Effect of different soil conditions on magnetic parameters of power-plant fly ashes

The effect of soil conditions on magnetic parameters of anthropogenic ferri magnetics was studied. Fly ash from a coal burning power plant (Pocerady, C zech Republic) was used as original contaminant material. whereas soil-reac tive medium was modelled by different soil solutions. Magnetic susceptibili ty, hysteresis parameters, and thermomagnetic curves were measured for samp les that under-went different leaching time periods. Virtually constant mag netic susceptibility values were obtained independently on the soil medium (acid and neutral). On the other hand, the original highly nonstoichiometri c maghemite phase has been rapidly transformed to stable magnetite. In some cases (model of free-draining soils), further decrease of Curie temperatur e (T-C) to 550-560 degreesC is observed. Unstable maghemite phase was not i dentified in contaminated soil horizons in the surroundings of the power pl ant. (C) 2001 Elsevier Science B.V. All rights reserved.