On the limitation of the term petroleum products in the determination of the oil pollution of bottom sediments

Problems related to the determination of the oil pollution of bottom sediments are discussed. Tarry substances resistant to degradation, whose content can be as high as 50% on a total oil basis, are accumulated in the bottom sediments. The conventional term petroleum products, which implies only a hydrocarbon fraction, does not adequately describe these substances; because of this, the really evaluated level of the oil pollution of bottom sediments becomes underestimated to a considerable degree. We proposed to determine tarry substances in bottom sediments by fluorescence spectrometry at 490–510 nm in combination with a stage of the chromatographic preconcentration and separation of oils and petroleum products into the following main group components: hydrocarbons, tars, and asphaltenes. The substances coextracted with the petroleum products (pesticides, phenols, pigments, etc.) occurred in a chromatographic zone of tars and asphaltenes, but they fluoresce at other wavelengths and do not interfere with the determination. The typical chromatograms of hydrocarbons from the bottom sediments of different water bodies obtained by gas chromatography are given.