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Prof. Maria Economou-Eliopoulos
Faculty of Geology & Geoenvironment, University of Athens, Panepistimiopolis, 15784 Athens, Greece

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Research Keywords & Expertise

0 Geochemistry of ore deposits and ore-forming processes
0 Mineralization of platinum-group elements (PGE)
0 Bio-mineralization
0 Contamination of soil and water by heavy metals and metalloids
0 Contamination of groundwater by Cr(VI)

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Contamination of soil and water by heavy metals and metalloids
Contamination of groundwater by Cr(VI)

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Short Biography

Prof. Maria Economou-Eliopoulos National and Kapodistrian University of Athens Maria Economou-Eliopoulos, Geologist and Chemist, Professor (1993-2014) of Economic Geology and Geochemistry, director of the Postgraduate program “Applied Environmental Geology” (2000-2014), Professor Emeritus currently. Her scientific interests include geochemistry of ore deposits, from the ore-forming processes to the environmental problems. Post-Doctoral research at the University of Toronto, Imperial College, U.S. Geological Survey (Reston), and Universities of Europe. Author (~ 160) of publications in scientific journals, thematic issues, chapters in books, monographs, Fellow Member of the SEG, evaluator of research proposals, reviewer of scientific papers, has ~ 3000 citations and an h-index of 30. Among her main distinctions are the Awards from the National Academy of Athens for the discovery of a new mineral (Theophrastite), palladium in a porphyry-Cu deposit of Greece, and constraints on the genesis of ore deposits.

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Review
Published: 16 July 2021 in Minerals
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The increasing development of industries, resulting in a large volume of mining, smelting, and combustion wastes, and intense agricultural activities, due to demand for food and energy, have caused environmental hazards for food quality and ecosystems. This is a review on the contamination of the soil–groundwater–crop system and a potential reduction of the contamination by a gradual shift towards green economy within the European Union and on a worldwide scale. Available mineralogical and geochemical features from contaminated Neogene basins have shown a diversity in the contamination sources for soil and groundwater, and highlighted the need to define the contamination sources, hot spots, degree/extent of contamination, and provide ways to restrict the transfer of heavy metals/metalloids into the food chain, without the reduction of the agricultural and industrial production. Among harmful elements for human health and ecosystems, the contamination of groundwater (thousands of μg/L Cr(VI)) by industrial activities in many European countries is of particular attention. Although Cr(VI) can be reduced to Cr(III) and be completely attenuated in nature under appropriate pH and Eh conditions, the contamination by Cr(VI) of coastal groundwater affected by the intrusion of seawater often remains at the hundreds μg/L level. A positive trend between B and Cr(VI) may provide insights on the role of the borate [B(OH)4] ions, a potential buffer, on the stability of Cr(VI) in coastal groundwater. Efforts are needed towards reducing toxic metal(loids) from the industrial wastewaters prior to their discharge into receptors, as well as the transformation of hazardous mining/industrial wastes to new products and applications to the optimization of agricultural management strategies.

ACS Style

Maria Economou-Eliopoulos; Ifigeneia Megremi. Contamination of the Soil–Groundwater–Crop System: Environmental Risk and Opportunities. Minerals 2021, 11, 775 .

AMA Style

Maria Economou-Eliopoulos, Ifigeneia Megremi. Contamination of the Soil–Groundwater–Crop System: Environmental Risk and Opportunities. Minerals. 2021; 11 (7):775.

Chicago/Turabian Style

Maria Economou-Eliopoulos; Ifigeneia Megremi. 2021. "Contamination of the Soil–Groundwater–Crop System: Environmental Risk and Opportunities." Minerals 11, no. 7: 775.

Review
Published: 03 February 2021 in Minerals
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Chromium concentrations in seawater are less than 0.5 μg/L, but the Cr(VI) in contaminated coastal groundwater affected by Cr-bearing rocks/ores and/or human activities, coupled with the intrusion of seawater may reach values of hundreds of μg/L. A potential explanation for the stability of the harmful Cr(VI) in contaminated coastal aquifers is still unexplored. The present study is an overview of new and literature data on the composition of coastal groundwater and seawater, aiming to provide potential relationships between Cr(VI) with major components in seawater and explain the elevated Cr(VI) concentrations. It is known that the oxidation of Cr(III) to Cr(VI) and the subsequent back-reduction of Cr(VI) processes, during the transport of the mobilized Cr(VI) in various aquifers, facilitate the natural attenuation process of Cr(VI). Moreover, the presented positive trend between B and Cr(VI) and negative trend between δ53Cr values and B concentration may suggest that seawater components significantly inhibit the Cr(VI) reduction into Cr(III), and provide insights on the role of the borate, [B(OH)4]− ions, a potential buffer, on the stability of Cr(VI) in coastal groundwater. Therefore, efforts are needed toward the prevention and/or minimization of the contamination by Cr(VI) of in coastal aquifers, which are influenced by the intrusion of seawater and are threatened by changes in sea level, due to climate change. The knowledge of the contamination sources, hotspots and monitoring of water salinization processes (geochemical mapping) for every coastal country may contribute to the optimization of agricultural management strategies.

