Polycyclic aromatic hydrocarbons in the water column of three hot spot areas, Jeddah coast, eastern of Red Sea

Jeddah coast receiving significant amount of persistent organic pollutants including polycyclic aromatic hydrocarbons (PAHs). Sources of PAHs mainly introduced to the coastal area from sewage influents, vehicle exhausts, industrial and Islamic harbor activates. In the present study, dissolved PAHs in the surface and near bottom waters were assessed in three highly polluted coastal areas in Jeddah city (Islamic Jeddah Port, Al-Arbaeen and Al-Shabab lagoons), eastern side of the Red Sea. The study aims to investigate vertical and horizontal distribution of PAHs in the water column, and explore the anthropogenic and environmental factors affecting their distribution. The total concentration of parent and methylated PAHs (∑25PAHs) in the near bottom waters were ranged between 377 and 1300 ng/L (average: 773 ± 329 ng/L), while the concentrations in surface waters (∑11PAHs) were ranged between 151 and 748 ng/L (average: 360 ± 174 ng/L). The concentrations of PAHs in the bottom waters were almost double those of surface waters. The area reached by particulate organic matter from sewage effluents that adsorbed low soluble high molecular weight PAHs from the surface waters on their way to the sediments then sediment-bottom water exchange released considerable amount of PAHs in bottom waters. The diagnostic ratios pointed out to a mixture of petrogenic and pyrogenic origins in the surface and near bottom waters. The toxic and mutagenic equivalent quotients for carcinogenic PAHs in the bottom waters were found 47 and 49 ng TEQ/L, respectively. The PAH levels in the study area indicated adverse effects are probable to occur.