Oil pollutants in alluvial sediments: Influence of the intensity of contact with ground waters on the effect of microorganisms

The influence of the intensity of interaction between oil pollutants and ground waters in alluvial sediments on the effect of microbial activity was investigated in this work. The study was based on a comparison of detailed analyses of two fractions of an oil pollutant originating from a Danube alluvial formation near the PanCevo Oil Refinery: fraction 1. separated from the aqueous layer by decantation, presumed to have been in less intensive interaction with water, and fraction 2, isolated from the aqueous emulsion by extraction with chloroform, presumed to have been in stronger interaction with water. Both fractions were shown to originate from the same type of oil pollutant. Nevertheless, significant compositional divergences between the two fractions were observed. A significantly pronounced domination of even carbon number homologues of C 1 8 -C 2 4 n-alkanes in fraction 2, atypical for crude oil pollutants, compared to the corresponding distribution observed in fraction 1, suggested a more intense activity. i.e., a much better effect of microorganisms in direct contact with the oil pollutant within the aqueous environment. The identification of even carbon number C 1 4 -C 1 8 n-alcohols and C 1 4 -C 1 8 fatty acids, as well as cholesterol, in fraction 2, suggested that microorganisms of the algal type in non-photosynthetic conditions were most probably responsible for the mentioned microbial processes.