Citation: Samara, T.; Spanos, I.; Papachristou, T.G.; Platis, P. Assessment of Heavy Metal Pollution Using Forest Species Plantations of Post-Mining Landscapes, Ptolemais, N. Greece. Mining 2022, 2, 578–588. https://doi.org/10.3390/mining 2030031 Academic Editor: Carmen Mihaela Neculita Received: 14 June 2022 Accepted: 22 August 2022 Published: 29 August 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). Article Assessment of Heavy Metal Pollution Using Forest Species Plantations of Post-Mining Landscapes, Ptolemais, N. Greece Theano Samara *, Ioannis Spanos, Thomas G. Papachristou and Panagiotis Platis Forest Research Institute of Thessaloniki, ELGO-DEMETER, Vassilika, 57006 Thessaloniki, Greece * Correspondence: theasam@fri.gr; Tel.: +30-2310-461-172 (ext. 205) Abstract: The main purpose of the study was the absorption of heavy metals in the leaves of forest tree species, which were planted in two different plots for forestry use and environmental restoration. Four species were studied Pinus brutia, Robinia pseudoacaccia, Quercus trojana and Fraxinus ornus. Forty-eight leaf samples were collected which consisted of six samples from each species at each plot. The heavy metal concentrations in the leaves were measured for the following nine heavy metals: iron (Fe), copper (Cu), chromium (Cr), nickel (Ni), cadmium (Cd), manganese (Mn), zinc (Zn), cobalt (Co) and lead (Pd). The determinative estimation of metal concentration was carried out in the clear filtrate, using ICP-OES. Statistically significant differences in the concentrations of the heave metals were found among the species, as well as between the two plots. It was only in Robinia peudoacacia’s leaves that the cadmium concentration showed a statistical difference among the other species. The same applied for manganese in Quercus trojana’s leaves and zinc for Pinus brutia. The careful selection and planting of the appropriate forest tree species provides for an overall improvement in the environment in heavy metal polluted sites, such as those resulting from thermal power plants. Keywords: lignite mines; air pollution; plantations; forestry and environmental use; environmental restoration 1. Introduction Lignite is the most common type of coal in Greece, occurring in more than 60 sedi- mentary basins [1]. Lignite is exclusively used in Greece for electrical power regeneration and has led to the production of the most cost-effective kilowatt hour within the European Community [2]. Four Thermal Power Stations (TPSs) with more than 4000 MW total in- stalled capacity are located in the Ptolemais-Amynteon basin, which is the most important natural lignite basin in south Europe and is located in west Macedonia, Greece [3]. The main potential source of air and soil pollution in this area are the four TPSs, which release fly ash into the atmosphere [4]. Fly ash is the main waste residue produced during pulverized lignite combustion and is collected by electrostatic precipitators. Despite the fact that most thermal power plants have been equipped with electrostatic precipitators in recent years, significant amounts of fly ash are still emitted into the atmosphere because of the high rate of lignite combustion [5]. Several studies have demonstrated the environmental impacts of fly ash air pollution [5–11]. This fly ash contains heavy metals in concentrations comparable to, and in some cases greater than, those found in the upper continental crust [4]. With the construction and operation of the four TPSs, the vegetation of the area has been exposed to pollution emissions. As a result, the environmental situation has been additionally complicated by the designation of special areas with reclaimed soils where lignite has been exhausted. Such reclaimed soils have led to extremely harsh stress conditions for plant survival [12]. The restoration of old mine areas, where lignite has been exhausted, is one of the goals of the Public Power Corporation (PPC). To achieve this, the PPC has selected woody Mining 2022, 2, 578–588. https://doi.org/10.3390/mining2030031 https://www.mdpi.com/journal/mining