A Thorough Study for PAHs in Dump Materials from Open-pit Lignite Mining, Maritsa Iztok Basin, Bulgaria

Abstract

Polycyclic aromatic hydrocarbons (PAHs) in six samples from Bulgarian Lignite Dumps Maritsa Iztok are tracked and amounts are determined. For isolation of soluble organic matter (SOM) ca: 40 g of powdered dump samples were Soxhlet extracted by chloroform. After asphaltenes precipitation, maltenes were separated via column chromatography. The first two fractions were further analyzed. Gas chromatography-mass spectrometry (GC-MS) was applied to appreciate organic matter sources and to identify and quantify PAHs in the samples. The set of PAHs determined pointed out that 3 and 4 ring unsubstituted PAHs as dominant in the dump extracts. Total organic carbon (TOC) values of the samples varied in the range 1.18-5.63 wt.%. Phenanthrene + Methylphenanthrene amounts were in the range 0.44-2.98 mg/kg TOC, while for Fluoranthene + Pyrene were in the range 0.06-0.52 mg/kg TOC. Total amounts of PAHs varied in the range 7-41 microg/kg sample. Values were compared with the legislation norms for PAHs in soils. All magnitudes were under the regulation norms for harmful substances in soil published by the Bulgarian National Legislation (2008). In conclusion, the study is in an equivocal proof for the negligible amounts of PAHs in dump materials from Maritsa Iztok lignite mining. However, their amounts in dumps should be measured and monitored bearing in mind the huge territories covered by these waste materials of mining industry.