Assessment of the Geochemical Availability and Ecological Risk of Trace Elements in Marine Sediments of the Tremiti Islands

Abstract

Marine protected areas (MPAs) near the coast are a global concern due to potential impact of anthropogenic activities highly relevant when it comes to trace elements pollution in sediment. This study aims to assess the levels of trace elements in sediment, their potential mobility and the ecological risk in Tremiti Islands, a sensitive and vulnerable MPA. Sediment was analyzed for granulometry, mineralogy, pseudo-metal concentrations and available fractions using BCR method. Statistical analysis and different pollution and ecological risk indices were applied to interpret the results, determine the contamination levels and assess the element availability and their potential impact using Sediment Quality Guidelines. Spatial variability in grain size and mineralogy was found across the sampling sites. The finer quartz-rich sediments exhibiting higher trace element concentrations. Site-specific enrichments were evident for As and Zn at Cala Spido and for Pb at Cala Matano. Cu and Mn showed notable potential bioavailability with residual fractions below 30% at all sites; low Cd concentrations were found, but it was highly available. Cala Spido and Grotta del Sale showed higher contamination-degree, while Pagliai and Cala Matano stood out for their higher ecological risk and availability indexes. These findings demonstrated that even within a Marine Protected Area, site-specific anthropogenic pressures can significantly influence sediment quality and ecological risk.