Land–sea carbon and nutrient fluxes and coastal ocean CO2 exchange and acidification: Past,present, and future

Epochs of changing atmospheric CO₂ and seawater CO₂–carbonic acid system chemistry and acidification have occurred during the Phanerozoic at various time scales. On the longer geologic time scale, as sea level rose and fell and continental free board decreased and increased, respectively, the riverine fluxes of Ca, Mg, DIC, and total alkalinity to the coastal ocean varied and helped regulate the C chemistry of seawater, but nevertheless there were major epochs of ocean acidification (OA). On the shorter glacial–interglacial time scale from the Last Glacial Maximum (LGM) to late preindustrial time, riverine fluxes of DIC, total alkalinity, and N and P nutrients increased and along with rising sea level, atmospheric PCO₂ and temperature led, among other changes, to a slightly deceasing pH of coastal and open ocean waters, and to increasing net ecosystem calcification and decreasing net heterotrophy in coastal ocean waters. From late preindustrial time to the present and projected into the 21st century, human activities, such as fossil fuel and land-use emissions of CO₂ to the atmosphere, increasing application of N and P nutrient subsidies and combustion N to the landscape, and sewage discharges of C, N, P have led, and will continue to lead, to significant modifications of coastal ocean waters. The changes include a rapid decline in pH and carbonate saturation state (modern problem of ocean acidification), a shift toward dissolution of carbonate substrates exceeding production, potentially leading to the “demise” of the coral reefs, reversal of the direction of the sea-to-air flux of CO₂ and enhanced biological production and burial of organic C, a small sink of anthropogenic CO₂, accompanied by a continuous trend toward increasing autotrophy in coastal waters.     

Phase equilibria in the systems Fe2O3-MgO-TiO2 and FeO-MgO-TiO2 between 1173 and 1473 K, and Fe2+-Mg mixing properties of ilmenite, ferrous-pseudobrookite and ulvöspinel solid solutions

Detailed phase relations have been determined within the systems Fe₂O₃-MgO-TiO₂ and FeO-MgO-TiO₂. Experiments were performed over the temperature interval 1173–1473 K by equilibrating pelletized, fine-grained oxide mixtures in either inert calcia-stabilized zirconia pots (Fe₂O₃-MgO-TiO₂ system) or evacuated silica tubes (FeO-MgO-TiO₂ system). Equilibrium phase assemblages were determined by combined optical microscope, X-ray diffraction and EMP examination. Phase relations in the Fe₂O₃-MgO-TiO₂ ternary are dominated by the instability of the M₂O₃ solid solution relative to the phase assemblage M₃O₄ + M₃O₅. A miscibility gap along the M₂O₃ binary also gives rise to two, 3-phase fields (α-M₂O₃ + M₃O₅ + M₃O₄ and α′-M₂O₃ + M₃O₅ + M₃O₄) separated by the M₃O₄ + M₃O₅ phase field. Phase relations in the FeO-MgO-TiO₂ ternary were divided into two sub-systems. For the FeTiO₃-MgTiO₃-TiO₂ sub-ternary, there is complete solid solution along the M₂O₃ and M₃O₅ binary joins at high temperature. At low temperatures (T < 1373 K) the M₃O₅ pseudobrookite solid solution decomposes to M₂O₃ + TiO₂. Increasing the concentration of MgO in M₃O₅ phase results in a decrease in the temperature at which M₃O₅ becomes unstable and compositional tie lines linking M₂O₃ and TiO₂ fan out, before the appearance of a three-phase region where M₂O₃, M₃O₅, and TiO₂ coexist. Within the expanded FeO-MgO-TiO₂ system, at temperatures above ∼1273 K there is a continuous solid solution along the M₃O₄ binary. At low temperatures (T < 1273 K) the Mg₂TiO₄ end-member breaks down to MgO and MgTiO₃. The M₃O₄ phase shows significant non-stoichiometry, down to at least 1173 K. Fe²⁺-Mg partitioning data were obtained for coexisting M₂O₃-M₃O₅ and M₂O₃-M₃O₄ pairs in the FeO-MgO-TiO₂ ternary. Assuming a regular solution mixing model for all phases, the M₂O₃ and M₃O₄ solid solutions were both found to exhibit moderate positive deviations from ideality (∼2600 J/mol), whereas the data for the M₃O₅ binary suggest close to ideal behaviour. Received: 22 May 1998 / Accepted: 3 November 1998     

Synthetic MgGa2O4-Mg2GeO4 spinel solid solution and β-Mg3Ga2GeO8: chemistry, crystal structures, cation ordering, and comparison to Mg2GeO4 olivine

