Pelagic micritic limestones within an upper Cretaceous accretionary complex in the Tavşanlı Zone, NW Turkey, preserve textures indicating incomplete prograde transformation of micritic calcite to aragonite, representing the only known example of this type. Aragonitization starts at the central parts of the micritic limestone beds and advances towards the lower and upper parts of the layers at t...

Introduction: The Mars Express OMEGA imaging spectrometer recently identified clay minerals (nontronite and montmorillonite) in several outcrops of Noachian age [1]. Clay minerals usually result from long term alteration of primary minerals by liquid water and on Earth are usually the products of weathering processes. The presence of clay minerals suggests a primary environment completely diffe...

rganic matter and clay miner0 als in soils have negatively charged surfaces that act much like cation exchange resins. When more than 15% of the exchange sites are neutralized by Na+ and the final ionic strength of the aqueous extract is less than about 0.04 M, the clays and organic matter are dispersed. Under these conditions, the solution pH is usually greater than 8.4, and carbonate (COi-) a...

Tailings produced during bitumen extraction from surface-mined oil sands ores (tar sands) comprise an aqueous suspension of clay particles that remain dispersed for decades in tailings ponds. Slow consolidation of the clays hinders water recovery for reuse and retards volume reduction, thereby increasing the environmental footprint of tailings ponds. We investigated mechanisms of tailings conso...

This work highlights the preparation of ceramic membranes from a low-cost naturally occurring clay material viz. red mud. Additives like sodium carbonate, sodium metasilicate and boric acid was added in standard stoichiometric ratio with the processed clay material, imparting characteristic properties. Paste casting method was followed for fabricating circular disc shaped membranes with 50 mm× ...

Abstract The Salar de Llamara, Atacama Desert is host to saline lakes known as Puquios, which are possible analogs for on early Earth or Mars. Here we examine associations between microbial communities, Mg-clay minerals, and carbonates in mat samples from the Puquios using scanning electron microscopy, energy dispersive X-ray spectroscopy, focused ion beam nanotomography, transmission microscop...

Effects of dissolved carbonate on arsenate [As(V)] reactivity and surface speciation at the hematite-water interface were studied as a function of pH and two different partial pressures of carbon dioxide gas [P(CO2) = 10(-3.5) atm and approximately 0; CO2-free argon (Ar)] using adsorption kinetics, pseudo-equilibrium adsorption/titration experiments, extended X-ray absorption fine structure spe...

Despite over a century of study and decades of intensive research, few fuel cell products have appeared on the market. The major inhibitor to mass commercialisation is cost. H2/air alkaline fuel cells (AFCs) containing KOH(aq) electrolyte promise the lowest cost devices, with the ability to use non-Pt catalysts. The fundamental problem with AFCs is that the KOH(aq) electrolyte reacts with CO2 (...