The level of heavy metals from the cultivated lands depends on the anthropogenous activities of the region, mining activities, rhythm and duration of fertilizer with anaerobic stabilized wastewater sludge, known as biosolids. The increase of heavy metlas concentration from soil determines the increase of bioaccumulation in grains, as in Hordeum vulgare (barley) species. Repeatedly adding organic matter as fertilizer (containing heavy metals) to the land can increase Cd and Pb ions bioavailability with 28-32% and for Zn up to 58%. Adding Tuf-Aln pillared volcanic tuff to biosolids determines a decrease of bioavailability compared with the bioaccumulation in crops from an untreated polluted soil.
The paper presents the results of studies with leguminous species grown on experimental parcels of new fly ash fertilized with biosolids (municipal sludge) and untreated indigenous volcanic tuff or pillared indigenous volcanic tuff. Fly ash comes from the dumps of ash from burning lignite in power plants. The resulting amount of biomass grown on new fly ash deposits is dependent on the treatment of topsoil (new fly ash). The experimental variants with new fly ash treated with biosolids and pillared indigenous volcanic tuff determined 50% of new fly ash with pillared indigenous volcanic tuff and biosolids caused a reduction in the bioaccumulation of heavy metals in the aerial part of plants by 35-45%, for Cu respectively Ni, 60% for Cr, and 78% for Pb.