Applications of speleothem calcite geochemistry in climate change studies require the evaluation of the accuracy and sensitivity of speleothem proxies to correctly infer paleoclimatic information. The present study of Harrison’s Cave, Barbados, uses the analysis of the modern climatology and groundwater system to evaluate controls on the C and O isotopic composition of modern speleothems. This ...

Adsorption of uranyl at the surface of calcite was investigated by using batch sorption experiments and synchrotron X-ray standing wave (XSW) measurements. Aqueous solutions containing 236U(VI) (4.5 x 10(-7) to 1.0 x 10(-4) M) and EDTA (5.0 x 10(-7) to 1.1 x 10(-4) M) were reacted for 90 s to 60 min with freshly cleaved calcite (104) surfaces and calcite powders. Surface exchange coefficients, ...

Often when calcite is found as a component of urinary calculi, they are considered false calculi or artifacts. We present a case of true calcite urolithiasis. The stone material was removed percutaneously from a severely malnourished anorectic woman and analyzed by infrared spectroscopy (IRS). In addition, calcite urolithiasis was confirmed in several recurrent stone events by IRS. Laxative abu...

The combined effect of templating and solution additives on calcite crystallization was studied. Self-assembled monolayers of mercaptoundecanoic acid supported on silver, as templates, induced the uniform, oriented nucleation of calcite from the (012) plane. The presence of Mg2+ in the crystallizing solution affected the crystal growth dramatically, due to the selective Mg binding to the calcit...

Calcium carbonate (CaCO3) occurs in two major polymorphs: rhombohedral calcite and orthorhombic aragonite, the latter is thermodynamically metastable. In this study, we first prepared aragonite needle-like particles by introducing CO2-containing gas into Ca(OH)2 aqueous slurry. Then, the resulted aragonite particles were heat treated at 500 ◦C for 1 h, in order to induce the aragonite–calcite p...

In this study, calcium carbonate crystals were obtained by mixing of calcium chloride and sodium carbonate in the presence of biopolymer, carboxymethyl inulin (CMI). The effect of the feed rate of reactant and the initial [Ca] concentration was investigated. The produced calcium carbonate (CaCO3) crystals were characterized by scanning electron microscopy (SEM), Fourier transform infrared spect...

Isotopic analyses of subglacially precipitated calcite from near a modern temperate glacier show that the delta(18)O (= (18)O/(16)O relative to standard mean ocean water) of the calcite records the delta(18)O of the ice from that glacier. It may therefore be possible to determine the delta(18)O of Pleistocene ice sheets on the basis of isotopic analyses of calcite formed under that ancient ice....

Dolomite or calcite, quartz and kaolinite in various proportions were reacted at 250-300~ temperatures and pressures up to 90 bars in a hydrous environment. Reactions which approached completion produced talc, calcite, montmorillonite, anorthite (both metastable hexagonal and stable triclinic polymorphs) and the rare Ca-zeolite, garronite. These reactions are applicable to diagenesis, low-grade...

After nuclear accident in 2011, incineration residue contaminated by radioactive cesium had been produced. Government decided in 2011 that incineration residue with less than 8000 Bq/kg of radioactivity could be disposed of into conventional MSW landfill. Since radioactivity of bottom ash was reported to be low compared with fly ash, it had been disposed of MSW landfill based on the government ...

Images reproduced by permission of Lia Addadi (outside) and James De Yoreo (inside) Other papers published in this issue include: Molecular dynamics simulations of the interaction of citric acid with the hydroxyapatite (0001) and (01-10) surfaces in an aqueous environment Calcite shape modulation through the lattice mismatch between the self-assembled monolayer template and the nucleated crysta...