 Structural parameters and cation ordering are determined for four compositions in the synthetic MgGa₂O₄-Mg₂GeO₄ spinel solid solution (0, 8, 15 and 23 mol% Mg₂GeO₄; 1400 °C, 1 bar) and for spinelloid β-Mg₃Ga₂GeO₈ (1350 °C, 1 bar), by Rietveld refinement of room-temperature neutron diffraction data. Sample chemistry is determined by XRF and EPMA. Addition of Mg₂GeO₄ causes the cation distribution of the MgGa₂O₄ component to change from a disordered inverse distribution in end member MgGa₂O₄, ^[4]Ga = x = 0.88(3), through the random distribution, toward a normal cation distribution, x = 0.37(3), at 23 mol% Mg₂GeO₄. An increase in a_o with increasing Mg₂GeO₄ component is correlated with an increase in the amount of Mg on the tetrahedral site, through substitution of 2 Ga³⁺⇄ Mg²⁺+Ge⁴⁺. The spinel exhibits high configurational entropy, reaching 20.2 J mol⁻¹ (four oxygen basis) near the compositional upper limit of the solid solution. This stabilizes the spinel in spite of positive enthalpy of disordering over the solid solution, where ΔH _D  = αx + βx ², α = 22(3), β = −21(3) kJ mol⁻¹. This model for the cation distribution across the join suggests that the empirically determined limit of the spinel solid solution is correlated with the limit of tetrahedral ordering of Mg, after which local charge-balanced substitution is no longer maintained. Spinelloid β-Mg₃Ga₂GeO₈ has cation distribution ^M1[Mg_0.50(2)Ga_0.50(2)] ^M2[Mg_0.96(2)Ga_0.04(2)] ^M3[Mg_0.77(2) Ga_0.23(2)]₂ (Ge_0.5Ga_0.5)₂O₈ (tetrahedral site occupancies are assumed). Octahedral site size is correlated to Mg distribution, where site volume, site distortion, and Mg content follow the relation M1<M3<M2. The disordered cation distribution provides local electrical neutrality in the structure, and stabilization through increased configurational entropy (27.6 J mol⁻¹; eight oxygen basis). Comparison of the crystal structures of Mg_{1+ N} Ga_{2−2 N} Ge _N O₄ spinel, β-Mg₃Ga₂GeO₈, and Mg₂GeO₄ olivine reveals β-Mg₃Ga₂GeO₈ to be a true structural intermediate. Phase transitions across the pseudobinary are necessary to accommodate an increasing divergence of cation size and valence, with addition of Mg₂GeO₄ component. Octahedral volume increases while tetrahedral volume decreases from spinel to β-Mg₃Ga₂GeO₈ to olivine, with addition of Mg and Ge, respectively. Furthermore, M-M distances increase regularly across the join, suggesting that changes in topology reduce cation-cation repulsion. Received: 9 November 1998 / Revised, accepted: 3 August 1999     

Shear modulus, heat capacity, viscosity and structural relaxation time of Na2O–Al2O3–SiO2 and Na2O–Fe2O3–Al2O3–SiO2 melts

The configurational heat capacity, shear modulus and shear viscosity of a series of Na₂O–Fe₂O₃–Al₂O₃–SiO₂ melts have been determined as a function of composition. A change in composition dependence of each of the physical properties is observed as Na₂O/(Na₂O + Al₂O₃) is decreased, and the peralkaline melts become peraluminous and a new charge-balanced Al-structure appears in the melts. Of special interest are the frequency dependent (1 mHz–1 Hz) measurements of the shear modulus. These forced oscillation measurements determine the lifetimes of Si–O bonds and Na–O bonds in the melt. The lifetime of the Al–O bonds could not, however, be resolved from the mechanical spectrum. Therefore, it appears that the lifetime of Al–O bonds in these melts is similar to that of Si–O bonds with the Al–O relaxation peak being subsumed by the Si–O relaxation peak. The appearance of a new Al-structure in the peraluminous melts also cannot be resolved from the mechanical spectra, although a change in elastic shear modulus is determined as a function of composition. The structural shear-relaxation time of some of these melts is not that which is predicted by the Maxwell equation, but up to 1.5 orders of magnitude faster. Although the configurational heat capacity, density and shear modulus of the melts show a change in trend as a function of composition at the boundary between peralkaline and peraluminous, the deviation in relaxation time from the Maxwell equation occurs in the peralkaline regime. The measured relaxation times for both the very peralkaline melts and the peraluminous melts are identical with the calculated Maxwell relaxation time. As the Maxwell equation was created to describe the timescale of flow of a mono-structure material, a deviation from the prediction would indicate that the structure of the melt is too complex to be described by this simple flow equation. One possibility is that Al-rich channels form and then disappear with decreasing Si/Al, and that the flow is dominated by the lifetime of Si–O bonds in the Al-poor peralkaline melts, and by the lifetime of Al–O bonds in the relatively Si-poor peralkaline and peraluminous melts with a complex flow mechanism occurring in the mid-compositions. This anomalous deviation from the calculated relaxation time appears to be independent of the change in structure expected to occur at the peralkaline/peraluminous boundary due to the lack of charge-balancing cations for the Al-tetrahedra.     

