Potentially toxic elements in fen peatland soils located near lignite-fired power plants in Central Poland

Abstract

The Grójec Valley (GV) peatland area in Central Poland is located close to lignite-fired power plants, which could be sources of potentially toxic elements (PTE). The aims of this study are: (1) to determine the effect of the lignite-fired power plants on soil pollution, (2) to evaluate pollution indices and magnetic susceptibility methods for determining the origin and distribution of PTE in soils, and (3) to demonstrate the importance of appropriate geochemical background (GB) selection for pollution studies in peatland soils. In order to comprehensively assess the soil pollution, four pollution indices (calculated using various types of GBs), and the mass-specific magnetic susceptibility method were used. The low content of analyzed PTE (Cd, Cr, Cu, Ni, Pb, Zn), the calculated pollution indices, and the magnetic susceptibility values (overall >20 × 10−8 m3 kg−1) indicated generally low pollution levels in the studied soils. This would suggest that power plants have had a minor impact on the fen soils, although exceptions were observed in the southernmost part of GV, the highest content of Cr (6.87–9.11 mg kg−1), Ni (7.11–10.3 mg kg−1) and Cu (14.1–19.5 mg kg−1). In addition, based on the Potential Ecological Risk (RI) and Contamination Security indexes (CSI), this area showed the highest potential ecological risk (81.9–102) and limit of toxicity (0.59–0.67) among the studied plots, respectively. The Enrichment factor (EF) and Contamination Security index (CSI) values were the most comparable, thus we consider that, in combination with magnetic susceptibility measurements, they comprise a useful set of tools for fen soil contamination studies. Furthermore, we suggest the application of an local organic GB (i.e. PTE content in the deeper organic layer) in such studies.