Anthropogenic Stress on Submerged Roman Ruins in the Phlegraean Fields Caldera: Implications for the Preservation of the Villa dei Pisoni (Baiae, Italy)

An interdisciplinary environmental baseline assessment was conducted on the submerged Roman remains of the Villa dei Pisoni, located within the Underwater Archaeological Park of Baiae (Pozzuoli Bay, southern Italy), to characterize the physical and geochemical conditions that may influence the site’s long-term preservation. High-resolution morpho-bathymetric data were integrated with sedimentological and geochemical analyses performed at seven environmental stations surrounding the submerged villa. Sediments are predominantly composed of poorly sorted gravelly sand, indicating a shallow, wave-influenced depositional environment. Organic geochemical analyses reveal a pronounced spatial heterogeneity in PAHs, with a maximum concentration of 3904 μg/kg at ENV_3, largely dominated by high-molecular-weight compounds. Diagnostic PAH ratios indicate a predominantly pyrogenic signature, suggesting a localized anthropogenic influence potentially related to maritime activities and the proximity of the site’s mooring area, although a direct fuel-spill contribution cannot be demonstrated. Inorganic geochemical analyses identify a regional enrichment in As, consistent with the geochemical influence of the active Phlegraean hydrothermal system, together with a distinct Cr–Ni–Rb anomaly at ENV_5, which is more consistent with local lithological and/or mineralogical controls. The results demonstrate that the environmental pressures affecting the site are inherently spatially heterogeneous and highlight the value of a holistic framework integrating sedimentological, geochemical, and high-resolution spatial data for the establishment of a comprehensive environmental baseline and the effective management of long-term preservation strategies.