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The western region of the southern Pantanal is characterised by soils with high phosphorus (P) contents, derived from materials from the surrounding lithostratigraphic units, accumulated by fluvial transport. However, studies on forms and availability of P in these soils are scarce. The objective of this study was to evaluate the different forms of inorganic P and their relationship with some attributes of carbonatic soils in the Pantanal of Mato Grosso do Sul, Brazil. Hedley's sequential fractionation scheme was used to evaluate the forms of P in soil profiles: Kastanozems (profiles PI and P3) and Gleysol (profile P2). Total P contents were similar in the three profiles, 3782-5637 mg [kg.sup.-1], with mean values of 22% for organic P and 46% for inorganic P (P.i). The P.i results indicated that in the profiles there was a predominance of inorganic forms of P in the following order: P-NaOH 0.5 mol [L.sup.-1] > P-NaHC[O.sub.3] > P-NaOH 0.1 mol [L.sup.-1] > P-HC1, that is, adsorbed to microaggregates, labile, adsorbed to oxides and precipitated with calcium (Ca), respectively. The highest values of total organic P were verified in the surface horizons, with high correlation with total P contents. Residual P contents were high in all profiles, representing 29.0-33.3% of the total P, being correlated with CaC[O.sub.3] contents. The studied profiles had high contents of labile P, with the highest values in the fraction P.i-NaHC[O.sub.3], possibly associated with the processes of reduction of iron during the periods of floods, making the adsorbed P available. The contents of P.i-NaOH 0.1 mol [L.sup.-1], a moderately labile fraction adsorbed to oxides, showed few differences compared to the non-labile fractions associated with Ca (P.i-HCl). Possibly, organic matter was bound to Ca, inhibiting the formation of precipitates of Ca with P and making P available for the more labile fractions. Keywords: Secondary carbonate, Flood cycle, Phosphorus fractionation, Organic matter, Iron reduction., Introduction The Pantanal, with an area of ~ 150 988 [km.sup.2] (IBGE 2019), is the largest humid complex in the world (Por 2012) and has 11 distinct sub-regions. The sub-regions [...]

Abstract: Pseudo-first-order rate constants ([k.sub.obsd]) were measured for nucleophilic substitution reactions of O-Y-substituted-phenyl O-phenyl thionocarbonates (4a-4h) with alkali metal ethoxides (EtOM, M = Li, Na, or K) in anhydrous ethanol [...]

Despite intensive commercial agriculture in the rift zone of Tanzania, mineralogical studies on the soils influenced by volcanic parent materials are scarce. A mineralogical investigation of the soils and two buried ash layers from an irrigated sugar estate was undertaken using X-ray diffraction, transmission electron microscopy and measurements of extractable iron, aluminium and silicon and the specific surface arca (SSA) of the clay fraction. The dominant mineral in the sand and silt fractions was sanidine. The clay fractions contained mainly high-defect kaolin, illitc and K-feldspar, with small amounts of calcite, talc and gibbsitc in some samples. Electron microscopy revealed the presence of tubular and spheroidal halloysitc and Additional keywords: allophane, halloysite, high-defect kaolinite, sanidine, specific surface area. Received 9 October 2014, accepted 11 April 2016, published online 22 August 2016, Introduction Soils in areas associated with volcanic activity often have a unique assembly of clay minerals comprising both nanocrystalline and layered silicate minerals (Shoji et al. 1993; Harsh et al. [...]

The islands of the Azores archipelago emerge from an oceanic plateau built on lithosphere increasing in age with distance from the Mid-Atlantic Ridge from 10 to 45 Ma. Here, we present the first comprehensive major and trace element and Sr-Nd-Pb isotope data from Santa Maria, the easternmost island of the archipelago, along with published data from the other Azores islands situated much closer to the Mid-Atlantic Ridge axis. We can show that the distinctively more variable and more enriched trace element ratios at Santa Maria combined with a relatively small range in Sr-Nd-Pb isotope ratios are the result of low degrees of partial melting of a common Azores mantle plume source underneath thicker lithosphere. This implies that melt extraction processes and melting dynamics may be able to better preserve the trace element mantle source variability underneath thicker lithosphere. These conclusions may apply widely for oceanic melts erupted on relatively thick lithosphere. In addition, lower Ti/Sm and K/La ratios and Si[O.sub.2] contents of Santa Maria lavas imply melting of a carbonated peridotite source. Mixing of variable portions of deep small-degree carbonated peridotite melts and shallow volatile-free garnet peridotite could explain the geochemical variability underneath Santa Maria in agreement with the volatile-rich nature of the Azores mantle source. However, Santa Maria is the Azores island where the C[O.sub.2]-rich nature of the mantle source is more evident, reflecting a combination of a smaller extent of partial melting and the positioning at the edge of the tilted Azores mantle plume. Keywords Ocean Island Basalts * Azores * Lithosphere thickness * Melting dynamics * Carbonated peridotite, Introduction Basalts erupted at Ocean Islands (OIB) display a larger trace element and isotopic variability compared to those erupted along mid-ocean ridges (MOR) (e.g., Dupre and Allegre 1983; Hofmann 1997; [...]

