Hydrocarbon-based parameters for the identification of oil contamination in an area with brown coal mining: Emphasis on pyrogenic index and alkylated PAHs

Abstract

The aim of the study was to propose hydrocarbon-based parameters that can ben used to identify oil derived contamination in an area with a long-term load of coal mining industry. Aliphatic hydrocarbons and PAHs have been quantified for bottom sediments in the Bílina River, Czechia. Presented data demonstrate that all river sediments are highly contaminated with PAHs. The results showed that the distribution of PAHs was not possible to interpret by using the standard evaluation due to multisource long-term sedimentation of petroleum by-products, coal tars, and accidents of processing industry in the river system. The presence of petroleum derived hydrocarbons has been initially screened by the bulk parameter TEH and confirmed by the occurrence of steranes, hopanes and the unresolved complex mixture (UCM) in the chromatograms. The identification of the biomarkers 25-Norhopane and Gammacerane point out onsite microbial degradation of parent hydrocarbon compounds. The interpretation of the ratios Fl/Py, An/P, BaAn/Ch were not decisive to prove petrogenic origin of PAHs in the river sediments. However, using the combined evaluation of TEH together with the ratio of low molecular over high molecular weight PAHs, pyrogenic index and the presence of specific oil derived biomarkers allowed to prove the presence of petroleum contamination. Environmental implicationDue to oil spill accidents and intensive coal mining over the years, polycyclic aromatic hydrocarbons (PAHs) have been present in extreme amounts in bottom sediments of a tributary of the Elbe River, so called the Bílina River. Due to its hydrophobic and carcinogenic character, mutual understanding of the fate of alkylated PAHs homologues are usually overlooked within EPA PAHs 16 monitoring programme. This study pays attention to alkylated PAHs homologues and conventional diagnostic ratios when identifying oil derived contamination.