Evaluation of past and present distribution of contaminants in surface marine sediments of coastal environments (northern Adriatic Sea)

The occurrence of contaminants in coastal sediments is often associated with anthropogenic inputs. This study focuses on the collection, analysis, and integration of historical data concerning inorganic and organic contaminants in marine-coastal sediments of the northern Adriatic Sea. The aim is to develop a comprehensive and up-to-date database that reflects the spatial distribution and concentration of contaminants in accordance with current regulatory frameworks. As a case study, a geochemical-environmental approach was applied to the eastern sector of the Gulf of Trieste, an area strongly influenced by urban and industrial activities, to identify the source (lithogenic or anthropogenic) of metal(loid)s, determine site-specific natural background values, and detect potential anomalies. Surface sediment samples revealed exceedances of environmental quality standards (EQSs) for Cr, Ni, Hg, Pb, As, and Cd. To account for the site-specific geochemical characteristics, a normalisation approach using Al as a grain-size proxy was applied, and enrichment factors (EFs) were calculated using regional functions derived from a sediment core collected in a less impacted area. Offshore sediments showed negligible contamination, whereas elevated EFs were observed near the coast indicating localised anomalies. The most notable enrichment was observed for Hg, with an average EF approximately 14 times higher than the local baseline, followed by Cu, Cd, Mo, Pb, and Zn. Conversely, Cr and Ni, despite exceeding EQS values, were found to be of lithogenic origin, highlighting the importance of site-specific assessment methods.