Distribution of metals and trace elements in sediments of three Alpine lakes
In three Alpine lakes (Jezero na Planini pri Jezeru, Krnsko jezero and in Jezero v Ledvicah) the distribution of some metals and trace elements was determined in sediment cores using multielemental instrumental neutron activation analysis. Sediments were analysed to depths of 32 cm, 19 cm and 16 cm, respectively. Dating of sediments was done on the basis of 210Pb measurements. It was found that the levels of rare earth elements and some other lithophilic elements such as Sc, Cr, Th and U in Krnsko jezero were significantly lower than those found in the other two investigated lakes. In all three lakes changes with depth were noticed for practically all anthropogenic elements, namely As, Br, Cd, Hg, Mo and Zn. Three periods of lake history can be distinguished which reflect industrial activities in the 19th and 20th century. In the sediment profile of lake Krnsko jezero three well expressed lows of all investigated elements were found at depths of 3-3.5 cm, 6-6.5 cm and 8 cm which can be linked to two earthquakes in 1976 and 1942 and the First World War. The influence of earthquakes on the distribution of trace elements in the other two lakes was less evident.