SIMULATION OF A QUAY WALL FOUNDATION ON AN IMPROVED SEABED. THE EXAMPLE OF THE NEW PORT OF PATRAS

Αντικείμενο της παρούσας εργασίας είναι η προσομοίωση της συμπεριφοράς κρηπιδότοιχου θεμελιωμένου σε βελτιωμένο, με χαλικοπασσάλους, εδαφικό πυθμένα με τη χρήση μεθόδων πεπερασμένων στοιχείων. Τα δεδομένα που αξιοποιήθηκαν προέρχονται από το έργο του Νέου Λιμένα Πατρών. Η διερεύνηση της συμπεριφοράς του έργου πραγματοποιήθηκε με την εκτέλεση παραμετρικών αναλύσεων και διαφοροποιώντας το μήκος και την πυκνότητα των χαλικοπασσάλων καθώς επίσης και την κλίση του επιχώματος προφόρτισης. Εξήχθησαν ενδιαφέροντα συμπεράσματα για τον συντελεστή ασφαλείας και τις παραμορφώσεις του έργου. Για την προσομοίωση χρησιμοποιήθηκε το πρόγραμμα πεπερασμένων στοιχείων PLAXIS 2D.The current study examines the possibility of simulating a quay wall foundation on a gravel pile improved seabed by using the finite element method. For this purpose data from the construction of the New Port of Patras were used. The behavior of the construction was simulated by conducting a series of parametric analyses altering the length and the density of the gravel piles as well as the gradient and the volume of the preloading embankment. Important conclusions regarding the safety factor and the deformations rate of the construction were finally extracted. The simulations were conducted by using PLAXIS 2D

Chromium and Nickel distribution in sediments of a coastal area impacted from metallurgical activities: the case of the Larymna Bay

In the present study, the distribution of Cr and Ni was investigated in the surface sediments from the Larymna Bay (Northern Evoikos Gulf) and in metallurgical slag samples discharged in the marine environment. The results were compared to concentrations of Cr and Ni in parent rocks that outcrop extensively in the catchment area of N. Evoikos in order to distinguish natural and anthropogenic sources of these two elements. Elevated concentrations of Cr and Ni as well as high values of magnetic susceptibility were determined in all samples. Low leachability was determined for Cr since chromite is the major crystalline phase of Cr in the samples analyzed whereas higher leachability was observed for Ni

Geochemical processes of trace metals in fresh–saline water interfaces. The cases of Louros and Acheloos estuaries

Fresh–saline water interfaces are sites of major transformations on the speciation and the distribution of trace metals, through complex processes. The present chapter considers trace metal geochemical processes at fresh–saline water interfaces of representative Greek riverine systems, namely of those of the perennial medium-sized Louros River and the big and highly fragmented Acheloos River. Dissolved and particulate metals, as well as metal fractions in the sediments, are considered in combination with physicochemical parameters, and mineral magnetic measurements are used for tracing the origin of particle populations (lithogenic, anthropogenic, authigenic), and their compositional alterations during their passage from the rivers, through the interfaces, to sea. The interfaces of the two systems have distinct characteristics both on a spatial and a temporal scale, thus allowing for a diversity of trace metal behaviour patterns to emerge. In the small, perennial Louros system, trace metals are trapped within the thin, yet stable salt wedge. In the heavily fragmented Acheloos system, variations of the water and sediment discharges have moved the active interface landwards, where due to the reduction of dilution effects by inert, detrital particles, the fingerprint of the authigenic and anthropogenic component of trace metals has become more pronounced. The results of the research carried out in the two distinctive fresh–saline water interface systems are important not only in order to enlighten us about the geochemical processes in nature, but also in order to provide the necessary knowledge to properly manage these systems for the benefit of the environment and the sustainable development of the impacted areas. © 2016, Springer International Publishing AG

Heavy Metals in Soil and Sand from Playgrounds of Çanakkale City (Turkey), and Related Health Risks for Children