Byline: G. Rosatelli (1), F. Wall (2), F. Stoppa (1), M. Brilli (3) Keywords: Extrusive carbonatite; Limestone; LAICPMS; Polino; Italy Abstract: Petrography-controlled laser ablation inductively coupled plasma mass spectrometry (LAICPMS) analyses of carbonate in fresh shallow level sub-volcanic Polino monticellite calcio-carbonatite tuffisite have been performed to assess the geochemical differences between fresh igneous, epigenetic carbonates and sedimentary accidental fragments. Igneous calcite has consistently high LREE/HREE ratios (La/Yb.sub.N, 15--130) due to high LREE ([summation over (term)]LREE, 425--1,269 ppm). Secondary calcite cements are characterized by progressively lower and more variable trace element contents, with lower LREE/HREE ratios. A distinguishing geochemical feature is progressively increasing negative Ce anomalies observed through coarse secondary calcite that can be related to the surface environment processes. The limestone accidental fragments in the tuffisite have trace element contents almost two orders of magnitude lower than igneous carbonate and low LREE ([summation over (term)]LREE < 9.5 ppm) with low LREE/HREE fractionation (La/Yb.sub.N ratios < 18). The stable isotope composition of different carbonate types is consistent with their formation in different environments. The tuffisitization processes during diatreme formation under high CO.sub.2-OH fugacity conditions may account for the differences noted in the igneous carbonates. Author Affiliation: (1) Dipartimento di Scienze della Terra, Universita G. d'Annunzio, Via dei Vestini, 30, 66013, Chieti, Italy (2) Camborne School of Mines, University of Exeter, Cornwall Campus, Penryn, TR10 9EZ, UK (3) CNR, Piazzale Aldo Moro, 00185, Rome, Italy Article History: Registration Date: 01/02/2010 Received Date: 12/05/2009 Accepted Date: 01/02/2010 Online Date: 19/03/2010 Article note: Communicated by J. Blundy. G. Rosatelli and F. Wall were formerly with the Natural History Museum, Cromwell Road, London, SW7 5BD, UK.

Molecular beam scattering experiments are used to investigate reactions of S[O.sub.2] at the surface of a molten alkali carbonate eutectic at 683 K. We find that two-thirds of the S[O.sub.2] molecules that thermalize at the surface of the melt are converted to gaseous C[O.sub.2] via the reaction S[O.sub.2](g) + C[O.sup.2-.sub.3] [right arrow] C[O.sub.2](g) + S[O.sup.2-.sub.3]. The C[O.sub.2] product is formed from S[O.sub.2] in less than [10.sup.-6]s, implying that the reaction takes place in a shallow liquid region less than 100 [Angstrom] deep. The reaction probability does not vary between 683 and 883 K, further' implying a compensation between decreasing S[O.sub.2] residence time in the near-interfacial region and increasing reactivity at higher temperatures. These results demonstrate the remarkable efficiency of S[O.sub.2] [right arrow], C[O.sub.2] conversion by molten carbonates, which appear to be much more reactive than dry calcium carbonate or wet slurries commonly used for flue gas desulfurization in coal-burning power plants. flue gas desulfurization | gas scrubbing | gas-liquid reactions | liquid surface | molecular beam scattering doi/ 10.1073/pnas.0910993107

