Source identification and eco-risk assessment of polycyclic aromatic hydrocarbons in the sediments of seawaters facing the former steel plant ILVA, Naples, Italy

Abstract

The study was designed to complement the results of a previous investigation which revealed a worrying contamination scenario by polycyclic aromatic hydrocarbons, PAHs, in the Gulf of Pozzuoli, GoP, in the south of Italy. This former study also evidenced the pyrolytic source of PAHs from the dismissed metallurgical brownfield site of Bagnoli in the east side of GoP. The environmental toxicological risk assessment was also carried out. Sampling transects were drawn in the west edge of the gulf, T1 and T2, in the east side, T5, T6, in the proximity of the industrial plant and outside GoP, MdP, where pollution was expected to be low. ΣPAHs largely exceeded, from 36 up to >220 times, the regulatory standard in the east area. Lower exceeding values were determined in all the west side. FLT and PYR were the dominant hydrocarbons and PAHs distribution profiles were quite similar from west to east sides, meaning a common pollution source. Moreover, sediments appeared enriched by 4, 5 and 6 aromatic rings, 47.2%, 25.7%, and 14.0%. PAHs diagnostic ratios for source screening confirmed the pyrolytic origin of the PAH mixtures at all sites. ΣPAHcarc/ΣPAH showed that ∼50% of PAHs were of carcinogenic nature at all sites. The total benzo(a)pyrene, BaP, equivalent toxicity (TEQ) values highlighted a dramatic scenario especially in the east part of GoP, with values from twenty-four fold and six hundreds fold those reported by the literature for moderate and low ecological risk environment. The output of the risk assay assessment revealed a situation of high risk in the east side of GoP, whereas a moderate to high risk level was determined throughout all GoP.