ARTICLE | doi:10.20944/preprints202012.0207.v1
Subject: Earth Sciences, Atmospheric Science Keywords: air pollution; lung mineralization; magnesian calcite; calcite; amorphous calcium carbonate
Online: 8 December 2020 (17:15:33 CET)
For the first time, it is shown that inhaled ambient air-dust particles settled in the human lower respiratory tract induce lung calcification. Chemical- and mineral compositions of pulmonary calcium precipitates in the lung right lower-lobe (RLL) tissues of 12 individuals who lived in Upper Silesia Conurbation in Poland and who had died from causes not related to lung disorder were determined by transmission- and scanning electron microscopy. Whereas calcium salts in lungs are usually reported as phosphates, calcium salts precipitated in RLL are almost exclusively carbonates, i.e. Mg-calcite and calcite. These constitute 37% of 1652 mineral particles examined. Mg-calcite predominates in the submicron size range with the MgCO3 content up to 50 mol%. Magnesium plays a significant role in the lung mineralization, a fact so far overlooked. The calcium phosphate (hydroxyapatite) content in RLL is negligible. The predominance of carbonates is explained by increased CO2 fugacity in RLL. Carbonates enveloped inhaled mineral-dust particles, including uranium-bearing oxides, quartz, aluminosilicates, and metal sulfides. Three possible pathways for the carbonates precipitation on the dust particles are postulated: (1) precipitation of amorphous calcium carbonate (ACC) followed by its transformation to calcite; (2) precipitation of Mg-ACC followed by its transformation to Mg-calcite; (3) precipitation of Mg-free ACC causing a localized relative enrichment in Mg ions and subsequent heterogeneous nucleation and crystal growth of Mg-calcite. The actual number of inhaled dust particles may be significantly greater than observed because of the masking effect of the carbonate coatings. There is no simple correlation between smoking habit and lung calcification.
ARTICLE | doi:10.20944/preprints202012.0448.v1
Subject: Earth Sciences, Atmospheric Science Keywords: lead removal; calcite; gypsum; coprecipitation
Online: 18 December 2020 (08:39:09 CET)
Anthropogenic lead pollution is an environmental problem that threatens the quality of soils and waters and endangers living organisms in numerous surface and subsurface habitats. Lead coprecipitation on mineral surfaces through dissolution-recrystallization processes has long term effects on lead bioavailability. Gypsum and calcite are among the most abundant and reactive rock forming minerals present in numerous geological settings. In this work, we study the interaction of slightly acidic (pHi = 5.5) Pb-bearing aqueous solutions ([Pb]i = 1 mM and 10 mM) with crystals of gypsum and /or calcite under atmospheric conditions. This interaction results in a reduction of the concentration of lead in the liquid phase due to the precipitation of newly formed Pb-bearing solid phases. The extent of this Pb removal mainly depends on the nature of the primary mineral phase involved in the interaction. Thus, when gypsum is the only solid phase initially present in the system the Pb-bearing liquid-gypsum interaction results in Pb removals in the 98-99.8 % range, regardless of [Pb]i. In contrast, when the interaction takes place with calcite, Pb removal strongly depends on [Pb]i. It reaches 99% when [Pb]i = 1 mM while it is much more modest (⁓13%) when [Pb]i = 10 mM. Interestingly, Pb-removal is maximized for both [Pb]i (99.9 % for solutions with [Pb]i = 10 mM and 99.7% for solutions with [Pb]i = 1 mM) when Pb-polluted solutions simultaneously interact with gypsum and calcite crystals. Despite the large Pb removals found in most of the cases studied, the final Pb concentration ([Pb]f) in the liquid phase always is well above the maximum permitted in drinking water (0.1 ppm), with the minimum ([Pb]f = 0.7 ppm) being obtained for solutions with [Pb]i =1 mM after their interaction with mixtures of gypsum and calcite crystals. This result suggests that integrating the use of mixtures of gypsum-calcite crystals might help to develop more efficient strategies for in-situ decontaminating Pb-polluted waters through mineral coprecipitation processes.
