Search

The concentrations of Al, Be, Cd, Cu, F, Fe, Mn, Pb, and Zn were monitored in five glacial lakes and one man-made lake in the southwestern part of the Czech Republic. The lakes had median pHs of 4.4 to 6.5 during 1984 to 1995. Decreases in the concentrations of Mn and Pb occurred in five acidified lakes. The concentrations of Al_T, Be, Cd, and F decreased in the four chronically acidified lakes, Zn decreased in two lakes. Concentrations of Cu and Fe remained unchanged. The decreases in Be, Mn, and Zn concentrations were proportional to the decrease in CSA (CSA = SO42- +NO3-+ Cl-); decreases in AlT, Cd, and Pb concentrations were proportionately higher, while F was lower. The greater decrease in the Pb concentrations (61 to 79%, at a rate up to 0.15 Mu g L-1yr-1) was caused by pronounced decreases in deposition of Pb derived from mobile sources. The decrease of AlT concentrations was dominated by a decrease in Al3+, whose concentration decreased by 51 to 86%. The concentrations of complexes Al(OH)2+, Al(OH)2+, AlF2+, and AlH3SiO42+ also decreased. The decrease in the concentrations ofinorganic forms of Al (Ali) compensated 65% of the decrease in CSA. The Cd concentrations were highly variable in the years 1986 to 1988 because of variable amounts of accumulation on particles. [ABSTRACT FROM AUTHOR]

The biogeochemistry of Ca, Mg, K, and Na were investigated in two forested catchments in the Czech Republic, one underlain by leucogranite, the other by serpentinite. High weathering rates at the serpentinite site at Pluhuv Bor resulted in Mg2+) as the dominant cation on the soil exchange complex and in drainage water. Other basic cations (Ca2+), K+, Na+) showed relatively low concentrations and outflow in streamwater. The catchment exhibited high base saturation in mineral soils (>70%), and near neutral soil and stream pH, despite elevated inputs of acidic deposition. Slow growth of Norway spruce at Pluhuv Bor may be caused by K deficiency, Mg oversupply and/or Ni toxicity. In contrast, the granitic siteat Lysina showed low concentrations of basic cations on the soil exchange complex and in streamwater. Soil and drainage water at Lysina were highly impacted by acidic deposition. Soil pH was extremely acidic (<4.5) throughout the soil profile, and the base saturation of the mineral soil was very low (<5%). Supplies of basic cations from atmospheric deposition and soil processes were less than inputs of SO42- on an equivalence basis, resulting in low pH andhigh concentrations of. total Al in drainage water. Needle yellowingin Norway spruce was possibly the result of Mg deficiency at Lysina.Because of their extremely different lithologies, these catchments serve as valuable end-members of ecosystem sensitivity to elevated levels of acidic deposition. [ABSTRACT FROM AUTHOR]