Characterization of anthropogenic magnetic phases in different soil layers and their correlation to heavy metals (Upper Silesia, Poland)
Abstract
The variability of magnetic phases was studied within selected soil profiles, sorted by age and type of soil, in a polluted area of Katowice province, Upper Silesia, Poland. The topsoils of this area have previously been screened for magnetic susceptibility within the EU project MAGPROX. Results indicated a strong enhancement of magnetic susceptibility, supplying the impetus for this present study. The explanation for the enhancement of the magnetic signal is to be found in the enduring industrial activity, among which cement plants and coal mining present in the area. In order to determine the long-term effects of anthropogenic influence on the development of a soil under defined conditions (same climate, known dust input, bedrock > 96% sand), the distribution of anthropogenic pollutants within the soil profile was investigated. The different pedogenic layers of different soil types covering a time span of 80 years were recognized and sampled. For all soils, the intensity of magnetic susceptibility is highest in the uppermost (organic - O) horizon, suggesting an enrichment in ferrimagnetic minerals in this section. Although this enhancement appears in the first centimeter for very young soils, its depth increases with age and development of the soil, indicating a shifting of the magnetic signal within the O horizon, from top (litter) to bottom (boundary to mineral horizon). A set of complementary magnetic and magneto-mineralogical experiments confirmed the presence of anthropogenic magnetic phases. Magnetite-like phases were identified through the IRM acquisition curves and by thermomagnetic measurements. ARM measurements also gave a good correlation with the magnetic susceptibility results for well-developed soils : the maximum ARM intensity appears in the uppermost horizons, followed by a continuous decrease with depth. Chemical analyses revealed an accumulation of heavy metals in organic layers, especially of Mn, Zn, Cu, Cd, Ni, Pb, and Cr, coinciding with the maximum of magnetic susceptibility and the ARM / IRM patterns. SEM and EDX methods provided additional data about the chemical composition, the mineralogy, the shape and the size of the anthropogenic particles targeted, characteristic of the different soil layers.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA.....8288S