The potential of polycyclic aromatic compounds as indicators for soil contamination by open-pit mining and utilization of lignite: a case study at Ptolemaida basin, Greece

The majority of Greek lignite fields and coal-fired power plants is accumulated in the centre of Western Macedonia in the Ptolemais-Amynteo region of Northern Greece (Ptolemaida basin). The corresponding environmental impact dominantly caused by the mining process itself but also due to the burning process of lignites needs to be considered. Therefore, this study aimed at assessing the potential of PAHs to trace the environmental impact of power plant and coal mining emissions on soil pollution in the Ptolemaida basin. Noteworthy, the study area exhibits some special features (e.g. geomorphological and meteorological conditions, well-defined emission sources) that allow to prove the suitability of PAHs as indicators for specific petrogenic contaminations. The different sets of PAH emission sources followed in this study (fly ashes, lignite dust, charred woody material) reflected the pollution as derived from the coal mining activities as well as agricultural measures. Different approaches from simple (total amount) to more complex fingerprinting (ring member classification; profiles of sulphur-/nitrogen- and oxygen-containing PACs) as well as the application of established specific PAH ratios revealed no significant correlation with the detected soil contamination or rather soil PAH profiles. However, the microscopic analyses contradicted this assumption, since relevant particle concentrations were evident for fly ash as well as lignite particles. Hence, a huge superimposition by a further PAH emission source is assumed, probably the exhaust fumes of car traffic. In general, the study demonstrated that the application of PAHs as source indicators in soil systems is very complex and needs a very thorough interpretation. Hence, the need of using additionally complementary parameters for an unambiguous emission source apportionment seems obvious.

Graphical abstract