Abstract
Saronikos Gulf is the marine area in Greece, encountering the most considerable environmental challenges due to heavy metal contamination, caused by urbanization and industrialization, making it the most studied area in the country, on environmental terms over the past 50 years. In the 1rst chapter, research articles focusing on the levels, patterns, and origins of heavy metals in the gulfs’ marine sediments were gathered to review the status of heavy metal pollution, set background values, summarizing the analytical methods used. The geographic information system (GIS) technique was also used to chartography sampling locations per decade of collected data and the ecological status of the area was estimated by the Pollution Loading Index (PLI), the Potential and Ecological Risk Index (PERI) and Human Health Risk Assessment (HHRA) indices analyzing the previously collected data. Systematic review revealed that Saronikos Gulf was mostly studied in specific regions due to point sources ex ...
Saronikos Gulf is the marine area in Greece, encountering the most considerable environmental challenges due to heavy metal contamination, caused by urbanization and industrialization, making it the most studied area in the country, on environmental terms over the past 50 years. In the 1rst chapter, research articles focusing on the levels, patterns, and origins of heavy metals in the gulfs’ marine sediments were gathered to review the status of heavy metal pollution, set background values, summarizing the analytical methods used. The geographic information system (GIS) technique was also used to chartography sampling locations per decade of collected data and the ecological status of the area was estimated by the Pollution Loading Index (PLI), the Potential and Ecological Risk Index (PERI) and Human Health Risk Assessment (HHRA) indices analyzing the previously collected data. Systematic review revealed that Saronikos Gulf was mostly studied in specific regions due to point sources existence. The severe contamination of heavy metals and organic carbon since the early 70s is closely associated with local economic development. Additionally, the re-assessment of the data referenced in the literature permitted their integrative comparisons that would be helpful in the management and sustainable development of the Saronikos gulf (Gkaragkouni et al., 2025 under submission). Additionally, nine (9) sediment cores were retrieved in the most burdened narrow straits of Inner Saronikos Gulf connecting Elefsina bay and the outer Gulf: Psyttalia -Keratsini and Perama – Salamina Straits. In chapter 2 the two study areas are being described (Psyttalia – Keratsini) and (Perama – Salamina) and the employed materials and methods are also presented. Given the fact that the central sewer of Athens had been discharging untreated sewage from 1950 until 1995 in the marine area between the island of Psyttalia and Keratsini, the surficial layer of organic mud that was formed covering the seafloor, was thoroughly investigated. To assess the spatial and temporal distribution of metal contaminants in the area, six sediment cores were collected and analyzed for grain composition, organic carbon content (Corg), and metal concentrations. ICP- MS and AAS were used to determine the following metal concentrations: Cu, Zn, Mo, Ag, Cd, Cr, Pb, Ni, Fe, As, Mn, and Co (Chapter 3). Four different lithofacies were identified based on grain size and macroscopic observations. The contamination of the sediments was assessed according to Enrichment factor (EF), Geo-accumulation Index (Igeo), and Pollution Loading Index (PLI), the latter was used to assess the overall toxicity status of the sediments. Factor analysis was also performed in the heavy metal, Corg, and Ca datasets. R-mode factor analysis indicates at least three different pollution sources in the area, while Q-mode analysis indicates three different groups of sediment samples according to their pollution degree (Gkaragkouni et al., 2021). In chapter 4 the levels and depth distributions of the natural radionuclides 238U, 232Th, 226Ra, 40K and the man-made 137Cs were analyzed by γ-ray spectrometry, while the concentrations of 26 chemical elements were measured by INAA in sediment samples collected from the organic mud layer that covers the Keratsini–Psyttalia strait. The average activity concentration values of 226Ra, 232Th and 40K were lower, whereas that of 238U was comparable to the average Greek and world values. The elemental contamination of the sediments was estimated based on the calculated EF values. The results revealed high EF values of As, Br, Cr, Ni, Sb, Se, Zn ranging from 160 for Br to 10 for Cr, whose main sources are probable related to contaminated sewage outfall from the area of Athens and the Piraeus Port (Papaefthymiou et al., 2017). In Chapter 5 the three marine sediment cores derived in the area between Perama (Attica) and the island of Salamina, were studied in terms of lithology, organic carbon content and heavy metal concentrations, aiming to address potential pollution loads. Statistical analysis, combined with 210Pb sediment dating, was used to investigate pollution sources through time. Ecological risk assessment was based on the Enrichment Factor, Geoaccumulation Index, Pollution Loading Index, mean Effect Range Median quotient and Potential ecological Risk Index indices. Results revealed that the upper 40 cm sediment layer experience contamination in the following metals: Ag, As, Cd, Cu, Ni, Pb, Sn and Zn, deposited during the past 65 years approximately, under high sedimentation rates and from different metal sources. A slight reduction trend of the heavy metal accumulation into the study area is noted for the most recent years (Gkaragkouni et al., 2024). In the last Chapter (six) the summary and synthesis of the present thesis is presented
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