Byline: M. Santosh (1,2), Toshiaki Tsunogae (3), Hisako Shimizu (3), Jean Dubessy (4) Keywords: Eclogite; High pressure granulite; Mineral phase equilibria; Fluid inclusions; CO.sub.2; Southern India; Gondwana Abstract: Eclogite-facies rocks and high-pressure granulites provide windows to the deeper parts of subduction zones and the root of mountain chains, carrying potential records of fluids associated with subduction-accretion-collision tectonics. Here, we report petrological and fluid inclusion data on retrogressed eclogite and high-pressure granulite samples from Sittampundi, Kanji Malai and Perundarai in southern India. These rocks occur within the trace of the Cambrian collisional suture which marks the final phase of amalgamation of the Gondwana supercontinent. The garnet--clinopyroxene assemblage in the eclogites preserves relict omphacite, whereas the high-pressure granulites are characterized by an assemblage of garnet and clinopyroxene in the absence of omphacite and with minor plagioclase, orthopyroxene, and quartz. Phase relations computed for the eclogite assemblage yield peak P--T conditions of 19 kbar and 1,010degC. The mafic granulites also preserve the memory of high to ultrahigh-temperature metamorphism followed by an isothermal decompression. Systematic fluid inclusion optical, microthermometric and laser Raman spectroscopic studies were conducted in garnet and plagioclase from the eclogite--high pressure granulite suite. The results suggest that the early fluids were a mixture of CO.sub.2, CH.sub.4 and N.sub.2 probably derived from decarbonation and devolatilization reactions in a subduction setting during the prograde stage. The later generation inclusions, which constitute the dominant category in all the samples studied, are characterized by a near-pure CO.sub.2 composition with moderate to high densities (up to 1.154 g/cm.sup.3). The highest density fluid inclusions recorded in this study occur within the mafic granulites from Sittampundi (0.968--1.154 g/cm.sup.3) and Kanji Malai (1.092--1.116 g/cm.sup.3). In some cases, carbonate minerals such as dolomite and calcite are associated with the CO.sub.2-rich fluid inclusions. The composition and densities of the later generation fluids closely match with those of the CO.sub.2-bearing fluid inclusions reported from ultrahigh-temperature granulites occurring proximal to the eclogite--high pressure granulite suite within this suture zone, and suggest a common tectonic link for the fluid regime. We evaluate the fluid characteristics associated with convergent plate margin processes and propose that the early aqueous fluids probably associated with the eclogites were consumed during the formation of the retrograde hydrous mineral assemblages, whereas the fluid regime of the high-pressure and ultrahigh-temperature granulites was mostly CO.sub.2-dominated. The tectonic setting of the rocks along a collisional suture marking the trace along which crustal blocks were welded through subduction--collision process is in favor of a model involving the derivation of CO.sub.2 from sub-lithospheric sources such as a carbonated tectosphere invaded by hot asthenosphere, or underplated mafic magmas. Author Affiliation: (1) Faculty of Science, Kochi University, Akebono-cho, Kochi, 780-8520, Japan (2) Department of Earth and Atmospheric Sciences, Center for Environmental Sciences, Saint Louis University, St. Louis, MO, 63108, USA (3) Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki, 305-8572, Japan (4) G2R(UMR 7566), Nancy Universite and CNRS, BP70239, 54506, Vandoeuvre-les-Nancy Cedex, France Article History: Registration Date: 16/07/2009 Received Date: 22/10/2008 Accepted Date: 16/07/2009 Online Date: 30/07/2009 Article note: Communicated by J.L.R. Touret. Electronic supplementary material The online version of this article (doi: 10.1007/s00410-009-0431-4) contains supplementary material, which is available to authorized users.

We hypothesized that CaC[O.sub.3] dissolution, coupled to sulfide oxidation, is an important mechanism by which solid-phase inorganic P (iP) becomes available to seagrass in tropical carbonate sediments. To examine this supposition, we measured field sulfate reduction rates and simulated the acidity (10-50 [micro]mol [H.sub.2]S[O.sub.4] [cm.sup.-3] sediment) generated by subsequent sulfide oxidation from high (western) and low (eastern) total P (TP) sediments in Florida Bay. Dissolution experiments were conducted using sediment slurries at field pH (pore-water pH ~6.5-7.5). While CaC[O.sub.3] dissolution (maximum 1.3% of sediment dry weight) was evidenced at all sites by leaching of [Ca.sup.2+] into slurries, at three of the four sites P[O.sup.3-.sub.4] was primarily recovered in the sediment exchangeable pools and at a lower P:Ca ratio than observed in source sediments. In contrast, no P[O.sup.3-.sub.4] was recovered from an eastern bay site with the lowest TP and finest-grained sediments, suggesting that P[O.sup.3-.sub.4] was either tightly adsorbed or incorporated into the carbonate matrix post-acidification. The potential for tight P[O.sup.3-.sub.4] resorption by sediment from the low-TP site was also supported by the rapid rate of isotopic exchange of [sup.33] P[O.sup.3-.sub.4] into the sediment matrix. These adsorptive and incorporation processes may explain the low P[O.sup.3-.sub.4] in pore waters in the eastern vs. western regions of Florida Bay, even upon dissolution of carbonates. Carbonate dissolution coupled to sulfide oxidation could potentially provide 1.8 and 23.5 [micro]mol iP [m.sup.-2] [d.sup.-1] at eastern and western bay sites, respectively, meeting 5% of eastern and 29% of western bay seagrass (Thalassia testudinum) P requirements.

