materiały: Calcium carbonate

Evidence: 100 • authority: 72

Calcium carbonate is a chemical compound with the chemical formula CaCO3. It is a common substance found in rocks as the minerals calcite and aragonite, most notably in chalk and limestone, eggshells, gastropod shells, shellfish skeletons and pearls. Materials containing much calcium carbonate or resembling it are described as calcareous. Naturally occurring calcium carbonate is important part of the carbon cycle, sequestering large amounts of carbon in geological formations. When acidic rain or water enters a natural deposit of calcium carbonate, it can lead to cave formation with stalactite and stalagmite. Calcium carbonate is the active ingredient in agricultural lime, an important ingre…

Evidence: 54 • authority: 72

Calcium bicarbonate, also called calcium hydrogencarbonate, has the chemical formula Ca(HCO3)2. The term does not refer to a known solid compound; it exists only in aqueous solution containing calcium (Ca2+), bicarbonate (HCO−3), and carbonate (CO2−3) ions, together with dissolved carbon dioxide (CO2). The relative concentrations of these carbon-containing species depend on the pH; bicarbonate predominates within the range 6.36–10.25 in fresh water. All waters in contact with the atmosphere absorb carbon dioxide, and as these waters come into contact with rocks and sediments they acquire metal ions, most commonly calcium and magnesium, so most natural waters that come from streams, lakes, a…

Evidence: 54 • authority: 88

Settings of cryogenic cave carbonate formation. Cryogenic cave carbonates (CCCs) and, more generally, cryogenic cave minerals, form by solute rejection mechanisms when water enters and freezes in caves, or parts of caves, at temperatures below the freezing point. Negative temperatures may occur in caves in conjunction with climatic factors ranging from seasonal (e.g., sag-type cave entrances or ventilated parts of caves) to millennial (development of permafrost in karst massifs) timescales. When using CCCs for paleoclimate reconstructions, it is important to understand the environment in which they were formed.Conventionally, two ‘end-members’ of cave microclimate settings are d…

Evidence: 47 • authority: 72

Limestone is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate CaCO3. Limestone forms when these minerals precipitate out of water containing dissolved calcium. This can take place through both biological and nonbiological processes, though biological processes, such as the accumulation of corals and shells in the sea, have likely been more important for the last 540 million years. Limestone often contains fossils which provide scientists with information on ancient environments and on the evolution of life. About 20% to 25% of sedimentary roc…

Evidence: 47 • authority: 88

Effect of calcium citrate in calcium carbonate nanoparticles on HK-2 cells in acidic environment. Metabolic acidosis exerts several cellular and tissue dysfunctions, such as increases mineral bone and protein degradation, induces inflammation, oxidative stress and cell death. These complications lead to multiple organ failure, including chronic kidney disease. Sodium bicarbonate and Shohl’s solution are commonly used to treat metabolic acidosis. However, these agents cause frequent gastrointestinal adverse effects. Hence, we invented the new calcium carbonate nanoparticles to use as a drug delivery system for carrying citrate to renal cell which we hypothesize to reduce adverse effects of m…

Evidence: 39 • authority: 80

Controlled Release of Oxygen from Calcium Peroxide in a Weak Acidic Condition by Stabilized Amorphous Calcium Carbonate Nanocoating for Biomedical Applications

Evidence: 39 • authority: 80

Threonine and Polythreonine Accelerate Calcium Carbonate Formation

Evidence: — • authority: 92

Negative pH, efflorescent mineralogy, and consequences for environmental restoration at the Iron Mountain Superfund site, California.. The Richmond Mine of the Iron Mountain copper deposit contains some of the most acid mine waters ever reported. Values of pH have been measured as low as -3.6, combined metal concentrations as high as 200 g/liter, and sulfate concentrations as high as 760 g/liter. Copious quantities of soluble metal sulfate salts such as melanterite, chalcanthite, coquimbite, rhomboclase, voltaite, copiapite, and halotrichite have been identified, and some of these are forming from negative-pH mine waters. Geochemical calculations show that, under a mine-plugging remediation…

Evidence: — • authority: 92

Microbial diversity in Pyrenean ice caves: extreme cryogenic environments as analogues for extraterrestrial habitability.. Pyrenean ice caves are the least studies cryogenic environments that preserve perennial ice. These caves host microbial communities adapted to extreme oligotrophy, low temperatures, and episodic water availability, making them valuable analogues for subsurface habitats on icy planetary bodies. This study investigated four ice caves in the Central Pyrenees (Devaux, Cotiella A294, Sarrios 1 and Somola SO-01) to (i) characterize bacterial and microeukaryotic assemblages, (ii) assess how ice origin, physicochemical gradients, and cave geology structure these communities, an…

Evidence: — • authority: 92

Shapes of ideal stalagmites.. Stalagmites are isolated columns of calcium carbonate growing on a cave floor; their growth is driven by the constant dripping of supersaturated solutions from the roof of the cave. In this paper, we derive a closed-form expression for the shape of a steadily growing stalagmite. Our analysis gives rise to three distinct shapes, all of them observable in nature, with the shape characterized by a single dimensionless parameter. Transitions between different shapes occur at a specific value of this parameter, with additional selection rules determining the shape and size of stalagmites evolving under specific cave conditions. Our theory shows that the stalagmite s…