Environmental Context. Industrial metal production, thermoelectric power plants, and similar technologies can release a large amount of particles (with sizes up to the millimetre scale) of heavy metals into the local surrounds. Up to 10% of these particles are strongly magnetic and easily detectable above the background magnetism. A map of the regional magnetic signals, which would be relatively simple and cheap to produce, provides a guide to pollution ‘hotspots’. But it’s not that simple: The authors integrate chemistry, microscopy, and magnetism studies of single particles of sediments from the Danube River to show rock magnetic parameters established for natural rocks cannot be directly used on environmental man-made particles.

Abstract. The presence of significant amounts of strongly magnetic phases in anthropogenic particulate industrial emissions allows the use of magnetic methods for fast and cheap detection of environmental pollution. The aim of our study is to check the validity of some of the constitutive magnetic parameters and their ratios used for estimation of grain sizes and distance from the pollution source. The results from our integrated magnetic, microscopic, and microchemical study on large, single, anthropogenic particles show that classical rock magnetic parameters (M_rs/M_r, B_cr/B_c) for mineral magnetic characterization cannot be directly applied to the anthropogenic phases. This results from their inhomogeneous composition, often with dendritic exsolution of iron oxides within an aluminosilicate matrix.