ACS Style

Ioannis-Porfyrios Eliopoulos; George Eliopoulos; Maria Economou-Eliopoulos. The Cr(VI) Stability in Contaminated Coastal Groundwater: Salinity as a Driving Force. Minerals 2021, 11, 160 .

AMA Style

Ioannis-Porfyrios Eliopoulos, George Eliopoulos, Maria Economou-Eliopoulos. The Cr(VI) Stability in Contaminated Coastal Groundwater: Salinity as a Driving Force. Minerals. 2021; 11 (2):160.

Chicago/Turabian Style

Ioannis-Porfyrios Eliopoulos; George Eliopoulos; Maria Economou-Eliopoulos. 2021. "The Cr(VI) Stability in Contaminated Coastal Groundwater: Salinity as a Driving Force." Minerals 11, no. 2: 160.

Journal article
Published: 08 September 2020 in Minerals
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Selenium (Se) is an essential micronutrient for humans and animals, but both Se excess and deficiency can cause various health risks. Since Greece is among the European countries where people have very low Se-serum, the present study is focused on the Se distribution in cultivated and non-cultivated plants and relative soil coming from the Neogene basins of Greece (Assopos-Thiva and Attica), aiming to define potential Se-source/es and factors controlling Se bio-accumulation and enrichment in food. The dry weight Se values are relatively low (0.1–0.9 mg/kg) with the highest Se contents in garlic, beet and lettuce from the Assopos basin, where the translocation percentage [(mplant/msoil) × 100] for Se, P and S is much higher compared to non-cultivated Attica basin. There is a diversity between the Se source in soil and coastal groundwater which is used for irrigation in the cultivated Assopos–Thiva basin. The soil pH and oxidizing conditions (Eh) are considered the main driving force to make Se available for plant uptake. Potential sources for Se in Greece are Fe-Cu-Zn-sulphide ores and peat deposits in northern Greece, with a Se content ranging from decades to hundreds of mg/kg. Application of the leaching testing protocol is necessary to select the most appropriate proportion of additives to improve the Se deficiencies in agricultural soil.

ACS Style

George D. Eliopoulos; Ioannis-Porfyrios D. Eliopoulos; Myrto Tsioubri; Maria Economou-Eliopoulos. Distribution of Selenium in the Soil–Plant–Groundwater System: Factors Controlling Its Bio-Accumulation. Minerals 2020, 10, 795 .

AMA Style

George D. Eliopoulos, Ioannis-Porfyrios D. Eliopoulos, Myrto Tsioubri, Maria Economou-Eliopoulos. Distribution of Selenium in the Soil–Plant–Groundwater System: Factors Controlling Its Bio-Accumulation. Minerals. 2020; 10 (9):795.

Chicago/Turabian Style

George D. Eliopoulos; Ioannis-Porfyrios D. Eliopoulos; Myrto Tsioubri; Maria Economou-Eliopoulos. 2020. "Distribution of Selenium in the Soil–Plant–Groundwater System: Factors Controlling Its Bio-Accumulation." Minerals 10, no. 9: 795.

Journal article
Published: 06 September 2020 in Geoscience Frontiers
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Extremely abundant PGE-minerals (PGM) hosted in chromitites from the Veria ophiolite complex in Macedonia (N. Greece) may be unique among ophiolite complexes. This study focuses on differences between the low- and high-PGE chromitites. New textural, mineralogical and geochemical constraints from those ores are presented, aiming to define factors controlling the PGE enrichment in a supra subduction environment, in the light of post-magmatic processes. The whole ore analyses for mmajor and trace elements indicated an unusually high-IPGE content (up to 25 ppm) and higher Fe, Ca, Mn, Zn and V contents in high-PGE compared to low-PGE in massive chromitites. The wide compositional variation of chromite, even in the same polished section, the occurrence of very fine PGM (less than 20 μm) as inclusions within chromite and extremely large (>1000 μm), angular or fine-grained PGM aggregates ones within a matrix of highly fragmented chromite - Cr-garnet matrix, may indicate crystallization/recrystallization of chromite from more than one precursor phases. Laurite (RuS2) is very limited, occurring as remnants surrounding by Ru–Os–Ir oxides/hydroxides, of a wide compositional variation. Irarsite occurs as euhedral crystals up to 200 μm, surrounding by chromite, as anhedral exsolutions 1–200 μm within laurite, or creating segregates with platarsite and relics of (Ru, Pt, Rh, Os) sulfarsenides. Platinum–Ru–Rh–Pd-minerals occur commonly as relatively fine-grained assemblages, up to 50 μm, along with irarsite and other relics of (Ru, Pt, Rh, Os) sulfarsenides. Pt-alloys show a variation ranging from tetraferroplatinum to Pt–Ir–Fe–Ni alloys. The presence of laurite relics in large IPGM, awaruite, heazlewoodite, and carbon-bearing material reflecting a super-reducing environment, and the transformation of primary PGM into Os–Ir–Ru-alloys and oxides/hydroxides in association with Fe-chromite and Fe3+-bearing garnet (andradite-uvarovite solid-solution series) may reflect changes of the redox conditions from reducing to oxidizing. The relatively high Na content in hydrous mineral inclusions within high-PGE chromitites suggest a hydrous mantle source and provide the possibility for estimation of the P (average 3.0 kbar) and T (average 874 oC), indicating formation at a shallow mantle environment.

