Resource depletion calculated by the ratio of the reserve plus cumulative consumption to the crustal abundance for gold

The magnitude of the world's mineral consumption has increased sharply, and there is no sign that growth is likely to stop in the near future. Currently, new discoveries and technology add to the reserves of varous mineral commodities at a rate that has exceeded depletion. As a result, life expectancies have remained nearly constant. However, it is questionable whether this condition is sustainable in the future. Therefore, most of our attention to the future has been focused on potentially recoverable resources. The potentially recoverable resources for 35 minerals in the Earth's crust were estimated based on the relationship between crustal abundance and the reserve of currently recoverable gold. The ratio of the reserve plus cumulative consumption to the abundance of gold is appropriate for calculating reserves of other mineral resources because gold has the highest profit margin for exploration of reserves. From an economic perspective, the price of gold is 350 times the mean value of 33 other resources for calculating production versus price. New mining technologies and new processing methods have been developed during the last 20 years as a response to high prices. As a result, five times the reserves available in 1970 have now been discovered, and two times the reserves available in 1970 were consumed during the past two decades. It is questionable whether other mineral commodities can reach the ratio of reserve plus cumulative consumption to abundance that gold does. Using this concept, the limit of the Earth's resources under present technology was calculated for 35 mineral resources, based on the ratio of the reserve plus cumulative consumption to abundance for gold. Even though recoverable tonnage of lead, silver, tin, boron, copper, and mercury from ore deposits in the Earth's crust is relatively low, the abundance of these metals is apparently sufficient for future supplies. However, considering the special situation of gold created by its very high price compared to world production, there is anxiety concerning steep increases in the price or depletion of these metals, which have a shorter lifetime from a geochemical point of view.     

Microstructures of olivine-plagioclase corona in meta-ultramafic rocks from Sefuri Mountains, NW Kyushu, Japan

Two types of reaction rims occur between olivine and plagioclase in ultramafic rocks from the Sefuri Mountains, NW Kyushu, Japan, which were metamorphosed under granulite-facies conditions. One occurs as a thin film of orthopyroxene along the boundary between olivine and plagioclase (orthopyroxene zone). The other is composed of two zones: symplectite of calcic amphibole and spinel on the plagioclase-side (symplectite zone) and calcic amphibole with sporadic orthopyroxene on the olivine-side (tremolite zone). In the tremolite zone, calcic amphibole shows a systematic decrease in Al content and increase in Mg/(Fe +Mg) with decreasing distance from olivine. Local equilibria maintained during the diffusion-controlled corona-forming reaction enable us to apply equilibrium thermodynamics to calcic amphibole and adjacent orthopyroxene. An integrated formulation of the Gibbs method for an Fe–Mg exchange reaction constrains the equilibrium temperature recorded in the tremolite zone to be 600–710 °C. It is significantly lower than the temperature of the granulite-facies metamorphism (800–900 °C) estimated using conventional geothermobarometry. Except for H₂O, the association of calcic amphibole and spinel in the symplectite zone is chemically equivalent to the association of olivine, plagioclase and orthopyroxene that was stable before the corona formation. This suggests that the following orthopyroxene-consuming reaction describes the paragenetic change taking place between 800–900 °C and 600–710 °C, olivine + plagioclase + orthopyroxene + aqueous fluid = calcic amphibole + spinel. In contrast, the overall reaction inferred from microstructures produces orthopyroxene as well as calcic amphibole and spinel at the expense of olivine and plagioclase. This reaction requires removal mainly of MgO that is also responsible for destabilizing the local association of olivine and plagioclase. These features suggest that the presence of orthopyroxene as a product in the corona is not always indicative of an orthopyroxene-producing reaction being responsible for the change of paragenetic relation. Microstructural features should be carefully applied to infer the reaction describing paragenetic change by which we argue the P–T path of the rocks.     

Molecular masses and chromophoric properties of dissolved organic ligands for copper(II) in oceanic water

The distribution of molecular masses of organic ligands for copper(II) in oceanic water was investigated. The bulk dissolved organic matter (DOM) was fractionated by ultrafiltration and organic ligands were extracted from the resultant fractions by using immobilized metal ion affinity chromatography (IMAC). Contributions of total organic ligands were 2.0–4.4% of the bulk DOM in surface waters, as determined by the UV absorbance. In the distribution of molecular masses of organic ligands, relative contribution of the fraction with low molecular masses (<1000 Da) was dominant (49–62%), while 26–33% of the total organic ligands was in the 1000–10,000 Da fraction, leaving 10–19% in the >10,000 Da fraction. The distribution of molecular masses of organic ligands shifted to higher molecular masses, as compared with that of the bulk DOM. The fluorescence intensities of organic ligands were shown to be associated with carboxyl contents, based on peak excitation/emission wavelengths and the pH-dependence of fluorescence. Two ligand classes with different conditional stability constants (log K_CuL′≈7 and 9) were determined from fluorescence quenching of ligand fractions during copper(II) titration. Organic ligands in low molecular mass fractions were relatively weak and strong ligands occurred in higher molecular mass fractions. It is suggested that the weaker ligand sites would consist of two or more carboxyl groups (log K_HL′=4), whereas carboxyl groups (log =2), which are protonated at lower pH, and primary amine may additionally contribute to the formation of more stable copper(II) complexes of the stronger ligand.     

