The crystal structure of (Fe<Subscript>4</Subscript>Cr<Subscript>4</Subscript>Ni)<Subscript>9</Subscript>C<Subscript>4</Subscript>

(Fe4Cr4Ni)9C4 is a metal carbide mineral formed by combination of Fe, Cr and Ni with C. It occurs in a chromite deposit in the Luobusha ophiolite, Tibet. Based on the determination of its crystal structure, the empirical formula is (Fe4.12Cr3.84Ni0.96)8.92C3.70 and the simplified formula is (Fe4Cr4Ni)4C9. The mineral is hexagonal with a = 1.38392(2) nm, c = 0.44690(9) nm, pace group P63 m c, Z=6 and the calculated specific gravity Dx = 7.089 g/cm3. Fe, Cr and Ni occupy different crystallographic sites and their coordination numbers are approximately 12, forming an alternate stacking sequence of flat and puckered layers along the c axis. Some metallic atoms have a defect structure. The interatomic distances of Fe, Cr and Ni are 0.2525-0.2666 nm, and the distances between Fe, Cr, Ni and C are 0.1893-0.2169 nm. The coordination number of carbon is 6. It occurs in interstices of the metallic atoms Fe, Cr and Ni to form trigonalprismatically coordinated polyhedra. These coordination polyhedra are linked with each other via shared corners or shared edges into a new type of metal carbide structure.     

Mineralogy and crystal structure determination of Mg-fillowite

Accurate crystal structure determination of complex phosphate Mg-fillowite.—Na₂Ca(Mn₄Mg₂Fe)₇[PO₄]₆ has been finished. Mg-fillowite occurs in muscovite-pegmatite in the Altay area, Xinjiang, China. It is of the trigonal lattice, with space group R-3, unit cell a=1.5143(3)nm, c=4.3191(2) nm, V=8.5736 nm³, Z = 18. The R-factor of the determination accuracy is R (I<2 σ(I)) = 0.0776. The cationic polyhedra consist of two kinds of structural units: compound column and screw column. In three-dimensional space, they are linked with each other through corner sharing or edge sharing to build the entire structure. There are 45 atoms in an asymmetric unit and 720 atoms in a unit cell. In terms of types and connection manners of the coordination polyhedra, the degree of complicity is rarely seen in all mineral crystal structures. Study of such a structure is significant for the classification of phosphate and the building rule of coordination polyhedra in a complex crystal structure.     

Structure refinement of astrophyllite

The crystal structure of astrophyllite K₂Na(Fe, Mn, Mg,□)₇[Ti₂(Si₄O₁₂)₂|O₃](OH, F)₄ has been refined. The dimensions of the triclinic unit cell are: a = 0.5359(2) nm,b = 1.1614(4) nm, c = 1.1861(4) nm, α= 113.16(2)°, β= 103.04(2)°,γ= 94.56(2)°,V = 0.6495(5) nm³, Z= 1, space group P1, R=0.057 for 5308 reflections |F_o|>3σ|F_o|. According to structural and compositional differences the monoclinic astrophyllite K₂NaNa(Fe, Mn)₄Mg₂Ti2[Si₄O₁₂]₂(OH)₄(OH, F)₂ and astrophyllite should be considered as two different mineral species. Astrophyllite, monoclinic astrophyllite, bafertisite and lamprophyllite contain heteropolyhedral sheets which topologically are related with Si, O sheets of mica where one or several SiO₄ tetrahedra are replaced by TiO _n polyhedra. Therefore this heterophyllotitanosilicate series represents a kind of functional substitution in inorganic crystals.     

Chemical record of the projectile in the graded fall-back sedimentary unit from the Ries Crater, Germany

The so-called “Graded Unit” comprises 17.2 m of the core from the research borehole Nördlingen 1973 and is thought to represent fall-back material, which has been sorted similar to tephra. Samples from six levels of these air-borne impact debris sediments in the Ries Crater have been analyzed for Ir, Ni, Co, Cr and Fe. The concentrations of these elements are negatively correlated with average grain size and accordingly the depth of the samples indicating the presence of a surface correlated component and are hence consistent with vapour deposition of meteoritic material on small dust grains. The largest Ir concentration found is 230 pg/g, a factor of 28 higher than the indigenous concentration. Enrichment factors in the uppermost layer of the “Graded Unit” are about 28 for Ir, approximately 2 for Fe, Co, Ni and 1.5 for Cr. If the enrichment of all elements determined were of meteoritic origin, then the “net meteoritic composition” is most closely matched by aubrites as suggested previously. However, it seems more likely that the observed concentration trends of Cr, Fe, Co and Ni are due to mineral sorting. Therefore the only as yet certain indication of meteoritic material is the presence of Ir, which is not sufficient to further constrain the nature of the projectile.     