ACS Style

George Tsoupas; Maria Economou-Eliopoulos. Transformation of PGM in supra subduction zones: Geochemical and mineralogical constraints from the Veria (Greece) podiform chromitites. Geoscience Frontiers 2020, 12, 827 -842.

AMA Style

George Tsoupas, Maria Economou-Eliopoulos. Transformation of PGM in supra subduction zones: Geochemical and mineralogical constraints from the Veria (Greece) podiform chromitites. Geoscience Frontiers. 2020; 12 (2):827-842.

Chicago/Turabian Style

George Tsoupas; Maria Economou-Eliopoulos. 2020. "Transformation of PGM in supra subduction zones: Geochemical and mineralogical constraints from the Veria (Greece) podiform chromitites." Geoscience Frontiers 12, no. 2: 827-842.

Journal article
Published: 28 May 2020 in Minerals
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This Special Issue “Innovative and Applied Research on Platinum-group and Rare Earth Elements” is dedicated to the work and memory of Demetrios Eliopoulos, IGME (Institute of Geology and Mineral Exploration), Greece who passed away on 19 April 2019

ACS Style

Maria Economou-Eliopoulos; Federica Zaccarini; Giorgio Garuti. Editorial for the Special Issue “Innovative and Applied Research on Platinum-Group and Rare Earth Elements”. Minerals 2020, 10, 1 .

AMA Style

Maria Economou-Eliopoulos, Federica Zaccarini, Giorgio Garuti. Editorial for the Special Issue “Innovative and Applied Research on Platinum-Group and Rare Earth Elements”. Minerals. 2020; 10 (6):1.

Chicago/Turabian Style

Maria Economou-Eliopoulos; Federica Zaccarini; Giorgio Garuti. 2020. "Editorial for the Special Issue “Innovative and Applied Research on Platinum-Group and Rare Earth Elements”." Minerals 10, no. 6: 1.

Journal article
Published: 18 May 2020 in Minerals
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Sulphide ores hosted in deeper parts of ophiolite complexes may be related to either primary magmatic processes or links to hydrothermal alteration and metal remobilization into hydrothermal systems. The Pindos ophiolite complex was selected for the present study because it hosts both Cyprus-type sulphides (Kondro Hill) and Fe–Cu–Co–Zn sulphides associated with magnetite (Perivoli-Tsoumes) within gabbro, close to its tectonic contact with serpentinized harzburgite, and thus offers the opportunity to delineate constraints controlling their origin. Massive Cyprus-type sulphides characterized by relatively high Zn, Se, Au, Mo, Hg, and Sb content are composed of pyrite, chalcopyrite, bornite, and in lesser amounts covellite, siegenite, sphalerite, selenide-clausthalite, telluride-melonite, and occasionally tennantite–tetrahedrite. Massive Fe–Cu–Co–Zn-type sulphides associated with magnetite occur in a matrix of calcite and an unknown (Fe,Mg) silicate, resembling Mg–hisingerite within a deformed/metamorphosed ophiolite zone. The texture and mineralogical characteristics of this sulphide-magnetite ore suggest formation during a multistage evolution of the ophiolite complex. Sulphides (pyrrhotite, chalcopyrite, bornite, and sphalerite) associated with magnetite, at deeper parts of the Pindos (Tsoumes), exhibit relatively high Cu/(Cu + Ni) and Pt/(Pt + Pd), and low Ni/Co ratios, suggesting either no magmatic origin or a complete transformation of a preexisting magmatic assemblages. Differences recorded in the geochemical characteristics, such as higher Zn, Se, Mo, Au, Ag, Hg, and Sb and lower Ni contents in the Pindos compared to the Othrys sulphides, may reflect inheritance of a primary magmatic signature.

ACS Style

Demetrios G. Eliopoulos; Maria Economou-Eliopoulos; George Economou; Vassilis Skounakis. Mineralogical and Geochemical Constraints on the Origin of Mafic–Ultramafic-Hosted Sulphides: The Pindos Ophiolite Complex. Minerals 2020, 10, 454 .

AMA Style

Demetrios G. Eliopoulos, Maria Economou-Eliopoulos, George Economou, Vassilis Skounakis. Mineralogical and Geochemical Constraints on the Origin of Mafic–Ultramafic-Hosted Sulphides: The Pindos Ophiolite Complex. Minerals. 2020; 10 (5):454.

Chicago/Turabian Style

Demetrios G. Eliopoulos; Maria Economou-Eliopoulos; George Economou; Vassilis Skounakis. 2020. "Mineralogical and Geochemical Constraints on the Origin of Mafic–Ultramafic-Hosted Sulphides: The Pindos Ophiolite Complex." Minerals 10, no. 5: 454.

