bluuebunny/crossref_metadata_2025 huggingface dataset:
The Political Economy of Globalism in South America: Strategic Implications for Foreign Direct Investment
Authors: Hemphill Thomas A.
Published: August 2008

In recent years, many South American countries have moved from policies embracing neoliberal, market-based economic policies to those supporting nationalization of industries and the re-institution of trade barriers (to protect domestic industries). This paper first addresses the concept of “globalism”, efforts at globalization of trade, and development of free markets in South America since the 1980s. Second, it reviews regional trade agreements, with a focus on Mercosur, the most important regional trade organization. Third, it discusses recent trends in South America's nationalization of industries. Fourth, a political risk analysis of future free trade and foreign direct investment in the region is undertaken. Fifth, conclusions and recommendations are offered, including: 1) the effects of increased government control of the economy may result in full-member status countries in Mercosur becoming less attractive as host nations for foreign direct investment, while conversely, non-full members may become more attractive; 2) center-left governments, unlike those embracing orthodox socialist policies, are not instituting policies discouraging foreign direct investment; and 3) where there are instances of host country expropriation of private property (without fair market compensation), a robust corporate policy of pursuing claims (with home country support) through the International Centre for Settlement of Investment Disputes is recommended.
The rise of the dragon in middle Byzantine hagiography
Authors: White Monica
Published: August 2008

Dragons were a well-established feature of the Byzantine supernatural imagination, and certain conventions governed their behaviour as described in hagiography. The textual traditions associated with Ss Perpetua, Marina of Antioch and Elisabeth the Miracle-Worker illustrate the changing role of the creatures from late antiquity through the middle Byzantine period. Although early works portray them as minor nuisances, compilations of the ninth century and later give them a new prominence, hinting at an editorial fascination with dragons which acted in a similar manner on otherwise unrelated texts.
Diglossia and register variation in Medieval Greek
Authors: Toufexis Notis
Published: August 2008

This article recognizes diglossia as a key phenomenon for the interpretation of the existence of different registers in the late Byzantine period (twelfth-fifteenth centuries). The main characteristics of Byzantine diglossia are outlined and associated with language production during this period. Learned and vernacular registers are approached as extreme poles of a linguistic continuum and linguistic variation as a defining characteristic of a diglossic speech community.
A modern poet reads ancient war texts: politics, life and death in George Seferis’ ‘The Last Day’
Authors: Tambakaki Polina
Published: August 2008

It has been argued that ‘The Last Day’, written during the Metaxas dictatorship and while the Second World War was looming on the horizon, constitutes Seferis’ answer to the exhausted model of the ‘national poet’. The aim of this article is to examine in detail the poem’s allusions to ancient war texts, in order to deal with what stood at the heart of this answer, namely the key concept of the ‘historical poet’. Of prime importance will be issues of language and gender raised by the poem, as well as the historical context of its writing and reception.
CO2 sequestration in basaltic rock at the Hellisheidi site in SW Iceland: stratigraphy and chemical composition of the rocks at the injection site
Authors: Alfredsson H. A. , Hardarson B. S. , Franzson H. , Gislason S. R.
Published: August 2008

Storage of CO2 as solid Ca, Mg, and Fe carbonates in basaltic rocks may provide a long-lasting solution for reduction of industrial CO2 emissions. Here, we report on the underground stratigraphy of the chemical composition and crystallinity of rocks and their alteration state at a targeted field site for injection of CO2-charged waters, the Hellisheidi area in SW Iceland.
In situ monitoring of the biofilm formation of Pseudomonas putida on hematite using flow-cell ATR-FTIR spectroscopy to investigate the formation of inner-sphere bonds between the bacteria and the mineral
Authors: Ojeda J. J. , Romero-Gonzalez M. E. , Pouran H. M. , Banwart S. A.
Published: August 2008

In situ flow-cell ATR-FTIR using a hematite-coated germanium crystal was used to investigate the chemical interactions between Pseudomonas putida and hematite in real time, when compared with cells not attached to the mineral surface. ATR-FTIR spectra of bacteria growing on hematite showed a shift in the carboxylate signal when compared to the samples obtained from free cells, indicating a chemical interaction between the carboxylate groups and the Fe metal ions of the hematite surface. Small differences in the polysaccharide and phosphoryl regions of the IR spectra of bacteria attached to hematite were also observed. This work shows how the use of in-situ flow-cell experiments with a mineral-coated germanium crystal allows a better description of the bacterial interactions with minerals in real time, as an initial step to understand the fundamental mechanisms involved in the relationship between bacteria and mineral surfaces.
In situ investigation of the redox front above an underground rock cavern and estimation of its moving rate
Authors: Oyama T. , Inohara Y. , Nagaoka T.
Published: August 2008

An investigation and evaluation of the redox conditions around an underground rock cavern are important from the viewpoint of the safety assessment of the subsurface geological disposal of radioactive wastes. The in situ redox conditions around a cavern excavated in Neogene pyroclastic rocks were investigated. Rock samples were collected from a tunnel wall crossing the oxidation front, and the properties of pore water seeping into small holes drilled in the tunnel wall were determined. Chemical analysis of the rock samples revealed that pyrite-bearing rocks belowthe oxidation front were oxidized by the dissolved oxygen in the groundwater infiltrating from the surface. The water properties changed with increasing oxidation of the rocks. From the amount of oxygen-consuming components in the rocks, the migration rate of the oxidation front was estimated to be ~0.2 mm/y due to the flowrate of groundwater (0.1 m/y) containing oxygen.
Weathering of soil minerals by angiosperm and gymnosperm trees
Authors: Andrews M. Y. , Ague J. J. , Berner R. A.
Published: August 2008