Children spend most of their time in playgrounds and, in parallel, constitute the social group most sensitive to contaminants. Here, we present the results of a comparative study of heavymetal contents between soils and sand from sandboxes obtained from playgrounds of Çanakkale city. Average contents of soils followed the order of iron (Fe) (12,901 mg kg−1) > manganese (Mn) (475 mg kg−1) > zinc (Zn) (58 mg kg−1) > copper (Cu) (28 mg kg−1) > nickel (Ni), chromium (Cr) (21 mg kg−1) > lead (Pb) (18 mg kg−1). Sand had lower contents, however, due to the reduction of particles size through prolonged use, and accumulation of Fe/Mn (oxyhydr)oxides on sand grains tended to diminish the differences between soils and sand. Through chemometric analysis, Cr and Ni were found to have a lithogenic origin, while the rest of metals were related to anthropogenic activities. Spatially, heavy-metal contents followed the pattern of the city’s sprawl. Risk estimates on children’s health showed that ingestion was the most important exposure route, followed by dermal contact and inhalation. Exposure of children to sand was of similar importance to that of soils. These findings are significant, as the contamination of sand has not yet received much attention compared to the soil of playgrounds. © 2022 by the authors. Licensee MDPI, Basel, Switzerland

Linking environmental magnetism to geochemical studies and management of trace metals. Examples from fluvial, estuarine and marine systems

Among the diverse research fields and wide range of studies encompassed by environmental magnetism, the present work elaborates on critical aspects of the geochemistry of trace metals that emerged through years of original research in a variety of environmental compartments. This review aims at sharing the insights gained on (a) tracing metal pollution sources; and (b) identifying processes and transport pathways from sources to depositional environments. Case studies on the Elefsis Gulf (Greece) and the Gulf of Lions (France) demonstrate the potential of combined magnetic measurements and chemical analysis to trace pollution signals resulting from land-based sources and atmospheric deposition. Case studies on estuarine environments, namely the Louros, Acheloos, and Asopos Estuaries (Greece), address modes of trace metal behavior under the influence of different hydrological regimes and elucidate in situ processes within the transitional estuarine zone, that define their ultimate fate. As sources, transport pathways, and processes of trace metals are fundamental in environmental management assessments, the involvement of magnetic measurements in the policy cycle could facilitate the development and implementation of appropriate regulatory measures for the integrated management of river basins, coastal, and marine areas. © 2014, by the authors; licensee MDPI, Basel, Switzerland

Assessment of heavy metal contamination and mineral magnetic characterization of the Asopos River sediments (Central Greece)

The content and distribution of heavy metals in sediments of the intermittent and contaminated Asopos River, located in Central Greece, was assessed by means of total dissolution, dilute acid and sequential extraction procedures. Mineral magnetic properties were used as proxy parameters of transport mechanisms of land-derived material to the sea. The combination of enrichment factors estimated against local background levels and the levels of labile metals revealed that surface sediments are enriched in Cu, Cd, Ni and Cr. The low flow of the system allows particles and organic matter to accumulate in the estuarine shallow " pools" where they undertake a series of redox reactions, authigenic formation, etc. The most fine of these particles, which are metal rich, are transported to relatively long distances off the Asopos River mouth, even under low energy conditions, converting the system to a secondary source of pollution for the adjacent marine environment. © 2010 Elsevier Ltd

Insights into the chemical partitioning of trace metals in roadside and off-road agricultural soils along two major highways in Attica's region, Greece

We report in this study the magnetic properties and partitioning patterns of selected trace metals (Pb, Zn, Cu, Cd, Ni) in roadside and off-road (>200 m distance from the road edge) agricultural soils collected along two major highways in Greece. Sequential extractions revealed that the examined trace metals for the entire data set were predominantly found in the residual fraction, averaging 37% for Cd up to 80% for Cu. Due to the strong influence of lithogenic factors, trace metal pseudototal contents of the roadside soils did not differ significantly to those of the off-road soils. Magnetic susceptibility and frequency dependent magnetic susceptibility determinations showed a magnetic enhancement of soils; however, it was primarily related to geogenic factors and not to traffic-derived magnetic particles. These results highlight that in areas characterized by strong geogenic backgrounds, neither pseudototal trace metal contents nor magnetic properties determinations effectively capture traffic-related contamination of topsoils. The vehicular emission signal was traced by the increased acid-soluble and reducible trace metal contents of the roadside soils compared to their off-road counterparts. In the case of Cu and Zn, changes in the partitioning patterns were also observed between the roadside and off-road soils. Environmental risks associated with agricultural lands extending at the margins of the studied highways may arise from the elevated Ni contents (both pseudototal and potentially mobile), and future studies should investigate Ni levels in the edible parts of plants grown on these agricultural soils. © 2016 Elsevier Inc