Byline: Steven Creighton (1), Thomas Stachel (1), Sergei Matveev (1), Heidi Hofer (2), Catherine McCammon (3), Robert W. Luth (1) Keywords: Mantle oxidation state; Mantle metasomatism; MARID; Kaapvaal craton; Kimberley kimberlite Abstract: The oxidation state, reflected in the oxygen fugacity (fO.sub.2), of the subcratonic lithospheric mantle is laterally and vertically heterogeneous. In the garnet stability field, the Kaapvaal lithospheric mantle becomes progressively more reducing with increasing depth from Ilog fO.sub.2 FMQ-2 at 110 km to FMQ-4 at 210 km. Oxidation accompanying metasomatism has obscured this crystal-chemical controlled depth-fO.sub.2 trend in the mantle beneath Kimberley, South Africa. Chondrite normalized REE patterns for garnets, preserve evidence of a range in metasomatic enrichment from mild metasomatism in harzburgites to extensive metasomatism by LREE-enriched fluids and melts with fairly unfractionated LREE/HREE ratios in phlogopite-bearing lherzolites. The metasomatized xenoliths record redox conditions extending up to Ilog fO.sub.2 = FMQ, sufficiently oxidized that magnesite would be the stable host of carbon in the most metasomatized samples. The most oxidized lherzolites, those in or near the carbonate stability field, have the greatest modal abundance of phlogopite and clinopyroxene. Clinopyroxene is modally less abundant or absent in the most reduced peridotite samples. The infiltration of metasomatic fluids/melts into diamondiferous lithospheric mantle beneath the Kaapvaal craton converted reduced, anhydrous harzburgite into variably oxidized phlogopite-bearing lherzolite. Locally, portions of the lithospheric mantle were metasomatized and oxidized to an extent that conversion of diamond into carbonate should have occurred. Author Affiliation: (1) Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Canada (2) Institut fur Geowissenschaften, Johann Wolfgang Goethe-Universitat, Frankfurt am Main, Germany (3) Bayrisches Geoinstitut, Universitat Bayreuth, Bayreuth, Germany Article History: Registration Date: 19/09/2008 Received Date: 29/04/2008 Accepted Date: 19/09/2008 Online Date: 19/10/2008 Article note: Communicated by J. Hoefs. Electronic supplementary material The online version of this article (doi: 10.1007/s00410-008-0348-3) contains supplementary material, which is available to authorized users.

Byline: Lili Xu (1), Jorg Renner (2), Marco Herwegh (3), Brian Evans (1) Keywords: Rheology; Carbonates; Constitutive laws; Solute strengthening; Normal grain growth Abstract: We extended a previous study on the influence of Mg solute impurity on diffusion creep in calcite to include deformation under a broader range of stress conditions and over a wider range of Mg contents. Synthetic marbles were produced by hot isostatic pressing (HIP) mixtures of calcite and dolomite powders for different intervals (2--30 h) at 850degC and 300 MPa confining pressure. The HIP treatment resulted in high-magnesian calcite aggregates with Mg content ranging from 0.5 to 17 mol%. Both back-scattered electron images and chemical analysis suggested that the dolomite phase was completely dissolved, and that Mg distribution was homogeneous throughout the samples at the scale of about two micrometers. The grain size after HIP varied from 8 to 31 um, increased with time at temperature, and decreased with increasing Mg content (>3.0 mol%). Grain size and time were consistent with a normal grain growth equation, with exponents from 2.4 to 4.7, for samples containing 0.5--17.0 mol% Mg, respectively. We deformed samples after HIP at the same confining pressure with differential stresses between 20 and 200 MPa using either constant strain rate or stepping intervals of loading at constant stresses in a Paterson gas-medium deformation apparatus. The deformation tests took place at between 700 and 800degC and at strain rates between 10.sup.-6 and 10.sup.-3 s.sup.-1. After deformation to strains of about 25%, a bimodal distribution of large protoblasts and small recrystallized neoblasts coexisted in some samples loaded at higher stresses. The deformation data indicated a transition in mechanism from diffusion creep to dislocation creep. At stresses below 40 MPa, the strength was directly proportional to grain size and decreased with increasing Mg content due to the reductions in grain size. At about 40 MPa, the sensitivity of log strain rate to log stress, (n), became greater than 1 and eventually exceeded 3 for stresses above 80 MPa. At a given strain rate and temperature, the stress at which that transition occurred was larger for samples with higher Mg content and smaller grain size. At given strain rates, constant temperature, and fixed grain size, the strength of calcite in the dislocation creep regime increased with solute content, while the strength in the diffusion creep regime was independent of Mg content. The results suggest that chemical composition will be an important element to consider when solid substitution can occur during natural deformation. Author Affiliation: (1) Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, 77 Mass. Avenue, Cambridge, MA, 02139, USA (2) Ruhr-University Bochum, 44780, Bochum, Germany (3) Institute for Geology, University Bern, 3012, Bern, Switzerland Article History: Registration Date: 15/08/2008 Received Date: 18/10/2007 Accepted Date: 15/08/2008 Online Date: 07/09/2008 Article note: Communicated by J. Blundy.

