Geochemical features of fossil fuel contaminants found in urban wastes (Siemianowice Śląskie, Poland)

In sludge samples collected in the "Centrum" wastewater treatment plant in Siemianowice Śląskie, Poland, the composition of aliphatic- and aromatic hydrocarbons and polar compound fractions were investigated by gas chromatography-mass spectrometry (GC-MS). Samples collected in accordance with Polish standards were extracted, the extracts were separated into fractions with preparative thin layer chromatography (TLC), which next were investigated by GC-MS. The following compound groups of the geochemical origin were identified: n-alkanes in the range of n-C₁₄ to n-C.₃₉, acyclic isoprenoids (mainly pristane and phytane), steranes, tri- and pentacyclic triterpanes. Based on the distribution of biomarkers and their parameters, it was established that the dominant component of extractable organic matter in sluge is petroleum material of an unspecified origin. Its geochemical features indicate that its most likely source was crude oil (or its products) of a relatively high degree of thermal maturity (catagenic stage of thermal evolution corresponding to vitrinite reflectance 0.7-0.8%). Aromatic hydrocarbons probably originated from petroleum also, though some of them can be attributed to the products of combustion or to sources such as bituminous coals, the ash from coal/biofuel combustion or coal wastes stored nearby.