Statistical chemistry of calcic amphiboles

Principal components analysis is used to study the chemistry of 639 calcic amphiboles. Eigenvectors representing multiple partial correlation coefficients give various sets of substitutional relationships. The relative significance of each set can be noted by the percent variation of the data it represents. The highest percent variation (36%) is associated with the substitutions $$Si + Mg \rightleftharpoons Al^{IV} + Al^{VI} + Ti + Fe^{3 + } + Fe^{2 + } + Na + K$$ . Other expected substitutions among the ions such as Al^IV + Na ? Si, the positive correlation between Al^IV and Al^VI etc. are shown statistically. The substitution of Al in T ₁ and T ₂ positions imposes an ordering in the M ₁, M ₂ and M ₃ sites. Variability of OH in the amphiboles is found to be significant. There is no definite correlation between OH and Fe³⁺ but OH and Ti are positively correlated. Under certain conditions and provided the concentration of Al^IV does not change significantly, Fe and Mg may be assumed to mix ideally in the amphibole solid solution.     

A model of Earth’s deep interior basedon mineralogical data

Summary ?We describe here a model of formation of the core and the early history of Earth based on recent experimental mineralogical data. In a nebular setting, where differentiated planetesimals with their iron cores were plentiful, hot condensing solids mixed with the planetesimal irons and formed the solid proto-core (Fe-Ni-S-C). FeO from unmixing in magnesiowustite and from a dissociation of perovskite in the newly accreted mantle concentrated at the core-mantle interface and reacted with the nascent core. The interface grew to form the liquid core (Fe-Ni-O-S-C) at the expense of the solid proto-core and the formation of much of the outer core was complete within the first 500 million years. The model is consistent with geochemical data and has important implications for the dynamics of the inner core.

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Zusammenfassung ?Das Innere der Erde: Ein Modell basierend auf mineralogischen Daten Wir pr?sentieren ein Modell zur Bildung des Erdkerns und der frühen Geschichte der Erde, das auf neuen experimentellen mineralogischen Daten basiert. In einem nebularen System, in dem differenzierte Planetesimals mit Eisenkernen sehr h?ufig waren, mischten sich kondensierte Festk?rper mit dem Eisen der Planetesimals, um einen festen Protokern (Fe-Ni-S-C) zu formen. FeO, das aus Magnesiowüstit entmischte und durch Dissoziation aus Perovskit im Mantel entstand, konzentrierte sich in der Kern – Mantel – Grenzzone und reagierte mit dem neugebildeten Kern. Diese Grenzzone wuchs und es entstand ein flüssiger (Fe-Mi-O-S-C) Kern auf Kosten des festen Protokerns. Die Bildung des ?u?eren Kerns war innerhalb der ersten 500 Millionen Jahre abgeschlossen. Dieses Modell ist mit geochemischen Daten konsistent und hat wichtige Auswirkungen auf die Dynamik des inneren Kerns.

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Received February 9, 1999;/revised version accepted April 9, 1999     

Fictive component model of pyroxenes and multicomponent phase equilibria

Pyroxenes are considered as ideal solid solutions of some real components (e.g. diopside or orthoenstatite) and some fictive or hypothetical components (e.g. orthodiopside or orthohedenbergite). Using the reversed experimental data in the CaO-MgO-SiO₂ system, the Gibbs free energy of formation of fictive orthodiopside and of fictive clinoenstatite have been determined in the temperature range of 1,000 to 1,600 °K. The data on free energies of components in the binary system can be used to extend the fictive component model to the ternary CaSiO₃-MgSiO₃-FeSiO₃ system. Using published phase diagrams on the pyroxene quadrilateral, Gibbs free energy of formation of fictive orthohedenbergite has been calculated. Application of the ideally mixing fictive component model to computation of phase equilibria leads to the determination of compositions of coexisting Fe-Mg-Ca pyroxenes at different temperatures.Abbreviations and symbols G _f ⁰ Gibbs free energy of formation from the elements at 1 bar and temperature - G ^Ex excess free energy of mixing in a solution - G molar Gibbs free energy - R gas constant - H enthalpy - S entropy - T absolute temperature - P pressure - KJ/M kilojoules per mole - j joules - Opx orthopyroxene - Cpx clinopyroxene - H hedenbergite - D diopside - E enstatite - F ferrosilite - X mole fraction - K equilibrium constant     

Book review

Sea Surveying, edited by Alan Ingham (London: John Wiley & Sons, 1975), 2 volumes, 306 and 233 pp., hardcover, $49.50.     

