Geochemical baselines and risk assessment of the Bagnoli brownfield site coastal sea sediments (Naples, Italy)

The Bagnoli brownfield site, one of the largest Italian dismantled industrial areas undergoing remediation, is located in the western sector of the urban territory of the city of Naples (Southern Italy) inside the active volcanic field of Campi Flegrei. The remediation project, funded by the Italian government, started in 1996 and was extended to the coastal area sea sediments facing the brownfield site in 2001.A total of 384 sea sediment samples were collected from 128 boreholes at different depths (0–20 cm, 20–30 cm, 30–50 cm, 100–120 cm, 150–180 cm, 180–200 cm, 280–300 cm, and 380–400 cm) down the seabed along the coastline. Analyzed samples show that the coastal area facing the Bagnoli brownfield site is strongly contaminated by metals whose distribution seems to be controlled by the grain size of the sea sediments, and by the presence of organic compounds (PAHs and PCBs).Geochemical mapping and R-mode factor score analysis allowed us to identify the groundwaters, emanating from the brownfield site to the sea across an artificial structure (“Colmata a mare”) limited by two piers and filled by scum, slag and landfill material, as the main source of contaminants.Since the groundwaters metal contamination was proven to be mostly dependent on a natural hydrothermal enrichment process related to the volcanic activity of Campi Flegrei, a remediation project would be needed primarily for PAHs and PCBs, which occur well above the concentration levels permitted by the Italian Law in the sea sediments facing the Bagnoli coastline.