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In the Aegean region (Cyclades – Greece), a large part of the Island of Anafi consists of exhumed high-grade metamorphic sequences (amphibolites, serpentinites and metasediments) that have been int...

The Cycladic Blueschist Unit (CBU) of the Aegean (Greece) contains several occurrences of metamorphosed Manganese mineralization within a Triassic volcaniclastic sequence. The latter includes quartz-mica schists intercalated with bimodal metavolcanics and blue-grey marble layers. SHRIMP U-Pb zircon dating has documented the Triassic age (~242 Ma) of the volcanic rocks. Herein we revisit the Mn metallogenic system of the CBU through an extensive study of Mn mineralization at Varnavas area, Northern Attica, and a similar occurrence at central Andros Island (Mparades hill). Manganese mineralogy at both localities is manifested in a typical high-P metamorphic silicate assemblage dominated by piemontite, spessartine garnet, and minor pyroxmangite (rhodonite). At Andros, Mn-rich subdomains contain brecciated braunite micronodules. The preservation of similar nodular form is documented from Varnavas, comprising dominant todorokite, lesser hollandite, pyrolusite, and minor Mn-bearing hematite. The contrasting Mn oxide mineralogy at the two sites is tentatively interpreted as the result of locally incomplete reduction of precursor Mn(IV) phases during metamorphism. Common geochemical characteristics of the Mn-rich rocks include low transition metal concentrations; positive-sloping, PAAS-normalized REE spidergrams; positive Ce anomalies of variable magnitude across individual samples; and high As, Ba, Pb. The geochemical variability recorded is ascribed to the varying mixing of a hydrothermal-sourced, hydrogenous metalliferous component that precipitated penecontemporaneously with the deposition of the host tuffs. The primary Mn precipitates are thought to have been in the form of tetravalent Mn assemblages, which may locally be partially preserved through metamorphism, as appears to be the case in the Varnavas occurrence. All these reveal the interplay between the felsic/intermediate back-arc volcanism and associated hydrothermal activity and the Mn mineralization within the rift setting of the CBU domain.

Detailed mapping and structural observations on the Cycladic Blueschist Unit (CBU) of Iraklia island integrated by detrital zircon (DZ) U-Pb ages elucidate the Mesozoic pre-subduction evolution and the Cenozoic orogenic events. Field data reveal that the Iraklia tectonostratigraphy includes a heterogeneous Lower Schist Unit juxtaposed against a Variegated Marble Unit and an overlying Upper Schist Unit. The contact is an extensional ductile-to-brittle-ductile, top-to-N shear zone, associated with the Oligo-Miocene exhumation. The DZ spectrum of the Lower Schist Unit characterized by Gondwanan/peri-Gondwanan provenance signatures points to Late Triassic maximum depositional ages (MDAs). A quartz-rich schist layer yielded Precambrian DZ ages exclusively, considered part of the pre-Variscan metasedimentary Cycladic Basement, equivalent to those observed on Ios island. A significant change occurred during the deposition of the Upper Schist Unit, revealing Late Cretaceous MDAs and a high amount of Late Paleozoic DZ ages, attesting to more internal Pelagonian source areas. The imprint of Paleotethyan vs. Neotethyan geodynamic events is revealed in the DZ U-Pb ages record. The Triassic DZ input demonstrates eroded volcanic material related to the final Paleotethys closure and the Pindos/CBU rift basin opening. Late Cretaceous metamorphic/magmatic zircons and ~48-56 Ma zircon rims constrain the onset of subduction and high-pressure metamorphism.

The disposal of lignite spoil and tailings poses a major environmental problem in lignite mining sites which is associated with the oxidation of sulfide minerals contained in the primary ore. This process renders acidic effluents. Lignite mining in the Oropos Neogene basin, North Attica, Greece operated since the last century and ceased in the late 1960s. Piles of complex waste material are dispersed close to the mining sites. The high sulfur content and low Net Neutralization Potential, i.e. values