2D and 3D rockfall hazard analysis and protection measures for Saptashrungi Gad Temple,Vani, Nashik,Maharashtra – A case study

The Saptashrungi gad temple (SGT) situated on basaltic hills belongs to Deccan volcanic of Upper Cretaceous to Lower Eocene, is one among the 51 Shakti Peeths and most holy place for pilgrims. Rockfall is a major problem in the past and causing danger to the lives of the villagers settled at the toe of the SGT hill as well as the pilgrims who perform parikrama along the tracks. On the evening of 16 April 2011, an old woman died due to rockfall at SGT hill when she was performing parikrama, moreover, two persons got injured during the deliverance process of this old woman from the continuous rockfall activity. The problem of rockfall could be linked to rainfall, jointing, weathering, man-made or the compounding of all. In this research, the rockfall hazard analysis at SGT hill is assessed using both 2D and 3D rockfall programs along the two parikrama paths: Parikrama Path 1 (or the Badi Parikrama Path ‘BPP’), and Parikrama Path 2 (or the Chhoti Parikrama Path ‘CPP’). Also, the study area of the SGT hill has been divided into eight zones (Zone#01 to Zone#08), based on field observations, orientations of joint sets and hill slope faces and eighteen topographic profiles (AA' to RR') have been taken from these eight zones for rockfall analysis. A detailed topographic survey along with field investigation has been carried out along the temple for ascertaining the nature of rock, discontinuity orientations, and slope geometry. DEM has been generated using topographic profile in ArcGIS to facilitate the 3D rockfall analysis. Maximum rock block sizes are taken into the analysis and run-out distance, bounce height, kinetic energy and velocity of the basaltic blocks are evaluated separately. Based on the analyzed data, the rockfall hazard zone map has been prepared and site having potential rockfall risks have been identified. Finally, wire/net meshing has been proposed after removal of unstable blocks as a stabilization and protection measures.It is worth mentioning here that for the first time rockfall hazard assessment was made in such detail for a site. Suggestions made are implemented by the State Government for the protection of the temple as well as the life of pilgrims performing the parikrama from the rockfall.     

Experimental partitioning of halogens and other trace elements between olivine, pyroxenes, amphibole and aqueous fluid at 2 GPa and 900–1,300 °C

We present new partition coefficients for various trace elements including Cl between olivine, pyroxenes, amphibole and coexisting chlorine-bearing aqueous fluid in a series of high-pressure experiments at 2 GPa between 900 and 1,300 °C in natural and synthetic systems. Diamond aggregates were added to the experimental capsule set-up in order to separate the fluid from the solid residue and enable in situ analysis of the quenched solute by LA–ICP–MS. The chlorine and fluorine contents in mantle minerals were measured by electron microprobe, and the nature of OH defects was investigated by infrared spectroscopy. Furthermore, a fluorine-rich olivine from one selected sample was investigated by TEM. Results reveal average Cl concentrations in olivine and pyroxenes around 20 ppm and up to 900 ppm F in olivine, making olivine an important repository of halogens in the mantle. Chlorine is always incompatible with Cl partition coefficients D _Cl ^{olivine/fluid} varying between 10^?5 and 10^?3, whereas D _Cl ^{orthopyroxene/fluid} and D _Cl ^{clinopyroxene/fluid} are ~10^?4 and D _Cl ^{amphibole/fluid} is ~5 × 10^?3. Furthermore, partitioning results for incompatible trace element show that compatibilities of trace elements are generally ordered as D ^amph/fluid ≈ D ^cpx/fluid > D ^opx/fluid > D ^ol/fluid but that D ^{mineral/fluid} for Li and P is very similar for all observed silicate phases. Infrared spectra of olivine synthesized in a F-free Ti-bearing system show absorption bands at 3,525 and ~3,570 cm^?1. In F ± TiO₂-bearing systems, additional absorption bands appear at ~3,535, ~3,595, 3,640 and 3,670 cm^?1. Absorption bands at ~3,530 and ~3,570 cm^?1, previously assigned to humite-like point defects, profit from low synthesis temperatures and the presence of F. The presence of planar defects could not be proved by TEM investigations, but dislocations in the olivine lattice were observed and are suggested to be an important site for halogen incorporation in olivine.     

