic (Ofh) soil subhorizon was characterized by increased accumulative capabilities of mercury, lead and presumably polynuclear aromatic hydrocarbons compared to underlying soil horizons. Moreover, the subhorizon-Ofh constrains the migration of these chemical species. Due to a substantial diversity of forest soils in the temperate zone, it may be regarded as a good pollution geoindicator for temperate forest ecosystems.