Fossil coral is an excellent archive to extend the radiocarbon (C) calibration beyond tree-ring records; however, published coral data older than 26,000 years before present are too disparate for practical calibration. We propose an explanation for these discrepancies: trace amounts of secondary calcite and organic matter in fossil corals shift the C ages toward younger ages. In a series of aci...

Coccoliths are micrometer scale shields made from 20 to 60 individual calcite (CaCO(3)) crystals that are produced by some species of algae. Currently, coccoliths serve as an important sink in the global carbon cycle, but decreasing ocean pH challenges their stability. Chalk deposits, the fossil remains of ancient algae, have remained remarkably unchanged by diagenesis, the process that convert...

Calcite cement is the dominant control on reservoir quality in turbidite sandstones of the Upper Permian Bell Canyon Formation, Delaware Basin. These well-sorted, very fine-grained arkoseswere deposited in a basin-floor setting by channel-levee systems terminating in broad lobes. Calcite cement distribution in the East Ford and Geraldine Ford fields was mapped using core, log, and thin-section ...

This paper examines the potential for calcium carbonate to reduce phosphate pollution in freshwaters by co-precipitation, a process known as a “self cleansing mechanism”. Calcium carbonate saturation levels and phosphate concentrations (SRP soluble reactive phosphate) across the major eastern UK river basins are examined to test for solubility controls. The study shows that calcite saturation v...

Field emission scanning electron microscopy (FESEM), two-dimensional X-ray diffraction (2DXRD), and transmission electron microscopy coupled with selected area electron diffraction (TEMSAED) analyses of the reactant/product textural relationship show that the thermal decomposition of Iceland spar single crystals according to the reaction CaCO3(s) → CaO(s) + CO2(g) is pseudomorphic and topotacti...

Wollastonite (CaSiO3; CSi) ceramic is a promising bioactive material for bone defect repair due to slightly fast degradation of its porous constructs in vivo. In our previous strategy some key features of CSi ceramic have been significantly improved by dilute magnesium doping for regulating mechanical properties and biodegradation. Here we demonstrate that 6 ~ 14% of Ca substituted by Mg in CSi...

Abstract: Fluorite is an important strategic mineral. In general, fluorite ores will contain a certain amount of calcite gangue mineral. Thus, they need to be separated from each other. For an economic separation, a reverse flotation process is used to float calcite gangue from fluorite. However, little information on the separation is available. In this study, a novel reagent schedule using ci...

Paleotemperature reconstructions rely on knowledge of the equilibrium separation of oxygen isotopes between aqueous solution and calcium carbonate. Although oxygen isotope separation is expected on theoretical grounds, the temperature-dependence remains uncertain because other factors, such as slow exchange of isotopes between dissolved CO2-species and water, can obscure the temperature signal....

Metabolites and residual compounds from pharmaceutic industry are considered as emerging contaminants an increasing source of environmental pollution, they used by a quantity people, due to their physicochemical properties, easily transported hydrological systems bodies water. Then, the elimination this kind water adsorption is one most promising techniques. The aim research was study kinetic i...

Based on oxygen (O2), pH, calcium (Ca2+), and carbonate (CO 22 3 ) sediment pore-water concentration profiles, we compare the benthic dissolution of autochthonous calcite in oligotrophic Lake Lucerne and eutrophic Lake Sempach. Despite their difference in trophic state, the two lakes have similar benthic O2 regimes because L. Sempach is artificially oxygenated. This peculiarity enabled the stud...