Mössbauer effect study of anapaite, Ca2Fe2+(PO4)2 · 4H2O, and of its oxidation products

Mössbauer spectra (MS) of anapaite (Ca₂ Fe²⁺(PO₄)₂?·?4H₂O) and of a sample after being immersed in a 4% H₂O₂ solution at room temperature (RT) over 12 days (hereafter an4ox) were collected at temperatures in the range 4.2 to 420?K and 11 to 300?K respectively. All MS consist of symmetrical doublets, hence magnetic ordering was not observed. The temperature dependencies of the Fe²⁺ centre shifts of anapaite and an4ox were analysed with the Debye model for the lattice vibrations. The characteristic Mössbauer temperatures were found as 370?K?±?25?K and 340?K?±?25?K, and the intrinsic isomer shifts as 1.427?±?0.005?mm/s and 1.418?±?0.005?mm/s respectively. From the external-field (60?kOe) MS recorded at 4.2 and 189?K for the non-treated sample, the principal component V _zz of the electric field gradient (EFG) is determined to be positive and the asymmetry parameter η?≈?0.2 and 0.4 respectively. The temperature variations of the quadrupole splittings, ΔE _Q(T), cannot be interpreted on the basis of the thermal population of the ⁵ D electronic levels resulting from the tetragonal compression of the O₆ co-ordination. The low-temperature linear behaviour of ΔE _Q(T) is attributed to a strong orbit-lattice coupling. A field of 60 kOe applied to anapaite at 4.2?K produces magnetic hyperfine splitting with effective hyperfine fields of ?136, ?254 and ?171?kOe along the principal axes Ox, Oy and Oz of the EFG tensor respectively. Additional oxidation treatments in solutions with various H₂O₂ concentrations up to 20% and subsequent Mössbauer experiments at room temperature, have revealed that the anapaite structure is not sensitive to oxidation since eventually only a small amount of Fe²⁺ (～6.5%) is converted into Fe³⁺.     

Effects of Pb^2＋, Cd^2＋ and Cu^2＋ on the Aqueous Zn^2＋ Sorption by Hydroxyapatite

In this paper, the behaviors of aqueous zinc sorption by hydroxyapatite in the co-existence of Pb^2＋, Cd^2＋ and Cu^2＋ are investigated, the effects of Pb^2＋, Cd^2＋ and Cu^2＋ on the sorption of Zn^2＋ are discussed, and the hydroxyapatite sorption capabilities for Pb^2＋, Cd^2＋, Cu^2＋ and Zn^2＋ are compared. The experimental results show that the Zn^2＋ removal efficiency decreases gradually with the increase of the Cd^2＋ concentration of the solution, and there is no sorption preference between Cd^2＋ and Zn^2＋. On the other hand, the Zn^2＋ removal efficiency rapidly decreases rapidly with the increase of the Cu^2＋ concentration of the solution, and there is a clear sorption preference between Cu^2＋ and Zn^2＋. It is noticed that the Zn^2＋ removal efficiency is hardly changed with the variance of Pb^2＋ concentration because the removal mechanisms for these two ions are totally different. It is concluded that the adsorption affinities of the heavy metals for the hydroxyapatite follows this sequence： pb^2＋〉 Cu^2＋〉 Cd^2＋〉 Zn^2＋.     

Zinc,Copper, and Lead Geochemistry of Oceanic Igneous Rocks—Ridges,Islands, and Arcs

Variations in the abundances of Zn, Cu, and Pb are found to be useful in identifying tectonic regimes and separating oceanisland basalts into enriched- and depleted-source categories. The average Zn, Cu, and Pb contents of normal mid-ocean ridge basalts (N-MORB) are 84, 70, and 0.35 ppm, respectively. Differences in average Zn contents for various ridges reflect more the varying degrees of differentiation than variations of Zn content in the source rocks. At a Mg# of 70, or Mg#₇₀, which is taken to represent primitive MORB, many MORB sequences converge at a Zn content of 58 ± 6 ppm, which is close to the value for primitive mantle (50 ppm) and ordinary chondrites (～55 ppm). Values of 0.1 to 0.15 ppm Pb in MORB at Mg#₇₀, best defined at the superfast-spreading Southern East Pacific Rise, are similar to estimates of Pb in the primitive mantle (0.12 to 0.18 ppm). They also are near the lower end of the range for ordinary chondrites. The very slow spreading Southwest Indian Ocean Ridge has a sequence with higher Pb contents, in addition to a more normal sequence, which has a visual best value of 0.4 ppm Pb at Mg#₇₀. With the exception of the Walvis Ridge, Zn and Cu appear to be little affected by proximity to hotspots (i.e., E-MORB); however, Pb contents are higher and average about 0.6 ppm.