Journal article
Published: 09 May 2020 in Plants
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Selenium deficiency in humans and animals can be reduced through dietary supplementation. Therefore, Se biofortification strategy is important in food plants and pastures. In this study, the effects of selenium (Se) addition (4 mg Se/kg) as sodium selenate (Na2SeO4) on lettuce (Lactuca Sativa L.) and berseem cultivation (Trifolium alexandrinum L.) were investigated. The experiment was conducted under greenhouse conditions with two different soil types, an acidic (pH = 6.3) and an alkaline (pH = 8.0) soil with different organic matter content, in a completely randomized design. The results indicated higher Se content in berseem cultivated on acidic soil. It was also observed a significant reduction (~ 45%) in plant biomass of lettuce in the acidic soil combined with Se application. The results showed that leaf Se content was negatively correlated with soil organic matter. The decreased Se content in plants cultivated on the alkaline soil with high organic matter content support that the effect of pH on Se uptake decreased as the soil organic matter content increased.

ACS Style

Myrto Tsioubri; Dionisios Gasparatos; Maria Economou-Eliopoulos. Selenium Uptake by Lettuce (Lactuca sativa L.) and Berseem (Trifolium alexandrinum L.) as Affected by the Application of Sodium Selenate, Soil Acidity and Organic Matter Content. Plants 2020, 9, 605 .

AMA Style

Myrto Tsioubri, Dionisios Gasparatos, Maria Economou-Eliopoulos. Selenium Uptake by Lettuce (Lactuca sativa L.) and Berseem (Trifolium alexandrinum L.) as Affected by the Application of Sodium Selenate, Soil Acidity and Organic Matter Content. Plants. 2020; 9 (5):605.

Chicago/Turabian Style

Myrto Tsioubri; Dionisios Gasparatos; Maria Economou-Eliopoulos. 2020. "Selenium Uptake by Lettuce (Lactuca sativa L.) and Berseem (Trifolium alexandrinum L.) as Affected by the Application of Sodium Selenate, Soil Acidity and Organic Matter Content." Plants 9, no. 5: 605.

Journal article
Published: 21 December 2019 in Minerals
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The application of Cr isotope compositions to the investigation of magmatic and post-magmatic effects on chromitites is unexplored. This study presents and compiles the first Cr stable isotope data (δ53Cr values) with major and trace element, contents from the Balkan Peninsula, aiming to provide an overview of the compositional variations of δ53Cr values in ophiolite-hosted chromitites and to delineate geochemical constraints controlling the composition of chromitites. The studied chromitites exhibit δ53Cr values ranging from −0.184‰ to +0.159‰, falling in the range of so-called “igneous Earth” or “Earth’s mantle inventory” with values −0.12 ± 0.11‰ to 0.079 ± 0.129‰ (2sd). A characteristic feature is the slightly positively fractionated δ53Cr values of all chromitite samples from Othrys (+0.043 ± 0.03‰), and the occurrence of a wide range of δ53Cr values spanning from positively, slightly negatively to the most negatively fractionated signatures (Pindos, δ53Cr = −0.147 to +0.009‰; Skyros, δ53Cr = −0.078 to +0.159‰). The observed negative trend between δ53Cr values and Cr/(Cr + Al) ratios may reflect a decrease in the δ53Cr values of chromitites with increasing partial melting degree. Alternatively, it may point to processes related to magmatic differentiation, as can be seen in our data from Mikrokleisoura (Vourinos).

ACS Style

Maria Economou-Eliopoulos; Robert Frei; Ioannis Mitsis. Factors Controlling the Chromium Isotope Compositions in Podiform Chromitites. Minerals 2019, 10, 10 .

AMA Style

Maria Economou-Eliopoulos, Robert Frei, Ioannis Mitsis. Factors Controlling the Chromium Isotope Compositions in Podiform Chromitites. Minerals. 2019; 10 (1):10.

Chicago/Turabian Style

Maria Economou-Eliopoulos; Robert Frei; Ioannis Mitsis. 2019. "Factors Controlling the Chromium Isotope Compositions in Podiform Chromitites." Minerals 10, no. 1: 10.

Journal article
Published: 06 December 2019 in Minerals
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Magnetite is a widespread mineral, as disseminated or massive ore. Representative magnetite samples separated from various geotectonic settings and rock-types, such as calc-alkaline and ophiolitic rocks, porphyry-Cu deposit, skarn-type, ultramafic lavas, black coastal sands, and metamorphosed Fe–Ni-laterites deposits, were investigated using SEM/EDS and ICP-MS analysis. The aim of this study was to establish potential relationships between composition, physico/chemical conditions, magnetite origin, and exploration for ore deposits. Trace elements, hosted either in the magnetite structure or as inclusions and co-existing mineral, revealed differences between magnetite separates of magmatic and hydrothermal origin, and hydrothermal magnetite separates associated with calc-alkaline rocks and ophiolites. First data on magnetite separates from coastal sands of Kos Island indicate elevated rare earth elements (REEs), Ti, and V contents, linked probably back to an andesitic volcanic source, while magnetite separated from metamorphosed small Fe–Ni-laterites occurrences is REE-depleted compared to large laterite deposits. Although porphyry-Cu deposits have a common origin in a supra-subduction environment, platinum-group elements (PGEs) have not been found in many porphyry-Cu deposits. The trace element content and the presence of abundant magnetite separates provide valuable evidence for discrimination between porphyry-Cu–Au–Pd–Pt and those lacking precious metals. Thus, despite the potential re-distribution of trace elements, including REE and PGE in magnetite-bearing deposits, they may provide valuable evidence for their origin and exploration.

