UPTAKE OF HEAVY-METALS BY PLANTS FROM AIRBORNE DEPOSITION AND POLLUTED SOILS

The concentrations of sulphur, zinc, copper, lead and cadmium in sprin g wheat grain and straw, Italian rye grass, timothy and lettuce were s tudied in a three-year field experiment conducted in southern Finland near a copper-nickel smelter and at nonpolluted control sites. A pot e xperiment with copper- and nickel-contaminated soils and with a nonpol luted soil as the control was conducted to determine the copper and ni ckel concentrations in soils phytotoxic for plants. Forty, 200 or 1000 mg of copper or nickel as cloride was added to 2 litres of soil. The nickel and copper concentrations in the shoots of oats were measured. The zinc, copper, lead, cadmium and nickel concentrations varied betwe en different plant species and also between experimental years. Near t he smelter, the uptake of nickel by different plant species was very e ffective, as was copper uptake by lettuce, timothy and Italian rye gra ss. The same applied to the zinc and cadmium uptake of plants grown on plots. Nickel, cadmium and copper were easily accumulated by plants f rom air deposition. In the pot experiment, high nickel concentrations in soil were more phytotoxic for oats than were high copper concentrat ions. In acidic soil, nickel and copper concentrations lower than 20 a nd 100 mg/kg of soil, respectively, decreased the dry matter yield of oats shoots. Liming clearly decreased copper and nickel phytotoxity. I n the most highly contaminated soil, the addition of Cu 20 mg/kg of so il decreased the yield of oats shoots.