Can we document if regulation and Best Available Techniques (BAT) have any positive impact on the marine environment? A case based on a steel mill in Greece

In order to document the impact of Best Available Techniques (BAT) and implementation of regulation on the improvement of the coastal marine environment state, we examined the case of a representative steel mill located at the Gulf of Elefsis (Greece). The evaluation of metal pollution was based on the analysis of major and trace elements, organic carbon, magnetic properties, and sediment accumulation rates, in sediment cores obtained from the vicinity of the plant. The analytical data are discussed in relation to steel production, changes of production routes, and adoption of BAT introduced in order to fulfill EU and national legislation. The results show that the input of pollutants to sediments and the degree of contamination were reduced by approximately 40–70% in the decade 2003–2015 in comparison to the periods of high discharges (1963–2002), whereas the toxicity risks from “high-to-extremely high” were reduced to “medium-to-high.”. © 2017, Springer International Publishing AG

Critical processes of trace metals mobility in transitional waters: Implications from the remote, Antinioti Lagoon, Corfu Island, Greece

The Antinioti Lagoon is a karstified, rather pristine, and shallow coastal lagoon located in the northern part of Corfu Island in NW Greece. The present study examines the levels of metals (Al, Fe, Mn, Cd, Cu, Pb, and Zn) in the dissolved and particulate phase, as well as in surface and core sediments, and identifies the critical processes that define their behavior. The major transport pathway of dissolved Mn, Cd, and Pb, and particulate Mn, Cd, and Zn into the lagoon is through freshwater springs, whereas surface runoff dominates the transport of particulate Al, Fe, and Cu. Interestingly, large particles (> 8 μm) contain higher amounts of Al, Fe and Mn than the finer ones (< 8 μm), due to flocculation of oxyhydroxides that, eventually, scavenge other metals, as well. Cadmium and Zn bound to the large particles were found to be less prone to desorption than the smaller ones and were effectively captured within the lagoon. In the sediments, diagenetic processes are responsible for post-depositional changes in the forms of metals (particularly Fe, Mn and Cd). Enrichment factors (EFs) based on local background showed that sediments are enriched in restricted areas in Cd and Pb by maximum factors 4.8 and 10, respectively. These metals were predominantly found in potentially labile forms. Thus, any interventions introducing changes in the physico-chemical conditions may result in the release of metals, with negative implications on the lagoon's ecological quality. © 2019 by the authors

Investigation of major and trace element distribution patterns and pollution status of the surficial sediments of a microtidal inner shelf influenced by a transboundary river. The case of the Alexandroupolis Gulf (northeastern Aegean Sea, Greece)

The present investigation examines the distribution patterns of major and trace elements of surficial sediments of the Alexandroupolis Gulf (NE Aegean shelf) which are influenced by the influxes of the transboundary river Evros. Fifty-three surficial sediment samples were analysed for 25 major and trace elements, together with the CaCO3, TOC and mud content. Factor analysis was conducted in order to reveal the major processes that control their behaviour. Pollution indices (enrichment factor, modified contamination degree) were used to evaluate pollution levels, the most widely used SQGs criteria (i.e. ERL/ERM and TEL/PEL) were used for the association with adverse effects on aquatic organisms whilst a new Index (OEI) was introduced to examine the Overall Environment status.The overall mineralogical and chemical elemental status of the Alexandroupolis Gulf is mainly dominated by the riverine inputs of Evros system, whereas, localised point sources contribute to the pollution status of the study area. According to the pollution indices used element enrichment and associated potential pollution were found to be related mostly to mud-sized sediments (10-30. m depth), whilst increased element concentrations are observed, spatially, close to Evros river mouths, within the harbour, and along the NW coast of the study area. The application of the SQGs on Cr, Cu, Ni, Pb and Zn showed that almost half of the sampling sites may occasionally be associated with toxic effects. However, according to the OEI, only Zn and Pb provide a widespread positive overall enrichment in the study area. © 2014 Elsevier B.V