Factors determining Cd, Co, Cr, Cu, Ni, Mn, Pb and Zn mobility in uncontaminated arable and forest surface soils in Hungary

Abstract

The aim of this work was the determination of the linkage between land use and mobility of potentially toxic elements in soil. A total of 193 soil samples taken from the surface soils of Hungary were used in the analysis. Based on the investigated properties [pH, soil organic matter (SOM), dissolved organic carbon (DOC) and clay], the forest soils were acidic with higher DOC concentration while arable soils were neutral with higher clay content. Three element fractions, the pseudo total (HNO3 + H2O2-soluble), plant-available (NH4-acetate + EDTA-soluble) and mobile (1 M NH4NO3-soluble) were used for the investigation. Total Cr, Cu, Ni, Zn and plant-available Cu, Mn and Ni concentrations were higher in arable soils, but the mobile concentrations of each element were higher in forest soils, probably due to the lower pH and CEC, and higher DOC concentration. The element mobility was calculated with two ratios [mobile/total] and [mobile/(plant-available − mobile)]. The chosen soil properties explained only a small part of the variability in the mobility. In most cases, the R 2 values of the regression equations were below 0.5. The mobility of elements investigated in forest soils was multiple of that in arable soils. For each investigated element, the regression equations were different in arable and forest soils. In forest soils, the mobility of Cd could be characterised by pH alone. DOC had an effect primarily on Cu mobility. The influence of the solid phase on element mobility could be attributed to SOM in forest soils and clay content in arable soils.