Geochemical composition of the uppermost prodelta sediments of the Evros River, northeastern Aegean Sea

Abstract

The Evros River is the second largest river of the Eastern Europe after the Danube River and is the largest river system that drains into the northeastern Aegean Sea (Eastern Mediterranean). Sediment cores recovered from the river's prodelta have been analysed in order to reveal the sedimentation rates and the heavy metal contamination history of the area. The results show the long term potential environmental impacts caused by reclamation works which have taken place in the subaerial part of the river delta since the 1950s. Sedimentation rates, based on 210Pb inventories, are ∼ 3.0 cm y − 1 in front of the river mouth and ∼ 0.4 cm y − 1 approximately 9 km offshore, however they have decreased more than 50% in the last 50 years. The rapid reduction of the sedimentation rate between the various regions of the Alexandroupolis Gulf reflects changes mainly in water circulation patterns of the area, mainly driven by the Samothraki Anticyclone. In addition, intensification of agricultural and industrial activities within the river basin have caused considerable increase of heavy metals, such as Cu (Enrichment Factor, EF: 2.2), Zn (EF: 2.0), Cd (EF: 6.0), and Pb (EF: 16.2), in the surface sediments of the Evros River prodelta.