ACS Style

Demetrios G. Eliopoulos; Maria Economou-Eliopoulos. Trace Element Distribution in Magnetite Separates of Varying Origin: Genetic and Exploration Significance. Minerals 2019, 9, 759 .

AMA Style

Demetrios G. Eliopoulos, Maria Economou-Eliopoulos. Trace Element Distribution in Magnetite Separates of Varying Origin: Genetic and Exploration Significance. Minerals. 2019; 9 (12):759.

Chicago/Turabian Style

Demetrios G. Eliopoulos; Maria Economou-Eliopoulos. 2019. "Trace Element Distribution in Magnetite Separates of Varying Origin: Genetic and Exploration Significance." Minerals 9, no. 12: 759.

Journal article
Published: 03 March 2019 in Minerals
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The role of post-magmatic processes in the composition of chromitites hosted in ophiolite complexes, the origin of super-reduced phases, and factors controlling the carbon recycling in a supra-subduction zone environment are still unclear. The present contribution compiles the first scanning electron microscope/energy-dispersive (SEM/EDS) data on graphite-like amorphous carbon, with geochemical and mineral chemistry data, from chromitites of the Skyros, Othrys, Pindos, and Veria ophiolites (Greece). The aim of this study was the delineation of potential relationships between the modified composition of chromite and the role of redox conditions, during the long-term evolution of chromitites in a supra-subduction zone environment. Chromitites are characterized by a strong brittle (cataclastic) texture and the presence of phases indicative of super-reducing phases, such as Fe–Ni–Cr-alloys, awaruite (Ni3Fe), and heazlewoodite (Ni3S2). Carbon-bearing assemblages are better revealed on Au-coated unpolished sections. Graphite occurs in association with hydrous silicates (chlorite, serpentine) and Fe2+-chromite, as inclusions in chromite, filling cracks within chromite, or as nodule-like graphite aggregates. X-ray spectra of graphite–silicate aggregates showed the presence of C, Si, Mg, Al, O in variable proportions, and occasionally K and Ca. The extremely low fO2 during serpentinization facilitated the occurrence of methane in microfractures of chromitites, the precipitation of super-reducing phases (metal alloys, awaruite, heazlewoodite), and graphite. In addition, although the origin of Fe–Cu–Ni-sulfides in ultramafic parts of ophiolite complexes is still unclear, in the case of the Othrys chromitites, potential reduction-induced sulfide and/or carbon saturation may drive formation of sulfide ores and graphite-bearing chromitites. The presented data on chromitites covering a wide range in platinum-group element (PGE) content, from less than 100 ppb in the Othrys to 25 ppm ΣPGE in the Veria ores, showed similarity in the abundance of graphite-like carbon. The lack of any relationship between graphite (and probably methane) and the PGE content may be related to the occurrence of the (Ru–Os–Ir) minerals in chromitites, which occur mostly as oxides/hydroxides, and to lesser amounts of laurite, with pure Ru instead activating the stable CO2 molecule and reducing it to methane (experimental data from literature).

ACS Style

Maria Economou-Eliopoulos; George Tsoupas; Vasilis Skounakis. Occurrence of Graphite-Like Carbon in Podiform Chromitites of Greece and Its Genetic Significance. Minerals 2019, 9, 152 .

AMA Style

Maria Economou-Eliopoulos, George Tsoupas, Vasilis Skounakis. Occurrence of Graphite-Like Carbon in Podiform Chromitites of Greece and Its Genetic Significance. Minerals. 2019; 9 (3):152.

Chicago/Turabian Style

Maria Economou-Eliopoulos; George Tsoupas; Vasilis Skounakis. 2019. "Occurrence of Graphite-Like Carbon in Podiform Chromitites of Greece and Its Genetic Significance." Minerals 9, no. 3: 152.

Journal article
Published: 11 July 2018 in Chemosphere
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Toxic chromium [(Cr(VI)] in food chain has created an alarming situation for human life and ecosystems. The present study through a greenhouse pot experiment aims to (a) investigate the ability of organic matter in reducing Cr uptake by lettuce (Lactuca sativa L.) from a sandy loam soil irrigating with Cr(VI)-water, (b) to provide a way for the restriction of Cr transfer from contaminated soils and irrigation water to plants/crops and (c) to contribute to the better management of soil (land) and water use, without reduction of the agricultural production. Since soil and groundwater contamination by Cr is a potential risk in a worldwide scale, due to industrial activities and/or natural processes, organic carbon may play a key role in the mobility of added Cr(VI) to soil via irrigation water, in a significant way. The cultivation of lettuce, using organic matter in the form of leonardite (10 and 30 wt%) and Cr(VI)-irrigation water (100, 200 and 300 mgL−1), showed that the uptake of Cr in both shoots and roots increased with increasing concentration of Cr in the irrigation water. The highest Cr values in shoots (average = 10 mg/kg) and in roots (average = 28 mg/kg) were recorded in those plants cultivated in soil after the addition of Cr(VI)- water without organic matter, whereas the lowest Cr values in shoots (average = 0.44 mg/kg) and in roots (average = 0.7 mg/kg) were recorded in those plants cultivated in soil with addition of 30 wt% organic matter. The used leonardite as organic matter that is an oxidized form of lignite, due to its high content of humic acid is considered to be a useful organic fertilizer that provides possibilities for combining food production with soil protection. Therefore, the application of the natural organic material leonardite, as a land management technique, seems to be a cost-effective method consistent to related protocols for the protection of the soil quality.

