نتایج جستجو برای: carbonate species
تعداد نتایج: 571248 فیلتر نتایج به سال:
The aim of this paper is to review recent literature regarding the determination of phosphorus species by ion chromatography (IC), and describe the implementation of new developments in sample treatment and ion chromatography methodology for the analysis of these compounds. Ion-exchange methods using both carbonate/hydrogencarbonate and hydroxide selective columns in combination with self-regen...
Anthropogenic ocean acidification threatens to negatively impact marine organisms that precipitate calcium carbonate skeletons. Past geological events, such as the Permian-Triassic Mass Extinction, together with modern experiments generally support these concerns. However, the physiological costs of producing a calcium carbonate skeleton under different acidification scenarios remain poorly und...
Anthropogenic CO(2) is reducing the pH and altering the carbonate chemistry of seawater, with repercussions for marine organisms and ecosystems. Current research suggests that calcification will decrease in many species, but compelling evidence of impaired functional performance of calcium carbonate structures is sparse, particularly in key species. Here we demonstrate that ocean acidification ...
A series of porphyrin metal(III) compounds of general formula LMX (where L = tetraphenylporphyrin, tetrakispentafluorophenylporphyrin and octaethylporphyrin, M = Al, Cr, Co, and X = Cl and OEt) has been synthesized and studied as catalysts for the ring opening polymerization of propylene oxide (PO) as well as copolymerization of PO with CO2 to produce polypropylene oxide (PPO), polypropylene ca...
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...
In several recent models of invertebrate skeletogenesis, Ca-carbonate crystallization occurs within a liquid-filled chamber. No explanation is given neither for the simultaneous occurrence of distinct polymorphs of Ca-carbonate within these liquid volumes, nor for the spatial arrangement of the mineral units which are always organized in species-specific structural sequences. Results of a serie...
Plankton manipulation experiments exhibit a wide range of sensitivities of biogenic calcification to simulated anthropogenic acidification of the ocean, with the “lab rat” of planktic calcifiers, Emiliania huxleyi apparently not representative of calcification generally. We assess the implications of this observational uncertainty by creating an ensemble of realizations of an Earth system model...
Magnesium-ion conducting gel polymer electrolytes (GPEs) based on PMMA with ethylene carbonate (EC) and propylene carbonate (PC) as a plasticizing solvent were prepared via the solution casting technique. Mg(CF3SO3)2 salt was used as source of magnesium ions, Mg 2+ . The variation of conductivity with salt concentrations, from 5 wt.% to 30 wt.% was studied. The gel polymer electrolyte with comp...
The reaction mechanism for the synthesis of cyclic carbonates from carbon dioxide and epoxides catalyzed by a zinc pyrrolidine complex has been elucidated using the density functional level of theory. The obtained potential energy surface shows that the recently proposed zinc complex is able to efficiently and selectively catalyze the formation of cyclic carbonate using carbon dioxide. In the p...
Reduction of U(VI) to U(IV) as the result of direct or indirect microbial activity is currently being explored for in situ remediation of subsurface U plumes, under the assumption that U(IV) solubility is controlled by the low-solubility mineral uraninite (U(IV)-dioxide). However, recent characterizations of U in sediments from biostimulated field sites, as well as laboratory U(VI) bioreduction...
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