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BACKGROUND: Nutrient recovery from wastewater is gaining attention in the frame of circular economy. In this study, Ca(OH)2-treated zeolite (CaT-Z), lignite fly ash (FA) and zeolitic fly ash (ZFA) were primarily used to adsorb phosphate phosphorus (PO4-P) from anaerobically digested olive mill wastewater (ADOMW). The simultaneous recovery of potassium (K) was also examined based on adsorption and desorption data. The fractionation of adsorbed P was determined as an important parameter for its plant availability. RESULTS: More P was adsorbed from ADOMW on ZFA and FA (up to 4.35 and 5.21 mg g−1, respectively) than on CaT-Z (2.62 mg g−1). An increased P adsorption on ZFA and FA was observed between incubation times of 7 and 14 days. The sequential desorption procedure verified the trend of P adsorption capacities and showed that the plant-available P (NaHCO3-P) amounted to 1.34, 2.34 and 1.69 mg g−1 CaT-Z, ZFA and FA, respectively. After 14 days, CaT-Z and ZFA adsorbed much more K (19.2 and 20.5 mg g−1, respectively) than FA (4.3 mg g−1). The desorption of exchangeable K confirmed this difference. Scanning electron microscopy–energy dispersive spectrometry analyses indicated P adsorption and surface precipitation as Ca–P phases as well as K+ for Ca2+ ion exchange on the loaded adsorbents. CONCLUSIONS: ZFA was more efficient for dual adsorption combining the properties of the zeolitic fraction (enhanced K adsorption) and pristine FA (P adsorption on Ca-bearing phases). The sufficient concentrations of plant-available P and K on the three adsorbents suggest their potential use as soil amendments. © 2022 Society of Chemical Industry (SCI). © 2022 Society of Chemical Industry (SCI).

Phosphate minerals (e.g., apatite (Ca₅[PO₄]₃[OH,Cl,F]), merrillite (Ca₉NaMg[PO₄]₇)) are emerging as crucial tools in the investigation of extraterrestrial volatile, thermal, and collisional histories. However, the mechanisms involved in the formation (and deformation/destruction) of phosphate minerals in primitive meteorites remain unclear, hindering our ability to confidently interpret an important record of chemical, isotopic, and structural information. Here, we provide further observations and arguments in support of a key role for olivine in the paragenesis of P-bearing phases in chondrites.

Ordinary chondrites record impact-related features, including high-pressure (HP) minerals, usually occurring in melt veins (MVs), yielding constraints on shock conditions and hence parameters such as the size of colliding bodies, impact velocity, etc. Here, we report the first observations of HP mineral polymorphs in the recent L6 chondrite fall of Viñales (Cuba, 1st February 2019; proposed shock stage S3 [1] and partly S4 [2]). The investigated thin section shows at least nine major, subparallel, MVs (50-600 μm wide) and a few thinner MVs at an angle to these. It is unclear whether they are of a single or multiple generations. We have so far identified, within a single melt vein, a region hosting the HP polymorphs majorite and albitic jadeite. These observations define a definite pressure range for this meteorite and contribute to the shock record of the L-chondrites in general.

In order to study the geomorphological and environmental characteristics of St. George bay, in western Naxos, Greece, a series of beachrock samples were examined. Special attention was given to the cement, to obtain information about the formation conditions of the beachrocks. In order to examine the cement of the beachrock samples, the methods of optical microscopy, secondary electron microscopy (SEM) and Raman Spectroscopy were used. The results of the beachrock samples analyses indicate that their formation took place under meteoric and marine vadose zone conditions. Certain characteristics relating to the composition and structure of the cement, sug-gest that the development of the beachrocks took place during sea level rise. © 2021 Gebr. Borntraeger Verlagsbuchhandlung, Stuttgart, Germany.

We investigate the potential to use concentrations and zoning patterns of phosphorus (P) in clinopyroxene as indicators of the rates of igneous and metasomatic processes, comparable to recent applications of P in olivine but applicable to more evolved rocks and lower temperatures of crystallization. Few high-P pyroxenes have been previously reported, and none have been analyzed in detail for the mechanism of P enrichment or the implications for mineral growth kinetics. Here, we report the discovery and characteristics of exotic phosphorus-rich secondary clinopyroxene in glassy pockets and veins in composite mantle xenoliths from the Cima Volcanic Field (California, USA) and the Middle Atlas Mountains (Morocco, West Africa). These glass-bearing xenoliths preserve evidence of melt infiltration events and the contrasting behavior of P in their pyroxene crystals constrains the different rates of reaction and extents of equilibration that characterized infiltration in each setting. We report optical petrography and chemical analysis of glasses and minerals for major elements by electron microprobe microanalyzer and trace elements by laser-ablation Inductively Coupled Plasma Mass Spectrometry. The Cima Volcanic Field specimen shows one end-member behavior, with unzoned P-rich clinopyroxene in a melt pocket. We attribute this occurrence to a slow crystallization process that occurred after the melt temperature reached near-equilibrium with the host rock and during which the P concentration in the melt was buffered by apatite saturation. In the Morocco xenolith, by contrast, clinopyroxene exhibits zonation with P increasing all the way to the rim, in contact with the glass. We ascribe this feature to a rapid growth process in which excess P was incorporated into the growing clinopyroxene from a diffusive boundary layer. We demonstrate quantitative agreement between the enrichment of P and other trace elements and their expected diffusion and partitioning behavior during rapid growth. We suggest that P has not been widely reported in clinopyroxene in large part because it has rarely been looked for and that its analysis offers considerable promise as a kinetic indicator both in xenoliths and volcanic rocks. © 2019 Elsevier Ltd