Weathering of terrestrial Ca- and Mg-bearing silicate minerals is an important control on atmospheric CO2 on geological time scales. It has been determined that vascular plants can accelerate mineral weathering as compared to non-vascular plants or non-vegetated surfaces. This indicates that the evolution of vascular plants, particularly the deep-rooted trees, may play a large role in the long-term carbon cycle and its regulation of the atmosphere. The weathering impact of the separate evolutionary appearances of the gymnosperms in the Palaeozoic and the angiosperms in the Mesozoic, and the shifting ecological dominance from the former to the latter, is currently poorly understood. This study aims to contribute to our understanding of the quantitative weathering rates of the angiosperms and gymnosperms by examining plant-mineral interactions of the two tree types in a temperate field setting underlain by granodiorite. Results include determinations of soil element fluxes and etching of minerals. The observed root-mineral interactions resulted in only slightly more weathering of Ca-bearing minerals by the angiosperms. However, we observed significantly more weathering of the Mg-bearing minerals by the gymnosperms. These results suggest that increasing dominance of the angiosperms in forests in the Mesozoic may have had a small or neutral impact on accelerating overall mineral weathering and regulating CO2, but that this impact may be lithology-dependent.
The effect of fluid composition on the mechanism of the aragonite to calcite transition
Authors: Perdikouri C. , Kasioptas A. , Putnis C. V. , Putnis A.
Published: August 2008

Experiments were performed to investigate the transformation of natural aragonite crystals to calcite by reaction with aqueous solutions of calcium carbonate at hydrothermal conditions for different periods of time. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy and Laser ablation inductively coupled mass spectrometry (LA-ICP-MS) were used to characterize the reaction product. The results indicate that the replacement of aragonite by calcite follows an interface-coupled dissolution-precipitation mechanism.
High-resolution imaging of biotite dissolution and measurement of activation energy
Authors: McMaster T. J. , Smits M. M. , Haward S. J. , Leake J. R. , Banwart S. , Ragnarsdottir K. V.
Published: August 2008

We have used a direct imaging technique, in situ atomic force microscopy(AFM) to observe the earliest stages of the dissolution of a biotite surface byoxalic acid at temperatures close to ambient conditions, using a speciallydesigned AFM liquid cell and non-invasive intermittent contact mode of operation. From the nm-resolution data sets in x, yand z dimensions, we have measured dissolution rates and determined activation energies for the process as a function of temperature, via a mass-loss calculation. The value of Ea obtained, 49±2 kJ mol-1, appears to be too high to indicate a diffusion-controlled process and is more in line with expectations based on a process limited by the rate of ligand-induced metal cation detachment from the (001) surface. This is consistent with visual observations of the relative rates of etch-pit formation and growth, and accepted knowledge of the biotite crystal structure. Separate calculations based on planar area etch-pit growth, and measurements of etch-pit perimeters confirm this result, and also indicate substantiallyhigher activation energy, up to 80 kJ mol-1, when the edge pits are in an incipient stage.
Aquifer characterization with tracer test technique; permanent CO2 sequestration into basalt, SW Iceland
Authors: Rezvani Khalilabad M. , Axelsson G. , Gislason S. R.
Published: August 2008

Mineral sequestration is among several promising methods of CO2 reduction. It involves incorporation of CO2 into a solid phase via precipitation of carbonate minerals. A prerequisite to carbonate precipitation is the availability of aqueous metal cations and a network of porous media for fluid flow and water-rock interactions. The Hellisheidi-Threngsli lava field in SW Iceland comprises ideal conditions for studying the feasibility of permanent CO2 storage as minerals in basaltic rocks. In this paper we report on a tracer test conducted between two wells at the Hellisheidi-Threngsli site to characterize the physical properties of the main aquifers. The results suggest that most of the water flow between the wells is through an homogenous thick layer with high tortuosity along flow paths and a high reactive surface area for water-rock interactions.
Ectomycorrhizal fungi in mineral soil
Authors: Rosling A. , Rosenstock N.
Published: August 2008

Ectomycorrhizal fungi are mutualistic symbionts of many forest trees and play a major role in nutrient uptake. They form diverse communities in boreal forest soils but functional differences within this group of fungi remain largely unknown. We study ectomycorrhzal fungi in mineral soil to determine how abiotic preferences influence their spatial distribution in stratified soil profiles. This is achieved by correlative field studies of species distribution and soil characteristics at a spatial resolution relevant to soil heterogeneity and mycelial size. Field sampling strategies are being evaluated to establish a protocol for simultaneous small-sample analysis of ectomycorrhizal community and soil chemical variables. Species-specific substrate preferences are examined by studies of regulation of enzymatic and biogeochemical activity in response to relevant organic and inorganic sources of phosphorus. Studies of four species in the genus Piloderma have demonstrated that different strategies to obtain phosphorus are reflected by their spatial distribution in a podzol soil profile.
Dissolution of diopside and basaltic glass: the effect of carbonate coating
Authors: Stockmann G. , Wolff-Boenisch D. , Gíslason S. R. , Oelkers E. H.
Published: August 2008

