Proceedings of the 13th International Conference of Environmental Science and Technology Athens, Greece, 5-7 September 2013
SEDIMENTOLOGICAL AND ENVIRONMENTAL INVESTIGATION OF THE SEA BED SEDIMENTS OF THE HERACLION GULF (CRETE) S.E. POULOS*, I.N. KOUKOUNARI*, M. DASSENAKIS**, C.G. DOUNAS*** and V. PARASKEVOPOULOU** * Department of Geography & Climatology, Faculty of Geology & Geoenvironment, University of Athens, Panepistimioupoli, Zografou GR-15784, Athens, Greece. Tel. +30210-7274143/ 7274195, Fax: +30210-7247569, e-mail for correspondence:
[email protected] ,
[email protected] ** Laboratory of Environmental Chemistry, Faculty of Chemistry, University of Athens, Panepistimioupoli, Zografou, GR-15771 Athens, Greece. Tel: +30210-7274269, Fax: + 30210-7274459, e-mail for correspondence:
[email protected],
[email protected] *** Institute of Biology & Genetics, HCMR at Gournes, Pediados P.O. Box 2214, Heraclion, GR-71003, Crete, Greece. Tel.+302810-337814, e-mail for correspondence:
[email protected] ABSTRACT The present study investigates the distribution of trace metals (Fe, Mn, Cr, Zn, Pb, Cu and Al), as indicators of pollution, in the surficial offshore shelf sediments along the northern coast of Heraclion Gulf of Crete. This is an intensely industrialized urban area also hosting significant touristic activity and the Heraklion harbour (the third in size and commercial importance in Greece).The concentrations and the spatial distribution of the trace metals examined are discussed against the existing sedimentological and hydrodynamic characteristics, and the anthropogenic coastal sources of potential pollutants. The results show that the levels of the trace metals are generally not considered to be dangerous to human health and aquatic life, when compared to sediment quality criteria with the exception of localized Cr concentrations. The relatively lower values of trace metal concentrations presented by the currently analyzed data set (Zn, Cu and Pb) compared to those of 1989 indicate an upgrade of the environmental state. This is attributed to both the control of terrestrial sources of pollution and to prevailing nearshore hydrodynamics and offshore shelf-water circulation. Keywords: trace metals, sediment, Cretan shelf, pollution, human health 1.
INTRODUCTION
Heavy metals participate in various biogeochemical mechanisms, have significant mobility and can affect the ecosystems through bio-accumulation and bio-magnification processes (GESAMP/UNESCO, 1994). Metals are present in the marine environment and coastal sediments deriving from natural sources (e.g. lithology) but they are also related to anthropogenic sources such as industrial wastewaters, untreated municipal sewage, urban and agricultural runoff, harbour activities and aquaculture. Several sediment pollution studies have taken place in the region of Mediterranean such as those of Gulf of Corinth (Iatrou et al., 2010), Evoikos Gulf (Dassenakis et al., 2003), Mesolonghi-Aitolikon lagoon complex (Papatheodorou et al., 2002), south west coast of Spain (Morillo et al., 2004), Turkish Black Sea coast (Duman et al., 2006) and Marmara Sea (Balkis and Ҫağatay, 2001).
The present study, investigates the distribution of trace metals (Fe, Zn, Mn, Cu, Cr and Pb, in the surficial shelf sediments collected along the northern coast of Heraklion Prefecture (Crete Island) in June 2010. Trace metal concentrations are investigated in relation to sedimentological characteristics, water circulation pattern and human coastal potential sources of pollution. Moreover, the present results are compared to those published by Poulos et al. (2009), whose sampling took place in September 1989. 2.
THE STUDY AREA
2.1 Physical geography The study area is located in the Heraklion Prefecture of Crete Island, Greece, in the coastline between Cape Panagia to the west and Malia Bay (approximately 40 km distance from east to west) to the east and extends to depths between 10 and 70 m. (Fig. 1). The area belongs to the southern continental margin of central Cretan Sea which is narrow (