ACS Style

Stavros Raptis; Dionisios Gasparatos; Maria Economou-Eliopoulos; Anastasios Petridis. Chromium uptake by lettuce as affected by the application of organic matter and Cr(VI)-irrigation water: Implications to the land use and water management. Chemosphere 2018, 210, 597 -606.

AMA Style

Stavros Raptis, Dionisios Gasparatos, Maria Economou-Eliopoulos, Anastasios Petridis. Chromium uptake by lettuce as affected by the application of organic matter and Cr(VI)-irrigation water: Implications to the land use and water management. Chemosphere. 2018; 210 ():597-606.

Chicago/Turabian Style

Stavros Raptis; Dionisios Gasparatos; Maria Economou-Eliopoulos; Anastasios Petridis. 2018. "Chromium uptake by lettuce as affected by the application of organic matter and Cr(VI)-irrigation water: Implications to the land use and water management." Chemosphere 210, no. : 597-606.

Journal article
Published: 08 March 2018 in Minerals
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The primary mineralization in the famous Lavrion mine in the Lavreotiki area, Attica (Greece), associated with a granodiorite intrusion of Upper Miocene age and composed of massive sulphide Pb-Zn-Ag ores [sphalerite, pyrite and galena (B.P.G)], has been extensively studied. The present study is focused on thin, hard, dark brown to black Fe-Mn crusts (a few mm to cm in thickness) in the Legrena valley, SW Lavreotiki, aiming to provide new insights on that type of Fe-Mn-mineralization. The scanning electron microscope (SEM)/energy dispersive spectroscopy (EDS) data presented revealed the presence of fine rounded fragments, resembling nodules (up to 200 μm) and fossilized bacteriomorphic Fe-Mn-oxides/hydroxides, within brecciated and foliated zones of carbonate rocks. They exhibit unusual features when compared to the common massive Fe-Mn mineralization with regards the following: (a) the extensive occurrence of bacteriomorphic Fe-oxides/hydroxides and their micro-textures; and (b) the minor elements (K, Na, P, S, Ca, As and Cl). The occurrence of abundant bacteriomophic Fe-Mn-oxides/hydroxides in the samples from the Legrena valley may reflect their catalytic role in the redox reactions during ore-forming processes. The characteristic features of that type of Fe-Mn mineralization seems to be the result of multistage supergene processes superimposed over initial hydrothermal stages. Such a multistage remobilization and precipitation of metals along open space surfaces on karstified carbonates during a subsequent stage of their initial precipitation may be widespread in the Attica region, Greece.

ACS Style

Charalampos Vasilatos; Maria Economou-Eliopoulos. Fossilized Bacteria in Fe-Mn-Mineralization: Evidence from the Legrena Valley, W. Lavrion Mine (Greece). Minerals 2018, 8, 107 .

AMA Style

Charalampos Vasilatos, Maria Economou-Eliopoulos. Fossilized Bacteria in Fe-Mn-Mineralization: Evidence from the Legrena Valley, W. Lavrion Mine (Greece). Minerals. 2018; 8 (3):107.

Chicago/Turabian Style

Charalampos Vasilatos; Maria Economou-Eliopoulos. 2018. "Fossilized Bacteria in Fe-Mn-Mineralization: Evidence from the Legrena Valley, W. Lavrion Mine (Greece)." Minerals 8, no. 3: 107.

Journal article
Published: 21 March 2017 in Minerals
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A detailed geochemical study and a thorough mineralogical description of the rare-earth elements (REE)-minerals and associated minerals were carried out in two vertical profiles of approximately 4 m length, from the Nissi (Patitira) bauxite laterite deposit, Lokris, Greece, characterized by the presence of goethite in small sizes resembling bacterial cell coated by goethite and a significant REE enrichment. The enrichment of the REE concentrated in bastnaesite-group minerals, the intergrowths between REE-minerals and Al–Ni–silicates with significant sulfur contents and their association with goethite microtextures interpreted as bacteriomorphic, indicate REE remobilization along with iron bio-leaching and re-precipitation on karstified limestone. In addition to the previous-reported hydroxylbastnaesites, a (La,Nd,Y)(CO3)F member of the bastnaesite-group associated with Al–Ni–silicates were identified, the stability of which may reflect the dependence on the source rocks and the local variations of pH-Eh. Interaction between downward percolating water and carbonate rocks seems to be a very effective mechanism for REE fluorocarbonates deposition under alkaline and reducing conditions.

