This study examines the heavy metal contamination in the surface sediments of six coastal lagoons in Northern Greece (Nestos River and Vistonikos complexes) in relation to particle size distribution, organic carbon, total phosphorus and total Kjeldahl nitrogen. Furthermore, the contamination degrees and the ecological risks were assessed using different indicators. The study of heavy metals in lagoon's sediments is important in evaluating natural contamination against anthropogenic impact, and consequently, providing knowledge that could lead to management measures to reduce heavy metal environmental risks. Lafri Lagoon is characterized by the highest metal levels in all elements, while Agiasma and Porto Lagos by the lowest. Comparison of metal (As, Cd, Cr, Cu, Mn, Pb, Zn and Ni) levels with Sediment Quality Guidelines showed that As and Cr were found above the toxic effect threshold values. Potential toxicity (RI) seems influenced mostly by As and Cd. CD and PLI values classified the lagoons under study as "very highly contaminated" and "polluted", respectively.
Keywords: Ecological risk assessment; Grain size distribution; Heavy metals; Lagoons; Organic carbon; Surface sediments.
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