Ewa Ociepa, Agnieszka Ociepa-Kubicka, Ewa Okoniewska, Joanna Lach
The overall goal of the presented work was to evaluate the effects of a fertilizing mixture of sewage sludge, brown coal and brown coal (O+W+P) ash on mobility of Zn and Cd in soil environment and metal uptake by Miscanthus Giganteus. The pot experiment was done in semi-natural conditions from April 2007 to January 2008. The soil that was used in the experiment was taken from surroundings of Huta Częstochowa and village Dyrdy. Both soils were poorly contaminated with zinc and cadmium (II0) but there was a difference in their profiles, pH, granulometric compositions, sorption properties etc. The soil used in experiments was taken from 30 points lying on the diagonal of the study area with a depth of 0 to 20 cm. The pots used in the experiment had a capacity of 11 dm3,filled with soil of its natural moisture content after sieving through a sieve with a mesh diameter of 5 mm. For each soil there were used 6 combinations of fertilization and each of the combination was repeated in four pots. The effect of the prepared formulation was compared with the operation of the same residues (O), the mixture of sludge and mineral fertilizer (NPK+O), a mixture of lignite and mineral fertilizer (NPK+W) and the fertilization with mineral fertilizers (NPK). During periods of no precipitation or low precipitation values, the plants were watered to obtain soil moisture level of 60%. Results of this study indicate that all types of fertilizer improved sorption properties of soils, but in varying degrees. The reason is the increase in total exchangeable cations and a significant increase in the sorption capacity of the soil and the degree of saturation of the sorption complex bases. Depending on the soil type, the application of the investigated fertilizing mixture resulted in the increase in pH by 0,3–0,4, sorption capacity by 3,0 cmol(+)kg-1 and degree of sorption complex saturation with bases by 10–40%. The applied fertilizing mixture had a significant effect on limitation of bioavailable forms of Zn and Cd in soils and the content of metals in plant biomass. The introduction of O+W+P and W + NPK mixtures mostly affected to reduction of soluble forms of Zn and Cd in 1 M HCl and 0.01 M CaCl2 in studied soils. To estimate the degree of immobilization of metals in media immobilization If ratios were calculated. If values confirmed that the fertilizations O+W +P and W+NPK contributed to the immobilization of Zn and Cd in both soils. In soil enriched with O+W +P there was an observed reduction of zinc content in plants by approximately 15.0% compared to plants grown on control soil. The reduction of the cadmium content in plants grown on enriched soil 1 O+W+P was approximately 15.0% and approximately 17.0% in soil 2 in relation to the content of the crops grown on unfertilized soils. This was primarily the result of the enrichment of soil by organic matter and soil pH increase which resulted in limiting the mobility and bioavailability of heavy metals.
substraty odpadowe; immobilizacja
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