Modeling the interaction between fluid flow and particle movement with discontinuous deformation analysis (DDA) method

Coupled hydro‐mechanical processes in granular media represent the interaction between solid particles movement and fluid flow during external and/or internal loading. The processes attract attention in geotechnical engineering since they cause many disasters such as landslide, slope collapse, boiling/quicksand and soil liquefaction, etc. This study presents a numerical method combining discontinuous deformation analysis (DDA) for mechanical calculation and finite element method for fluid flow simulation to model the interaction between solid particles' movement and fluid flow from microscopic point of view. The term of hydraulic pressure was newly formulated and introduced to the original DDA. The simplified examples are given to verify the new method, and the computational results correlate well with the theoretical calculations, further development is also considered. Copyright © 2010 John Wiley & Sons, Ltd.     

High-pressure Raman studies and heat capacity measurements on the MgSiO<Subscript>3</Subscript> analogue CaIr<Subscript>0.5</Subscript>Pt<Subscript>0.5</Subscript>O<Subscript>3</Subscript>

Raman spectroscopy and heat capacity measurements have been used to study the post-perovskite phase of CaIr_0.5Pt_0.5O₃, recovered from synthesis at a pressure of 15 GPa. Laser heating CaIr_0.5Pt_0.5O₃ to 1,900 K at 60 GPa produces a new perovskite phase which is not recoverable and reverts to the post-perovskite polymorph between 20 and 9 GPa on decompression. This implies that Pt-rich CaIr_1−xPt_xO₃ perovskites including the end member CaPtO₃ cannot easily be recovered to ambient pressure from high P–T synthesis. We estimate an increase in the thermodynamic Grüneisen parameter across the post-perovskite to perovskite transition of 34%, of similar magnitude to those for (Mg,Fe)SiO₃ and MgGeO₃, suggesting that CaIr_0.5Pt_0.5O₃ is a promising analogue for experimental studies of the competition in energetics between perovskite and post-perovskite phases of magnesium silicates in Earth’s lowermost mantle. Low-temperature heat capacity measurements show that CaIrO₃ has a significant Sommerfeld coefficient of 11.7 mJ/mol K² and an entropy change of only 1.1% of Rln2 at the 108 K Curie transition, consistent with the near-itinerant electron magnetism. Heat capacity results for post-perovskite CaIr_0.5Rh_0.5O₃ are also reported.     

A development of the discontinuous deformation analysis for rock fall analysis

Discontinuous deformation analysis (DDA), a discrete numerical analysis method, is used to simulate the behaviour of falling rock by applying a linear displacement function in the computations. However, when a block rotates, this linear function causes a change in block size called the free expansion phenomenon. In addition, this free expansion results in contact identification problems when the rotating blocks are close to each other. To solve this problem of misjudgment and to obtain a more precise simulation of the falling rock, a new method called Post‐Contact Adjustment Method has been developed and applied to the program. The basic procedure of this new method can be divided into three stages: using the linear displacement function to generate the global matrix, introducing the non‐linear displacement function to the contact identification, and applying it to update the co‐ordinates of block vertices. This new method can be easily applied to the original DDA program, demonstrating better contact identification and size conservation results for falling rock problems than the original program. Copyright © 2005 John Wiley & Sons, Ltd.     

Determination of reaction kinetics using grain size: An application for metamorphic zircon growth

The reaction kinetics of metamorphic minerals can be subdivided into interface‐ and diffusion‐controlled kinetics. The discrimination of reaction kinetics is crucial for estimating reaction rates. Here, we propose a new and simple method for discriminating reaction kinetics. This method requires measuring only the initial and final grain sizes during growth. The reaction kinetics is inferred from different plotted arrays of initial vs. final grain sizes after the mineral growth. Using metamorphic zircon, we take detrital core sizes as the initial sizes and post‐metamorphic grain sizes as the final sizes. The application of the method to the subduction‐related high‐pressure Nagasaki metamorphic complex in Japan shows that this metamorphic zircon grew under interface‐controlled kinetics even at the relatively low temperature of 440°C. This method is potentially applicable to other minerals that have time‐markers, such as chemical zoning or internal structures that are captured at a given point in time during growth.     

A fluorescent approach to the identification of grout injected into fissures and pore spaces

A new fluorescent approach was developed to visualize grouting processes. The evaluation of the effect of grouting is carried out by methods based mainly on physical measurements such as permeability and porosity characteristics. However, these estimates do not necessarily correlate with practical grouting data. In this paper, the distributions of various grout mixtures containing fluorescent substances were clearly visualized under ultraviolet light, using a borehole television system or a microscope. Since this approach enabled direct observation of grout distribution, it is considered that this approach is useful for analysis of grouting mechanisms, designing grout curtains, etc.     

Effluent trading for water quality management: concept and application to the Chesapeake Bay watershed

This paper examines the present and potential role of effluent trading in water quality management. In particular, it focuses upon the case of the Chesapeake Bay on the east coast of the US, where the implementation of a trading system has been discussed and undertaken. Potential benefits of effluent trading include advantages such as the following: (1) With appropriate monitoring and enforcement, the total pollutant loadings can be kept at or below the prespecified level. (2) New and expanding dischargers can be accommodated, as long as they purchase credits. (3) Abatement costs of pollutants can be reduced. (4) Flexible regulations incorporating trading can reduce the incentive for industries to relocate to areas with less stringent water quality regulation. (5) Broader environmental goals can be addressed, such as wildlife habitat provision and endangered species protection. (6) Preliminary studies with a view to trading-system implementation encourage discussion and dialogue among stakeholders, and positively foster concerted, holistic solutions for maintenance of water bodies.