Elements in size-fractionated bottom sediments of the Elbe River in its Czech part

The concentrations of 45 elements, and the content of organic substances, amorphous inorganic substances and minerals were determined in 26 samples of Elbe River bottom sediments to determine the correlation between the element composition and the grain size in the ￡ \le 4, 4--8, 8--16, 16--32, 32--63 7m and bulk samples ￡ \le 63 7m fractions. The purpose of this study was to obtain information about the role of particle size and their mineral composition as a control of element concentrations in sediments, the potential remobilization of elements under changing environmental conditions, and the chemical speciation of the large excess concentrations of elements in this system.¶About 22--56% of the estimated element yield was associated with sediments with a grain size of less than 4 7m and 82--97% of the element yield was found in the fraction smaller than 32 7m. Sequential extraction carried out for 20 potentially reactive elements in the ￡ \le 63 7m bulk samples and the ￡ \le 4 7m fraction showed the increased importance of exchangeable ions in the order Mn = Ni < Mg < Sr < Cu < Zn < Ca < K < Cd < Na < Mo, reducible fractions Zn < Sr < Mo < Co < Cu < Ni < Pb < Mn < Cr < Be < V = Fe < As < Ag, oxidizable chemical phases As = Ca < Cd < K < Sr < Fe = Mn < Zn = Mg < Mo < Co = Ag < Pb < Li < Cu = V < Ni < Cr = Na < Be with small concentrations from lithogenic phases Mn < As < Pb < Sr < Zn = Cu = Na < Be < V < Ni < Cr < Fe < K < Mg < Li. The major accumulative phases were identified for the individual elements.     

Mineralogy and petrology of the Abee enstatite chondrite breccia and its dark inclusions

The Abee E4 enstatite chondrite breccia consists of clasts (many rimmed by metallic Fe, Ni), dark inclusions and matrix. The clasts and matrix were well equilibrated by thermal metamorphism, as evidenced by uniform mineral compositions, recrystallized chondrules, low MnO content of enstatite and high abundance of orthoenstatite. The clasts acquired their metal-rich rims prior to this metamorphic episode. The occurrence in Abee of relatively unmetamorphosed dark inclusions, clasts with nearly random magnetic orientations and a matrix with a uniform magnetic orientation [18,19] indicates that clast and matrix metamorphism occurred prior to the agglomeration of the breccia.The dark inclusions are an unusual kind of enstatite chondritic material, distinguished from the clasts and matrix by their relative enrichments in REE [21–23], low relative abundances of kamacite, total metallic Fe, Ni and silica, lower niningerite/(total sulfide) ratios, high relative abundances of oldhamite and martensite, smaller euhedral enstatite, more heterogeneous enstatite and metallic Fe, Ni, more calcic enstatite and more nickeliferous schreibersite.We propose the following model for the petrogenesis of the Abee breccia: The maximum metamorphic temperature of breccia parent material was?- 840°C (the minimum temperature of formation of Abee niningerite) and perhaps near 950–1000°C (the Fe-Ni-S eutectic temperature). Euhedral enstatite crystals in metallic Fe, Ni- and sulfide-rich areas grew at these metamorphic temperatures into pliable metal and sulfide. Breccia parent material was impact-excavated from depth, admixed with dark inclusions and rapidly cooled (700 to 200°C in about 2 hours) [15]. During this cooling, clast and matrix material acquired thermal remanent magnetization. Random conglomeration of clasts and unconsolidated matrix materials caused the clasts to have random magnetic orientations and the matrix areas to have net magnetic intensities of zero (due to the cancellation of numerous randomly oriented magnetic vectors of equal intensity in the matrix). A subsequent ambient magnetic field imparted a uniform net magnetic orientation to the matrix and caused the magnetic orientations of the clasts to be somewhat less random. The Abee breccia was later consolidated, possibly by shock or by shallow burial and very long-period/low-temperature (< 215°C) metamorphism.     