Byline: John R. Bowman (1), John W. Valley (2), Noriko T. Kita (2) Abstract: Oxygen isotope ratios have been measured by ion microprobe and millimeter-scale dental drill along detailed sampling traverses across the boundary between periclase-bearing ([delt[a].sup.18]O = 11.8[per thousand]) and periclase-free ([delt[a].sup.18]O = 17.2[per thousand]) marble layers in the periclase (Per) zone of the Alta Stock aureole, Utah. These data define a steep, coherent gradient in [delt[a].sup.18]O that is displaced a short distance (~4 cm) into the periclase-free (Cal + Fo) layer. SEM and ion microprobe analyses show two isotopically and texturally distinct types of calcite at the grain scale. Clear (well polished) calcite grains are isotopically homogeneous (within analytical uncertainty +-0.27[per thousand], 2SD). More poorly polished (pitted), texturally retrograde 'turbid'-looking calcite has lower and more variable [delt[a].sup.18]O values, and replaces clear calcite along fractures, cleavage traces or grain boundaries. Despite significant lowering of the [delt[a].sup.18]O values in calcite throughout both layers during prograde metamorphism, ion microprobe analyses indicate that individual clear calcite grains are now isotopically homogeneous across the entire gradient in [delt[a].sup.18]O. Diffusion calculations indicate that conservative time scales required for isotopic homogenization of calcite grains by volume diffusion, 30,000--62,000 years at 575--600degC, exceed significantly the timescale (~1,250 years) estimated for the prograde development of the [delt[a].sup.18]O gradient at the boundary between these two marble layers. The ion microprobe data and these diffusion calculations suggest instead that surface reaction mechanisms accompanying recrystallization are responsible for the observed oxygen isotope homogeneity of these calcite grains. Thus, the ion microprobe data are consistent with the formation of calcite in oxygen isotope exchange equilibrium with infiltrating fluid during prograde reaction and recrystallization. Author Affiliation: (1) Department of Geology and Geophysics, University of Utah, Salt Lake City, UT, 84112, USA (2) Department of Geology and Geophysics, University of Wisconsin-Madison, Madison, WI, 53706, USA Article History: Registration Date: 20/06/2008 Received Date: 26/01/2008 Accepted Date: 20/06/2008 Online Date: 20/08/2008 Article note: Communicated by J. Hoefs. Electronic supplementary material The online version of this article (doi: 10.1007/s00410-008-0321-1) contains supplementary material, which is available to authorized users.

The ability of mudrock seals to prevent C[O.sub.2] leakage is a major concern for geological storage of anthropogenic C[O.sub.2]. The long-term performance of a mudrock seal, which provides a natural analogue, in the North Sea Miller oil field has been evaluated. This mudrock seal is immediately above a natural C[O.sub.2]-rich reservoir. The paper reports the stable isotopes of carbon from carbonate minerals in the mudrock that have precipitated in contact with COg during 4 km of burial. A well-defined linear trend of upward-decreasing [[delta].sup.13]C traces the progressive penetration of free-phase C[O.sub.2] causing dissolution and reprecipitation of carbonate minerals. The C[O.sub.2] was emplaced ca. 70-80 Ma, and has only penetrated 12 m vertically in this case. The infiltration rate is estimated as ~9.8 x [10.sup.-7]g [cm.sup.-2] [yr.sup.-1]. Engineered C[O.sub.2] storage under this type of mudrock seal will have a considerable safety margin.

