Usefulness of rock dust waste for the remediation of zinc contaminated soils / Przydatność odpadowego pyłu skalnego do remediacji gleb zanieczyszczonych cynkiem

The aim of this study was to check whether the addition of waste rock dust to the soil contaminated with zinc will improve the yield of reed canary grass and reduce excessive amounts of zinc in its biomass. The study was carried out in the micro-plots made of concrete, as a two-factorial experiment, in a randomized complete block design, with four replicates. The first factor of the experiment was the level of soil contamination with zinc: 1) Zn₀ - the soil with natural Zn concentration; 2) Zn₁ - 200; 3) Zn₂ - 400; 4) Zn₃ - 800 mg/kg soil. The second factor was the level of remediation: 1) control, without remediation, 2) with remediation (rock dust applied at the rate 3 kg • m^-2). The results of the study indicate that application of waste rock dust can improve the conditions of reed canary grass growth in the soil contaminated with zinc. At the highest level of contamination (Zn₃), soil amendment with rock dust resulted in increased yields of reed canary grass dry matter, in two crops, by 136 and 176%, respectively, as compared with corresponding control objects without dust addition. At the same time, the concentrations of zinc in the plants grown in the soil amended with dust were about 16% lower, and the soluble forms of this element in soil, determined in extraction with 1 mol HCl • dm^-3, were about 25% lower, as compared with control plots.