An investigation of the applicability of oil fingerprinting as a tool in soil contamination in Flanders

From inspection of the literature it is clear that sufficient analytical instruments for the application of oil fingerprinting on soil contamination problems are available. However well defined requirements have to be fulfilled. Among these prerequisites are the availability of unique oil signatures and sufficient variation within the different fuels on the Flemish market. On behalf of the Public Waste Agency of Flanders (OVAM), it was investigated if these constraints are met and consequently if sufficient analytical instruments are available enabling the linking of a suspected contamination source to an observed soil contamination. Particularly gas chromatography enables one to determine very specific characteristic patterns for the contamination and the source. However weathering alters these patterns drastically, complicating further comparison. Characteristic ratios are available for polycyclic aromatic hydrocarbons and persistent biomarkers like isoprenoids. In distillates from crude oil like most fuels, these chemicals are only present in limited amounts. Consequently application of such ratios is not always possible. Other interfering factors are changes in the composition and the limited specificity of the fuels circulating on the Flemish market. The diagnostic ratios in diesel fuels are not always unique and in some cases the differences between diagnostic ratios of different diesels is too small, not allowing to link the contamination source to the observed soil contamination. Chromatograms of soil samples do not always enable determination of the diagnostic ratios. Improvement of the detection level and the chromatographical resolution might solve this problem. For gasoline fuels differentiation was carried out based on specific chromatograms for the alkanes and the monocyclic aromatic hydrocarbons since biomarkers were not present. Concentrations of methyl-t-butyl-ether and benzene were used additionally. Also, for gasoline the link between source and contamination could not be determined unambigously.