Editorial

2 pages, 160 KiB

Open AccessEditorial

Editorial for the Special Issue “Bio-Geochemistry of Heavy Metals/Metalloids”

by Ifigeneia Megremi and Maria Economou-Eliopoulos

Minerals 2023, 13(3), 347; https://0-doi-org.brum.beds.ac.uk/10.3390/min13030347 - 01 Mar 2023

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This Special Issue “Bio-Geochemistry of Heavy Metals/Metalloids” contains a series of papers that cover a range of topics highlighting the role of microorganisms in ore-forming biochemical processes and potential environmental risk (the first to fourth papers), in the assessment of potentially toxic element [...] Read more.

This Special Issue “Bio-Geochemistry of Heavy Metals/Metalloids” contains a series of papers that cover a range of topics highlighting the role of microorganisms in ore-forming biochemical processes and potential environmental risk (the first to fourth papers), in the assessment of potentially toxic element contamination using plants and living benthic Foraminifera (the fifth and sixth papers), and in the phytoremediation of contaminated land (the seventh paper) [...] Full article

(This article belongs to the Special Issue Bio-Geochemistry of Heavy Metals/Metalloids)

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18 pages, 2542 KiB

Open AccessFeature PaperArticle

Assessment of Potentially Toxic Element Contamination in the Philippi Peatland, Eastern Macedonia, Greece

by Ioannis Zafeiriou, Dionisios Gasparatos, Ifigeneia Megremi, Dafni Ioannou, Ioannis Massas and Maria Economou-Eliopoulos

Minerals 2022, 12(11), 1475; https://0-doi-org.brum.beds.ac.uk/10.3390/min12111475 - 21 Nov 2022

Cited by 3 | Viewed by 1556

Abstract

The Philippi peatland is considered the biggest peat deposit in the Balkan Peninsula and one of the deepest in the world. The purpose of this study was to access the impact of eight potentially toxic elements (PTEs), i.e., As, Se, Pb, Cr, Ni, [...] Read more.

The Philippi peatland is considered the biggest peat deposit in the Balkan Peninsula and one of the deepest in the world. The purpose of this study was to access the impact of eight potentially toxic elements (PTEs), i.e., As, Se, Pb, Cr, Ni, Zn, Mn and Cu, on the local environment. PTE content was determined in corn grains and surface soil samples collected from 16 sites in the peatland, and pollution indices were calculated to evaluate the environmental risks. Soil organic matter ranged between 93 and 557 g kg⁻¹ soil, whereas the soil pH was >7, classifying the soils as neutral to slightly alkaline. Mean PTE contents in soil samples were 24.6 mg kg⁻¹ soil for As, 1.68 mg kg⁻¹ soil for Se, 113 mg kg⁻¹ soil for Pb, 32 mg kg⁻¹ soil for Cr, 36.3 mg kg⁻¹ soil for Ni, 141.4 mg kg⁻¹ soil for Zn, 35.5 mg kg⁻¹ soil for Cu and 845 mg kg⁻¹ soil for Mn. In corn grain samples, 0.06 mg kg⁻¹ grain for As, 0.14 mg kg⁻¹ grain for Se, 1.34 mg kg⁻¹ grain for Cr, 0.69 mg kg⁻¹ grain for Ni, 27 for Zn, 8.4 mg kg⁻¹ grain for Cu and 3.2 mg kg⁻¹ grain for Mn were recorded. No Pb was detected in the corn grains. The bioaccumulation factor (BF) was high for Cu, Zn and Se, indicating increased mobility of these elements in the soils and preferential plant uptake. For most soil samples, the geoaccumulation index (Igeo) and single pollution index (PI) showed low to moderate contamination. However, Igeo and PI values of Se in many sampling sites and of Pb and Zn in few were substantially increased, pointing to heavily contaminated soils. According to potential ecological risk (RI), the PTE content in the peat soils of Philippi imposes low to moderate risk on the environment. Full article

(This article belongs to the Special Issue Bio-Geochemistry of Heavy Metals/Metalloids)

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14 pages, 5179 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Microbial Mat Stratification in Travertine Depositions of Greek Hot Springs and Biomineralization Processes

by Christos Kanellopoulos, Vasiliki Lamprinou, Artemis Politi, Panagiotis Voudouris, Ioannis Iliopoulos, Maria Kokkaliari, Leonidas Moforis and Athena Economou-Amilli

Minerals 2022, 12(11), 1408; https://0-doi-org.brum.beds.ac.uk/10.3390/min12111408 - 04 Nov 2022

Cited by 4 | Viewed by 2495

Abstract

The study of microbial mats in extreme environments is of high scientific interest from geological, ecological, and geomicrobiological aspects. These mats represent multilayer bio-structures where each taxonomic group dominates a specific vertical layering distribution resulting from its growth and metabolic activity. In the [...] Read more.

