Modeling environmental sensitivity and risk assessment of PAHs in sediments along two marine coastal areas in Egypt

Modeling the environmental sensitivity index (ESI) is vital in the planning and management processes, especially along the coastal areas. The main objectives of the study were to define the main sources of polycyclic aromatic hydrocarbons (PAHs), establish an ESI model, and measure the risk of PAHs on humans and the environment using various equations. The methodology of the research involved analyzing PAHs according to the EPA 550 methodology in sediments of the coastline in two important coastline areas in Egypt, namely the Gulf of Suez and the Mediterranean Sea, modeling the sensitivity of PAHs using ArcGIS 10.5 by integrating different physical, biological, and land use/cover factors, identifying the sources, and performing a risk assessment. Nine sediment samples were collected from each area. The produced sensitivity map could explain the highly sensitive areas along the Mediterranean Sea and Gulf of Suez coastlines (especially areas that were near drains' outlets, industrial sites, and sea ports). The highest mean PAH concentrations were Acenaphthylene and Fluorine in the Mediterranean Sea and Suez Gulf, respectively. It's obvious that the individual PAH concentrations were within the ERL, ERM, and PEL threshold limits, indicating no adverse biological impacts. The ratios of BaA/BaA + Chy, Flu/Flu + Py, and Ant/Ant + Phe gave an indication that most PAH sources were petrogenic (63.64%) and others (36.36%) were from petroleum combustion. The principle component analysis (PCA) indicated a diverse correlation among the isomer ratios and LU/LC activities. The carcinogenic risk values were in the very low category (<10⁻⁶) for both children and adults. The most significant contributors to carcinogenicity were IP and BkFlu in the Mediterranean Sea and Suez Gulf, respectively. Increasing sources of carbon in seawater, especially with climatic change, may impact the aquatic environment and have impacts on organisms and coral reefs. So it is highly recommended to keep shorelines and seawater free of oil spillage activities along the coastal areas or take actions towards this.