Both Zn and Pb in MORB are incompatible elements (i.e., favor the melt), but Cu is a compatible element. At Mg#₇₀, there is the suggestion of a value of 100 ppm for Cu, with lower values possibly representing partial removal of sulfides and their associated Cu from the source. Nonetheless, Cu contents of primitive MORB tend to be much higher than even high estimates for the primitive mantle (28 ppm), and are closer to ordinary chondrites (～90 ppm). Therefore, Zn, Cu, and Pb all approximate chondritic values in the primitive MORB melt.

Average contents of Zn, Cu, and Pb in oceanic island basalts (OIB) are 115, 62, and 3.2 ppm, respectively. At Mg#₇₀, values of Zn and Cu are similar to the respective averages for OIB, with Zn higher and Cu lower than MORB. At a Mg# of ～40, however, OIB and MORB tend to have similar Zn contents. With further differentiation, OIB trachytes can contain >200 ppm Zn. Unlike MORB, OIB can differentiate to high Cu contents of 200 ppm at Mg#s of 40 to 60. In contrast to Zn and Cu, Pb regresses to a value of 0.83 ppm at Mg#₇₀ for Hawaiian and Reunion volcanics, which is much less than the average value for Pb in OIB volcanics, but higher than for MORB.

Average Zn, Cu, and Pb contents of magmatic-arc basalts are 77, 108, and 1.9 ppm, respectively. In basalts, Zn tends to be incompatible, but a dual incompatible and compatible behavior can occur at high SiO₂ contents. Dacites may average near 55 ppm Zn, but peralkalic rhyolite can contain >300 ppm Zn. A dual compatible and incompatible nature occurs for Cu. Most common, particularly in submarine volcanics, is a compatible trend, with a Cu content of around 80 ppm at a Mg# of 60, which decreases to less than 40 ppm at a Mg# of 30. The incompatible trend of increasing Cu can achieve >200 ppm at a Mg# of 30, leaving a gap approaching 100 ppm at that Mg#. The gap is less obvious on a plot of Cu vs. SiO₂, but is still there. The compatible trend is proposed to result from sulfur-saturated magmas, whereas the incompatible trend is believed to result from sulfur-deficient magmas. Support for this hypothesis is found in sparse sulfur-isotope data. Zn and Cu both can be incompatible over an extended range of Mg#s or silica content. When Zn and Cu are both compatible, Cu decreases more than twice as rapidly as Zn.

Primitive magmas at Mg#₇₀ average about 50 ppm Zn for submarine Mariana arc basalts and 58 ppm for forearc boninites, contents close to MORB values. Mariana arc basalts have a Zn content of ～45 ppm estimated at Mg#₇₀. Cu varies more widely than Zn in primitive magmas, being about 50 ppm Cu for Mariana Islands volcanics and 120 ppm for Kermadec Islands volcanics, a range broadly around MORB values. Average Pb contents are 1.9 ppm for island-arc tholeiites, 5.6 ppm for high-Al basalt, and 3.2 ppm for alkali basalt with average boninite of approximately 1.8 ppm. Back-arc-basin basalts in the deepest parts of the Mariana trough have Pb contents of 0.45 ppm, but more shallow parts may exceed 1.0 ppm Pb. Although the lower contents are similar to MORB values, the ²⁰⁸Pb/²⁰⁴Pb values are greater than Pacific Ocean MORB. At Mg#₇₀ for rocks from the Tonga and Kermadec island arcs, the Pb content is about 0.1 ppm, similar to MORB.     

Fractionation,distribution and transport of mercury in rivers and tributaries around Wanshan Hg mining district,Guizhou Province,Southwestern China: Part 2 – Methylmercury

Water samples were collected during normal flow (2007) and during a drought period (2008) from five rivers and tributaries draining the Wanshan Hg mining district, Guizhou, China. Unfiltered methylmercury (MeHg) as well as particulate and dissolved fractions of MeHg (P-MeHg, D-MeHg) were measured to assess the spatial and temporal variation of MeHg contamination in the local river system. Most locations (about 80%) displayed higher MeHg concentrations during drought period than during normal discharge conditions. Concentrations of MeHg during the drought period ranged from <0.035 to 11 ng L⁻¹ (geometric mean: 0.43), while during normal flow the concentrations ranged from <0.035 to only 3.4 ng L⁻¹ (geometric mean: 0.21). Concentrations of MeHg were positively correlated with total Hg (THg) concentrations (R² = 0.20–0.58, P < 0.001) and inversely related to distance from the calcines, during both sampling periods (R² = 0.34 and 0.23, P < 0.001, for low and normal flow, respectively) indicating that calcines may be important sources of MeHg to the downstream environment. Approximately 39% of MeHg was bound to particulates and the rest was transported in the dissolved phase along stretches of the entire river, which was different from THg, as this was mainly transported bound to particulates (commonly more than 80%).     

