Magnetic properties of alluvial soils contaminated with lead, zinc and cadmium

Several proxy methods have been used recently to outline increased levels o f pollution, One of them is based on measurements of the concentration of ( ferri)magnetic minerals of anthropogenic origin. This method has been used recently in the mapping of both polluted and unpolluted areas. In order to validate this method, a more detailed study of links between magnetic param eters characterising the physical shape of magnetic minerals and concentrat ions of heavy metals is needed. In this study, we analysed the magnetic cha racteristics of alluvial soils, formed as a result of several breakdowns of wet deposit sink of ashes from a lead ore smelter. The soils were previous ly analysed for concentration of lead, zinc and cadmium. Our results show t hat in this case of a shared source of heavy metals and magnetic minerals, simple measurements of magnetic susceptibility discriminate well between po lluted and clean areas. In addition, the concentration pattern agrees with the concentrations of the heavy metals studied in deeper soil layers that w ere not affected by post-depositional changes due to climate and remediatio n efforts. (C) 2001 Elsevier Science B.V. All rights reserved.