Heavy metal mobility in soils under the application of sewage sludge

M. Teoharov, I. Atanassova, N. Velichkova

Abstract: One of the main issues relating to sewage sludge (SS ) disposal is the introduction of heavy metals and organic pollutants. The aim of this research work was to assess the mobility of heavy metals via measurement of the soluble and easily exchangeable metals in soils on which sewage sludge had been deposited 10 years before analysis and clarify patterns and relationships between heavy metals in the amended soils as opposed to un-amended control soils. There are few studies on the leaching potential of heavy metals in sludge-amended soils through measurement of the soluble and easily exchangeable metal forms. Mobile heavy metals (soluble + easily exchangeable Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn) were measured via extraction with 0.05 M Ca(NO 3)2. We observed: (i) elevated Cd, Cr, Zn and Cu concentrations in the sludge treated soils; (ii) no effect of sludge application was found, as far as Pb, Mn, Fe, Ni and Co mobilities are concerned; (iii) the statistical analysis showed that slight perturbations in heavy metals relationships were observed in the sewage sludge treated soils in comparison with the control soils, especially as Cu and Cr sources of soluble forms are concerned; (iv) concentrations of the nine measured elements fall in the background range of published data on wide variety of soils.

Keywords: heavy metals; sewage sludge; soil

Date published: 2019-06-28