Vertical Distribution and Chemical Fractionation of Heavy Metals in Dated Sediment Cores from the Saronikos Gulf, Greece

Eleni Prifti,Christina Zeri,Panagiotis Michalopoulos,Michael Scoullos,Vasiliki Paraskevopoulou,Stylianos Iliakis,Manos Dassenakis,Helen Kaberi

doi:10.3390/jmse10030376

Abstract

The Saronikos Gulf is under a lot of anthropogenic pressure, such as the urban expansion of the metropolitan area of Athens, the port of Piraeus and marinas, industrial activities, and tourism. Heavy metal pollution has been a major environmental problem in the area for many decades. Sedimentary cores have proven to be an invaluable indicator of heavy metal pollution, as they can reveal not only the current metal inputs but also the evolution of pollution over time, and with the appropriate geochemical analyses, they can provide information on the potential toxicity of metals. In this study, the temporal evolution and the chemical speciation of eleven elements were examined in sediment cores from Elefsis Bay and the Inner Saronikos Gulf, with an emphasis on the emerging environmental hazards (V and Ag). The results showed extensive pollution of the sediments by Ni, Cr, Cu, Zn, As, Mo, Cd, and Pb from the 1910s and 1960s in Eastern and Western Elefsis Bay, respectively. A significant decrease of the sediment enrichment in V, Ni, Cr, Cu, Zn, As, Cd, Pb, and Ag since 2000 was observed in the part of the Inner Saronikos Gulf that is mainly influenced by the WWTP of Athens. However, a toxicity assessment using the metal contents of the surface sediments showed that most of the trace elements studied still pose a moderate to high risk of toxicity to benthic ecosystems. The present study highlighted the urgent need for focused research and the management of trace element inputs, particularly Ag in the Inner Saronikos Gulf, where severe sediment modification was evident.

Highlights

Sediments have been preferentially used to assess the metal pollution degree of marine environments, since they have the advantage of recording environmental events and provide useful temporal and spatial information [1,2]
The present study focuses on two sub-areas: the Inner Saronikos Gulf and Elefsis
The present study focuses on the northern part of the gulf, which consists the Inner Saronikos Gulf and Elefsis Bay (Figure 1)

Summary

Introduction

Sediments have been preferentially used to assess the metal pollution degree of marine environments, since they have the advantage of recording environmental events and provide useful temporal and spatial information [1,2]. It is well-understood that the speciation/phase distribution of metals in sediments is required to complement the total metal concentrations and assess the potential release of metals into the sediment–water interface, bioavailability, and possible toxicity [3–5]. For this reason, over the last thirty years, many techniques and methods have been introduced to assess the speciation of metals in sediments via sequential metal extractions with reagents that extract the different chemical fractions. The most commonly used procedure is the modified BCR protocol and accompanying Certified Reference Material (IRMM—Institute for Reference Materials and Measurements of the European Commission) [8]

Methods

Results

Discussion

Conclusion