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

Polycyclic aromatic hydrocarbons (PAHs) in marine sediments of the Hellenic coastal zone, eastern Mediterranean: Levels, sources and toxicological significance

Purpose: Polycyclic aromatic hydrocarbons (PAHs) are widespread in sediments, particularly near areas of intense human activities. Due to their mutagenic and carcinogenic behaviour, PAHs are classified as priority contaminants to be monitored in environmental quality control schemes. The purpose of this study was to determine the levels of PAHs in major coastal areas of Greece that receive various pressures, investigate their sources and evaluate their potential toxicity by comparison against effects-based Sediment Quality Guidelines (SQG). Materials and methods: Forty-one sediment samples were collected from four areas of the Hellenic coastline. PAH concentrations were determined by GC-MS, after Soxhlet extraction and fractionation by silica column chromatography. Source apportionment was conducted by isomeric ratio diagnostic criteria. The mean quotient Effects Range-Median (m-ERM) was used to evaluate the potential of adverse effects posed to benthic organisms. Results and discussion: The levels of PAHs were found to vary widely from 100 to more than 26,000 ng g-1. The highest levels were found in the close vicinity of an alumina production plant in the Gulf of Corinth. High levels of PAHs were also found at a few sites in each of the areas studied, close to a nickel production plant (North Evoikos Gulf), at the rainwater and wastewater outfalls of the great urban areas of Athens and Thessaloniki and at the industrialized area of Elefsis Bay (Saronikos Gulf). At the most contaminated sites PAH had a pyrolytic origin. Comparison of PAH levels to the SQG indicated that less than 15% of the sites studied have an intermediate probability (24-49%) of being toxic. Conclusions: In general, discrete point sources were identified as the major contributors of PAH contamination in the Hellenic coastal zone. Therefore, source control measures should be considered for protecting, or restoring, sediment quality, particularly in areas that support a diversity of anthropogenic activities (e. g. fishing, tourism, industry). © 2011 Springer-Verlag

Settled bus dust as a proxy of traffic-related emissions and health implications of exposures to potentially harmful elements

Limited information on potentially harmful elements (PHEs) contents of settled bus dusts and associated health risks for commuters is available in the literature. Here, magnetic measurements were combined with geochemical analysis to provide insight into the origin and occurrence of PHEs (Cr, Cu, Fe, Hg, Ni, Pb, and Zn) in settled bus dust samples from the urban area of Athens, Greece. Microscopic observations showed the abundance of angular and spherical Fe-rich particles, carbonaceous spherules, and a variety of Ba, Cu, Pb, and Zn-containing particles, typically deriving from vehicular emissions. Settled bus dust was magnetically enhanced in relation to the road-verge Athens soil, and exhibited a ten-fold (Hg), eight-fold (Zn, Cu), and four-fold (Pb) enrichment. The oral bioaccessibility of PHEs followed the order Zn > Pb > Cu > Cr > Ni > Fe > Hg. Potential adverse health risk effects through ingestion, inhalation of particles and Hg vapors, and dermal contact were assessed using the U.S. EPA risk assessment model. Potential cancer risk for drivers and children (1–6 years old), commuting four days per week for 120 min per day, were above the regulatory levels of 1 × 10−4. Non-cancer risks may also arise, mainly because of inhalation of Hg vapors. Despite the intrinsic uncertainty related mainly to toxicity data and exposure parameters, the risk assessment helped to prioritize Cr and Hg as the elements of major concern. © 2020 Turkish National Committee for Air Pollution Research and Contro

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

Agricultural geochemistry in viticulture: An example of Cu accumulation and geochemical fractionation in Mediterranean calcareous soils (Nemea region, Greece)