ACS Style

Sofia Kalatha; Maria Perraki; Maria Economou-Eliopoulos; Ioannis Mitsis. On the Origin of Bastnaesite-(La,Nd,Y) in the Nissi (Patitira) Bauxite Laterite Deposit, Lokris, Greece. Minerals 2017, 7, 45 .

AMA Style

Sofia Kalatha, Maria Perraki, Maria Economou-Eliopoulos, Ioannis Mitsis. On the Origin of Bastnaesite-(La,Nd,Y) in the Nissi (Patitira) Bauxite Laterite Deposit, Lokris, Greece. Minerals. 2017; 7 (3):45.

Chicago/Turabian Style

Sofia Kalatha; Maria Perraki; Maria Economou-Eliopoulos; Ioannis Mitsis. 2017. "On the Origin of Bastnaesite-(La,Nd,Y) in the Nissi (Patitira) Bauxite Laterite Deposit, Lokris, Greece." Minerals 7, no. 3: 45.

Journal article
Published: 06 January 2016 in Geosciences
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Thermodynamic data for platinum group (Os, Ir, Ru, Rh, Pd and Pt) minerals are very limited. The present study is focused on the calculation of the Gibbs free energy of formation (ΔfG°) for selected PGM occurring in layered intrusions and ophiolite complexes worldwide, applying available experimental data on their constituent elements at their standard state (ΔG = G(species) − ΔG(elements)), using the computer program HSC Chemistry software 6.0. The evaluation of the accuracy of the calculation method was made by the calculation of (ΔGf) of rhodium sulfide phases. The calculated values were found to be ingood agreement with those measured in the binary system (Rh + S) as a function of temperature by previous authors (Jacob and Gupta (2014). The calculated Gibbs free energy (ΔfG°) followed the order RuS2 < (Ir,Os)S2 < (Pt, Pd)S < (Pd, Pt)Te2, increasing from compatible to incompatible noble metals and from sulfides to tellurides.

ACS Style

Spiros Olivotos; Maria Economou-Eliopoulos. Gibbs Free Energy of Formation for Selected Platinum Group Minerals (PGM). Geosciences 2016, 6, 2 .

AMA Style

Spiros Olivotos, Maria Economou-Eliopoulos. Gibbs Free Energy of Formation for Selected Platinum Group Minerals (PGM). Geosciences. 2016; 6 (1):2.

Chicago/Turabian Style

Spiros Olivotos; Maria Economou-Eliopoulos. 2016. "Gibbs Free Energy of Formation for Selected Platinum Group Minerals (PGM)." Geosciences 6, no. 1: 2.

Journal article
Published: 12 March 2014 in Geosciences
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Porphyry Cu–Au–Pd±Pt deposits are significant Au resources, but their Pd and Pt potential is still unknown. Elevated Pd, Pt (hundreds of ppb) and Au contents are associated with typical stockwork magnetite-bornite-chalcopyrite assemblages, at the central parts of certain porphyry deposits. Unexpected high grade Cu–(Pd+Pt) (up to 6 ppm) mineralization with high Pd/Pt ratios at the Elatsite porphyry deposit, which is found in a spatial association with the Chelopech epithermal deposit (Bulgaria) and the Skouries porphyry deposit, may have formed during late stages of an evolved hydrothermal system. Estimated Pd, Pt and Au potential for porphyry deposits is consistent with literature model calculations demonstrating the capacity of aqueous vapor and brine to scavenge sufficient quantities of Pt and Pd, and could contribute to the global platinum-group element (PGE) production. Critical requirements controlling potential of porphyry deposits may be from the metals contained in magma (metasomatized asthenospheric mantle wedge as indicated by significant Cr, Co, Ni and Re contents). The Cr content may be an indicator for the mantle input.

ACS Style

Demetrios G. Eliopoulos; Maria Economou-Eliopoulos; Maria Zelyaskova-Panayiotova. Critical Factors Controlling Pd and Pt Potential in Porphyry Cu–Au Deposits: Evidence from the Balkan Peninsula. Geosciences 2014, 4, 31 -49.

AMA Style

Demetrios G. Eliopoulos, Maria Economou-Eliopoulos, Maria Zelyaskova-Panayiotova. Critical Factors Controlling Pd and Pt Potential in Porphyry Cu–Au Deposits: Evidence from the Balkan Peninsula. Geosciences. 2014; 4 (1):31-49.

Chicago/Turabian Style

Demetrios G. Eliopoulos; Maria Economou-Eliopoulos; Maria Zelyaskova-Panayiotova. 2014. "Critical Factors Controlling Pd and Pt Potential in Porphyry Cu–Au Deposits: Evidence from the Balkan Peninsula." Geosciences 4, no. 1: 31-49.