Byline: Alexis K. Ault (1,2), Jane Selverstone (1) Keywords: Alps; Fluid--rock reaction; Graphite; Titanite; Carbonic fluid; Embrittlement Abstract: Schists from two mylonitic localities in the footwall of a low-angle normal fault in the eastern Alps record different degrees of embrittlement during exhumation, depending on the extent to which fluid--rock reactions proceeded. At one site, graphitic schists preserve textural evidence for two metamorphic reactions that modified X.sub. CO.sub.2 and/or fluid volume: (1) reaction between graphite and aqueous fluid that increased X.sub. CO.sub.2 without changing the molar amount of fluid, and (2) replacement of titanite by rutile, calcite, and quartz. The latter reaction involved net consumption of increasingly CO.sub.2-rich fluid. Areas where the first reaction proceeded are associated with abundant Mode I microcracks. Fluid inclusion arrays within the microcracks show that X.sub. CO.sub.2 increased from [proportional to]0.1 to 0.6 during decompression from 4.75 to 2 kbar at a reference temperature of 500degC. Titanite consumption is most pronounced within transgranular Mode I microcracks, but microcracks do not crosscut products of this reaction fluid consumption during reaction was coeval with the end of microcracking, at least on a local scale. At the other site, graphitic schists lack small-scale Mode I cracks as well as evidence for graphite consumption during decompression. SEM imaging shows that graphite is anhedral and pitted at the first site, but occurs in clusters of euhedral grains at the second site. Mass balance calculations demonstrate that rocks with partially consumed graphite were infiltrated by an externally derived, [H.sub.2]O-rich fluid that drove subsequent graphite-fluid reaction. Evidence for similar fluid infiltration is absent at the second site. Variations in the degree of reaction progress indicate that fluid pathways and deformation style were heterogeneous on the scale of millimeters to kilometers during exhumation from mid-crustal depths. Author Affiliation: (1) Department of Earth and Planetary Sciences, University of New Mexico, MSC03 2040, Albuquerque, NM, 87131-0001, Mexico (2) Department of Geological Sciences, University of Colorado at Boulder, 2200 Colorado Ave, Boulder, CO, 80309, USA Article History: Registration Date: 17/03/2008 Received Date: 31/08/2007 Accepted Date: 17/03/2008 Online Date: 29/03/2008 Article note: Communicated by T.L. Grove.

The reactions of hydrated electron with various radicals are studied in pulse radiolysis experiments. The rate constants of hydrated electron reactions with various reactive radicals are measured over a temperature range of 5-75 degree C, which helps in understanding the hydrated electron radical reaction rates.

Neutron diffraction with isotopic substitution (NDIS) experiments and molecular dynamics (MD) simulations are applied to characterize the structure of aqueous guanidinium carbonate solutions. The presence of clustering on the nanometer length scale is confirmed by using small-angle neutron scattering experiments, which suggests a molecular-level explanation for the contrasting denaturant properties of guanidinium salts in solution.

Chemiluminescence energy transfer reaction is investigated for the on-line preparation of peroxymonocarbonate and Eu(II) - dipicolinate complex. The peroxymonocarbonate system is a simple, inexpensive and relatively nontoxic alternative to other oxidants and hence can be used in a mild, neutral-pH environment.

The redox behavior and complexation equilibria of Mn(super 2+) are investigated in aqueous solutions of bicarbonate by voltammetry and electron paramagnetic resonance (EPR) spectroscopy and the implications for the uptake of Mn(super 2+) by mangano-cluster enzymes such as photosystem II (PSII) are discussed. The derived molecular structures include Mn(super 2+)(HCO(sub 3)(super -))(OH2)(sub 4-5) for the 1 is to 1complex and Mn(super 2+=)(CO(sub 3)(super 2-))(HCO(sub 3)(super -))(OH2)(sub 3) for the 1 is to 2 complex.

Diastereoselective palladium-catalyzed formate reduction of allylic carbonates presents unique opportunities for application in organic synthesis provided that stereoselectivity in the course of this metal-catalyzed reaction can be controlled. Developments on efficient metal-catalyzed process exploiting resident stereocenters on the substrates as a means to control stereoselectivity en route to preparing propionate units containing an array of stereochemical patterns are presented.

Moller-Plesset perturbation theory and density functional theory calculations are used to study decomposition mechanisms of polymerization initiators, such as diethyl peroxydicarbonate, trifluoroacetyl peroxide, and acetyl peroxide, which posses a general structure of RC(O)OO(O)CR. Geometrical and energetic analyses indicate that despite the similar structures of the peroxydicarbonates, quite different decomposition energy barriers are determined by the nature of the R groups.