The Nemea region has been devoted to viticulture from historic times, and currently, is one of the most important wine-producing areas in Greece. In this study we report the extent of Cu and other element (As, Cd, Co, Cr, Mn, Ni, Pb, and Zn) enrichment, their geochemical partitioning into the soil components (evaluated by a seven-step sequential extraction procedure) and the plant availability of Cu (defined as the diethylene triamine pentaacetic acid, DTPA –extracted Cu). Major soil properties were also determined. Total Cu contents in the Nemea topsoil were in the range 33.1–291 mg kg−1. Enrichment Factors (EF), calculated against uncultivated soils from the neighboring Argos region, showed that the Nemea topsoil was significantly enriched with Cu (median EF 5.9) and in a limited number of samples moderately enriched (median EFs: 2–5) with P, As, Cd and Mn. On average, 20% of total Cu was readily available for plant uptake. Application of principal component analysis (PCA) showed that natural Cu present in Nemea soil was principally associated with the residual and oxidizable fractions. On the other hand, anthropogenic related Cu was linked to acid soluble and reducible geochemical phases, exhibiting a strong affinity with the plant available Cu. Nickel and Cr were principally found in the residual fraction, supporting their origin from ophiolitic rocks; Manganese and Co were mostly associated with Mn oxides, Cd was found in labile fractions, whereas As, Pb and Zn were bound, more or less, to reducible and oxidizable substrates. Copper and P were the only elements that were found to decline at the 50 cm soil depth. Despite the decline with depth, Cu contents did not reach background levels. We did not find differences in Cu availability and partitioning between the surface and deep soil samples, inferring that Cu migrated to the soil profile by tillage practices. Finally, the comparison of the geochemical composition of vineyard soils with the nearby Argos citrus soils revealed the pronounced enrichment of the citrus soils with P, Zn and Cd due to intensive fertilizer applications. In contrast, the vineyard soils are more susceptible to Cu and As accumulation. © 2017 Elsevier Lt

Environmental availability of trace elements (Pb, Cd, Zn, Cu) in soil from urban, suburban, rural and mining areas of Attica, Hellas

The environmental availability of trace elements (Pb, Cd, Zn, Cu) in soil samples from the urban area of Athens and Piraeus is compared to that from samples of suburban, uncontaminated rural and the nearby historical mining area of Lavrion in Attica. These trace elements had been previously shown to be related to anthropogenic activities in the urban chemical environment of Athens. Trace element environmental availability is determined by using three single stage chemical extractions of (i) nitric acid (HNO3), (ii) ethylenediaminetetraacetic acid (EDTA) and (iii) acetic acid (CH3COOH), and the respective extractabilities are calculated as ratios relative to total element concentrations. All elements showed the same decreasing concentration trend in the order mining > urban > suburban ≈ rural soil categories. Median concentration, based on aqua regia dissolution, are 185, 173, 86, 0.4 mg/kg and 2.26% for Pb, Zn, Cu, Cd and Fe, respectively, for the urban soil samples. Whereas, the corresponding median concentrations of Pb, Zn and Cd in Lavrion soil are over ten times higher. The ratios of the extractable concentrations of Pb, Zn and Cd, relative to the aqua regia extractable content in soil, are also higher for the mining soil category. Extractable concentrations for all the studied elements are highly dependent on their respective aqua regia extractable values in all land use categories; extractability ratios are also controlled by HNO3 extractable Fe in soil. For the two toxic elements, Pb and Cd, the data of this study suggest that environmental availability has to be assessed on a site-specific basis as local conditions, and in particular the mineralogical composition of soil, may influence their relative extractability. © 2017 Elsevier B.V

Surface–ground water interactions and hydrogeochemical evolution in a fluvio-deltaic setting: The case study of the Pinios River delta

River deltas sustain important ecosystems with rich biodiversity and large biomass, as well as human populations via the availability of water and food sources. Anthropogenic activities, such as urbanization, tourism and agriculture, may pose threats to river deltas. The knowledge of the factors controlling the regional water quality regime in these areas is important for planning sustainable use and management of the water resources. Here, hydrochemical methods and multivariate statistical techniques were combined to investigate the shallow aquifer of the Pinios River (Thessaly) deltaic plain with respect to water quality, hydrogeochemical evolution and interactions between groundwater and surface water bodies. Water quality assessment indicated that most of the river and groundwater samples fully comply with the criteria set by the Drinking Water Directive (98/83/EC). The river is recharged mainly from springs of the Tempi valley and the shallow aquifer, and to a lesser degree from precipitation, throughout the year. The hydrogeochemical characteristics indicated a cation (Ca, Mg, and Na) bicarbonate water type, which evolves to calcium-chloride, sodium-bicarbonate and sodium-chloride water type, in the northern part of the delta. Calcite and dolomite dissolution determined the major ion chemistry, but other processes, such as silicate weathering and cation exchange reactions, also contributed. In the northern part of the plain, the interaction with the deeper aquifer enriched the shallow aquifer with Na and Cl ions. Principal Component Analysis showed that five components (PCs) explain 77% of the total variance of water quality parameters; these are: (1) salinity; (2) water-silicate rocks interaction; (3) hardness due to calcite dissolution, and cation exchange processes; (4) nitrogen pollution; and (5) non-N-related artificial fertilizers. This study demonstrated that the variation of water hydrochemistry in the deltaic plain could be attributed to natural and anthropogenic processes. The interpretation of the PCA results dictated the parameters used for the development of a modified Water Quality Index (WQI), to provide a more comprehensive spatial representation of the water quality of the river delta. © 2018 Elsevier B.V