Far-from-equilibrium dissolution experiments with diopside and basaltic glass in mixed-flow reactors at 70°C and pH 8.2 show that solute concentrations do not reach steady state over the experimental duration of 45—60 days. Chemical modelling indicates that during the dissolution experiments, solutions have become supersaturated with respect to carbonates in the case of diopside, and carbonates, clay minerals and zeolites in the case of the basaltic glass. Decreasing dissolution is therefore interpreted as a result of secondary surface precipitates blocking the reactive surface area. Calcite formation was supported in both experiments by a significant increase in Ca (and Sr) concentrations as pH was abruptly lowered from 8.2 to 7 because this change increased carbonate solubility and caused all potential carbonate precipitates to re-dissolve. The reduction in pH also led to an increase in Si concentration for diopside and a decrease in Si concentration for basaltic glass. This observation is in accordance with previous experiments on the pH-dependent dissolution rates of pyroxenes and basaltic glass.
Solute profiles in soils, weathering gradients and exchange equilibrium/disequilibrium
Authors: White A. F. , Schulz M. S. , Stonestrom D. A. , Vivit D. V. , Fitzpatrick J. , Bullen T.
Published: August 2008

The spatial and temporal changes in hydrology and pore water elemental and 87/86Sr compositions were used to determine contemporary weathering rates in a 65 to 226 ky old soil chronosequence formed from granitic sediments deposited on marine terraces along coastal California. Cl-corrected Na, K and Si increased with depth denoting inputs from the weathering of plagioclase and K-feldspar. Solute 87/86Sr exhibited progressive mixing of sea water-dominated precipitation with inputs from less radiogenic plagioclase. Linear approximations to these weathering gradients were used to determine plagioclase weathering rates of between 0.38 and 8.9x10-15 moles m-2 s-1. The lack of corresponding weathering gradients for Ca and Sr indicated short-term equilibrium with the clay ion exchange pool which requires periodic resetting by natural perturbations to maintain continuity, in spite of soil composition changes reflecting the effects of long-term weathering.
Anaerobic pyrite oxidation rates determined via direct volume-loss measurements: a Vertical Scanning Interferometric approach
Authors: Avery E. R. , Benning L. G.
Published: August 2008

Presented here are quantitative dissolution rate data (volume of pyrite lost/time) for the inorganic oxidation of pyrite in synthetic, anaerobic and acidic (pH 2) hydrothermal vent fluids (HVF) from experiments where the volume loss was measured directly via Vertical Scanning Interferometry (VSI). The VSI-derived reaction rate was 2.12x10-10±1.14x10-1 mol/m2/min, which is ∼2 to 4 orders of magnitude slower than pyrite oxidation rates previously determined using traditional batch experiments where rates are calculated based on changes in solution chemistry. This lower rate stems primarily from differences in experimental conditions (i.e. water to rock ratios, vigorous vs. gentle stir rates, grain-size effects, time), yet the rates derived here are believed to be more representative of pyrite oxidation in natural environments where more static and high solution to solid rate conditions prevail, such as seafloor conditions or acid-mine-drainage environments.
Dissolution rates of crystalline basalt at pH 4 and 10 and 25-75°C
Authors: Gudbrandsson S. , Wolff-Boenisch D. , Gíslason S. R. , Oelkers E. H.
Published: August 2008

Far-from-equilibrium dissolution rates of crystalline basalt were measured in a mixed-flow reactor at pH 4 and 10, and at temperatures from 25 to 75ºC. The material used was obtained from a dyke on Stapafell Mountain on Reykjanes peninsula in Iceland because of its similarity with previous experiments on dissolution rates on basaltic glass by Oelkers and Gislason (2001) and Gislason and Oelkers (2003). Comparison of dissolution rates of basaltic glass and of crystalline basalt of similar chemical composition (from Gislason and Oelkers, 2003) indicates lower rates for crystalline material.
Evolution of the microstructure and crystallographic orientation during shell growth in Psilunio littoralis and Nautilus belauensis
Authors: Alvarez-Lloret P. , Rodriguez-Navarro A. B. , Checa A. G.
Published: August 2008

Thin sections of shells from different species of mollusc have been analysed by X-ray synchrotron diffraction using the BM16 at the European Synchrotron Radiation Facility (ESRF), Grenoble, France. A sequence of 2-D X-ray diffraction patterns were acquired in transmission mode at regular intervals across the shell thickness. From the 2D patterns, 2θ- and χ-scans were calculatedan d analysed. We studied the evolution of the shell microstructures by analysing several parameters from calculated scans: (1) the intensity of the most intense aragonite reflections in the calculated 2θ scans; (2) the crystallinity calculated from the full width at half maximum values of the main reflections in those scans; and (3) the degree of orientation of crystals, measured from the angular width (in angle) of the arches displayed in the Debye-Scherrer rings which appeared in the 2D diffraction patterns. The determined parameters displayed sharp changes at the transitions between microstructurally distinct shell layers indicating that the microstructural switch occurred very rapidly and was precisely controlled.
Synchrotron X-ray studies of heavy metal mineral-microbe interactions
Authors: Brown G. E. , Wang Y. , Gélabert A. , Ha J. , Cismasu C. , Ona-Nguema G. , Benzerara K. , Miot J. , Menguy N. , Morin G. , Juillot F. , Guyot F. , Calas G. , Farges F. , Trainor T. P. , Gescher J. , Cordova C. , Spormann A. M.
Published: August 2008

