Acidity status and mobility of Al in podzols near SO2 emission sources on the Kola Peninsula, NW Russia

Soil acidity status and Al mobility in podzols was examined on a broad scale near the large emission sources of SO2 and heavy metals on the Kola Peninsula (the Severonikel and Pechenganikel smelter complexes) in NW Russia and in neighbouring parts of Norway and Finland. Acidification of the upper podzol horizons and depletion of mobile base cations were only evident at sites where ecosystems are severely destroyed, in the immediate vicinity of the Severonikel smelter complex. The high content of base cations in the parent material (till) near the emission sources may mask the acidification effect of pollution. Both strong anthropogenic (SO2) emissions and natural acidification (in situ weathering of black schist) accelerate weathering and mobilize Al. However, drainage conditions seem to be the most important factor determining the content of mobile Al in the podzols.