The study of microbial mats in extreme environments is of high scientific interest from geological, ecological, and geomicrobiological aspects. These mats represent multilayer bio-structures where each taxonomic group dominates a specific vertical layering distribution resulting from its growth and metabolic activity. In the present study, microbial mats in a hot spring environment from Aedipsos (Euboea Island, Greece) resulting in the creation of thermogenic travertine, were studied through an interdisciplinary approach. The mineralogical composition was determined by optical microscopy, XRD, and SEM-EDS microanalysis, and the identification of Cyanobacteria was made primarily on morphological characteristics. The main mineral phase in the studied samples is calcite and, to a less extent, aragonite, with several trace elements in the mineral-chemistry composition, i.e., up to 1.93 wt. % MgO, up to 0.52 wt. % SrO, up to 0.44 wt. % Na₂O, up to 0.17 wt. % K₂O, and up to 3.99 wt. % SO₃. The dominant facies are lamination and shrubs, which are the most common among the facies of thermogenic travertines of the area. Several layers were identified, (i) a top mainly abiotic layer consisting of calcium carbonate micritic crystals, (ii) a second biotic layer–the Cyanobacteria layer, dominated by the species Leptolyngbya perforans, (iii) a third biotic layer where Leptolyngbya perforans, Chloroflexus and other bacteria occur, and (iv) a deeper abiotic part with several layers where no photosynthetic microorganisms occur. In the upper layers, nineteen (19) species of Cyanobacteria were identified, classified in the orders Chroococcales (37%), Synechococcales (31%), Oscillatoriales (16%), and Spirulinales (6%). Among the identified Cyanobacteria, there are typical thermophilic and limestone substrate species. These Cyanobacteria are found to participate in the biomineralization and biologically-influenced processes, i.e., (i) filamentous Cyanobacteria are trapping calcium carbonate crystals, and diatoms, (ii) extracellular polymeric substances (EPS) create crystal retention lattice contributing to the biomineralization process, and (iii) filamentous sheaths of Cyanobacteria are calcified, resulting in the creation of calcium carbonate tubes. Full article

(This article belongs to the Special Issue Bio-Geochemistry of Heavy Metals/Metalloids)

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19 pages, 4356 KiB

Open AccessArticle

Bio-Geochemical Processes: Insights from Fe-Mn Mineralization in the Aegean Sea (Greece)

by Charalampos Vasilatos, Evdokia E. Kampouroglou, Ifigeneia Megremi and Maria Economou-Eliopoulos

Minerals 2022, 12(10), 1303; https://0-doi-org.brum.beds.ac.uk/10.3390/min12101303 - 16 Oct 2022

Cited by 2 | Viewed by 2354

Abstract

In this study, we have compiled new and existing mineralogical and geochemical data on Fe-Mn mineralization from the Aegean region [Attica (Grammatiko, Legrena, and Varnavas), Evia and Milos islands], aiming to provide new insights on the genesis of Fe-Mn mineralization in that region [...] Read more.

In this study, we have compiled new and existing mineralogical and geochemical data on Fe-Mn mineralization from the Aegean region [Attica (Grammatiko, Legrena, and Varnavas), Evia and Milos islands], aiming to provide new insights on the genesis of Fe-Mn mineralization in that region and its potential environmental implications. A common feature of those deposits is the relatively low Cr, Co, V, Ni, Mo, and Cd content, whereas Ba, As, W, Cu, Pb, and Zn show remarkably variable values. The Mn-Fe deposits from Milos exhibit the highest tungsten content, while a positive trend between MnO and W, combined with a negative trend between MnO and Fe₂O₃ suggests the preference of W to Mn-minerals. The occurrence of bacterio-morphic Fe-Mn-oxides/hydroxides within Mn-Fe mineralizations in the studied region, indicates the important role of micro-organisms into redox reactions. Moreover, the presence of micro-organisms in the Fe-Mn-deposits, reflecting the presence of organic matter confirms a shallow marine environment for their deposition. A salient feature of the Varnavas and Milos Mn-Fe ores is the presence of sodium chloride coated fossilized micro-organisms, suggesting development from a solution containing relatively high Na and Cl concentrations. Furthermore, from an environmental point of view, consideration is given to the bioavailability of elements such as As, Pb, and W, related to the above-mentioned mineralizations. The high bio-accumulation factor for W (W_plant/W_soil × 100) recorded in the Neogene sedimentary basins of Attica, related to the Grammatiko Fe-Mn mineralization, reflects the high W mobility under alkaline conditions and the potential environmental impact of similar deposits with elevated W content. Full article