The availability of analytical methods that utilize the very intense and bright X-rays from synchrotron radiation sources has fundamentally changed the way in which geoscientists, environmental scientists and soil scientists study complex environmental samples and decipher the chemical and biological processes that impact the speciation, transport and potential bioavailability of environmental toxins (Brown et al., 2006). Such samples are often mixtures of crystalline and amorphous phases in particle-sizes ranging from cm to nm, adsorbed metal ions and organic molecules, natural organic matter, microbial organisms, algae, plant materials and aqueous solutions. The processes that affect the chemical forms and environmental fate of contaminants in such mixtures range from surface adsorption, desorption, precipitation and dissolution reactions, often involving a combination of hydrolysis, ligand exchange and electron transfer, to biological interactions in which microbial organisms, algae or plants interact with mineral surfaces and environmental contaminants.
Applications of time-resolved synchrotron X-ray diffraction to cation exchange, crystal growth and biomineralization reactions
Authors: Heaney P. J. , Post J. E. , Fischer T. B. , Hummer D. R. , Lopano C. L. , Wall A. J.
Published: August 2008

Advances in the design of environmental reaction cells and in the collection of X-ray diffraction data are transforming our ability to study mineral-fluid interactions. The resulting increase in time resolution now allows for the determination of rate laws for mineral reactions that are coupled to atomic-scale changes in crystal structure. Here we address the extension of time-resolved synchrotron diffraction techniques to four areas of critical importance to the cycling of metals in soils: (1) cation exchange; (2) biomineralization; (3) stable isotope fractionation during redox reactions; and (4) nucleation and growth of nanoscale oxyhydroxides.
Reduction of antimony by nano-particulate magnetite and mackinawite
Authors: Kirsch R. , Scheinost A. C. , Rossberg A. , Banerjee D. , Charlet L.
Published: August 2008

The speciation of antimony is strongly influenced by its oxidation state (V, III, 0, —III). Redox processes under anaerobic groundwater conditions may therefore greatly alter the environmental behaviour of Sb. Employing X-ray absorption and photoelectron spectroscopy, we show here that Sb(V) is reduced to Sb(III) by magnetite and mackinawite, two ubiquitous Fe(II)-containing minerals, while Sb(III) is not reduced further. At the surface of magnetite, Sb(III) forms a highly symmetrical sorption complex at the position otherwise occupied by tetrahedral Fe(III). The Sb(V) reduction increases with pH, and at pH values >6.5 Sb(V) is completely reduced to Sb(III) within 30 days. In contrast, at the mackinawite surface, Sb(V) is completely reduced across a wide pH range and within 1 h. The Sb(V) reduction proceeds solely by oxidation of surface Fe(II), while the oxidation state of sulphide is conserved. Independent of whether Sb(V) or Sb(III) was added, an amorphous or nano-particulate SbS3-like solid formed.
Weathering, soil formation and initial ecosystem evolution on a glacier forefield: a case study from the Damma Glacier, Switzerland
Authors: Bernasconi S. M. ,   Biglink Project Members
Published: August 2008

The understanding of biogeochemical processes at the interface between geosphere, hydrosphere and biosphere is of paramount importance for many questions related to global climate and environmental change at very different time and spatial scales. In addition, soils are the principal resource for food production and the understanding of soil formation processes and biological interactions within soils is indispensable for the development of sustainable land-use strategies. In this contribution we present a research initiative, the multidisciplinary ‘BigLink’ Project, aiming at a better understanding of the links between weathering, soil formation and ecosystem evolution and how these biosphere-geosphere interactions are influenced (and themselves influence) climate and environmental change.
The first environmental science experiments on the new microfocus spectroscopy beamline at Diamond
Authors: Mosselmans J. F. W. , Quinn P. D. , Roque Rosell J. , Atkinson K. D. , Dent A. J. , Cavill S. I. , Hodson M. E. , Kirk C. A. , Schofield P. F.
Published: August 2008

Synchrotron based μ-XRF, μ-XAS and μ-XRD have made a major impact in the field of environmental science in the last ten years. One of the first seven ‘day one’ beamlines on the Diamond Light Source is a microfocus spectroscopy beamline, beamline I18. Here the current status of the beamline and the opportunities it presents in the field of environmental science are described, with results from two of the first experiments also included. The first is based on the use of bonemeal to remediate soil. We used Zn K-edge and Pb L3-edge spectroscopy to characterize the speciation of these two elements on a soil after bonemeal treatment. The results are compared with bulk measurements taken on the whole soil and standard materials. The second experiment described here is a study of the speciation and association of Ni in a laterite from Moa Bay, Cuba. Here the differences in the Ni speciation associated with Mn oxides are examined and compared with Fe oxides phases.
Microscopy and spectroscopy with X-rays for studies in the environmental sciences
Authors: Thieme J. , Gleber S.-C. , Guttmann P. , Prietzel J. , McNulty I. , Coates J.
Published: August 2008

