Assessment of Potentially Toxic Element Contamination in the Philippi Peatland, Eastern Macedonia, Greece

Abstract

The Philippi peatland is considered the biggest peat deposit in the Balkan Peninsula and one of the deepest in the world. The purpose of this study was to access the impact of eight potentially toxic elements (PTEs), i.e., As, Se, Pb, Cr, Ni, Zn, Mn and Cu, on the local environment. PTE content was determined in corn grains and surface soil samples collected from 16 sites in the peatland, and pollution indices were calculated to evaluate the environmental risks. Soil organic matter ranged between 93 and 557 g kg−1 soil, whereas the soil pH was >7, classifying the soils as neutral to slightly alkaline. Mean PTE contents in soil samples were 24.6 mg kg−1 soil for As, 1.68 mg kg−1 soil for Se, 113 mg kg−1 soil for Pb, 32 mg kg−1 soil for Cr, 36.3 mg kg−1 soil for Ni, 141.4 mg kg−1 soil for Zn, 35.5 mg kg−1 soil for Cu and 845 mg kg−1 soil for Mn. In corn grain samples, 0.06 mg kg−1 grain for As, 0.14 mg kg−1 grain for Se, 1.34 mg kg−1 grain for Cr, 0.69 mg kg−1 grain for Ni, 27 for Zn, 8.4 mg kg−1 grain for Cu and 3.2 mg kg−1 grain for Mn were recorded. No Pb was detected in the corn grains. The bioaccumulation factor (BF) was high for Cu, Zn and Se, indicating increased mobility of these elements in the soils and preferential plant uptake. For most soil samples, the geoaccumulation index (Igeo) and single pollution index (PI) showed low to moderate contamination. However, Igeo and PI values of Se in many sampling sites and of Pb and Zn in few were substantially increased, pointing to heavily contaminated soils. According to potential ecological risk (RI), the PTE content in the peat soils of Philippi imposes low to moderate risk on the environment.