Triassic geodynamic phenomena in the Aegean area are largely controlled by subduction of the Paleotethys ocean and opening of the Neotethys oceans. Triassic volcanosedimentary sequences have a complex composition in many cases, reflecting both subduction and rifting setting.Detailed mapping of NE Attica (Penteli Mt., Marathonas, Varnavas) revealed the existence of a structurally lower meta-volcanosedimentary sequence, which, comprises quartzofeldspathic rocks, schists, quartzite, metabasite and acid meta-volcanics This sequence is isoclinally folded in the macro-scale with marble layers and the axial plane foliation displays greenschist facies assemblages, whereas earlier HP minerals are mostly preserved as inclusions in albite porphyroblasts. The sequence of rocks has been investigated for their geochemical composition and their field relationships. Two assemblages of volcanic rocks are distinguished based on geochemical criteria: (a) a predominant subalkaline andesite-rhyolite series with a significant proportion of meta-tuffs in the stratigraphic sequence and (b) minor alkali basalts. Lenses of felsic meta-volcanic rocks alternate with siliciclastic layers showing sedimentary banding and allow for an interpretation of a volcano-sedimentary succession.The geochemical characteristics of the alkali basalts are typical of rift settings (positive anomalies in Nb, Ta, Ti and P) and plot in the field of within plate basalts in the tectonic discrimination diagrams. The trace element and Rare Earth Element characteristics of the andesites and rhyolites in the subalkaline group show many characteristics of subduction zone melts e.g. negative Nb and Ta anomalies, positive Pb anomaly and LREE-enriched suggesting that a metasomatized mantle wedge source played an important role in the formation of the calcalkaline magmas. A geodynamic model of rift formation in the active continental margin of Pelagonia is proposed to explain the transition from a subduction- to an extension-related magmatic activity in the Late Permian/Triassic time in the broader NE Attica-central Evvia region.

The nature of the protolith(s) of high-grade gneisses from the Aegean Cycladic Basement Unit of the islands of Paros and Serifos is investigated using whole-rock geochemistry and Sr–Nd–O isotopes, in order to better understand their origin and to compare with possible equivalents from the southern Aegean region. On Paros, the basement unit consists of heterogeneous, mylonitized upper amphibolite-grade paragneisses and associated migmatitic rocks, whereas on Serifos, it consists of a mylonitized felsic gneiss, intercalated with layers and lenses of S-type leucogranites and minor mafic metavolcanics. New Nd, Sr and O isotope data suggest a predominantly crustal-derived source in the gneiss protolith from both islands: high initial 87Sr/86Sr ratios (≥7052 to 0.711, calculated at 300 Ma), negative initial eNd (−2.8 to −7.7) values for bulk-rock gneiss samples, and high δ18O values of quartz separates (+10 to +12.7 ‰). Major and trace-element variations corroborate that chemical differentiation within the NW Paros gneiss subunit results from progressive migmatitization. Peraluminous gneisses from eastern Paros share clear similarities with metapelitic gneisses from the Naxos gneiss dome, in terms of their trace-element patterns, eNd (300) and O isotope characteristics. The mineral assemblage, the fine grain size (due to intense mylonitization), and the metaluminous affinity of the South Serifos grey quartzofeldpathic gneiss do not allow for an unambiguous interpretation for these undated rocks; however, a combination of geochemical parameters and tectonic discrimination diagrams indicates an immature siliciclastic (greywacke) protolith from a continental island arc setting. Sr–Nd isotopic systematics indicates an increasing lower crustal component in gneisses from NW Paros, which is closer to the migmatitic core of the Paros dome. The overall isotopic trend of the gneissic Cycladic Basement Unit on Paros is spatially correlated with that of the Naxos gneiss dome.

Beneficiation of a rare earth element (REE) ore from heavy mineral (HM) sands by particle size classification in conjunction with high-intensity magnetic separation (HIMS) was investigated. The HM sands of Nea Peramos, Kavala, Northern Greece, contain high concentrations of REE accommodated mainly in silicate minerals, such as allanite. However, the potential of the Northern Greek placer for REE exploitation has not been fully evaluated due to limited on-shore and off-shore exploration drilling data. Characterization of the magnetic separation fractions using XRD and bulk ICP-MS chemical analysis showed that the magnetic products at high intensities were strongly enriched in the light REE (LREE), relative to the non-magnetic fraction. Allanite and titanite are the major host mineral for REE in the magnetic products but mainly allanite controls the REE budget due its high concentration in LREE. SEM/EDS and ICP-MS analysis of the different particle size fractions showed LREE enrichment in the fractions &minus, 0.425 +0.212 mm, and a maximum enrichment in the &minus, 0.425 +0.300 mm. The maximum enrichment is achieved after magnetic separation of the particle size fractions. Mass balance calculations showed that the maximum REE recovery is achieved after magnetic separation of each particle size fraction separately, i.e., 92 wt.% La, 91 wt.% Ce, and 87 wt.% Nd. This new information can contribute to the optimization of beneficiation process to be applied for REE recovery from HM black sands.