X-ray spectromicroscopy is a powerful tool for addressing key questions in the environmental sciences due to its high spectral and spatial resolution. It has been used successfully for material research, biology and environmental studies, e.g. in the form of μ-X-ray fluorescence and spectromicroscopy with a spatial resolution of <100 nm. With the combination of high-resolution microscopy and spectroscopy it is possible to determine elemental composition as well as chemical speciation, and also identify trace elements to nm-resolution. Samples from soils and groundwater aquifers have been imaged to visualize the appearance of structures on the nm- and μm-scale. The effectof changing chemical conditions in an aqueous environment on the appearance of these structures has been imaged and evaluated. Clay dispersions, microhabitats and morphological effects of biologically-induced redox changes of humic substances have been imaged tomographically, conveying a detailed threedimensional presentation of the specimen structure. Using the spectromicroscopy potential, the distribution of organic and inorganic components, as well as different inorganic components, has been studied. Spectra were analysed for major chemical constituents and were used, for example, to assess differentsulphur species in an entire soil profile.
Transformation of ferrihydrite to hematite: anin situinvestigation on the kinetics and mechanisms
Authors: Vu H. P. , Shaw S. , Benning L. G.
Published: August 2008

The kinetics and mechanisms of the transformation of 2-line ferrihydrite (FH) to hematite (HM), in the presence of Pb at elevated temperatures and high pH condition, were elucidated using synchrotron-based,in situenergy dispersive X-ray diffraction (EDXRD). The time-resolved diffraction data indicated that HM crystallization occurred via a two-stage process. Based on the EDXRD data, combined with high-resolution electron microscopic images, an aqueous-aided 2D growth mechanism is proposed for both HM crystallization stages.
Biological control over the formation and storage of amorphous calcium carbonate by earthworms
Authors: Briones M. J. I. , López E. , Méndez J. , Rodríguez J. B. , Gago-Duport L.
Published: August 2008

The earthworm calciferous gland produces a concentrated suspension of calcium carbonate and in certain species precipitates as concretions of CaCO3, which then enter the soil. Here we investigated the initial stages of CaCO3 formation in the earthworm Lumbricus friendi by means of Fourier transform infrared and electron microscopy techniques (field-emission scanning electron microscopy, transmission electron microscopy, high resolution electron microscopy and selected area electron diffraction). In addition, comparisons between the IR spectra of the water-dissolved carbonic anhydrase (CA) and the glandular secretion (‘milky fluid’) were performed in order to investigate the mechanisms involved in CaCO3 precipitation. Our results strongly suggest that carbonation starts with the dissolved CO2, which is transformed via deprotonation to HCO3-, then to CO32- and finally to amorphous calcium carbonate (ACC). While ACC stabilization takes place under the biological control, further transformation stages leading to calcite concretions seem to be inorganically driven by an Ostwald ripening process.
Distribution of sulphated polysaccharides within calcareous biominerals suggests a widely shared two-step crystallization process for the microstructural growth units
Authors: Cuif J. P. , Dauphin Y. , Farre B. , Nehrke G. , Nouet J. , Salomé M.
Published: August 2008

Synchrotron-based XANES characterization of sulphated sulphur combined with atomic force microscopy and transmission electron microscopy (imaging and diffraction) allow insights into the crystallization of the calcareous units produced by invertebrates. As a result of a series of converging data, reticulate crystallization of the amorphous Ca-carbonate molecules conveyed to the micron-thick growth layer by the sumicrometric organo-mineral units seems a reasonable hypothesis, providing us with a method of explaining the multiple and taxonomy-linked ‘vital effects’ which have long been recognized among the calcareous biocrystals.
Oxygen isotope equilibrium in brachiopod shell fibres in the context of biological control
Authors: Cusack M. , A. Pérez-Huerta  , Chung P. , Parkinson D. , Dauphin Y. , Cuif J.-P.
Published: August 2008

With their long geological history and stable low-Mg calcite shells, Rhynchonelliform brachiopods are attractive sources of environmental data such as past seawater temperature (Buening and Spero, 1996; Auclair et al., 2003; Brand et al., 2003; Parkinson et al., 2005). Concerns about the influence of vital effects on the stable isotope composition of brachiopod shells (Popp et al., 1986), led to isotope analyses of different parts of brachiopod shells in order to identify those parts of the shell that are influenced by any vital effect and those parts that may be suitable recorders of seawater temperature via stable oxygen isotope composition (Carpenter and Lohmann, 1995; Parkinson et al., 2005). Such detailed studies demonstrated that the outer primary layer of acicularcalcite is isotopically light in both δ18O and δ13C while the secondary layer, composed of calcite fibres, is in oxygen-isotope equilibrium with ambient seawater(Fig. 1) (Parkinson et al., 2005).
The nanostructural unity of Mollusc shells
Authors: Dauphin Y.
Published: August 2008

Calcite and aragonite shell layers of the main classes of Molluscs are composed of monocrystalline units (prisms, tablets, laths or fibres). Scanning electron and atomic force microscopy studies show these units are composed of small round granules with a thin cortex (amorphous calcium carbonate and/or organic matrix). These granules are organo-mineral composites. A comparison of the size and shape of the granules in different taxa (Mollusca, Brachiopoda) suggests a possible relationship with taxonomy and/or phylogeny.
Biocalcification by Emiliania huxleyi in batch culture experiments
Authors: de Bodt C. , Harlay J. , Chou L.
Published: August 2008

