Content of Heavy Metals in Reclaimed Soil Material and Hard Coal ash 15 Years After the Experiment

The paper the results obtained during hard coal ash reclamation. This model was created by covering the ash surface with the layers consisting of ash, organic by-products and mineral fertilizers. The aim of the studies, undertaken 15 years after the experiment set up, was the assessment of the efficacy of ash waste reclamation on the basis of the overall and solubility analyses of the metal content, including heavy metals, soluble in 1 M HCl. In 2003, on the premises of Dolna Odra Power Station in Nowe Czarnowo (53,20°N; 14,48°E) near Gryfino (53,25°N; 14,48°E) in Poland, a hard coal ash reclamation experiment was conducted. A 40 cm thick surface layer (fertile), termed upperlay, composed of the mixture of various materials was applied to ash substrate. One part was fertilized with mineral fertilizers NPK-60–70–70, the other was left unfertilized. After 15 years, in the autumn of 2018, the samples of upperlays (0–40 cm) and underlays (40–60 cm) were collected from plots overgrown with grass. Fifteen years after the experiment, none of the underlays or upperlays showed an excess of threshold values, as specified in the current Regulation of the Minister of the Environment of 2016. The particularly favourable effect was identified with respect to the application of fermented municipal sewage sludge and GWDA compost which were factors resulting in a decrease of the upperlay content of cadmium, zinc, copper and lead in the form available for plants. The characteristics of upperlays with respect to metal content indicate the conditions favourable to plant cultivation on the reclaimed area. The recorded results on the change of the overall and bioavailable content of metals in upperlays and underlays justify the continuation of the undertaken reclamation experiment.