The Late Miocene (11.6–9.5 Ma) granitoid intrusion on the island of Serifos (Western Cyclades, Aegean Sea) is composed of syn- to post-tectonic granodiorite with quartz monzodiorite enclaves, cut by dacitic and aplitic dikes. The granitoid, a typical I-type metaluminous calcic amphibole-bearing calc-alkaline pluton, intruded the Cycladic Blueschists during thinning of the Aegean plate. Combining field, textural, geochemical and new Sr–Nd–O isotope data presented in this paper, we postulate that the Serifos intrusion is a single-zoned pluton. The central facies has initial ^(87)Sr/^(86)Sr = 0.70906 to 0.7106, e_(Nd)(t) = − 5.9 to − 7.5 and δ^(18)Ο_(qtz) = + 10 to + 10.6‰, whereas the marginal zone (or border facies) has higher initial ^(87)Sr/^(86)Sr = 0.711 to 0.7112, lower e_(Nd)(t) = − 7.3 to − 8.3, and higher δ^(18)Ο_(qtz) = + 10.6 to + 11.9‰. The small range in initial Sr and Nd isotopic values throughout the pluton is paired with a remarkable uniformity in trace element patterns, despite a large range in silica contents (58.8 to 72 wt% SiO_2). Assimilation of a crustally derived partial melt into the mafic parental magma would progressively add incompatible trace elements and SiO2 to the evolving mafic starting liquid, but the opposite trend, of trace element depletion during magma evolution, is observed in the Serifos granodiorites. Thermodynamic modeling of whole-rock compositions during simple fractional crystallization (FC) or assimilation-fractional crystallization (AFC) processes of major rock-forming minerals—at a variety of pressure, oxidation state, and water activity conditions—fails to reproduce simultaneously the major element and trace element variations among the Serifos granitoids, implying a critical role for minor phases in controlling trace element fractionation. Both saturation of accessory phases such as allanite and titanite (at SiO_2 ≥ 71 wt%)(to satisfy trace element constraints) and assimilation of partial melts from a metasedimentary component (to match isotopic data) must have accompanied fractional crystallization of the major phases.

Native iron has been identified in an active thermogenic travertine deposit, located at Ilia area (Euboea Island, Greece). The deposit is forming around a hot spring, which is part of a large active metallogenetic hydrothermal system depositing ore-bearing travertines. The native iron occurs in two shapes: nodules with diameter 0.4 and 0.45 cm, and angular grains with length up to tens of &mu, m. The travertine laminae around the spherical/ovoid nodules grow smoothly, and the angular grains are trapped inside the pores of the travertine. Their mineral-chemistry is ultra-pure, containing, other than Fe, only Mn (0.34&ndash, 0.38 wt.%) and Ni (&le, 0.05 wt.%). After evaluating all the possible environments where native iron has been reported up until today and taking under consideration all the available data concerning the study area, we propose two possible scenarios: (i) Ilia&rsquo, s native iron has a magmatic/hydrothermal origin i.e., it is a deep product near the magmatic chamber or a peripheral cooling igneous body that was transferred during the early stages of the geothermal field evolution, from high temperature, reduced gas-rich fluids and deposited along with other metals in permeable structural zones, at shallow levels. Later on, it was remobilized and mechanically transferred and precipitated at the Ilia&rsquo, s thermogenic travertine by the active lower temperatures geothermal fluids, (ii) the native iron at Ilia is remobilized from deep seated ophiolitic rocks, originated initially from reduced fluids during serpentinization processes, however, its mechanical transport seems less probable. The native iron mineral-chemistry, morphology and the presence of the other mineral phases in the same thermogenic travertine support both hypotheses.

