Ecological quality of the “Torfowisko pod Węglińcem” nature reserve (SW Poland) based on magnetic and geochemical studies

Abstract

In this research a combination of magnetic, geochemical and microscopic techniques was used to investigate the ombrothropic peat bog, which covers the “Torfowisko pod Węglińcem” nature reserve, situated in south-western Poland. Hysteresis parameters and measurements of magnetic susceptibility show that the surface layer (∼15 cm) of the protected peat bog area is contaminated by strongly-magnetic materials e.g. low-coercivity magnetite. Geochemical analyses revealed higher concentrations of certain chemical elements (e.g. Li, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ga, Ba and Pb) in the approximately 10 cm surface peat layer. The vertical distribution of the magnetic susceptibility and most of the analyzed chemical elements exhibit strong correlation and this demonstrates that the identified anthropogenic contaminants accumulate via atmospheric deposition. The microscopic analyses of the magnetic material separated from the peat samples identified two types of metal-rich particulates: spherules and irregularly shaped particles including an octahedral magnetic crystals (mean diameter of both types ∼10–300 μm). The magnetic bi-plots show that even finer magnetic grains (<10 μm) may be found at the studied area. The radiocarbon (14C) dating of the surface samples suggests that the formation of the contaminated top peat layer has occurred during last 300 years. In such case the analyzed magnetic material may be the proof of both: historical as well as the present atmospheric deposition.