Application of magnetometry for delineation of anthropogenic pollution in areas covered by various soil types

Soil magnetometry is already frequently applied as a tool for rapid evaluation of contamination in different case-studies. It relies on the well established fact that most of the industrial wastes contain strongly magnetic fraction, which enhances magnetic response of the top-soil. Current regional-scale study applies magnetometry on ∼ 2800 km2 area in north-eastern Bulgaria. The main pollution sources are several plants of chemical industry (soda production, polymers, fertilizers), cement plant and power plants. Pollutants emitted as a result of these industrial productions do not contain as much magnetic fraction in order to cause extreme magnetic enhancement of top-soils, which is a typical feature for the metallurgical industries, mining, coal-burning power plants. A new approach is proposed to correct the data (field and laboratory) for the effect of different soil types in the area, which is not a negligible factor in such case. As a result, more precise lateral distribution of the anthropogenic magnetic fraction is obtained, delineating all affected by pollution regions. The efficiency of the newly proposed method for taking into account differences in soil types is validated through correlation analysis between magnetic parameters and heavy metal content in selected samples. Correlation between the corrected magnetic susceptibility values, Co, Ni, As, Pb and the Enrichment Factors (EF = ∑Ci/Ck, Ci — measured concentrations of Pb, Zn, Cu, Co, Ni, As; Ck — background concentrations for the corresponding elements) increase after the applied correction.