Magnetic susceptibility as indicator of environmental pollution of soils in Tallinn

Low-field magnetic susceptibility (kappa) and concentration of 40 elements were determined for 531 samples collected from top-soils on the territory of the biggest industrial centre of Estonia. This study was carried out during a small-scale geochemical mapping and monitoring of soils in the frame of the project "Urban geochemistry of Tallinn" supported by NATO. The main purpose was to establish the sources of pollution and to study applicability of kappa for determining geochemical anomalies. Relationship between kappa and element concentrations in the topsoil was studied by means of correlation and factor analyses. Higher than average kappa values were observed in soils on the territory of phosphorite deposits at Maardu. The susceptibility anomaly is caused by particular geological circumstances and can be related to high contents of ferromagnetic minerals in the host rocks. Strong positive correlation of magnetic susceptibility with Cr, Pb, Zn and Cu observed in soils from the central part of the city are conditioned by industrial contamination mainly by metalworking factories and by traffic. These heavy metals, known as the most hazardous elements, are easily extracted by plants from the soils in the studied area. In addition to traditional geochemical mapping, the magnetic susceptibility was successfully applied in determining heavy metal pollution of soils on the city territories. (C) 1999 Elsevier Science Ltd. All rights reserved.