Natural background values for heavy metals in the sediments of a contaminated Northern Adriatic lagoon environment: a geochemical perspective
1 Dipartimento di Matematica & Geoscienze, Università di Trieste, Via Weiss 2, 34128 Trieste, ITALY
2 Osservatorio Alto Adriatico, Agenzia Regionale per la Protezione dell’Ambiente del Friuli Venezia Giulia (ARPA-FVG), Via Cairoli 14, 33057, Palmanova, ITALY
Major and trace elements were determined in 14 sediment cores collected from the Marano and Grado Lagoon (northern Adriatic sea). The lagoon is contaminated by several harmful priority substances, heavy metals included, and it has also been declared a “polluted site of national interest” (SIN) mainly due to high Hg concentrations in sediments. Based on a normalization procedure involving predicted linear relationships for “metal vs Al” obtained from the core subsamples, background values for each metal were evaluated on a regional scale and according to the grain-size variability. Compared to Environmental Quality Standards reported in the Italian laws and regulations, the estimated background ranges show that bottom sediments are naturally “enriched” in some metals, such as Cr, Ni and Cd especially in sediments with a high percentage of the fine component. A correct evaluation on sediment quality status should be made on the basis of regional background values for each metal, taking into account local geochemical characteristics, i.e. mineralogical composition and grain-size variability of sediments.
Key words: Heavy metals / normalization procedure / background / coastal sediments / Environmental Quality Standards
© Owned by the authors, published by EDP Sciences, 2013
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 2.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.