Greece is the fifth largest world producer of lignite and the second largest within the European Community. The Western Macedonia Lignite Center (WMLC) produces annually more than 50 million tons of lignite. The WMLC in Greeceis located in the basin of Ptolemais-Kozani region (400 Km2), formed between the mounts of Vermion (east) and Askio (west). It is the richest lignite-field of the country, containing the 65-70% of his total lignite deposits (Sahanidis et al. 2001). Today located in the same area, exist many lignite open-pit mines, and 6 power plants operated by the Public Power Corporation SA (PPC), using lignite as solid fuel and providing the country with about 70% of its total electricity consumption.
The exploitation of the lignite deposits of the region for the generation of electricity began in 1956 by a privet company and in 1974 the property passed to the PPC. Until today more than 150 Km2 have been expropriated for excavation of lignite. The environmental protection is a major task for all mining companies, and the WMLC apply a program of reclamation for agricultural and forest uses in the areas that are gradually released from mining. Many researchers have shown interest for this area (Kolovos et al, 2002; Georgakopoulos et al, 2002; Filipidis et al, 2002; Pendari et al, 2006).
The soil can be considered as a kind of geochemical sink for contamination. Maintenance however of the ecological and agricultural capacity of soil is necessary for its productivity, which is indispensable for the survival of mankind. The composition of soils is extremely diverse from a place to another and depends on many factors including its parent material (weathering and pedogenic processes of underlying rocks), climatic conditions and human activities (Alina Kabata-Pendias 2002). The metal content of the soil is the sum of metals originating from natural processes and human activities. Generally, it has being supported that the contribution of metals from natural sources is lower than that of the anthropogenic origin, as a consequence of the increasing industrial production throughout the world (Nriagu et al. 1998). However, it is often difficult to assign the source or the sources of trace elements to a particular location and sometimes too much emphasis is given to anthropogenic sources (Swaine, 2001). The metals enter the soil by different pathways, including aerial deposition, decomposition of the aboveground parts of plants, waste material and application of pesticides and fertilizers (Alina Kabata-Pendias 2002).
The lignite is composed not only of those elements generally considered to be organic (C, H, O and N), but also contains significant quantities of inorganic elements. Trace elements are inorganic elements whose concentration is less than 0.02% wt (200 ppm). The concentration and the distribution of trace elements in coal is not the same in all coal deposits, and is determined by geological parameters such as the natural and geochemical characteristics of rocks, the climate, the hydrological pattern and leaching processes near the coal bearing formation (Swaine DJ and Goodarzi F., 1995).
References
Georgakopoulos, A., Kolovos, N., Filipidis, A., Kavouridis, C., 2002, The effects on the Mined Lignite Quality Characteristics by the Intercalated Thin Layers of Carbonates in Ptolemais Mines, Northern Greece, Energy sources, 24; 761-772.
Filipidis, A, Georgakopoulos, A., Kassoli, A, Iordanidis, A., Fernandez-Turiel, J., Gimeno, D., 2002, Environmentally important elements in Fly ashes and their leachates of the Power stations of Greece, Energy sources, 24; 83-91.
Kabata-Pendias,A, 2002, Trace Elements in Soils and Plants, Third edition, CRC Press, 126, 225-230, 253-260, 289-291, 299-302, 314-320p.
Kolovos, N., Georgakopoulos, A., Fillipidis, A., Kavouridis, C. Environmental Effects of Lignite and Intermediate Steriles Coexcavation in the Southern Lignite Field Mine of Ptolemais, Northern Greece, Energy Sources, 2002, 24 (6), 561.
Niagu JO et al., Quantitative assessment of worldwide pollution of air water & soils by trace metals. Nature 333, 134-130, 1998.
Pentari, D., Typou, J., Goodatzi, F., Foskolos, A.E., 2006, Comparison of elements of environmental concern in regular and reclaimed soils, near abandoned coal mines Ptolemais-Amynteon, northern Greece: Impact on wheat crops, International Journal of Coal Geology, 65, 51-58.
Sachanidis, C. et al., 2001, Proceeding of the 9th International Congress, Athens.
Swaine, D.J., 2001, Why trace elements are important, Fuel Processing Technology, 65-66, 21-33.
Swaine, DJ, Goodarzi, F., 1995, Environmental Aspects of Trace Elements in Coal, Kluwer.