Magnetic particles in indoor dust as marker of pollution emitted by different outside sources

The potential relation between outdoor pollutants and the quality of indoor air was evaluated. A case study was carried out in the small town of Zyrardow situated south-west of Warsaw, Poland. The indoor dust from 20 apartments from several parts of the town that are anticipated to be exposed to various levels of pollution was investigated: a mildly polluted area (suburban), a heating plant area, a post-industrial area and the city center. For evaluation of indoor dust several magnetic parameters (mass-specific magnetic susceptibility χ, its temperature dependence, anhysteretic remanent magnetization, hysteresis loop parameters) were applied. Analysis of magnetic properties was supplemented by analysis of chemical elements: Cd, Cu, Co, Cr, Fe, Mn, Ni, Pb and Zn. Depending on the location of apartments, large variations in concentration, mineralogy and grain-size of magnetic particles were detected. The thermomagnetic analysis revealed magnetite as a primary magnetic phase. In indoor dust, the Curie temperature of ~760°C and soft hysteresis loops with relatively low coercivity values of ~1.5-5 mT are an attribute of metallic iron. The dust collected from apartments located near the local heating plant area, in contaminated post-industrial and suburban areas contains mainly magnetite and only a small amount of metallic iron. Mass-specific magnetic susceptibility is in the range from 40 to 200 × 10^-8 m³kg^-1 and linearly correlates with concentration of individual heavy metals: Ni, Cr, Co and Zn. Magnetic fraction of dust from the city center mainly consists of magnetite and variable amounts of metallic iron. Magnetic susceptibility shows linear correlations with concentration of Fe and concentration of individual heavy metals (Zn, Ni and Co) considered as traffic-related. The study demonstrates that metallic iron present in indoor dust is a potential marker of trafficrelated sources and it makes it possible to use magnetic methods as a tool for evaluation of traffic-related impact on indoor air levels.     

Spatial distribution and bonding forms of heavy metals in sediments along the middle course of the River Elbe (km 287ċ390)

Sediments of eight groyne fields along the middle course of the River Elbe (river km 287?390) were geochemically studied. The 78 sediment samples were analysed for pH and grain size distribution. The grain size fraction < 2 μm was used for mineralogical and chemical analysis: semiquantitative clay mineral analysis; total element content (Al, Ca, Fe, K, Mn, Cd, Cr, Cu, Ni, Pb, Zn), total inorganic and organic C, and bonding form fractionation with a six‐step sequential chemical extraction. The latter was performed on selected samples (n = 32). The sediments along the Elbe's course are still contaminated with heavy metals far above the local geogenic background level. An enrichment factor of more than 15 was calculated for zinc. Cr and Ni are the elements with the lowest enrichment. The bonding form analysis of selected heavy metals shows a dominance of relatively immobile bonding forms, e. g. the moderately reducible and the residual fraction, which implies a relative low mobility potential. Only Zn poses a higher potential threat to the environment, since it has a higher percentage of the first three extracted phases: adsorbed, carbonate, and easily reducible fraction.     

The influence of parent material on topsoil geochemistry in eastern England

The topsoil of around 10 000 km² in eastern England has recently been sampled intensely at 4609 sites to characterize its geochemistry. The parent materials, which include both solid geology and Quaternary sediments, range in age from Permian to Holocene. The distributions of the concentrations of major and trace elements have been characterized geostatistically, and the role of parent material on their spatial structure (anisotropy) and their spatial relationships (coregionalization) have been investigated. Analysis of variance with the sites grouped by major parent material type showed that this classi?cation accounted for 14 to 48 per cent of the variance for the various elements. Global variograms of 13 elements (Al, As, Ca, Cr, Cu, Fe, Mg, Mo, Ni, P, Pb, Ti, and U) have been computed and modelled. Eleven of the variograms seem to comprise two structures, both of which we modelled with spherical functions, one of short range, 3·5 to 9 km, and the other with a range of 15 to 23 km. The models included a nugget variance, which varied from 27 per cent (for As, Fe, and Mg) to 63 per cent (for P) of the total. The long‐range structures are related to the separations of the major parent materials. The variograms of several elements showed appreciable anisotropy, most notably that of Mg. Anisotropy is evident at short ranges of less than 5 km. This accords with the geological structure of the beds which dip from west to east so that their outcrops are elongated from north to south. A linear model of coregionalization ?tted to the data emphasized several important geochemical associations, which we interpret. Elements commonly associated with clay minerals (Mg, Al) and the clay size fraction (Ti) are dominated by the long‐range structure of the coregionalization, whilst several trace elements (As, Cr, Ni and U) are spatially correlated with Fe over short distances, through adsorption of the former on the surfaces of Fe oxyhydroxides. The topsoil around large urban areas is enriched in lead, but it is not clear whether anthropogenic sources are responsible for this metal's anomalous spatial relationships with other elements. Crown copyright © 2003. Reproduced with the permission of Her Majesty's Stationery Of?ce. Published by John Wiley & Sons, Ltd.     

