Their concentrations in precipitation were of the order of 10-1μgl-1 for cadmium, 100μgl-1 for lead and copper, and 101μgl-1 for zinc. Their total monthly deposition, in kg per square km, was 0.12-0.70 for lead, 0.01-0.06 for cadmium, 0.12-0.88 for copper, and 0.17-4.71 for zinc. An approximate mass balance of the microelements was set up for the upper Vltava and Luznice river basins.