Biomineralization is a known natural phenomenon associated with a wide range of bacterial species. Bacterial-induced calcium carbonate precipitation by marine isolates was investigated in this study. Three genera of ureolytic bacteria, Sporosarcina sp., Bacillus sp. and Brevundimonas sp. were observed to precipitate calcium carbonate minerals. Of these species, Sporosarcina sp. dominated the cu...

A method is described for the determination of total carbonate by means of acoustic emission. Acoustic signals are generated from effervescence of carbon dioxide when aqueous samples containing carbonate or hydrogencarbonate are acidified. Two approaches are evaluated. The first involves direct mixing of carbonate and acid streams in a flow system. Detection limits around 0.1 M are observed wit...

The decrease in elastic moduli (Young's, bulk, and shear modulus), the variations in their asymmetries, the Poisson's ratio and the linear compressibility due to carbonate formation in NaX, have been compared to those produced by dealumination of the zeolite HY framework, from the Al-Si-Al fragment positioned in joined 4R rings. All these systems have been considered at the density functional t...

Oligotrophic regions represent up to 75% of Earth’s open-ocean environments. They are thus areas of major importance in understanding the plankton community dynamics and biogeochemical fluxes. Here we present fluxes of total planktonic foraminifera and 11 planktonic foraminifer species measured at the Oceanic Flux Program (OFP) time series site in the oligotrophic Sargasso Sea, subtropical west...

The carbonate mineralogy of the calcified hydrozoan family Stylasteridae is controlled largely by phylogenetic rather than environmental factors. In a comprehensive study— the first of its kind—of the mineralogy of almost an entire family of calcareous organisms, this finding is well documented. X-ray diffraction analyses of 24 of 25 genera indicate that the skeletons of most species analyzed (...

Carbonate anion exchange reactions with water in the uranyl-carbonate and calcium-uranyl-carbonate aqueous systems have been investigated using computational methods. Classical molecular dynamics (MD) simulations with the umbrella sampling technique were employed to determine potentials of mean force for the exchange reactions of water and carbonate. The presence of calcium counter-ions is pred...

The role of coccolithophores in the biogenic carbonate cycle was studied in the coastal upwelling zone off Concepción, Chile (36°S), and in adjacent oceanic waters during spring 2004. Coccolithophore abundance and diversity increased steadily from coastal to oceanic regions. The presence of an active coastal upwelling center clearly partitioned the study area into coastal, transition and two oc...

Carbonate mud is a major constituent of recent marine carbonate sediments and of ancient limestones, which contain unique records of changes in ocean chemistry and climate shifts in the geological past. However, the origin of carbonate mud is controversial and often problematic to resolve. Here we show that tropical marine fish produce and excrete various forms of precipitated (nonskeletal) cal...

Propylene carbonate can be used as a green solvent for the asymmetric synthesis of cyanohydrin trimethylsilyl ethers from aldehydes and trimethylsilyl cyanide catalysed by VO(salen)NCS, though reactions are slower in this solvent than the corresponding reactions carried out in dichloromethane. A mechanistic study has been undertaken, comparing the catalytic activity of VO(salen)NCS in propylene...