Non-eutectic,graphic, micrographie and graphic-like “myrmekitie” structures and textures

True graphic quartz structures in pegmatites from Carrara/Giggiga and Harrar (town) districts of Ethiopia, are compared with the micrographic quartz textures in the Rapakiwi granite of Finland. Graphic-like textures of uraninite in microcline are also discussed and compared with these graphic structures.A quartz vein, about 1–2 meters in thickness, intersects a pegmatite in the Carrara/Giggiga district. This quartz vein extends into the microcline of the pegmatite as fine quartz veins which attain the form and character of graphic quartz. Also the graphic quartz of the Harrar pegmatites is observed to extend into and occupy cracks in the microcline.Comparable in origin to these graphic textures is the micrographic quartz in the Rapakiwi granite. Observations show micrographic quartz following the cleavage directions in the orthoclase as well as the interzonal spaces and the boundaries of inclusions in the K-feldspar.On the basis of the observed structures and textures these graphic and micrographic intergrowths are considered to be due to solutions penetrating or infiltrating into existing structures and not due to simultaneous crystallisation as conditions of eutectic crystallisation would require.In addition to the well known graphic structures there occur graphic or myrmekitic-like intergrowths of uraninite in microcline which, from a structural and physico-chemical point of view, cannot be considered to be due to eutectic crystallisation.     

Natural siliceous dust and human health： Pathways, toxicity, and impact

Fine atmospheric dust includes mineral particles and aggregates, fibrous minerals and fibrous organic material. Generation, dislodgement and transport （deflation） of natural dust with the finer （〈4 microns） components suspended as silt-size aggregates, is widespread in and adjacent to the world＇s drylands, as well as deriving from volcanic vents. Silica is a highly fibrogenic agent in lung tissue. Long-term inhaling of siliceous dusts can lead to a number of fibrotic lung diseases, including natural （non-occupational） pneumoconioses （notably silicosis, but including asbestosis and others）. Different polymorphs of silica show different levels of toxicity in interaction with lung tissue. Particles with highly active surfaces may release radicals, causing cell damage. Some types of inhaled particulates are degraded by macrophages, but many are highly resistant and persist in the lungs, some stimulating fibroblastic cells to deposit collagen. Silicosis is an inflammation of the lung commonly caused by silicate mineral particles, leading to fibrosis. Three types are recognized： nodular pulmonary fibrosis （simple or chronic silicosis）, acute silicosis, and accelerated silicosis. Generally, finer particulates have greater oxidative capacity than the coarser fractions. They contain more reactive oxygen species, their greater bioreactivity making them more toxic to pulmonary tissue. Nevertheless, inhalation of large dust particles （〉 10μm） may constitute a health risk if the mineralogy is toxic, regardless of where the grains lodge in the respiratory system. Dust may absorb harmful gases, disease-generating bacteria and carcinogenic hydrocarbon compounds. Silica-related respiratory disease may also an exacerbate cardiac problem, and epidemiology suggests a link with tuberculosis. Quantification of dust loading and exposure requires study of spatial and temporal patterns, supported by meteorological analysis, airflow modeling and satellite-borne imagery. Some acute, short-term health impacts have been assessed using atmospheric and health records both before and after a dust storm or by comparison of populations within and outside such events. Analysis of the size, shape, mineralogy and geochemistry of ambient dust particulates provides information on natural dust sources, dust concentrations, and potential particulate toxicity, as well as providing a datum for assessment of human exposure levels.     

Thermodynamic properties of tellurite (β-TeO2), paratellurite (α-TeO2), TeO2 glass,and Te(IV) phases with stoichiometry M2Te3O8, MTe6O13, MTe2O5 (M2+ = Co,Cu, Mg,Mn, Ni,Zn)