Changes in Agricultural Biodiversity： Implications for Sustainable Livelihood in the Himalaya

Himalayan mountain system is distinguished globally for a rich biodiversity and for its role in regulating the climate of the South Asia.Traditional crop-livestock mixed farming in the Himalaya is highly dependent on forests for fodder and manure prepared from forest leaf litter and livestock excreta. Apart from sustaining farm production, forests provide a variety of other tangible and intangible benefits, which are critical for sustainable livelihood of not only 115 million mountain people, but also many more people living in the adjoining plains. Extension of agricultural landuse coupled with replacement of traditional staple food crops by cash crops and of multipurpose agroforestry trees by fruit trees are widespread changes. Cultivation of Fagopyrum esculentum,Fagopyrum tataricum, Panicum miliaceum, Setaria italica and Pisum arvense has been almost abandoned. Increasing stress on cash crops is driven by a socio-cultural change from subsistence to market economy facilitated by improvement in accessibility and supply of staple food grains at subsidized price by the government. Farmers have gained substantial economic benefits from cash crops. However, loss of agrobiodiversity implies more risks to local livelihood in the events of downfall in market price/demand of cash crops, termination of supply of staple food grains at subsidized price, pest outbreaks in a cash crop dominated homogeneous landscape and abnormal climate years. Indigenous innovations enabling improvement in farm economy by conserving and/enhancing agrobiodiversity do exist, but are highly localized. The changes in agrobiodiversity are such that soil loss and run-off from the croplands have dramatically increased together with increase in local pressure on forests. As farm productivity is maintained with forest-based inputs, continued depletion of forest resources will result in poor economic returns from agriculture to local people,apart from loss of global benefits from Himalayan forests. Interventions including improvement in traditional manure and management of on-farm trees,participatory development of agroforestry in degraded forest lands and policies favoring economic benefits to local people from non-timber forest products could reduce the risks of decline in agricultural biodiversity and associated threats to livelihoods and Himalayan ecosystems.     

Mid-term periodicities and heliospheric modulation of coronal index and solar flare index during solar cycles 22–23

We applied fast Fourier transform techniques and Morlet wavelet transform on the time series data of coronal index, solar flare index, and galactic cosmic ray, for the period 1986–2008, in order to investigate the long- and mid-term periodicities including the Rieger (({sim }130) to ({sim }190) days), quasi-period (({sim }200) to ({sim }374) days), and quasi-biennial periodicities (({sim }1.20) to ({sim }3.27) years) during the combined solar cycles 22–23. We emphasize the fact that a lesser number of periodicities are found in the range of low frequencies, while the higher frequencies show a greater number of periodicities. The rotation rates at the base of convection zone have periods for coronal index of ({sim }1.43) years and for solar flare index of ({sim }1.41) year, and galactic cosmic ray, ({sim }1.35) year, during combined solar cycles 22–23. In relation to these two solar parameters (coronal index and solar flare index), for the solar cycles 22–23, we found that galactic cosmic ray modulation at mid cut-off rigidity ((hbox {Rc} = 2.43hbox {GV})) is anti-correlated with time-lag of few months.     

