Petroleum hydrocarbon fingerprinting and sediment transport assessed by molecular biomarker and multivariate statistical analyses in the Eastern Harbour of Alexandria, Egypt

The Eastern Harbour (EH) of Alexandria, a heavily polluted southeastern Mediterranean basin, is subjected to petroleum contamination from two different sources. Surficial bottom sediments sampled inside and outside the harbour were analysed for organic geochemical markers in order to assess and track the aliphatic hydrocarbon signature in the bottom sediments. The aliphatic hydrocarbon compositions were determined both quantitatively and qualitatively for the alkanes, UCM, and biomarkers, including acyclic isoprenoids, tri- and tetracyclic terpanes, hopanes, and steranes/diasteranes. The data indicated a petroleum product end member characteristic of the EH. In order to differentiate among the possible petroleum sources in the area, biodegradation indices derived from the biomarker data were calculated for two possible end member sources, namely untreated sewage and petrochemicals, then compared statistically and experimentally with the data for the surficial bottom sediments. As a result, high levels of sewage-derived petroleum hydrocarbons were dominant in the area rather than direct input from boating activities or urban run-off. A multivariate statistical approach, including both factor analysis and linear programming technique, was used to determine the end member compositions and evaluate sediment partitioning and transport in the EH area.