Sediment heavy metals of a Mediterranean coastal lagoon: Agiasma, Nestos Delta, Eastern Macedonia (Greece)

Abstract

1 - Sediment cores of Agiasma, Nestos Delta lagoon, characterized by the perennial angiosperm Ruppia cirrhosa and by the opportunistic macroalga Ulva sp. were analyzed for six heavy metals. The aim was to contribute (a) in quantifying origin and degree of heavy metal pollution, (b) in developing sediment pollutants base line data for eastern Mediterranean, and (c) in exploring the role of heavy metals in habitat type shifts. 2 - The maxima of total concentrations (in ppm dry weight) were the following: Cu (up to 37), Pb (up to 158.2), Ni (up to 59.2), Zn (up to 70.4), Cr (up to 112.3), and Hg (up to 0.1). These values are lower compared to the maxima measured in polluted lagoons and coastal ecosystems of the Mediterranean Sea. Mean total concentrations in Ulva habitat type were only for lead two times higher than in Ruppia habitat type. This result along with the Euclidean distance cluster analysis based on total metal concentrations suggested heavy metal pollution not to be a determinant factor of the habitat type shift in the Agiasma lagoon. 3 - Of two enrichment factors (ref, R), calculated only the “ref” indicated that habitat type of Ulva is slightly polluted by lead. The overall detected heavy metal surcharge could be attributed to local, e.g. fisherman, as well as to watershed, e.g. fresh waters, urban sewages, anthropogenic activities.