The ophiolitic rocks of the Attic-Cycladic crystalline belt are considered of key importance for understanding the Mesozoic tectonic evolution of the Aegean region. Unresolved questions concern their tectono-stratigraphic relationships across the region. The mode of occurrence of the Cycladic ophiolites varies, as they appear as: (a) dismembered blocks (olistoliths) within the supra-detachment units of Paros and Naxos; (b) mélange formations in the upper structural unit of western Samos and Skyros; and (c) meta-ophiolitic mélange in the Cycladic Blueschist Unit (CBU) from central Samos. The trace element geochemistry and Pb-Sr-Nd isotopes of the mafic ophiolitic rocks indicate four geochemical groups: (a) the upper unit metabasites from Paros and western Samos (Kallithea) display an evolved basaltic composition (Mg# 40.2–59.6), with low Zr/Nb values (5–16) and high Ce/Y values (1.3 to 2.6) compared to MORB, indicating island-arc tholeiite affinities; (b) Naxos upper unit metabasalts show spider diagrams patterns indicating ocean island basalt (OIB-type) affinities; (c) Central Samos metagabbros (CBU) are primitive rocks with Back-Arc Basin basalt affinities; (d) the Skyros metadolerites and Tinos (Mt Tsiknias) and S. Evia (CBU) metagabbros, cluster as a separate geochemical group; they exhibit high MgO values (>10 wt %), very low TiO2 values (0.1–0.2 wt %), Y and Yb, and depleted trace element N-MORB normalized patterns, similar to volcanic rocks formed in modern oceanic fore-arc settings, such as boninites. A combination of the Pb- and Sr-isotopic compositions of Cycladic metabasites indicate that the Pb and Sr incorporated in the Cycladic ophiolites correspond to mixtures of magmatic fluids with seawater (206Pb/204Pb = 18.51–18.80; 207Pb/204Pb = 15.59–15.7; 208Pb/204Pb = 39.03–39.80 and initial 87Sr/86Sr80 = 0.705–0.707). Furthermore, peridotite relicts from Samos, Paros, and Naxos—irrespective of the structural unit—display chemical affinities of ocean floor peridotites formed in a supra-subduction zone. The characteristics of harzburgite relicts in Cycladic serpentinites and Skyros indicate a highly residual nature of the mantle source. Geochemical data from this study shed further light on the complex structure of the oceanic lithosphere from which the Cycladic ophiolites originated.

Identification of silver-rich sulfide mineralization in the abandoned mines at northern Hymittos Mt (central Attica, Greece) district has made this region important due to its structural relation to the world-class Lavrion mining district (25 km SE of Hymittos Mt.). At Agios Ioannis Kynigos mine veins of oxidized Fe-Pb-Zn-Ag ore are hosted in mylonitic marbles that were predominantly affected by brittle-ductile deformation associated with the West Cycladic Detachment System. The major sulfides are galena and arsenian pyrite which develop as open-space filling (fractures and vugs), disseminations and veinlets. Galena contains abundant inclusions of Pb-As-Sb-Cu-Ag sulfosalts (tetrahedrite group minerals, bournonite, jalpaite). An unusual silver-rich galena ore i.e from 192 to 1500 ppm Ag, is recorded from the present study, with Ag hosted mainly in Ag-tetrahedrite, acanthite and jalpaite. Compositionally pyrite shows As enrichment and the highest As concentration i.e. up to 3.9 wt% is found in the core of the oscillatory zoned pyrites. Values of δ34S of galena are isotopically light (−11.2 to −12.2‰), which suggests a sedimentary component to the ore fluid, that is likely derived from leaching of the meta-sedimentary (calc-mica schists) wall rocks. Carbon and oxygen isotope compositions of ore-stage carbonates show values i.e δ13CV-PDB (‰) = −8.2 to −11.7‰ and δ18O = 24.3 to 25.9‰ and for the non-mineralized carbonates δ13CV-PDB (‰) = +0.33 to 2.52‰ and δ18O = 20.8 to 26.1‰. The C and O isotopic composition of the carbonate wall rock distal to the orebody is typical of marine carbonates, whereas hydrothermal carbonates (brown calcite and dolomite) are dominated by an external, light C source. The lowest δ13CV-PDB values are recorded from cerussite and correspond to the low temperature supergene alteration from meteoric waters. The homogenized values of δ18O in the mineralized carbonates indicate interaction of fluid with host carbonates under a low fluid/rock ratio. The Pb-Zn-Ag mineralization at Agios Ioannis Kynigos bears many similarities with the low-temperature carbonate replacement-style mineralization in Kamariza, Lavrion area. Ore deposition in the northern Hymittos detachment fault is focused in the structurally upper parts of the detachment fault where circulation of meteoric fluids is dominant in the hydrothermal system.

