engleski

Three-step extraction of heavy metals in garden soils

The 22 soil samples from Osijek-Baranja and Vukovar-Srijem counties were analysed for basic agrochemical soil properties and 4 fractions of heavy metals. The total heavy metal content (Fe, Mn, Zn, Cr, Ni, Cu, Pb and Cd) was determined by summarizing all 4 extracted fractions. There were 2 basic groups of soils: urban garden and arable land used as gardens. Also, limed arable land samples were analyzed. The aim of research was to determine total heavy metals concentrations, as well as different fractions impacted by pH and organic matter. Soil samples were analyzed using BCR (Community Bureau of Reference) three-step procedure for extraction of heavy metals. The highest total content of Fe was determined, followed by Mn, Zn, Cr, Cu, Ni, Pb and Cd. The orders of metals’ concentrations of the exchangeable (1st) fraction differ significantly from the total contents. Oxidizing (3rd) and residual (4th) fractions were in the same order of elements as total concentration, while in the reducing fraction (2nd) exceptions were Pb and Cr. Shares of metals in fractions were significantly different. The largest share of Cd and the lowest share of Fe were in exchangeable fraction, while residual fraction was vice versa. Given the pH reaction, it was found that in acidic soils were higher proportions of exchangeable fraction of Cu, Fe and Pb, and a smaller of Zn, Mn, Cr and Ni than in alkaline soils. Increasing humus content decreases exchangeable share, and increases the share of the reducing and oxidizing Pb fractions. Humus content significantly affects fraction of Ni and Zn. The analyzed fractions could be predicted by regression equations based on total concentration, acidity and humus content of the soil. Effect of liming on the concentration of the analyzed heavy metals was significant reducing the average concentration of exchangeable fraction of Fe, Zn, Cu, Ni, Pb, and Cd

heavy metals ; fractionation ; microelements ; detrimental metals ; availability

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