Lettuce yields as an indicator of remediation efficacy of soils contaminated with trace metals emitted by copper smelting

The aim of the study was to determine the adverse impact of excess copper, zinc, lead and cadmium on lettuce grown on soils from an area affected by emissions from a copper smelting plant of KGHM Polska Miedz S.A., and to analyze the effectiveness of counteracting the contamination by adding peat and higher rates of superphosphate to the soil. For comparison, analogous soils (outside the emission area), uncontaminated or simulation polluted were tested. The phytotoxicity of the metals in soils where contamination was simulated, caused a decrease in the lettuce yield by 29-52% when no remediation measures were applied, whereas in soils polluted with emissions from the KGHM smelter, the yield loss was 14-32% of the yield obtained on natural soils. Yield loss was accompanied by elevated concentrations of the metals in plant tissues. The best soil remediation effects on lettuce yield were achieved in treatments where peat and higher rates of superphosphate were applied jointly. Then, the yield of lettuce on simulation polluted soils could reach 77% and on soils affected by emissions from the KGHM plant - up to 90% of the yields from natural (control) soils.