Thermodynamic properties of several TeO₂ polymorphs and metal tellurites were measured by a combination of calorimetric techniques. The most stable TeO₂ polymorph is α-TeO₂, with its enthalpy of formation (Δ_fH^o) selected from literature data as ?322.0 ± 1.3 kJ·mol^?1. β-TeO₂ is metastable (in enthalpy) with respect to α-TeO₂ by +1.40 ± 0.07 kJ·mol^?1, TeO₂ glass by a larger amount of +14.09 ± 0.11 kJ·mol^?1. >200 experimental runs and post-synthesis treatments were performed in order to produce phase-pure samples of Co, Cu, Mg, Mn, Ni, Zn tellurites. The results of the hydrothermal and solid-state syntheses are described in detail and the products were characterized by powder X-ray diffraction. The standard thermodynamic data for the Te(IV) phases are (standard enthalpy of formation from the elements, Δ_fH^o in kJ·mol^?1, standard third-law entropy S^o in J·mol^?1·K^?1): Co₂Te₃O₈: Δ_fH^o = ?1514.2 ± 6.0, S^o = 319.2 ± 2.2; CoTe₆O₁₃: Δ_fH^o = ?2212.5 ± 8.1, S^o = 471.7 ± 3.3; MgTe₆O₁₃: Δ_fH^o = ?2525.8 ± 7.9, S^o = 509.2 ± 3.6; Ni₂Te₃O₈: Δ_fH^o not measured, S^o = 293.3 ± 2.1; NiTe₆O₁₃: Δ_fH^o = ?2198.7 ± 8.2, S^o = 466.5 (estimated); CuTe₂O₅: Δ_fH^o = ?820.2 ± 3.3, S^o = 187.2 ± 1.3; Zn₂Te₃O₈: Δ_fH^o = ?1722.5 ± 4.0, S^o = 299.3 ± 2.1. The solubility calculations show that the Te(IV) concentration in an aqueous phase, needed to produce such phases, must be at least 3–5 orders of magnitude higher than the natural Te background concentrations. The occurrence of these minerals, as expected, are restricted to hotspots of Te concentrations. In order to produce more reliable phase diagrams, more work needs to be done on the thermodynamics of potential competing phases in these systems, including Te(VI) phases.     

Coupled asteroid impacts and banded iron-formations,Fortescue and Hamersley Groups,Pilbara, Western Australia

Asteroid impact spherule layers and tsunami deposits underlying banded iron-formations in the Fortescue and Hamersley Groups have been further investigated to test their potential stratigraphic relationships. This work has included new observations related to the ca 2.63 Ga Jeerinah Impact Layer (JIL) and impact spherules associated with the 4th Shale-Macroband of the Dales Gorge Iron Member (DGS4) of the Brockman Iron Formation. A unit of impact spherules (microkrystite) correlated with the ca 2.63 Ga JIL is observed within a >100 m-thick fragmental-intraclast breccia pile in drill cores near Roy Hill. The sequence represents significant thickening of the impact/tsunami unit relative to the JIL type section at Hesta, as well as relative to the 20–30 m-thick ca 2.63 Ga Carawine Dolomite spherule-bearing mega-breccia. The ca 2.48 Ga-old Dales Gorge Member of the Brockman Iron Formation is underlain by an ?0.5 m-thick rip-up clast breccia located at the top of the ca 2.50 Ga Mt McRae Shale, and is interpreted as a tsunami deposit. We suggest that the presence of impact ejecta and tsunami units stratigraphically beneath a number of banded iron-formations, and units of ferruginous shale in the Pilbara and South Africa may result from a genetic relationship. For example, it could be that under Archean atmospheric conditions, mafic volcanism triggered by large asteroid impacts enriched the oceans in soluble FeO. If so, seasonal microbial and/or photolytic oxidation to ferric oxide could have caused precipitation of Fe₂O₃ and silica. In view of the possible occurrence of depositional gaps and paraconformities between impact ejecta units and overlying ferruginous sediments, these relationships require further testing by isotopic age studies.     

气相色谱法测定岩石矿物中CO2,SO2,H2O^＋,H2O^—,CH4

选择Ｃｈｒｏｍｓｏｒｂ１０４作固定相，解决了Ｈ２Ｏ对测ＳＯ２的干扰，也避免了酸分解法测ＣＯ２的干扰，可一次实现四种成份连测，具有快速，灵敏（万分之几至十万分之几）用样量少等特点，很适宜批量样品的分析。     

Self-consistent pressure scales based on the equations of state for ruby,diamond, MgO,B2–NaCl,as well as Au,Pt, and other metals to 4 Mbar and 3000 K

Based on the modified formalism of Dorogokupets and Oganov (2007), we calculated the equation of state for diamond, MgO, Ag, Al, Au, Cu, Mo, Nb, Pt, Ta, and W by simultaneous optimization of the data of shock-wave experiments and ultrasonic, X-ray diffraction, dilatometric, and thermochemical measurements in the temperature range from ~ 100 K to the melting points and pressures of up to several Mbar, depending on the material. The obtained room-temperature isotherms were adjusted with a shift of the R1 luminescence line of ruby, which was measured simultaneously with the unit cell parameters of metals in the helium and argon pressure media. The new ruby scale is expressed as P(GPa) = 1870?Δλ / λ0(1 + 6?Δλ / λ0). It can be used for correction of room-pressure isotherms of metals, diamond, and periclase. New simultaneous measurements of the volumes of Au, Pt, MgO, and B2-NaCl were used for interrelated test of obtained equations of state and calculation of the room-pressure isotherm for B2-NaCl. Therefore, the constructed equations of state for nine metals, diamond, periclase, and B2-NaCl can be considered self-consistent and consistent with the ruby scale and are close to a thermodynamic equilibrium. The calculated PVT relations can be used as self-consistent pressure scales in the study of the PVT properties of minerals using diamond anvil cell in a wide range of temperatures and pressures.     

