Composition, Distribution and Sources of Polycyclic Aromatic Hydrocarbons (PAHs) in Sediments of the Western Harbour of Alexandria, Egypt
Alaa El-Din R. Mostafa1, Assem O. Barakat1, Yaorong Qian2, Terry L. Wade2
(1) Alexandria University, Alexandria, Egypt (2) Texas A&M University, Texas, TX
The composition, distribution and the source of polycyclic aromatic hydrocarbons (PAHs) in surficial sediments of the Western Harbour of Alexandria were investigated. To document the spatial PAH input, surficial sediment samples from 23 locations throughout the harbour were analysed. The total PAH load determined in the surficial sediment samples ranged from 7.9 to 131149 ng g-1 dry wt. Generally, most of the samples having total concentrations of PAHs greater than 5000 ng g-1 dry weight. The highest concentration of total PAHs was recorded in sediments of the inner harbour. Ratio values of specific compounds such as phenantherene to antheracene, fluoranthrene to pyrene, methyl-phenanthrene to phenanthrene, methyl-dibenzothiophenes to dibenzothiophenes, alkylated to non-alkylated and high molecular weight to low molecular weight PAH, were calculated to evaluate the possible source of PAH contamination in the harbour sediments. However, chrysene and perylene were used as indicator of terrigenous input. Two main sources of PAH in the study area have been found: pyrolitic and petrogenic. Interferences of rather petrogenic and pyrolytic PAH contaminations were noticed for most samples. The dominant sources of PAH appear to be the combustion processes through run-off, industrial and sewage discharges, and atmospheric input. The concentrations of PAHs were generally above levels expected to cause adverse biological effects.