Assessment of the Bottom Sediments State After Oil Spill

Abstract

Abstract The paper has deal with the monitoring of the lake bottom sediments which were contaminated by oil during emergency spill. The results of geochemical study of chloroform bitumoids extracted from sediment samples showed that the processes of transformation of oil hydrocarbons lasted for 10 years since the oil spill. This is indicated a decrease in the residual oil content and changes in the chemical composition of bitumoids. The hydrocarbons content was decreasing and resinous-asphaltene components was increasing as oxygen-containing groups and bonds in the chemical structure of bitumoids. In the individual composition of hydrocarbons the significant redistribution of saturated hydrocarbons was occurring both within the homologous series and between different homologous series, the CPI coefficient and the biodegradation coefficient Prophy/nC17+nC18 was increasing. By 2017 in absence of new oil spills the chemical composition of bottom sediments had closed to a state inherent in the native organic matter of bottom sediments of coastal lake facies, which characterized by the presence of compounds typical for higher plant lipids (dominance of high molecular weight n-alkanes of composition nC23–nC33 with a significant predominance of odd homologues, a high content of oxygen-containing compounds – solid saturated fatty acids, aliphatic esters and saturated ketones).