REVIEW | doi:10.20944/preprints202104.0019.v1
Subject: Engineering, Civil Engineering Keywords: bioconcrete; microbes; biomineralization; self-healing; calcite precipitation
Online: 1 April 2021 (12:56:36 CEST)
The advancement of bioconcrete over cementitious composites has brought us to the application of microbes in the field of construction materials. Certain microbes like bacteria, algae, and fungi have been discussed in the review. The purpose of applying these microbes in the matrix is mainly to enhance the concrete’s strength and other properties such as durability, resistance, and self-healing ability. As these microbes are able to induce calcite biomineralizations, the process is also known as Microbiologically Induced Calcite Precipitation (MICP). Some known microorganisms with their mentioned ability are Bacillus subtilis and Bacillus cohnii (bacteria), Chlorella vulgaris and Spirulina platensis (algae), and Trichoderma reesei, Aspergillus niger, and Neurospora crassa (fungi). The paper provides a “state-of-the-art” review of research into the effects of bioconcrete and discusses the overall methodologies of every medium with their physiological, physicochemical and bioengineering properties in the light of recent researches done so far in the same field.
ARTICLE | doi:10.20944/preprints201803.0188.v1
Subject: Earth Sciences, Geochemistry & Petrology Keywords: recycled aggregates; cement paste; carbonation; calcite; pH
Online: 21 March 2018 (07:52:05 CET)
In this study, four samples of recycled aggregates from construction and demolition waste of Mexico City were characterized, in order to find innovative uses for this type of materials. Gravel and sand from a recycling plant were analyzed, as well as recycled aggregates in the laboratory from demolished concrete collected in landfills. The characterization was carried out by means of XRD, chemical microanalysis (EDS), pH measurement and sieve analysis. The results reveal that the minerals present in the analyzed materials are triclinic feldspars, cristobalite and pyroxene which correspond to the natural aggregates, as well as variable amounts of calcite, product of the carbonation of the cement paste adhered to these aggregates and in a smaller proportion calcium hemicarboaluminate, rosenhanite and tobermorite. It was determined that the quality (amount of cement) of the original concrete that was recycled, has great influence on the granulometry and the chemical-mineralogical composition of the aggregates, since there will be different quantities and qualities of cement paste adhered to the aggregates of according to size. Finally the pH values measured in all samples fluctuate between 10.15 and 12.08, therefore it is suggested that these materials can be used in soil stabilization.
ARTICLE | doi:10.20944/preprints201708.0028.v1
Subject: Physical Sciences, Condensed Matter Physics Keywords: crystal growth; calcite; microfluidic; nanoconfinement; reflection interference contrast microscopy.
Online: 8 August 2017 (08:09:11 CEST)
Slow growth of calcite in confinement is abundant in Nature and man made materials. There is ample evidence that such confined growth may create forces that fracture solids. The thermodynamic limits are well known but since confined crystal growth is transport limited and difficult to control in experiment we have almost no information on the mechanisms or limits of these processes. We present a novel approach to in situ study of confined crystal growth using microfluidics for accurate control of the saturation state of the fluid and interferometric measurement of the topography of the growing confined crystal surface. We observe and explain the diffusion limited confined growth structures observed and can measure the crystal "floating" on a fluid film of 10-40~nm thickness due to the disjoining pressure. We find that there are two end member behaviours: smooth or intermittent growth in the contact region, the latter being faster than the former.
CASE REPORT | doi:10.20944/preprints202110.0047.v1
Subject: Earth Sciences, Geophysics Keywords: shock waves; mechanism and dynamics of destruction; quartz; granites; calcite
Online: 4 October 2021 (11:03:20 CEST)
The spectra of the plasma emitted from the studied samples consist of several dozens of narrow bands superimposed on each other. Tables of spectral lines were used to interpret the spectra. It turned out that the largest number of bands corresponds to the radiation of positively charged ions and atoms of elements that make up the crystal lattices of minerals that make up the studied rocks. Thus, the spectra of the plasma emitted from quartz corresponded to the radiation of atoms and positively charged silicon ions, the charge of which varied from 1 to 4, as well as atoms and positively charged oxygen ions, the charge of which varied from 1 to 3. Positively charged ions and atoms of Si, O, K, Ca, Al and Na, which are part of the crystal lattices of quartz and feldspar, flew out of granites. Positively charged ions and Ca, C and O atoms flew out of the calcite.