Coccolithophores, among which Emiliania huxleyi is the most abundant and widespread species, are considered the most productive calcifying organism on earth. The export of organic carbon and calcification are the main drivers of the biological CO2 pump and are expected to change with oceanic acidification. Coccolithophores are further known to produce transparent exopolymer particles (TEP) that promote particle aggregation. As a result, the TEP and biogenic calcium carbonate (CaCO3) contribute to the export of carbon from the surface ocean to deep waters. In this context, we followed the development and the decline of E. huxleyi using batch experiments with monospecific cultures. We studied the link between different processes such as photosynthesis, calcification and the production of TEP. The onset of calcification was delayed in relation to photosynthesis. The timing and the general feature of the dynamics of calcification were closely related to the saturation state of seawater with respect to calcite, Ωcal. The production of TEP was enhanced after the decline of phytoplankton growth. After nutrient exhaustion, particulate organic carbon (POC) concentration increased linearly with increasing TEP concentration, suggesting that TEP contributes to the POC increase. The production of CaCO3 is also strongly correlated with that of TEP, suggesting that calcification may be considered as a source of TEP precursors.
Crystallization of calcite from amorphous calcium carbonate: earthworms show the way
Authors: Lee M. R. , Hodson M. E. , Langworthy G. N.
Published: August 2008

Darwin (1881) was one of the first scientists to formally record that earthworms excrete calcium carbonate granules, with some up to 2 mm in diameter. However, since Darwin’s studies they have received relatively little attention. The function of the granules remains a mystery, but may be related to regulation of Ca, CO2, pH or some other as yet undiscovered metabolic process (Robertson, 1936; Piearce, 1972). There has recently been an increase in research activity focussed on earthworm calcium carbonate granules driven by the work of Canti (Canti, 1998, 2007; Cantian d Piearce, 2003) and largely relating to their potential use in archaeology.
Terrestrial plant-Si and environmental changes
Authors: Meunier J. D. , Guntzer F. , Kirman S. , Keller C.
Published: August 2008

The importance of silica in terrestrial land plants has been recognized since the middle of the 19th century with applications in agronomy and palaeovegetation reconstruction. In this presentation, we will review the latest advances in our understanding of phytolith formation and present a few examples of applications in the field of global environmental changes.
Exploring the role of ions and amino acids in directing the growth of minerals from solution
Authors: Piana S. , Jones F. , Taylor Z. , Raiteri P. , Gale J. D.
Published: August 2008

The influence of both sulphate ions and aspartic acid on directing the growth of baryte has been explored using computer simulation. Both species are found to significantly reduce the activation free-energy to growth under appropriate conditions, with the influence of sulphate being surface specific. This offers the potential for a new approach to morphology control without inhibition that may have implications for biomineralization.
Dehydration behaviour of the Ca(SO4,HPO4).2H2O solid solution
Authors: Pinto A. J. , Jimenez A. , Prieto M.
Published: August 2008

Gypsum (CaSO4·2H2O) and brushite (CaHPO4·2H2O) are minerals with similar structures, despite not being isostructural. They both belong to the monoclinic system, but crystallize in different space groups. It is known that, to some extent, phosphate and sulphate groups can substitute for each other within the structure of these minerals. In the present work, the dehydration behaviour of experimentally produced Ca(SO4,HPO4)·2H2O solid solutions is assessed from thermogravimetrical (TG and DTG) and differential scanning calorimetry (DSC) analyses. For the applied experimental conditions it was not possible to obtain homogenous precipitates with compositions within 0.27 < XBr < 0.53, where XBr is the brushite mole fraction. The results reveal that the dehydration behaviour of solid solutions with compositions within the 0 < XBr < 0.27 interval tend to approach the dehydration process of pure gypsum. On the other hand, solid solutions with compositions within 0.53 < XBr < 1 involve higher dehydration temperatures than the brushite end-member, in a two-step process.
How to make ‘stable’ ACC: protocol and preliminary structural characterization
Authors: Rodriguez-Blanco J. D. , Shaw S. , Benning L. G.
Published: August 2008

A reproducible and simple protocol to synthesize and stabilize the metastable CaCO3·nH2O phase termed amorphous calcium carbonate (ACC) was developed in order to allow the characterization of its structure at the nanoscale using high-resolution microscopy combined with Raman spectroscopy and X-ray diffraction. ‘Stable’ ACC consists of relatively smooth spherical particles, 50—200 nm in size, that have XRD and Raman patterns with no intense peaks or sharp bands, as expected from amorphous material. Furthermore, high-resolution imaging also supports this finding but in addition, beam-damage induced crystallization and the concomitant formation of locally ordered domains in the ACC spheres are discussed.
The size and polydispersity of silica nanoparticles under simulated hot spring conditions
Authors: Tobler D. J. , Benning L. G. , Knapp J.
Published: August 2008

