Spatial variation of soil magnetic susceptibility in relation to different emission sources in southern Poland

Publication date: October 2015
Source:Geoderma, Volumes 255–256
Author(s): Tadeusz Magiera , Henryk Parzentny , Leokadia Róg , Ryszard Chybiorz , Małgorzata Wawer
The study in the area surrounding the Rybnik urban agglomeration (southern Poland) was conducted to determine the influence of various emission sources on the occurrence of local magnetic anomalies observed in the forest topsoils. For this reason field measurement of volume-specific magnetic susceptibility (κ) was conducted in forest topsoil on the area of study. The measurements were performed twice: directly on the surface and after removal of forest litter to see the influence of the litter on the magnetic signal measured on the soil surface. The maps of surface distribution of κ value revealed that magnetic anomalies were observed 2.0km around the residential areas dominated by low emission sources, 2.1km around the coke plant, 2.8km around the old steelworks, 1.4km around the coal-mining waste heaps, and 4.0km around the combined heat and power plant and coal mines. On the 43% of the study area, the topsoil magnetic susceptibility was between 50 and 100×10⁻⁵ SI units; on the 5.2% of the area, κ value was between 100 and 200×10⁻⁵ SI units; and on the 1.2% of the research area, the κ value was over 200×10⁻⁵ SI units. Also the vertical distribution of technogenic magnetic particles (TMPs) along the topsoil profile was analysed using topsoil 30cm cores. Two κ value maxima were observed in the soil profile. The upper one (κaverage =333.9×10⁻⁵ SI units) was found in either the Oa or Ah subhorizons at the depth of 3cm to 8cm dependently of thickness of organic horizon. The lower one (κaverage =53.4×10⁻⁵ SI units) was observed in the B or C horizon at the depth of 19cm to 23cm. The upper maxima was of anthropogenic origin with large content of the magnetic fraction (magnetic spherules), whereas the lower maxima containing isometric crystals of iron oxides was of pedogenic or geogenic origin. The soil magnetometry seems to be a useful tool in identification of anthropogenic “hot spots” caused by industrial and urban dust deposition from different emission sources.