Μικρές εμφανίσεις μεταλλοφορίας οξειδίων του σιδήρου στην περιοχή Σέσι, Κορωπί, Ν. Υμηττός, αναπτύσσονται κατά μήκος μιας κατακλαστικής ζώνης αποκόλλησης ανάμεσα σε ανθρακικούς σχηματισμούς των ενοτήτων "Υμηττού" αι "Βάρης-Κύρου Πύρα". Ένα 2026 άλλο μικρής κλίσης ρήγμα, φέρνει σε επαφή του σχιστολίθους της υπερκείμενης ενότητας "Λαυρίου" που περιλαμβάνουν τεμάχη από μετα-βασικά πετρώματα και σερπεντινίτες. Η όλη δομή κόβεται από μεγάλης κλίσης κανονικά ρήγματα, που ριζώνουν στην κατακλαστική ζώνη αποκόλλησης, συντελώντας στην τεκτονική εκλέπτυνση της ενότητας "Υμηττού", με αποτέλεσμα σε αρκετές περιπτώσεις να έρχονται σε επαφή οι μετα- οφιολιθικές λιθολογίες με τα ανθρακικά της ενότητας "Βάρης-Κύρου Πύρα". Η εμφάνιση του σιδηρομεταλλεύματος εντοπίστηκε μέσα σε τρείς μικρές διερευνητικές στοές εξόρυξης όπου υπάρχουν ενδείξεις για περιορισμένη εξόρυξη στο πρόσφατο παρελθόν. Η μεταλλοφορία αναπτύσσεται στην κατακλαστική ζώνη του ρήγματος αποκόλλησης, έχει πάχος λίγων μέτρων (3-5μ), και σχηματίζει λεπτούς μαύρους φλοιούς και ζώνες εξαλλοίωσης με χαρακτηριστική καφέ-κόκκινη έως κίτρινη απόχρωση. Η ορυκτολογική μελέτη της μεταλλοφορίας του σιδηρομεταλλεύματος έδειξε ότι αποτελείται από αιματίτη (πρωτογενής μεταλλοφορία) και γκαιτίτη (δευτερογενής μεταλλοφορία από αντικατάσταση). Μελέτη των μικροδομών του γκαιτίτη έδειξε ότι παρουσιάζει τυπική μορφολογία κολλοειδούς μορφής, που είναι χαρακτηριστική πλήρωσης κοιλοτήτων του ανθρακικού πετρώματος (ξενιστής). Σύμφωνα με τις παρατηρήσεις υπαίθρου και την τεκτονική μακροδομή της ευρύτερης περιοχής, η ανάπτυξη της σιδηρούχου μεταλλοφορίας συνδέεται με κυκλοφορία υδροθερμικού ρευστού κατά μήκος της κατακλαστικής ζώνης αποκόλλησης. Η σιδηρούχος εξαλλοίωση των ανθρακικών σχηματισμών είναι έντονη σε συγκεκριμένες ζώνες κατάκλασης κατά μήκος τέτοιου τύπου μικρής κλίσης κατακλαστικών ζωνών αποκόλλησης σε όλη την κεντρική και ΝΑ Αττική, από τον Β. Υμηττό μέχρι το Λαύριο. Αυτό υποδηλώνει ότι αυτού του τύπου η μεταλλοφορία δεν παρατηρείται μόνο τοπικά, αλλά έχει μια ευρύτερη ανάπτυξη και επομένως σημασία για την τεκτονική εξέλιξη της NA Αττικής., Small occurrences of iron-oxide deposits at Sesi-Koropi in S. Hymittos, are hosted by an extensional brittle detachment zone between carbonate rocks of "Vari-Kirou Pira" and "Hymittos" units. Another low-angle fault separates a heterogeneous formation of schists, containing meta-ophiolitic blocks ("Lavrion" Unit), which is cut by high-angle normal faults that root in the detachment zone, reducing the total structural thickness of "Hymittos" marbles and bringing in contact the meta-ophiolitc lithologies with the "Vari-Kirou Pira" dolomites. Three mine caves were found along the detachment zone indicating that these iron deposits were possibly mined on a very small scale in the past. The mineralization is developed in a cataclastic zone a few meters thick (3-5m), forming thin rusty black encrustations and larger zones of alteration with a reddish to yellow brown hue. Scanning Electron Microscope (SEM) mineralogical study of the iron-ore deposit indicated that hematite is the primary iron-oxide mineral extensively replaced by goethite. Goethite appears with the typical colloidal form within voids showing typical open-space filling type microstructures. According to field evidence and the tectonic macro-structure of the area, the mineralization is associated with hydrothermal fluid circulation along the brittle detachment zone between meta-ophiolitic lithologies and carbonate rocks. Similar type iron-oxides mineralization in cataclastic zones were observed along other detachment zones in northern and southeastern Hymittos Mt. and further south towards Lavrion. This suggests that this type of mineralization is not local but has a broader development and regional implications for the tectonic evolution of the central and SE Attica

