Limnochemical studies at small Black Forest lakes (FRG) with special emphasis to acidification

Summary

Most of the drainage basins of the northern Black Forest lakes (FRG) are situated on a red sandstone bedrock formation with extremely low buffer capacity where mainly spruce forests affected by the “Acid Rain” in duced Central European forest decline are growing on podsolic soils. Paleolimnological analysis in lake sediment cores prove strongest pH decline for the last 100 years (Steinberg et al. 1987). Actual acidification is detectable during the time of snow melt and after heavy rains in inlet waters and in the pelagic zone of the lakes themselves, when strong pH-depressions are correlated with increased NO3, SO4 and Al concentrations (Thies et al. 1988). The short retention time of the lakes leads to high susceptibility to acid stress for the lakes and their water organisms in relation to the numerous observed acidic pulses. Severe damages to biota have already been proved (e.g. for amphibians). The tendency to meromictic behaviour may somehow counteract the external input of acidifying substances to a certain extent.

This work was kindly supported by the Federal Environmental Protection Agency (Berlin, FRG) within the project “Water 102 04 342”.