ARTICLE | doi:10.20944/preprints201802.0173.v1
Subject: Earth Sciences, Other Keywords: flooded chalk; Raman spectroscopy; enhanced oil recovery; carbonates; calcite; magnesite
Online: 27 February 2018 (04:59:33 CET)
Understanding the chalk-fluid interactions and the associated mineralogical and mechanical alteration at sub-micron scale are major goals in Enhanced Oil Recovery. Mechanical strength, porosity, and permeability of chalk are linked to mineral dissolution that occurs during brine injections, and affect the reservoir potential. This paper presents a novel "single grain" methodology to recognize the varieties of carbonates in rocks and loose sediments: Raman spectroscopy is a non-destructive, quick, and user-friendly technique representing a powerful tool to identify minerals down to 1 µm. An innovative working technique for oil exploration is proposed, as the mineralogy of micron-sized crystals grown in two flooded chalk samples (Liége, Belgium) was successfully investigated by Raman spectroscopy. The drilled chalk cores were flooded with MgCl2 for c. 1.5 (Long Term Test) and 3 years (Ultra Long Term Test) under North Sea reservoir conditions (Long Term Test: 130°C, 1 PV/day, 9.3 MPa effective stress; Ultra Long Term Test: 130°C, varying between 1-3 PV/day, 10.4 MPa effective stress). Raman spectroscopy was able to identify the presence of recrystallized magnesite along the core of the Long Term Test up to 4 cm from the injection surface, down to the crystal size of 1-2 µm. In the Ultra Long Term Test core the growth of MgCO3 affected nearly the entire core (7 cm). In both samples, no dolomite or high-magnesium calcite secondary growth could be detected when analysing 557 and 90 Raman spectra on the Long and Ultra Long Term Test, respectively. This study can offer Raman spectroscopy as a breakthrough tool in petroleum exploration of unconventional reservoirs, due to its quickness, spatial resolution, and non-destructive acquisition of data. These characteristics would encourage its use coupled with electron microscopes and energy dispersive systems or even electron microprobe studies.
ARTICLE | doi:10.20944/preprints201911.0048.v2
Subject: Earth Sciences, Geology Keywords: calcite; seismic anisotropy; texture; CPO; thrust; shear zone; neutron diffraction; crust
Online: 24 December 2019 (11:03:19 CET)
Eight samples of limestones and marbles were studied by neutron diffraction to collect 2 Quantitative Texture (i.e., Crystallographic Preferred Orientations or CPO) of calcite deforming at 3 different depths in the crust. We studied the different Texture patterns developed in shear zones at 4 different depth and their influence on seismic anisotropies. Samples were collected in the French and 5 Italian Alps, Apennines, and Paleozoic Sardinian basement. They are characterized by isotropic to 6 highly anisotropic (e.g., mylonite shear zone) fabrics. Mylonite limestones occur as shear zone horizons 7 within the Cenozoic Southern Domain in Alpine thrust-and-fold belts (Italy), the Briançonnais domain 8 of the Western Alps (Italy-France border), the Sardinian Paleozoic back-thrusts or in the Austroalpine 9 intermediate units. The analyzed marbles were collected in the Carrara Marble, in the Austroalpine Units 10 in the Central (Mortirolo) and Western Alps (Valpelline). The temperature and depth of development of fabrics vary from < 100◦C, to 800◦C and depth from <10 km to about 30 km, corresponding from upper 12 to lower crust conditions. Quantitative Texture Analysis shows different types of patterns for calcite: 13 random to strongly textured. Textured types may be further separated in orthorhombic and monoclinic 14 (Types A and B), based on the angle defined with the mesoscopic fabrics. Seismic anisotropies were 15 calculated by homogenizing the single crystal elastic tensor, using the Orientation Distribution Function 16 calculated by the Quantitative Texture Analysis. The resulting P- and S-waves anisotropies show a wide 17 variability due to the textural types, temperature and pressure conditions, and dip of the shear planes.