Fluid Composition, δD of Channel H2O,and δ18O of Lattice Oxygen in Beryls: Genetic Implications for Brazilian,Colombian, and Afghanistani Emerald Deposits

The fluid composition, δD of channel H₂O, and δ₁₈O of lattice oxygen have been determined in beryl and emerald from a variety of geological environments and used to constrain the origin of the parental fluids from which beryl has grown. Step-heating analyses performed by quadrupolar mass spectrometry were used to quantify the composition of the fluid phases in beryl from granitic pegmatites and greisens and emerald from Brazil, Colombia, and Afghanistan. An important conclusion is that beryl and emerald have a similar fluid composition, with concentrations of H₂O being greater than 90% of the total water in the mineral irrespective of the age of formation (2.0 Ga to 32 Ma) and tectonic settings. However, the Brazilian Santa Terezinha shear-zone emerald deposit contains abundant CO₂, up to 13 wt% of the total fluid. A second conclusion is that the channel H₂O content for some Brazilian emeralds is higher than the range defined for beryl in the literature, especially for those related to the shear-zone type (2.99 lt; H₂O < 3.16 wt%) and the pegmatite type from the Pombos, Pela Ema, and Pirenopolis deposits (2.78 < H₂O < 3.01 wt%). Colombian emeralds have very low H₂O contents (1.30 < H₂O < 1.96 wt%), among the lowest in the world.

Brazilian, Colombian, and Afghanistani emeralds have contrasting and restricted ranges of δ¹⁸O values. In Brazil, emeralds related to pegmatites have a systematic δ¹⁸O inter-deposit variability (+6.3 < δ¹⁸O < +12.4‰). The calculated δ¹⁸O of the fluid was buffered by the host ultrabasic rocks during fluid-rock interaction. Emerald and cogenetic phlogopite related to shear-zone-type deposits have a quite restricted δ¹⁸O range (+12.0 < δ¹⁸O 7lt; +12.4‰); the calculated is interpreted to represent the original isotopic composition of the hydrothermal fluid. Relative to Brazil, the δ¹⁸O of Colombian and Afghanistani emeralds shows strong enrichment in ¹⁸O (+13.4 < δ¹⁸O < +23.6‰), and the high calculated δ¹⁸O of the fluid suggests extensive reaction with 18O-rich sedimentary or metasedimentary rocks.

In Brazil, the δD composition of channels in emerald and the calculated δ¹⁸O^H₂O for phlogopite are compatible with both magmatic and metamorphic origins. A magmatic origin is supported for emeralds associated with the pegmatitic Socotó and Carnaiba deposits (mean δD = ?37.8 ± 8‰) and a metamorphic origin is suggested for the Santa Terezinha shear-zone type (mean δD = ?32.4 ± 3‰). A metamorphic origin is proposed for Colombian emeralds. Afghanistani emeralds have a δD composition of channels (mean δD = ?46.3 ± 1.3‰) that is compatible with both magmatic and metamorphic origins.     

EPR investigation of NO2 and CO2 − and other radicals in beryl

A number of different impurities are located in the open channels of natural beryl crystals. The rare Maxixe beryl contains an unusual amount of NO₂. The isoelectronic CO₂ ⁻ radical is found in the irradiated Maxixe-type beryl. The NO₂ radicals are distributed in the Be–Al plane of the crystal, with the nitrogen atom close to the oxygens of the beryl cavity wall. These oxygens repel the negative CO₂ ⁻ radical, which is located at the center of the beryl cavity and rotates around its O–O axis, which is parallel to the crystal c-axis. When there is a nearby alkali ion at the center of the beryl channel, it reorients the CO₂ ⁻ radical so that its bisector is parallel to the c-axis and points toward the positive ion. Different signals are analyzed for Li⁺, Na⁺, and another counter-ion, which probably is Cs⁺. The related NO₃ and CO₃ ⁻ radicals are the color centers in the investigated deep blue beryls. The slow decay of the color, which makes these beryls useless as gem stones, is related to the decay of the hydrogen atoms which are present in these crystals. Evidence is given that NO₃ is created in Maxixe beryl by a natural process, while CO₃ ⁻ in Maxixe-type beryl has been created by irradiation. The temperature dependence of the EPR signals of these two radicals was investigated, but a definitive proof that they rotate at the center of the beryl cavity could not be given. EPR signals from some other radicals in beryl have been observed and described.