I sedimenti dell'Alto Adriatico

Heavy metals in the coastal sediments of the northern Adriatic sea: has the contamination degree changed after 20 years?

Covelli S., Balocchi C., Focardi S., Brambati A. 2003. Heavy metals in the coastal sediments of the northern Adriatic sea: has the contamination degree changed after 20 years? 6th International Symposium on Environmental Geochemistry, Edimburgh (UK), 7-11 September 2003, Book of Abstracts, p. 148.
Abstract: 
The Northern Adriatic sea is a shallow marine basin, bordered by several urban areas and large industrial sites (e.g. Porto Marghera, Venice Lagoon) and influenced by high freshwater inputs from important rivers such as Po and Adige draining a highly anthropized and extensive cultivated inland. Several studies have been performed since ‘70’s in order to assess if bottom marine sediments can be considered as final sink for heavy metals and other pollutants discharged directly into the coastal zone and, through dumping operations, in the offshore area. The most comprehensive dataset, covering the whole area extending from the Gulf of Trieste to the Po river mouth (2500 km2), dates back to the end of ’80s. From that time, industrial and urban wastes have been more intensively processed through treatment plants whereas dumping operations have reduced and finally stopped. One hundred surface sediment samples were collected in June 2001, and analysed for determining textural properties and concentrations of some major (Al and Fe) and trace (Cd, Cr, Cu, Mn, Ni, Pb, Zn) elements. The main goal of this study has been to quantify the contamination degree (EF) of present sediments on the basis of regional baselines through a normalisation procedure and to define dispersion and accumulation pattern of pollutants in comparison with the past situation. Our results confirm that most of the highest anomalies are concentrated in front of the tidal inlets of Venice Lagoon and are basically relate to industrial wastes dumped in the marine area (EF: Cd up to about 17; Cr and Zn > 4, Fe and Pb > 3). Besides, the prodelta zone of Adige and Po rivers, where the finest riverborne sediments accumulate, show relevant (Cd EF up to 6) and moderate (Cu, Zn and Cr) enrichments due to anthropogenic sources.