The nucleation and growth of silica nanoparticles in supersaturated geothermal waters was simulated using a flow-through geothermal simulator system. The effect of silica concentration ([SiO2]), ionic strength (IS), temperature (T) and organic additives on the size and polydispersity of the forming silica nanoparticles was quantified. A decrease in temperature (58 to 33°C) and the addition of glucose restricted particle growth to sizes <20 nm, while varying [SiO2] or ISdid not affect the size (30—35 nm) and polydispersity (±9 nm) observed at 58°C. Conversely, the addition of xanthan gum induced the development of thin films that enhanced silica aggregation.
Bacterial EPS as a mediator of calcium carbonate morphology and polymorphism
Authors: Tourney J. , Ngwenya B. T.
Published: August 2008

Biologically influenced mineralization either on the surfaces of, or in close proximity to bacterial cells may produce minerals that display distinct mineralogical or morphological features as a consequence of the microbial influence on the precipitation process. Characterizing such distinguishing features could potentially facilitate identification of early life in the geological record.
Climate, water and CO2: a geological perspective
Authors: Veizer J.
Published: August 2008

The development of a palaeothermometer for ancient oceans has been a prime goal of stable isotope geochemistry since its inception in the middle of the last century. Following the calibration of the calcite oxygen isotope palaeothermometer by Epstein et al. (1953), and expanding on the seminal papers by Cesare Emiliani, the technique blossomed into a widely applied tool of palaeoceanography. These studies resulted in major advances in our understanding of Quaternary, and to some extent Tertiary oceans, but for older time periods the effort is mired by controversy and is at a standstill. In part this is due to the dearth of well-characterized carrier phases for the temperature signal, such as foraminifera shells, in the pre-Tertiary strata, but an intractable disagreement among practitioners as to the oxygen isotopic composition of ancient seawater is probably a more important stumbling block.
Simulations of monosaccharide on calcite surfaces
Authors: Yang M. , Harding J. , Stipp S. L. S.
Published: August 2008

Organic molecules control calcite growth byadsorbing preferentiallyonto particular surfaces of the crystal. Adsorption of a monosaccharide (-galactose) on various calcite surfaces has been simulated with molecular dynamics. The calculations of Z-density, mean square displacement (MSD) and adsorption energyindicate that the adsorption of monosaccharide on the acute-stepped calcite (31.8) surface is more favourable than that on the obtuse-stepped (31.16) surface, which suggests that monosaccharides maybe able to selectivelycover some surfaces, inhibit crystal growth on these surfaces, and as a result shape the calcite crystals as seen in biominerals, e.g. coccoliths.
Global sensitivity of weathering rates to atmospheric CO2 under the assumption of saturated river discharge
Authors: Arens S. , Kleidon A.
Published: August 2008

The sensitivity of the global river-borne flux of Ca2+ to atmospheric pCO2 was obtained from model simulations under the assumption of saturation of CaCO3. The response was subdivided into contributions from changes in runoff, temperature and partial CO2 pressure and these were then used to parameterize the different direct and indirect effects of a changing climate on carbonate weathering and equilibria. The parameterizations are comparable/compatible to those of Walker et al. (1981) for silicate weathering, but are taken directly from models demonstrating the potential of this approach in weathering studies.
Changes in the flux of Saharan dust to the East Mediterranean Sea since the last glacial maximum as observed through Sr-isotope geochemistry
Authors: Box M. R. , Krom M. D. , Cliff R. , Almogi-Labin A. , Bar-Matthews M. , Ayalon A. , Schillman B. , Paterne M.
Published: August 2008

We present a dust flux (g m-2yr-1) record for the East Mediterranean Sea constructed using 87Sr/86Sr ratio measurements on the fine fraction of carbonate-free sediment from core 9501 from the north Levantine basin. The Saharan dust flux profile shows a first order correspondence with Atlantic dust-flux records in showing: (1) small dust fluxes during the last glacial maximum, a dust pulse associated with the Heinrich 1 (H1) event; (2) a small peak corresponding with the younger dryas (YD); (3) a decrease during the African Humid Period (AHP); and (4) an abrupt return to dustier conditions between ~5.7—5.2 ky BP.
U-series constraints on aquifer groundwater residence time: the Adour-Garonne district case (southwest France)
Authors: Innocent C. , Négrel P.
Published: August 2008

U-series were investigated in groundwaters from two water bodies of the Eocene sands aquifer, southwest France. The 234U/238U activity ratios are always larger than the equilibrium value, some waters being highly enriched in 234U (as large as 13.5). In the southern water body, 234U/238U ratios correlate with 14C ages (with one exception). Such U isotopic signatures may allow the evaluation of the residence time of groundwaters within their aquifer using an open-system model based on U activity ratios and concentrations. It is suggested that the ‘oldest’ groundwaters from the southern water body are no older than 38 ky, whereas the maximum ‘age’ of groundwaters from the northern water body, though overall of the same order of magnitude, could be slightly younger (25 ky).
Effects of Ca-enrichment on authigenic carbonate formation at cold vent sites off Costa Rica: a numerical model approach
Authors: Karaca D. , Hensen C. , Wallmann K.
Published: August 2008