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. © 2019 Elsevier B.V.

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 87Sr/86Sr = 0.70906 to 0.7106, εNd(t) = − 5.9 to − 7.5 and δ18Οqtz = + 10 to + 10.6‰, whereas the marginal zone (or border facies) has higher initial 87Sr/86Sr = 0.711 to 0.7112, lower εNd(t) = − 7.3 to − 8.3, and higher δ18Οqtz = + 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% SiO2). 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 SiO2 ≥ 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. © 2017, Springer-Verlag GmbH Germany, part of Springer Nature.

The color of quartz and other minerals can be either caused by defects in the crystal structure or by finely dispersed inclusions of other minerals within the crystals. In order to investigate the mineral chemistry and genesis of the famous prase (green quartz) and amethyst association from Serifos Island, Greece, we used electron microprobe analyses and oxygen isotope measurements of quartz. We show that the color of these green quartz crystals is caused by small and acicular amphibole inclusions. Our data also shows that there are two generations of amphibole inclusions within the green quartz crystals, which indicate that the fluid, from which both amphiboles and quartz have crystallized, must have had a change in its chemical composition during the crystallization process. The electron microprobe data also suggests that traces of iron may be responsible for the amethyst coloration. Both quartz varieties are characterized by isotopic compositions that suggest mixing of magmatic and meteoric/marine fluids. The contribution of meteoric fluid is more significant in the final stages and reflects amethyst precipitation under more oxidizing conditions. © 2018 by the authors. Licensee MDPI, Basel, Switzerland.

We evaluate the petrography and geochemistry of an unusual suite of subduction-related Phanerozoic high-MgO rocks from the Othris ophiolite complex in Greece, some of which have previously been described as komatiitic lavas. In particular, we study ultramafic, olivine-phyric lavas from the Agrilia area and high-Mg basaltic dykes from the Pournari area. We seek to define primary magmatic MgO contents and initial liquidus temperatures as well as the differentiation sequence and cooling rates experienced by the lavas and dykes. One of our goals is to relate the Othris case to known komatiite and boninite occurrences and to address whether Othris documents an important new constraint on the temporal evolution of ambient mantle temperature, plume-related magmatism, and subduction of oceanic lithosphere. We conclude that, despite whole-rock MgO contents of 31–33 wt%, the olivine-phyric lavas at Agrilia had an upper limit liquid MgO content of 17 wt% and are therefore picrites, not komatiites. The Agrilia lavas contain the unusual Ti-rich pyroxenoid rhönite; we discuss the significance of this occurrence. In the case of the Pournari high-Mg dykes, the distinctive dendritic or plumose clinopyroxene texture, though it resembles in some ways the classic spinifex texture of komatiites, is simply evidence of rapid cooling at the dyke margin and not evidence of extraordinarily high liquidus temperatures. We correlate the dendritic texture with disequilibrium mineral chemistry in clinopyroxene to constrain the cooling rate of the dyke margins. © 2017 Elsevier B.V.

We studied the effects of water quality on the hydration of quicklimes prepared from calcitic limestone and dolomitic limestone during calcination at 1050 °C. At a low total chloride and sulfate content, reactivity is insensitive to concentration and no effect on quicklime slaking is seen. At higher concentrations, however, we observe a chromatographic effect for chlorides and sulfates. Concentrated chlorides react with the slaking water, forming products such as CaCl2 that are much more soluble than Ca(OH)2, which facilitates transformation of quicklime to slaked lime. In the range of sulfate concentrations in natural waters we observed no effect of sulfates during quicklime hydration. Consequently, in natural waters and their mixtures (conductivity < 2600 μS cm-1), only chloride concentrations are found to promote quicklime hydration. These results suggest that water treatment technologies, applied to natural light brackish water compositions, will not lead to quality improvement for lime-industry products. This journal is © The Royal Society of Chemistry 2016.