Petroleum Hydrocarbon Contamination in Surface Sediments of Beiluohe Basins, China

Abstract

Twenty-two surface sediment samples were collected from Beiluohe River, China, in 2005. Saturated hydrocarbons analysis was carried out on different river sediments in order to detect possible contaminations by petroleum development. Total concentrations of hydrocarbons in the sediments ranged from 6.4-147.3 microg g(-1) (dry wt) with an average of 76.8 microg g(-1), revealing relatively low to medium contamination in studied areas in spite of oil development for many years. The THC levels in the mainstream of Beiluohe River were relatively low. Sediment samples with higher total hydrocarbon concentrations were from the sites related to the petroleum activities or urban discharges. Gas chromatographic distribution patterns of n-alkanes are characteristic of petroleum in most samples. They show a strong unresolved complex mixture (UCM) with a small predominance of odd on even numbered n-alkanes. On the other hand, pentacyclic triterpanes and steranes occurred in all analyzed sediments and displayed similar signatures that are characteristic of mature organic matter contribution from oil contaminations. Hydrocarbons of terrestrial origin were also detected in the samples. However, contribution from plantwax hydrocarbons is overshadowed in samples by hydrocarbons of petroleum origin. This is obvious by the presence of the high relative abundance of UCM, and the identification of mature hopane and sterane in samples.