The Costa Rican forearc is characterized by active fluid venting related to mud diapirism and volcanism. The geochemical compositions of fluids obtained from dewatering sites indicate that mineral precipitation or dehydration is the major driver of fluid mobilization and upward migration. The peculiar situation at the latter sites is that Ca concentrations in the upward migrating fluids are well above seawater levels. In turn, these Ca-enriched fluids could offer a potential reason for widespread carbonate caps on top of the mounds.
Chemostatic modes of the ocean-atmosphere-sediment system through Phanerozoic time
Authors: Mackenzie F. T. , Arvidson R. S. , Guidry M.
Published: August 2008

The essential state of the Phanerozoic ocean-atmosphere system with respect to major lithophile and organic components can be bounded by sedimentary observational data and relatively few model assumptions. The model assumptions are in turn sufficient to constrain and compute the remaining fluxes that result in a comprehensive model describing atmospheric and oceanic evolutionary history over the past 500 m.y. that is in accord with the sedimentary observational data. Two central themes emerge. First, there is a strong coupling of the state of various reservoirs throughout the entire system imposed mainly by negative physical, chemical and biological feedbacks. Second, there is a significant overprint of ‘physical’ processes, such as weathering, by biologically-mediated processes and ecosystem evolution. Ultimately, the Phanerozoic is characterized by two modes of seawater major-ion chemistry, pH and carbonate saturation state, and atmospheric CO2. Importantly, the transition between these two modes may result from the previous state of the system whose impacts lag by tens of millions of years. Thus, the instantaneous state of the system at any given point in time may reflect in part the ‘memory’ ofa previous period when fluxes and processes were not in balance. The modern-day problem of ocean acidification mainly reflects the fact that human activities of fossil fuel burning and land use changes are resulting in geologically rapid releases of CO2 to the atmosphere and its absorption by the surface ocean and does not reflect the longer term processes and feedbacks that led to the acidic oceans of the past.
Controlled biomineralization of magnetite (Fe3O4) by Magnetospirillum gryphiswaldense
Authors: Moisescu C. , Bonneville S. , Tobler D. , Ardelean I. , Benning L. G.
Published: August 2008

Results from a study of the chemical composition and micro-structural characteristics of bacterial magnetosomes extracted from the magnetotactic bacterial strain Magnetospirillum gryphiswaldense are presented here. Using high-resolution transmission electron microscopy combined with selected-area electron diffraction and energy dispersive X-ray microanalysis, biogenic magnetite particles isolated from mature cultures were analysed for variations in crystallinity and particle size, as well as chain character and length. The analysed crystals showed a narrow size range (~14—67 nm) with an average diameter of 46±6.8 nm, cuboctahedral morphologies and typical Gamma type crystal size distributions. The magnetite particles exhibited a high chemical purity (exclusively Fe3O4) and the majority fall within the single-magnetic-domain range.
Variscite dissolution rates in aqueous solution: does variscite control the availability of phosphate in acidic natural waters?
Authors: Roncal-Herrero T. , Oelkers E. H.
Published: August 2008

The dissolution rates of natural well-crystallized variscite (AlPO4.2H2O) were measured from the evolution of aqueous Al and P concentrations in closed and mixed-flow through reactors at 25°C and from 1.5 to 9 pH. Measured dissolution rates decrease with increasing pH from 5.05x10-16 mol/cm2/s at pH = 1.51 to 4.92x10-17 mol/cm2/s at pH = 5.89 and then increase with increasing pH to 1.64x10-17 mol/cm2/s at pH = 8.99. Estimates of the time required to equilibrate a mildly acidic, initially Al- and P-free solution with variscite based on measured dissolution rates and solubility products suggests it takes no more than several weeks to equilibrate this mineral with soil pore fluids. This result suggests that variscite can buffer aqueous phosphate concentrations in a significant number of near surface environments.
Ethanol adsorption on the {104} calcite surface: preliminary observations with atomic force microscopy
Authors: Sand K. K. , Stipp S. L. S. , Hassenkam T. , Yang M. , Cooke D. , Makovicky E.
Published: August 2008

Preliminary atomic force microscopy investigations of the {104} calcite surface cleaved in ethanol indicate a different surface behaviour than that of the {104} surface cleaved in air. The results are consistent with recent theoretical studies and suggest strong ordering of ethanol over the termination of the bulk calcite structure.
Impacts of changing ocean chemistry in a high-CO2 world
Authors: Turley C.
Published: August 2008

Over the last ∼200 years, since the start of the industrial revolution, the increase in the burning of fossil fuels, cement manufacturing and changes to land use has increased atmospheric CO2 concentrations from ∼80 to 385 ppm. These are the highest levels experienced on Earth for at least the last 800,000 years, possibly for the past 10’s of millions of years. The 2007 IPCC report on climate change predicts a continued rapid rise in atmospheric CO2 leading to significant temperature increases in the atmosphere and ocean in the coming decades, as well as other climate changes. The IPCC (2007) also reports, for the first time, that increasing anthropogenic CO2 will result in increased acidity of the world’s surface oceans. This process is already happening and further rapid decreases in ocean pH will occur this century, concomitantly with warming seas, creating multiple threats to the marine environment. The future addition of massive amounts of CO2 to surface waters will have a profound impact on ocean chemistry and could have an equally profound impact on biogeochemical cycles, marine organisms, ecosystems and the services they provide. ‘Ocean acidification’ is a strong additional argument to that of climate change for urgent and substantial reduction of CO2 emissions.