Water-soluble organics in atmospheric particles: A critical review of the literature and application of thermodynamics to identify candidate compounds

Although organic compounds typically constitute a substantial fraction of the fine particulate matter (PM) in the atmosphere, their molecular composition remains poorly characterized. This is largely because atmospheric particles contain a myriad of diverse organic compounds, not all of which extract in a single solvent or elute through a gas chromatograph; therefore, a substantial portion typically remains unanalyzed. Most often the chemical analysis is performed on a fraction that extracts in organic solvents such as benzene, ether or hexane; consequently, information on the molecular composition of the water-soluble fraction is particularly sparse and incomplete.This paper investigates theoretically the characteristics of the water-soluble fraction by splicing together various strands of information from the literature. We identify specific compounds that are likely to contribute to the water-soluble fraction by juxtaposing observations regarding the extraction characteristics and the molecular composition of atmospheric particulate organics with compound-specific solubility and condensibility for a wide variety of organics. The results show that water-soluble organics, which constitute a substantial fraction of the total organic mass, include C2 to C7 multifunctional compounds (e.g., diacids, polyols, amino acids). The importance of diacids is already recognized; our results provide an impetus for new experiments to establish the atmospheric concentrations and sources of polyols, amino acids and other oxygenated multifunctional compounds.     

Cyclone Frame Prediction by Gaussian Mixture Modeling of the Three Penultimate Time-Lapse Frames

A fast cyclone frame prediction is proposed in this paper that fits a Gaussian Mixture model on the spatio-temporal data extracted from the three penultimate time-lapse frames, prior to fuzzy regression. Unlike the previous work in Verma and Pal (In: Applied Imagery Pattern Recognition Workshop (AIPR), pp. 1–8, 2010) that models the entire history on a per pixel basis, a single Gaussian mixture is used for fitting the spatio-temporal data within the time-span of the last three frames, making the process faster and more accurate. The increase in accuracy is attributed to the fact that cyclones evolve over time and thus the recent frames give a more meaningful insight into the predictions for the next frame. The number of components in the Gaussian mixture is determined from the occurrence of equally likely modes that correspond to high entropy peaks. Our results on satellite videos of recent cyclones that hit the Indian seas show a high accuracy of frame prediction.     

Gas-Phase Formation of Water-Soluble Organic Compounds in the Atmosphere: A Retrosynthetic Analysis

Atmospheric particles contain a myriad of organiccompounds, including many multifunctional,water-soluble organic compounds. Many of thesecompounds are postulated to be secondary of origin. This work investigates the possible precursors ofseveral classes of multifunctional, water-solublesecondary organic compounds by analyzing the pathwaysleading to their formation, based on known gas-phasereactions. The analysis is termed `retrosynthetic'due to the backward direction of the analysis, fromproducts to precursors. Pathways for multi-functionalcompounds were generated combinatorially, consideringthe formation of one functional group at a time.Many multifunctional organic compounds with carboxylicacid, carbonyl, and hydroxy functional groups werefound to be first- or second-generation products ofcommon anthropogenic and biogenic volatile organiccompounds such as alkanes, alkenes, aromatics, andcyclic alkenes. The estimated yields of water-solubleorganic compounds from primary precursors ranged fromless than 1% to over 10%, based on stoichiometricconsiderations. The SOA formation index, whichcombines the concepts of yields and rates, was used tocompare the feasibility of the retrosyntheticpathways. Many of the candidate pathways involve theisomerization reaction of alkoxy radicals andoxygenated intermediate products such asmonocarboxylic acids and hydroxyaldehydes.     

Absolute sea level determination for the subtropical Atlantic Climate Study

The Subtropical Atlantic Climate Study (STACS) is a subprogram in the NOAA climate program designed to access the feasibility of monitoring horizontal fluxes in the Gulf Stream system off Florida. Transport in the Florida Current fluctuates on time scales which are reflected in sea level records monitored at tide gauges. Geodetic leveling, connecting tide gauges along the east coast of the United States, allows intercomparison of sea level records alongstream, but the cross-stream and alongstream records in the Bahamas and Cuba are not connected. In this study, various methods to determine absolute sea level differences across the Straits of Florida between Miami, Florida and Cat Cay, Bahamas, a part of the STACS area, were investigated; the desired accuracy of the sea level difference is ± 1 cm. This study indicates that a combination of dense gravity data with satellite altimeter (TOPEX and GEOSAT) data in the STACS area could provide a ± 1 cm absolute sea level difference accuracy across the Straits of Florida. This paper also provides discussion of other conventional methods.