Contamination and ecological risk assessment of the seaport of Naples (Italy): Insights from marine sediments

In this study, the state of inorganic, organic and microbiological contamination of the seaport of Naples (Southern Italy), one of the main ports in the Mediterranean Sea, was investigated. We analyzed 55 surficial marine sediment samples for Potentially Toxic Elements (PTEs), Hydrocarbons (HCs) and Polycyclic Aromatic Hydrocarbons (PAHs). In addition microbiological parameters, such as Escherichia coli, Salmonella, sulfite-reducing Clostridia (SRC) and Streptococcus faecalis were determined in 26 sampled points. The data were statistically analyzed to 1) evaluate contamination degree based on background concentration values, 2) reconstruct the contaminants spatial distribution, 3) identify geochemical pattern and potential sources, 4) assess toxic effects for aquatic biota. Our results supported an anthropogenic enrichment for certain PTEs (Hg > Cd > Zn > Pb > Cu > Cr) responsible for contamination of the marine area together with PAHs and HCs. Indeed, the Principal component analyses (PCA) biplot highlighted distinct groups of contaminants and controlling processes. Sediment grain size and, to a greater extent, TOC content can be recognized as a controlling factor in both organic compounds and elements occurrence in the port of Naples and are related to pollution of shipyard activities and the disused industrial area. Conversely, elements such as Al, As, Fe and V are mainly due to natural inputs and are characterized by no/low contamination. Based on the analysis of the toxic equivalent quantity and sediment quality guideline quotient, the contamination of Cu, Hg, Pb, Zn and PAHs in sediments pose a frequently observed effect and may represent a biological risks to marine organisms. The cumulative mean toxic effect, used to assess the hazard degree, indicated a higher probability of toxicity connected to sediment chemistry in the areas where shipyard activities (in the central sector of the port) and disused industrial area (eastern sector) occur. More attention should be paid on industrial, ship repair activities and maritime traffic related discharges for the port environmental protection.