(This article belongs to the Special Issue Bio-Geochemistry of Heavy Metals/Metalloids)

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14 pages, 3926 KiB

Open AccessArticle

Cycling of Pt, Pd, and Rh Derived from Catalytic Converters: Potential Pathways and Biogeochemical Processes

by Ioannis-Porfyrios Eliopoulos, George Eliopoulos, Theodora Sfendoni and Maria Economou-Eliopoulos

Minerals 2022, 12(7), 917; https://0-doi-org.brum.beds.ac.uk/10.3390/min12070917 - 21 Jul 2022

Cited by 5 | Viewed by 1732

Abstract

The present study is an integrated approach to the Pt, Pd, and Rh cycling derived from catalytic converters along highway roadsides of the Athens Basin, including their contents, the dispersed Pt- and Pd-bearing nano- and microparticles in dust and bioaccumulation in plants, aiming [...] Read more.

The present study is an integrated approach to the Pt, Pd, and Rh cycling derived from catalytic converters along highway roadsides of the Athens Basin, including their contents, the dispersed Pt- and Pd-bearing nano- and microparticles in dust and bioaccumulation in plants, aiming to assess the auto-catalyst-derived environmental impact to the large city of Athens and the potential human health risk. The determined mean values of 314 Pt, 510 Pd, and 23 Rh (all in μg/kg) in dust samples are much lower than the 2070 μg/kg Pt and 1985 μg/kg Pd contents in gully pots in the Katechaki peripheral highway and higher than the mean values of 230 Pt, 300 Pd, and 13 Rh (all in μg/kg) in the soil samples. With the exception of two samples from gully pots, from 51% to 70% of the samples (for the Pd and Pt, respectively) fall in the range from 100 to 400 μg/kg. The calculated accumulation factors showed means of 3.88 μg/kg Pd and 2.95 μg/kg Pt for plants and tree leaves, but any significant difference (t-test) is lacking, and they are much lower than those reported for roots of plants (literature data). Although the Pt, Pd, and Rh bioaccumulation factors for shoots of plants/crops are relatively low, the increasing number of cars with catalytic converters in Greece and the relatively high bioaccumulation in the food chain may highlight a potential risk for human health and ecosystems, and the need for special attention on their bioaccumulation and bioaccessibility on a global scale. Full article

(This article belongs to the Special Issue Bio-Geochemistry of Heavy Metals/Metalloids)

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17 pages, 1599 KiB

Open AccessArticle

Mineral Neutralizers as a Tool for Improving the Properties of Soil Contaminated with Copper

by Andrzej Cezary Żołnowski and Mirosław Wyszkowski

Minerals 2022, 12(7), 895; https://0-doi-org.brum.beds.ac.uk/10.3390/min12070895 - 17 Jul 2022

Cited by 5 | Viewed by 1663

Abstract

In phytoremediation processes implemented in highly contaminated areas, there is a high risk of contaminant toxicity during the germination of freshly sown plants. In such conditions, it is recommended to support phytoremediation by using neutralizing additives. The present study aimed at assessing the [...] Read more.

In phytoremediation processes implemented in highly contaminated areas, there is a high risk of contaminant toxicity during the germination of freshly sown plants. In such conditions, it is recommended to support phytoremediation by using neutralizing additives. The present study aimed at assessing the effect of the addition of mineral neutralizers (MNs), i.e., limestone, clay, and zeolite, to soil contaminated with copper (0, 200, 400, 600 mg kg⁻¹). Basic soil indicators were analyzed, such as pH, hydrolytic acidity (HAC), total exchangeable bases (TEB), cation exchange capacity (CEC), base saturation (BS), electrolytical conductivity (EC), total organic carbon (TOC), total nitrogen (Ntot), carbon to nitrogen ratio (C:N),, and interactions of soil micronutrients, such as Cu, Zn, Cd, Cr, Ni, Pb, Mn, and Fe with MNs. Copper contamination significantly decreased the soil pH and increased its HAC. A decrease in the share of TEB was found, which resulted in a decrease in the CEC and in BS of the soil. Among the additives, limestone had the most beneficial effect on reducing soil acidity, contributing to a significant increase in TEB, CEC, and BS. The least favorable effect was shown for clay, which generally caused the deterioration of soil properties. The MNs significantly increased the content of Zn, Cr, and Fe and lowered the content of Ni in the soil compared to the control. The demonstrated interactions indicate the diversified activity of MNs at different levels of soil contamination with copper. Full article