The melting relationships in the system CaMg[Si.sub.2][O.sub.6] (Di)--C[O.sub.2] have been studied in the 3-8 GPa pressure range to determine if there is an abrupt decrease in the temperature of the solidus accompanying the stabilization of carbonate as a subsolidus phase. Such a decrease has been observed previously in peridotitic and some eclogitic systems. In contrast, the solidus in the Di--C[O.sub.2] system was found to decrease in a gradual fashion from 3 to 8 GPa. This decrease accompanies an evolution in the composition of the melt at the solidus from silicate-rich with minor C[O.sub.2] at 3 GPa to carbonatitic at 5.5 GPa, where the carbonation reaction Diopside + C[O.sub.2] = Dolomite (Dol) + Coesite (Cst) intersects the solidus. The near-solidus melt remains carbonatitic at higher pressure, consistent with carbonate being the dominant contributor to the melt. Based on previous studies in both eclogitic and peridotitic systems, this conclusion can be extended to more complicated systems: once carbonate is a stable subsolidus phase, it plays a major role in controlling both the temperature of melting and the composition of the melt produced.

Alkylation of metal carbonate in various ionic liquids with 1-bromo-3-phenylpropone as a model reactant was investigated. A new phosgene-free method for the synthesis of symmetrical organic carbonates through alkylation of metal carbonate with various alkyl halides and sulfonates in 1-n-butyl-3-methyl-imidazolium hexafluorophosphate, as an ecofriendly reaction media was reported.

A demonstration showing that the bis(triphenylphosphine)immium (PPN) manganese carbonyls and more interestingly the off-the-shelf reagent PPN(super +)Cl(super -) are good catalysts for the coupling reactions of CO2 with epoxides to yield cyclic carbonates is presented. The reactions are clean with no polycarbonate contamination and are performed in neat substrates with no need of organic solvents.

The reactions of anilines with 4-nitrophenyl, 4-methylphenyl, and 4-chlorophenyl 4-nitrophenyl carbonates are studied in the aqueous ethanol, to clarify the mechanisms of the aminolysis of diaryl carbonates. The main goal is to evaluate the influence of the amine nature and that of the leaving and nonleaving groups of the carbonate on the kinetics and mechanisms.

The reaction of CO2 with a variety of epoxides is examined in the presence of ionic liquids (ILs) wherein tetrahaloindate(III)-based ILs are found to exhibit interactions in the [Q][InX3Y]-catalyzed coupling reactions. The effects of various parameters such as temperature, pressure, and molar ratio of propylene oxide to catalyst are investigated, and the plausible reaction mechanism based on the (super 1)H and (super 13)C NMR studies is presented for the formation of propylene carbonate.

Benzotriazole reagents for thioacylation, thiocarbamoylation, aryl/alkoxy-thioacylation, and aryl/alkythiothiocylation are synthesized. Their utility is assessed of representative hetroaryl thioureas, thioamides, thionoesters, thiocarbamates, thuiocarbamates, thiocarbonates, and bithiocarbonates.

Phenyl 4,6-di-O-benzyl-2,3-O-carbonyl-beta-D-glucothiopyranoside and the regiosiomeric phenyl 2,6-di-O-benzyl-3,4-O-carbonyl-beta-D-glucothiopyranoside are prepared and studied as glucosyl donors at -60 degrees Celsius in dichloromethane with preactivation by 1-benzenesulfinyl piperidine before addition of the acceptor alcohol. The 2,3-O-carbonate protected donor showed moderate to excellent beta-selectivity under these conditions depending on the acceptor employed.

The reactions of secondary alicyclic (SA) amines with O-4-nitrophenyl S-methyl thiocarbonate, O-(2,4-dinitrophenyl) S-methyl thiocarbonate and with O-(2,3,4,5,6-pentafluorophenyl) S-methyl thiocarbonate are examined in order to study the kinetics and mechanisms of the aminolysis of O-aryl S-alkyl thiocarbonates. The reactions of quinuclidines (QUI) with O-4-nitrophenyl S-methyl thiocarbonate and with O-(2,4-dinitrophenyl) S-methyl thiocarbonate are hence examined.

Enantioenriched 4-hydroxyalk-2-ynyl carbonates are prepared by stereoselective zinc-mediated addition of alkyl 2-propynyl carbonates to aldehydes. Their partial reduction to Z-olefins followed by cyclization under mild Pd-catalyzed conditions allowed a straightforward access to enantioenriched syn-1,2-diols protected as cyclic carbonates.

Associations of different lithium alkyl dicarbonates resulting from the reductive degeneration of organic carbonates and playing a vital role on the formation of a solid electrolyte interphase in Li-ion batteries are examined. It is observed that the lithium alkyl dicarbonates exist on the anode surface forming 2-dimensional and 3-dimensional n-mers rather than monomers.

The structure and hydrogen bonding of water in solutions containing EC at different concentrations are studied using infrared (ATR) spectroscopy. Factor analysis and curve fitting show two concentration-dependent regions wherein the structure of water in the mixture is critically disrupted and hydrogen bonding is significantly changed.