Hydrogeochemical investigation of Cr in the ultramafic rock-related water bodies of Loutraki basin, Northeast Peloponnese, Greece

This research aims to determine the hydrogeochemical characteristics, origin, and geochemical evolution of the Cr enriched alkaline waters in the ultramafic rock-related water bodies of Loutraki basin in Northeast Peloponnese, Greece. The significance of the particular research lies in the fact that Cr occurrence raises concerns with respect to health risks associated with the utilization of such aquifers for drinking water supply. Therefore, the investigation of water–rock interaction processes leading to Cr mobilization in such environments is of great importance. A total of 41 water samples including groundwater from the alluvial and fractured aquifers as well as surface water were collected and analyzed for major and trace elements during the wet and dry seasons of 2015. Solid samples including soils, sediments and rocks were also collected to provide evidence of elemental mobilization due to water–rock interaction, with special focus on Cr. Τhe main Cr-bearing minerals identified were Cr-spinel, ferrichromite, magnetite, clinopyroxene, chlorite and serpentine. The observed dissolution textures within the magnetite rim and across the magnetite–chromite boundary indicate that these latter can be also active sources of Cr(III). Both groundwater and surface waters are of Mg–HCO3 type due to CO2-driven dissolution of serpentine minerals and Mg-carbonates/hydroxides. The formation of hydromagnesite aggregates is attributed to precipitation from Mg2+-rich alkaline waters. The highest Cr(VI) concentrations were measured in the alluvial aquifer (6.7–74.3 μg L−1) and the lowest in the fractured ophiolitic aquifer (1.9–14.3 μg L−1); while in surface water, the maximum measured Cr(VI) concentration was up to 3.9 μg L−1. Finally, the identification of Mn-rich hematite indicates that the oxidation of Cr(III) to Cr(VI) is probably performed by manganese–iron oxides. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature

A DPSIR Approach to Selected Cr(VI) Impacted Groundwater Bodies of Central Greece

The holistic approach of Driver-Pressure-State-Impact-Response (DPSIR) methodology was applied to selected Cr(VI) impacted groundwater bodies of Central Greece. The main driving forces in the study areas are agricultural activities, urban and industrial development as well as tourism. The main pressures induced by the anthropogenic activities are fertilizer use, uncontrolled urban sewage disposal and industrial effluents discharges. Groundwater stress is caused by the qualitative degradation due to Cr(VI), NO3−, Cl− and SO42− contamination. Hexavalent chromium occurrence is attributed to both geogenic and anthropogenic sources. The maximum Cr(VI) concentration (11.7 mg/L) was measured in Oinofyta area. Important impacts are the deterioration of groundwater body chemical status as well as the decline of groundwater use efficiency. Based on the applied DPSIR, a management framework is proposed in order to address the complex environmental issue of Cr(VI) in the study areas. © 2020, Springer Science+Business Media, LLC, part of Springer Nature

Estimating remobilization of potentially toxic elements in soil and road dust of an industrialized urban environment

The mobility of potentially toxic elements (PTEs) is of paramount concern in urban settings, particularly those affected by industrial activities. Here, contaminated soils and road dusts of the medium-size, industrialized city of Volos, Central Greece, were subjected to single-step extractions (0.43 M HNO3 and 0.5 M HCl) and the modified BCR sequential extraction procedure. This approach will allow for a better understanding of the geochemical phase partitioning of PTEs and associated risks in urban environmental matrices. Based on single extraction procedures, Pb and Zn exhibited the highest remobilization potential. Of the non-residual phases, the reducible was the most important for Pb, and the oxidizable for Cu and Zn in both media. On the other hand, mobility of Ni, Cr, and Fe was low, as inferred by their dominance into the residual fraction. Interestingly, we found a significant increase of the residual fraction in the road dust samples compared to soils. Carbonate content and organic matter controlled the extractabilities of PTEs in the soil samples. By contrast, for the road dust, magnetic susceptibility exerted the main control on the geochemical partitioning of PTEs. We suggest that anthropogenic particles emitted by heavy industries reside in the residual fraction of the SEP, raising concerns about the assessment of this fraction in terms of origin of PTEs and potential environmental risks. Conclusively, the application of sequential extraction procedures should be complemented with source identification of PTEs with the aim to better estimate the remobilization of PHEs in soil and road dust influenced by industrial emissions. © 2022, The Author(s), under exclusive licence to Springer Nature Switzerland AG