(This article belongs to the Special Issue Bio-Geochemistry of Heavy Metals/Metalloids)

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15 pages, 3455 KiB

Open AccessArticle

Response of Living Benthic Foraminifera to Anthropogenic Pollution and Metal Concentrations in Saronikos Gulf (Greece, Eastern Mediterranean)

by Margarita D. Dimiza, Maria V. Triantaphyllou, Mélanie Portela, Olga Koukousioura and Aristomenis P. Karageorgis

Minerals 2022, 12(5), 591; https://0-doi-org.brum.beds.ac.uk/10.3390/min12050591 - 06 May 2022

Cited by 7 | Viewed by 2423

Abstract

The Saronikos Gulf, including the industrial zone of Elefsis Bay, is subjected to a variety of urban and industrial impacts that significantly contribute to environmental degradation. Benthic foraminifera comprise a significant component of meiobenthic communities and they are widely used as reliable indicators [...] Read more.

The Saronikos Gulf, including the industrial zone of Elefsis Bay, is subjected to a variety of urban and industrial impacts that significantly contribute to environmental degradation. Benthic foraminifera comprise a significant component of meiobenthic communities and they are widely used as reliable indicators for the determination of the natural environmental and anthropogenic impact in shallow coastal systems. The present study analyses the living benthic foraminifera composition and its relation to environmental parameters such as grain size, organic carbon content, and heavy metal concentrations, from the surficial sediment layer collected in the Elefsis Bay and the Inner Saronikos Gulf in February 2016. Canonical correspondence analysis and Spearman’s rho correlation show that the foraminiferal species composition is significantly influenced by the increase of organic carbon and Cu, Pb, Zn content. In particular, a relatively low diversity fauna dominated by the stress-tolerant species Ammonia tepida, Bulimina elongata, Bulimina marginata, and Nonionella turgida occurs in the restricted environment of the Elefsis Bay, demonstrating the negative environmental impact caused by the relatively elevated organic carbon and heavy metal contents. Full article

(This article belongs to the Special Issue Bio-Geochemistry of Heavy Metals/Metalloids)

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15 pages, 3301 KiB

Open AccessArticle

Biogeochemical Redox Processes Controlling the Element Cycling: Insights from Karst-Type Bauxite, Greece

by Maria Economou-Eliopoulos, Marioka Kontou and Ifigeneia Megremi

Minerals 2022, 12(4), 446; https://0-doi-org.brum.beds.ac.uk/10.3390/min12040446 - 05 Apr 2022

Cited by 4 | Viewed by 1971

Abstract

The occurrence of very-high-grade bauxite ores of karst-type deposits resulting from Fe-leaching is of particular importance, because they are widespread in the Mediterranean metallogenetic province and result in the natural beneficiation of the ore quality. The present study focuses on mineral transformations and [...] Read more.

The occurrence of very-high-grade bauxite ores of karst-type deposits resulting from Fe-leaching is of particular importance, because they are widespread in the Mediterranean metallogenetic province and result in the natural beneficiation of the ore quality. The present study focuses on mineral transformations and variations of major and trace elements, including platinum-group elements (PGE) and mineral chemistry along a bauxite profile from the Parnassos-Ghiona deposit, Greece underlying a fault. The most salient feature of the multicolor ores (grey–whitish, yellowish, deep red, deep grey to brown-red color, from top to bottom) is their association with fossilized and present-day microorganisms, which, by their reducing and/or oxidizing activity, catalyze redox reactions and provide nucleation sites for the precipitation of secondary minerals. Texture relationships between mineral and variations in the mineral chemistry, suggesting the sequence in their formation, indicate a multistage evolution. The recorded compositional variations show that the Al enrichment is accompanied by increase in the TOC, As, Pd and U, and chondrite-normalized REE patterns exhibit a similar trend and positive Ce anomalies. A lower (Pt + Pd) content and higher Pd/Pt ratio, ranging from 1.0 to 5.5 in the bauxite profile compared to those in Fe-Ni laterite deposits with the Pd/Pt ratio ranging from 0.1 to 0.68, reflect the higher solubility and mobility of Pd compared to that of Pt, and differences in their origin and genesis. A positive correlation between Pd and As and the elevated As content (up to 960 mg/kg) in multicolor ores compared to brown-red samples (average 10 mg/kg As) confirms their mobilization and redeposition. Full article

(This article belongs to the Special Issue Bio-Geochemistry of Heavy Metals/Metalloids)

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