The synthesis of 2-substituted indenes is achieved through a palladium-catalyzed carboannulation of propargylic carbonates with nucleophiles. This new method has accommodated a variety of nucleophiles and has afforded the substituted indenes in good yields.

The Warburton Basin of central Australia has experienced a complex tectonic and fluid-flow history, resulting in the formation of various authigenic minerals. Geochemical and geochronological analyses were undertaken on vein carbonates from core samples of clastic sediments. Results were then integrated with zircon U-Pb dating and uraninite U-Th-total Pb dating from the underlying granite. Stable and radiogenic isotopes (δ[sup.18]O, Sr and ζNd), as well as trace element data of carbonate veins indicate that >200 °C basinal fluids of evolved meteoric origin circulated through the Warburton Basin. Almost coincidental ages of these carbonates (Sm-Nd; 432 ± 12 Ma) with primary zircon (421 ± 3.8 Ma) and uraninite (407 ± 16 Ma) ages from the granitic intrusion point towards a substantial period of active tectonism and an elevated thermal regime during the mid Silurian. We hypothesise that such a thermal regime may have resulted from extensional tectonism and concomitant magmatic activity following regional orogenesis. This study shows that the combined application of geochemical and geochronological analyses of both primary and secondary species may constrain the timing of tectonomagmatic events and associated fluid flow in intraplate sedimentary basins. Furthermore, this work suggests that the Sm-Nd-isotopic system is surprisingly robust and can record geologically meaningful age data from hydrothermal mineral species. Keywords Thermal and tectonic history * Warburton Basin * [sup.147]Sm-[sup.144]Nd geochronology * Water-rock interaction * Vein carbonates, Introduction Thermal perturbations experienced by sedimentary basins can result from a number of processes including emplacement of magmatic bodies and lithospheric thinning due to extensional tectonism (Armstrong 2005). Tensional stress [...]

One-pot synthesis of 2-aminobenzoxazoles by using commercially available tetramethyl orthocarbonate or 1,1-dichlorodiphenoxymethane, an amine, and an optionally substituted 2-aminophenol is described. The scope of the reactions conducted under mild conditions which provided 2-aminobenzoxazoles in modest to excellent yields was examined by using a variety of amines and substituted 2-aminophenols.

The combined use of the bimetallic aluminum(salen) complex [[Al(salen)].sub.2]O and tetrabutylammonium bromide (or tributylamine) has catalyzed the reaction between epoxides and carbon disulfide, which has produced 1,3-oxathiolane-2-thiones and 1,3-dithiolane-2-thiones as main products. The structure and stereochemistry of three of the 1,3-dithiolane-2-thiones is determined and is used to correct errors concerning the synthesis of cyclic di- and trithiocarbonates.

Palladium(0)-catalyzed cyclization of bromoallenes, propargyl chlorides, and carbonates bearing hydroxy and benzamide groups as internal nucleophiles has produced functionalized tetrahydrofuran. Cyclization reactivity is dependent on the relative configuration of the benzamide and leaving groups and the bis-cyclization is used as the key step in a short total synthesis of pachastrissamine.

Several experimental and theoretical analyses are conducted to explain the nucleofugality patterns that are observed in the aminolysis, as well as phenolysis of the various S-aryl and O-aryl thiocarbonates. A comparison of the relative structures in the two complexes is also presented.

Iodoalkyl tert-butyl carbonates and carbamates have undergone clean free-radical addition to thiomaleic anhydride to produce substituted thiosuccinic anhydrides on treatment with tris(trimethylsilyl)silane and a radical initiator. The tert-butyloxycarbonyl group is converted to amides through reaction with electron-deficient sulfonamides or to aldehydes and ketones by the reactions of thioesters with either thiophenol or phenylboronic acid.

The Bronsted plots for the concerted pyridinolysis of aryl 2,4,6-trinitrophenyl carbonates is described. The concerted mechanism is attributed to the title carbonates which possess two O-aryl groups and one exceptionally good nucleofuge.

The displacement of a methylsulfinyl group from the 6-position of the pyridine ring is used to explain the characteristics of 2-aminopyridines with a variety of polar 6-substituents. The synthesis of 6-thiomethyl pyridines from reaction of 2-(l-phenylethylidene)propanedinitriles with dimethyl N-cyanodithiominocarbonate is also described.

Enantiomerically pure 1-arylpropenols are prepared by resolution of the corresponding racemates by using the lipase formulation Novozyme 435. Deprotonation of the latter alcohols with n-BuLi, followed by derivatization with ([(t-BuO).sub.2]CO, has produced the corresponding carbonates.