HEAVY METAL DISTRIBUTION IN SEDIMENTS FROM PSITTALIA-KERATSINI STRAIT, SARONIKOS GULF,

A. Gkaragkouni 1, G. Papatheodorou 1*, H. Papaefthymiou 2, D. Christodoulou 1 and M. Geraga 1 1 Laboratory of Marine Geology & Physical Oceanography, Deparment of Geology, University of Patras, Greece - [email protected] 2 Department of Chemistry, University of Patras, Greece

Abstract In Psittalia –Keratsini strait the outfall sewer of discharged untreated sewage for a period of over 40 years. As a result a surface layer of organic mud has been formed covering the seafloor. Copper, Zn, Mo, Ag, Cd, Pb, Cr, As, Ni, Fe and Co are highly enriched in the organic mud layer compared to underlying natural sediments.

Keywords: Sewage pollution, Metals, Sediments, Gulf of Saronikos

Introduction all the examined sediments the surface layer consists of high percentages of Corg North Saronikos gulf receiving sewage from the industrial area of Elefsina and and silt/clay size particles (Table 1). On the contrary, the underlying natural port is a heavily polluted marine environment. In particular, the area sediments are characterized by increased percentages of sandy particles and low between the island of Psittalia and Keratsini, was receiving the urban and a large organic carbon content (Table 1). The mean metal concentrations in the organic part of the industrial waste of the city of Athens through the main sewer mud layer are among the higher reported in marine sediments collected from (MSA) in Keratsini for many decades. In 1994, a biological treatment plant was other harbours, gulfs and coastal areas in Greece and Mediterranean Sea [3, and installed in Psittalia Island [1]. Until then, the sewage through MSA was references within]. Enrichment factors obtained from the results follow the flowing without any treatment, directly to the sea through a diversion channel order: Cu>Zn>Mo>Ag>Cd>Pb>Cr>As>Ni>Fe>Co>Mn. Metal concentrations from the Keratsini outlet works. In 2001 an integrated marine remote sensing are positively correlated with the fine fractions of organic mud and their spatial survey revealed the presence of a surface layer of organic mud covering the distribution presents a clear decreasing trend with increasing distance from the natural seabed [2]. The present paper presents the geochemical data from the sewage outfall. The natural seabed sediments just beneath the organic mud area aiming to the evaluation of the spatial and temporal distribution of metal appear to be affected by the metalliferous organic mud. These elevated metal contaminants in the seabed. The dataset includes the results of analysis of grain concentrations are probably attributed to the effect of fine-grained organic mud composition, organic carbon content (Corg) and metal concentrations from six soaking on the underlying coarse-grained natural sediments. Moreover, the metal sediment cores selected from the area (Fig. 1). concentrations present a general downcore decreasing trend. This probably reflects the gradual growth of urban population and thus the increase of urban and industrial pollution in Athens metropolitan area and accordingly in the seabed of north Saronikos gulf.

Tab. 1. Gravel, sand, silt, clay, organic carbon (%) and metal concentration (ppm) in organic mud and natural sediments in the study area.

Fig. 1. Map showing the sediment cores locations in Psittalia - Keratsini Strait. References 1 - Theodorou A. J. and Perissoratis C.,1991. Environmental considerations for Material and Methods design of the Athens sea outfall, Saronikos Gulf, Greece. Environmental The collected sediment cores were transferred to the laboratory and stored Geology and Water Sciences, 17(3): 233-248. o vertically at 4 C. Prior to analyses, the cores were gently cut longitudinally 2 - Klironomos D., Kotronakis A., Christodoulou D., Gkaragkouni A., using a Plexiglas sheet. The sediment of the uppermost 2 cm of all cores together Papatheodorou G., Ferentinos G., 2004. Marine Geographical Information with sediment samples of about 2 cm in thickness taken along the sediment core, System (G.I.S.). : An environmental implementation in Psittalia- Keratsini were used for the elemental analyses. A quantity of each sediment sample was Strait, Saronikos Gulf, Greece. Seventh Geographical Conference of E.G.E., 1: digested using a mixture of acids (HNO3, HClO4, HF, HCl) (conventional 262-269. method - open system) for elemental total concentration measurements by ICP- 3 - Papaefthymiou H., Papatheodorou G., Christodoulou D., Geraga M., MS [3]. Grain size analysis was carried out by dry and wet (pipette method) Moustakli A., Kapolos J., 2010. Elemental concentrations in sediments of the sieving methods. Patras Harbour, Greece, using INAA, ICP-MS and AAS. Microchemical Journal 96: 269–276. Results and Discussion The organic mud surface layer which is associated with the untreated sewage discharges has a thickness ranging from 0.6 to 2.0m. Macroscopic and granulometric study of the sediment cores showed that the thickness of the organic mud layer decreases with increasing distance from the sewage outfall. In

824 Rapp. Comm. int. Mer Médit., 40, 2013

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