Chemistry of headwater lakes studied in the EU project Acidification of mountain lakes : palaeolimnology and ecology (AL:PE)

The AL:PE project, involving research institutes from 11 countries, was launched in 1991 to study sediments, diatoms, fish, invertebrates, and water chemistry of 28 lakes in relation to atmospheric pollutant inputs. This paper discusses the chemical results and the analytical quality control used to ensure good comparability of the results. Lake waters show varied chemical characteristics-from very diluted, poorly buffered or acidic waters to lakes with high base cation concentrations-with electric conductivity values ranging from 0.4 to 6 mS m -1 at 25°C. Nitrate shows a high range of variability, from values close to zero (Svalbard and Portugal), to 11-25 μeq l -1 (Alps), and up to 50 μeq l -1 (Tatra Mountains).