Permalink : http://hdl.handle.net/2115/49962

KEYWORDS : beech;cadmium;critical loads;lead;reservoir;spruce;stream water

The current study was designed to determine the critical loads of lead (Pb) and cadmium (Cd) for two types of vegetation (broadleaves and coniferous) and freshwaters (stream water and reservoir), in order to evaluate the effect of Cd and Pb deposition on investigated ecosystems by comparative simultaneous study at a mountainous LTER site in Bulgaria. Bulk precipitation and throughfall chemistry were monitored during the period 2005-2010 at two forest stands (Fagus sylvatica and Picea abies). Monitoring of water, sediment and bulk precipitation chemistry at two water bodies (stream and reservoir) were carried out too. The removal of Pb and Cd by the biomass and their vertical migration with drainage water was determined. It has been found that the tolerance of surface water to the pollution of Pb has been comparable with forests but aquatic ecosystems are more sensitive to the deposition of Cd due to the low values of critical loads meaning that critical loads for forest can not protect the surface water from the same catchment. Steady state critical loads of Pb and Cd for forests based on human health approach have remained stable and have not been exceeded during the study period. Real risk of harmful effect in the future has been discovered for surface waters because of higher input of Cd than critical loads obtained by ecotoxicological approach.