Neogene igneous activity in the Aegean region comprised both extrusive volcanism and intrusive granitoid plutonism. Granitoid plutonism in the Cyclades was established in the mid-Miocene period and lasted until late Miocene (18 to 9 Ma). The timing of granitoid intrusion was associated with the initiation of extensional tectonics in the Aegean. These intrusions form a broad belt about 200 km long running from the west (Lavrium and Serifos) to the eastern Aegean. Both S-type and I-type granitoids are present, the former generally being emplaced earlier than the I-types (~ 15 to 8.3 Ma). Major and trace element variations reveal that three end-member components are involved in the granitoids, but the proportions of these vary in the different plutons. Initial isotopic compositions of all the granitoids are typical of crust-derived magmas from heterogeneous metasedimentary sources (I-type: 87 Sr/ 86 Sr = 0.7091–0.712, e Nd = − 6.4 to − 10.4; S-type: 0.710–0715, e Nd = − 7.5 to − 10.1). Three end-member sources have been identified: 1) One end-member appears to be a metasedimentary biotite-gneiss (greywacke-type) such as that forming the metamorphic core complexes (Naxos and Paros); this is a dominant (but not the only) component in the S-types. 2a) Major, trace element and Sr–Nd isotopic composition correlations of the S-type granitoids with basement gneiss require an extra source of Sr and Ca, having lower initial 87 Sr/ 86 Sr indicating a more depleted metasedimentary source at depth, due to possible interaction, of metamorphic fluids with marbles and amphibolites and infiltration through the gneissic units, at mid-crustal levels. 2b) A possible second end-member could be the marble component, as indicated by the buffered values of the Initial Sr isotopic ratios. Major element variation of the mafic microgranular (quartz diorites and tonalites) enclaves are compatible with dehydration melting of a mafic source similar to the amphibolites (island arc tholeiites) at medium pressure (~ 8 kb) conditions. 3) Amphibolite is another end-member which may contribute mostly to the source of the younger intrusions, along the western flank of the arc.

The effectiveness of lignite fly ash for stabilization of Pb, Zn and Cd in tailings and contaminated soils was examined. Fly ash was mixed with the contaminated soil or oxidic tailings samples at various doses and pot experiments were performed. The effectiveness of stabilization was mainly evaluated by the standard US EPA TCLP toxicity test. The 5-stage sequential extraction procedure was also applied to determine the form of contaminants in the fly ash amended soil or tailings samples. Complementary EDTA extraction tests were also carried out. The fly ash treatment resulted in the reduction of TCLP solubility of Pb, Zn and Cd to below the respective regulatory limits at 5 and 10% w/w fly ash addition rates in tailings and soil, respectively. Speciation of lead, in the treated soil and tailings samples indicated that there was a significant transition of the heavy metals form from the exchangeable and carbonate fractions to reducible and residual, suggesting that the potential mechanisms of heavy metals retention are, apart from increase of pH, sorption on the oxides and hydroxides surfaces and binding with the hydrated fly ash compounds.