ARTICLE | doi:10.20944/preprints201801.0172.v1
Subject: Materials Science, Biomaterials Keywords: amyloids; Gad m 1, EF-hand motif, calcium carbonate precipitation, calcite
Online: 18 January 2018 (15:13:24 CET)
Acid proteins capable of nucleating Ca2+ and displaying aggregation capacity play key roles in the formation of calcium carbonate biominerals. EF-hands are among the largest Ca2+-binding motif in proteins. Gad m 1, an Atlantic cod β-parvalbumin isoform, is a monomeric EF-hand protein that acts as a Ca2+ buffer in fish muscle and is able to form amyloids under acidic conditions. Since nucleating Ca2+ protein have a propensity to form extended β-strand structures, we wondered whether amyloid assemblies of a protein containing refolded EF-hand motifs were able to influence the in vitro calcium carbonate crystallization. Here we have used the Gad m 1 chain as model to generate monomeric and amyloid assemblies and analyze their effect on in vitro calcite formation. We found that only amyloid assemblies alter calcite morphology.
ARTICLE | doi:10.20944/preprints201809.0551.v1
Subject: Earth Sciences, Geochemistry & Petrology Keywords: : silicocarbonatite; melteigite; calcite; nepheline; zeolite group minerals; garnet; crystal fractionation; Breivikbotn; Northern Norway
Online: 27 September 2018 (17:37:30 CEST)
The present work reports new mineralogical and whole rock geochemical data from the Breivikbotn silicocarbonatite (Seiland igneous province, North Norway), allowing conclusions to be drawn concerning its origin and the role of late fluid alteration. The rock shows a rare mineral association: calcite + pyroxene + amphibole + zeolite group minerals + garnet + titanite, with apatite, allanite, magnetite and zircon as minor and accessory minerals, and it is classified as silicocarbonatite. Calcite, titanite and pyroxene (Di36-46 Acm22-37 Hd14-21) are primarily magmatic minerals. Amphibole of hastingsitic composition has formed after pyroxene at a late-magmatic stage. Zeolite group minerals (natrolite, gonnardite, Sr-rich thomsonite-(Ca)) were formed during hydrothermal alteration of primary nepheline by fluids/solutions with high Si-Al-Ca activities. Poikilitic garnet (Ti-bearing andradite) has inclusions of all primary minerals, amphibole and zeolites, and presumably crystallized metasomatically during a late metamorphic event (Caledonian orogeny). Whole rock chemical compositions of the silicocarbonatite differs from the global average of calciocarbonatites by elevated silica, aluminium, sodium and iron, but show comparable contents of trace elements (REE, Sr, Ba). Trace element distributions indicate within-plate tectonic setting of the carbonatite. The spatial proximity of carbonatite and alkaline ultramafic rock (melteigite), the presence of “primary nepheline” in carbonatite together with the trace element distributions indicate that the carbonatite was derived from crystal fractionation of a parental carbonated foidite magma. The main prerequisites for the extensive formation of zeolite group minerals in silicocarbonatite are revealed.
ARTICLE | doi:10.20944/preprints202207.0352.v1
Subject: Engineering, Civil Engineering Keywords: Calcareous sand; Microbially induced calcite precipitation; Dynamic shear modulus; Resonant column test; Reference shear strain
Online: 25 July 2022 (05:56:36 CEST)
Calcareous sand deposits are widely distributed along the shoreline in ropical and subtropical regions. Microbially induced calcite precipitation treatment (MICP) is a relatively new method to improve the stiffness and strength of the soil. Little is known about the small-strain shear modulus and damping ratio of MICP-treated calcareous sand, which are two crucial parameters for the prediction of the dynamic behavior of soil. A series of resonant column tests are performed to investigate the dynamic performance of MICP-treated calcareous sand, with special attention paid to the influence of treatment duration and confining stress on the stiffness and damping characteristics. The relationship between the initial dynamic shear modulus and unconfined compressive strength is analyzed. Additionally, the empirical equations of the reference shear strain between treatment duration and confining stress are given. The G/G0 of MICP-cemented calcareous sand presents a higher strain sensitivity than that of untreated sand, and its attenuation pattern can be described by Hardin-Drnevich model. The σc has an apparent effect on the degradation characteristics of the dynamic shear modulus of MICP-treated calcareous sand with a low cementation level, however, its effect decreases with the increasing treatment duration. The relationship between the reference shear strain and the treatment duration and confining stress can be described by a power and a linear formula, respectively.