Journal article
Published: 09 April 2013 in Geosciences
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The investigation of the contamination in soil, plants and groundwater revealed a spatial evolution, with an increasing trend in the Cr, Fe, Ni, Mn and Co contents in soils from the Assopos to Thiva basin, followed by C. Evia and Ni-laterite deposits, suggesting that the latter and their parent ophiolites are a potential source for these metals. In contrast, the contamination in groundwater by Cr(VI), ranging from 2 to 360 μg/L Cr, and a varying degree of salinization is probably due to both human activities and natural processes. A diverse source for the contamination of soil and groundwater in the Assopos-Thiva basins is consistent with the increasing trend of the Mg/Si ratio and Cr(VI) concentration in water. The use of deep karst-type aquifer instead of the shallow-Neogene one may provide a solution to the crucial environmental problem. The selective extraction by EDTA and alkaline solution showed that Cr and Fe are less available than Mn. The Cr contents in plants range from <1 to tens of mg/kg, due probably to the high resistance of chromite. However, the average Crtotal contents in plants/crops are higher than normal or sufficient values, whilst Crtotal accumulation [(% metals in plants × 100)/metal in soil] and Cr(VI) accumulation are relatively low. There is a very good positive correlation between accumulation factors for Cr and Fe (R2 = 0.92), suggesting a similarity concerning their uptake.

ACS Style

Maria Economou-Eliopoulos; Ifigeneia Megremi; Cathy Atsarou; Christina Theodoratou; Charalambos Vasilatos. Spatial Evolution of the Chromium Contamination in Soils from the Assopos to Thiva Basin and C. Evia (Greece) and Potential Source(s): Anthropogenic versus Natural Processes. Geosciences 2013, 3, 140 -158.

AMA Style

Maria Economou-Eliopoulos, Ifigeneia Megremi, Cathy Atsarou, Christina Theodoratou, Charalambos Vasilatos. Spatial Evolution of the Chromium Contamination in Soils from the Assopos to Thiva Basin and C. Evia (Greece) and Potential Source(s): Anthropogenic versus Natural Processes. Geosciences. 2013; 3 (2):140-158.

Chicago/Turabian Style

Maria Economou-Eliopoulos; Ifigeneia Megremi; Cathy Atsarou; Christina Theodoratou; Charalambos Vasilatos. 2013. "Spatial Evolution of the Chromium Contamination in Soils from the Assopos to Thiva Basin and C. Evia (Greece) and Potential Source(s): Anthropogenic versus Natural Processes." Geosciences 3, no. 2: 140-158.

Journal article
Published: 31 January 2008 in Ore Geology Reviews
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More than 100 small, isolated chromite occurrences form elongated lenses that follow the NW–SE trend of the host serpentinized dunite within a 60 km2 area 15 km SE of Veria, northern Greece. They occur only within mylonite shear zones, characterized by a strong overprint of late brittle deformation. Detailed investigation of chromitites by scanning electron microscope with energy-dispersive X-ray analysis shows that chromite is dominantly of high-Cr composition, with the atomic Cr/(Cr + Al) ratio ranging from 0.55 to 0.84, and an average value of 0.7. Interstitial primary silicates in chromitites have been replaced by secondary phases consisting of mostly Cr-andradite, Cr-chlorite and serpentine flakes in lesser amounts. The most salient feature is the high total platinum-group element (PGE) content (up to 25 ppm), coupled with the presence of extremely abundant solitary platinum-group element minerals (PGM) within massive chromite samples located along a shear zone. These PGM fragments are angular, rarely corroded grains or fine-grained aggregates and occur in a matrix of Cr-garnet. They are mostly Os–Ru–Ir–Fe alloys containing small amounts of Cr, Co ± Mn, followed by irarsite. Laurite (RuS2) with variable Os and Ir contents occurs as remnants surrounding by Ru–Os–Ir oxides of varying composition. Available geological, mineralogical and geochemical data indicate a prolonged multistage evolution (at least four stages) for the PGE mineralization. The relatively high IPGE enrichment in chromitites seems to be related to post-magmatic processes encompassing a long period of deformation episodes, beginning with plastic deformation in the asthenospheric mantle and culminating with brittle deformation in the crust. Metasomatic fluids have, during a process of rodingitization and serpentinization at a low state of sulfidation, substantially modified the composition of primary laurite towards Fe-, Cr-, Co-, and Mn-bearing Fe–Os–Ir–Ru alloys and oxides. The most prospective locations for chromitite–PGM targets seem to exclusively be small chromite occurrences that are found along shear zones within ophiolite complexes. These shear zones post-date the initial magmatic deposition of the host chromitites.

ACS Style

G. Tsoupas; M. Economou-Eliopoulos. High PGE contents and extremely abundant PGE-minerals hosted in chromitites from the Veria ophiolite complex, northern Greece. Ore Geology Reviews 2008, 33, 3 -19.

AMA Style

G. Tsoupas, M. Economou-Eliopoulos. High PGE contents and extremely abundant PGE-minerals hosted in chromitites from the Veria ophiolite complex, northern Greece. Ore Geology Reviews. 2008; 33 (1):3-19.

Chicago/Turabian Style

G. Tsoupas; M. Economou-Eliopoulos. 2008. "High PGE contents and extremely abundant PGE-minerals hosted in chromitites from the Veria ophiolite complex, northern Greece." Ore Geology Reviews 33, no. 1: 3-19.