The effectiveness of municipal sewage sludge for the stabilisation of Pb, Zn and Cd in a heavily contaminated soil was evaluated by performing pot experiments on soil-sludge mixtures. The soil sample originated from the Montevecchio mining district, Sardinia, Italy, and presented high Pb, Zn and Cd content, as well as US EPA TCLP solubility values for Pb and Cd, which exceeded the respective regulatory limits. Sewage sludge application increased the soil pH. Stabilisation experiments showed that 10% w/w sewage sludge addition effectively reduced Pb and Cd solubilities below the TCLP regulatory limits. At the same addition rate, the EDTA extractable fraction of Pb, Zn, Cd in the treated soil was reduced by 12, 47 and 50% respectively compared with the untreated sample. The five-stage sequential extraction procedure applied on the untreated and treated soil samples, showed a remarkable shift of the metals towards more stable forms. The reducible fractions of Zn and Cd and the residual fraction of Pb were increased by 12, 20 and 18% respectively, while a corresponding decrease in the mobile fractions (exchangeable and carbonate) occurred which accounted for 14, 23 and 25% respectively.

The effectiveness of an in situ heavy metals fixation technique aimed at converting contaminants to low solubility and low bioavail-ability forms, eliminating the risk posed by oxidic tailings and ...

The chemical immobilization of Pb and As in contaminated soil from Lavrion, Greece, using monocalcium phosphate and ferrous sulfate as stabilizing agents was investigated. Monocalcium phosphate was added to contaminated soil at PO(4) to Pb molar ratios equal to 0, 0.5, 1, 1.5 and 2.5, whereas ferrous sulfate was added at Fe to As molar ratios equal to 0, 2.5, 5, 10 and 20. Phosphates addition to contaminated soil decreased Pb leachability, but resulted in significant mobilization of As. Simultaneous immobilization of Pb and As was obtained only when soil was treated with mixtures of phosphates and ferrous sulfate. Arsenic uptake by plants was also seen to increase when soil was treated only with phosphates, but co-addition of ferrous sulfate was efficient in maintaining As phytoaccumulation at low levels. The addition of at least 1.5M/M phosphates and 10M/M iron sulfate to soil reduced the dissolved levels of Pb and As in the water extracts to values in compliance with the EU drinking water standards. However, both additives contributed in the acidification of soil, decreasing pH from 7.8 to values as low as 5.6 and induced the mobilization of pH sensitive elements, such as Zn and Cd.

Everything in and on the Earth - mineral, animal and vegetable - is made from one, or generally some combination of, the natural chemical elements occurring in the rocks of the Earth’s crust and the surficial materials derived from them. Everything that is grown, or made, depends upon the availability of the appropriate elements. The existence, quality and survival of life depends upon the availability of elements in the correct proportions and combinations. Because natural processes and human activities are continuously modifying the chemical composition of our environment, it is important to determine the present abundance and spatial distribution of the elements across the Earth’s surface in a much more systematic manner than has been attempted hitherto” (Darnley et al., 1995). Although such a global database is urgently needed for multi-purpose use, the systematic attempt is still in its infancy because of the non-existence of a manual of comprehensive and standardised methods of sampling and other supporting procedures. The current ‘International Union of Geological Sciences Manual of Standard Methods for Establishing the Global Geochemical Reference Network’ fills this gap. The Manual follows the concept of 7356 Global Terrestrial Network grid cells of 160x160 km, covering the land surface of Earth, with five random sites within each grid cell for the collection of samples. This allows the establishment of the standardised Global Geochemical Reference Network with respect to rock, residual soil, humus, overbank sediment, stream water, stream sediment and floodplain sediment. Apart from the instructions for the collection of samples, the Manual covers sample preparation and storage, development of reference materials, geoanalytical methods, quality control procedures, geodetic and parametric levelling of existing geochemical data sets, data conditioning for the generation of time-independent geochemical data, management of data and map production, and finally project management. The methods described herein, apart from their use for Establishing the Global Geochemical Reference Network, can be used in other geochemical surveys at any mapping scale.