ARTICLE | doi:10.20944/preprints201911.0008.v1
Subject: Engineering, Civil Engineering Keywords: hydroxyapatite; calcite; vivianite; onsite wastewater treatment; phreeqc; precipitation; groundwater contamination; septic tank; drainfield; reactive filter
Online: 1 November 2019 (11:21:52 CET)
The objective of this work was to evaluate the removal of phosphorus and carbon dioxide capture of a conventional septic system upgraded with a sidestream steel slag filter used in recirculation mode. A pilot scale sidestream experiment was conducted with two septic tank and drainfield systems, one with and one without a sidestream slag filter. The experimental system was fed with real domestic wastewater. Recirculation ratios of 25%, 50% and 75% were tested. Limestone soils and silica soils were used as drainfield media. The phosphorus removal efficiency observed in the second compartment of the septic tank was 30% in the slag filter upgraded system, compared to -3% in the control system. The drainfield of silica soils achieved very high phosphorus removal in both control and upgraded systems. In the drainfield of limestone soil, the slag filtration reduced the groundwater phosphorus contamination load by up to 75%. Phosphorus removal in the septic tank with a slag filter was attributed to either sorption on newly precipitated calcium carbonate or precipitation of vivianite, or both. Recirculation ratio design criteria were proposed based on simulations. Simulations showed that the steel slag filter partly inhibited biological production of carbon dioxide in the septic tank. The influent alkalinity strongly influenced the recirculation ratio needed to raise the pH in the septic tank. The control septic tank produced carbon dioxide, whereas the slag filter upgraded septic tank was a carbon dioxide sink.
ARTICLE | doi:10.20944/preprints201905.0387.v1
Subject: Earth Sciences, Environmental Sciences Keywords: high resolution, endogenic varves, calcite precipitation, pollen sedimentation, meromixis, freshwater glycerol dialkyl tetraether, subfossil pigments, long-term ecology
Online: 31 May 2019 (11:20:30 CEST)
In the Quaternary paleosciences, the rationale behind analogical inference presupposes that former natural changes can be explained by causes operating now, although their intensity and rates can vary through time. In this paper we synthesise synthetize the results of different modern analog studies and discuss their value to obtain the best inferences from high resolution past records. This synthesis is based on the following: 1) The monthly monitoring of calcite precipitation reveals a strong connection with primary producers and between-years variability; this precipitation produces a seasonal signal with imprint on varve formation. 2) Clear pollen sedimentation peaks occur in spring/summer and fall/winter that coincide with temperature, precipitation, relative humidity and winds; this pattern converges with the two-layer coupled varves representing the same seasonality. 3) We assess the lake’s contemporary oxygenation dynamics over a three- year period; a combination of sedimentary REDOX proxies revealed different scenarios of oxic/anoxic shifts since 1500 CE. 4) We investigate presence of seasonality in the production/distribution of glycerol dialkyl glycerol tetraethers and derived temperature estimates in soils and particulate matter. Branched glycerol dialkyl glycerol tetraethers signatures and some derived temperature estimates proxies appear to mainly depend on the non-seasonal shifts in soil properties. 5) Currently we examine relationships and similarities between extant phytoplankton and derived pigments in water and traps, and their correspondence with subfossil pigments; some preliminary results are presented here.Keywords: high resolution, endogenic varves, calcite precipitation, pollen sedimentation, meromixis, freshwater glycerol dialkyl tetraether, subfossil pigments, long-term ecology.