CHEMICAL INPUT-OUTPUT BALANCE FOR A MODERATELY POLLUTED FOREST CATCHMENT IN SOUTHERN POLAND

A four-year study in a forest catchment exposed to a moderate level of anthropogenic pollution indicated heavy accumulation of hydrogen (H+) , manganese (Mn), zinc (Zn), copper (Cu) and lead (Ph) in the ecosyste m and phosphorous (P), potassium (K) and cadmium (Cd) to a lesser exte nt. Nitrogen, which is also accumulated, is leached mainly as NO3-, ev en though the input is dominated by NH4+. Magnesium (Mg), calcium (Ca) and sodium (Na) are leached from the catchment, presumably due to int ensive weathering processes in deeper layers of mineral soil. Chloride ion (Cl-) is also lost from the ecosystem. The output of sulphate (SO 42-) with stream water exceeds its input only slightly. Although it ap pears that the catchment as a whole has a large buffering capacity (av erage stream water pH=7.43, rainfall pH=4.33), the upper biologically active soil layers are probably more susceptible to acidification and pollution. With constant accumulation of H+ and heavy metal ions this may lead to degradation of forest health.