The Adhi Kot breccia and implications for the origin of chondrules and silica-rich clasts in enstatite chondrites

The Adhi Kot EH4 enstatite chondrite breccia consists of silica-rich clasts (12+mn; 5 vol.%), chondrule-rich clasts (55+mn; 10 vol.%) and matrix (35+mn; 10 vol.%). The silica-rich clasts are a new kind of enstatite chondritic material, which contains more cristobalite (18–28 wt.%) than enstatite (12–14 wt.%), as well as abundant niningerite and troilite. The bulk atomic Mg/Si ratios of the clasts (0.22–0.40) are much lower than the average for enstatite chondrites (0.79). Kamacite and martensite (with 8–11 wt.% Ni and a martensitic structure) occur in all three breccia components. The clasts have kamacite-rich rims, and kamacite-rich aggregates occur in the matrix.A unidirectional change in the ambient pS₂/pO₂ ratio in the region of the solar nebula where Adhi Kot agglomerated can explain many of the breccia's petrologic features. If this region initially had a very high pS₂/pO₂ ratio in a gas of non-cosmic composition, sulfurization of enstatite and metallic Fe (e.g., MgSiO₃ + 2Fe + C + 3H₂S = MgS + SiO₂ + 2FeS + H₂O + CH₄) may have occurred, producing abundant niningerite, free silica and troilite at the expense of enstatite and metallic Fe. The Ni content of the residual metal would have increased, perhaps to ～ 8–10 wt.%. The silica-rich clasts agglomerated under these conditions; a significant fraction of the originally produced niningerite was lost (perhaps by aerodynamic size-sorting processes), lowering the clasts' bulk Mg/Si ratios.The pS₂/pO₂ ratio then decreased (perhaps because of infusion of additional H₂O) and sulfurization of metallic Fe and enstatite ceased. The chondrule-rich clasts agglomerated under these conditions, acquiring little free silica and niningerite. An episode of chondrule formation occurred at this time (by melting millimeter-sized agglomerates of this relatively silica-poor enstatite chondrite material and concomitant fractionation of an immiscible liquid of metallic Fe,Ni and sulfide). The chondrule-rich clasts agglomerated many such chondrules. Subsequently, the matrix agglomerated, acquiring the few remaining chondrules. Kamacite-rich aggregates formed, after the cessation of metal sulfurization, and agglomerated with the matrix. The kamacite-rich clast rims were acquired at this time.The components of Adhi Kot accreted to the EH chondrite parent body, where the breccia was assembled, buried beneath additional accreting material, and metamorphosed at temperatures of ? 700°C. Impact-excavation of the breccia and deposition onto the surface caused the formation of martensite from taenite inside the clasts and the matrix. At the surface, impact-melting produced an albite glass spherule, which was incorporated into the matrix. However, the absence of solar-wind-implanted rare gases in bulk Adhi Kot indicates that the breccia spent little time in a regolith.     

Thermomagnetic analysis of meteorites, 3. C3 and C4 chondrites

Thermomagnetic analysis was made on samples of all known C3 and C4 chondrites in a controlled oxygen atmosphere. Considerable variation was noted in the occurrence of magnetic minerals, comparable to the variation observed earlier in the C2 chondrites. Magnetite was found as the only major magnetic phase in samples of only three C3 chondrites (2–4 wt.%) and the Karoonda C4 chondrite (7.7 wt.%). The magnetite content of these three C3 chondrites is only about one-third that observed in the C1 and C2 chondrites which were found to contain magnetite as the only magnetic phase. Five C3 chondrites were observed to undergo chemical change during heating, producing magnetite: this behavior is characteristic of troilite oxidation. Upper limits on initial magnetite content of about 1–9% were established for these meteorites. Samples of the remaining five C3 chondrites and the Coolidge C4 chondrite were found to contain both magnetite and metallic iron. In two samples, iron containing ≤2% Ni was observed, while in the other four, the iron contained 6–8 wt.% Ni. In addition to containing both magnetite and iron metal, three of these samples reacted during heating to form additional magnetite. Variations in the magnetic mineralogy and, hence by inference bulk mineralogy, of C3 and C4 chondrites indicate a more complex genesis than is evident from whole-rock elemental abundance patterns.     

Assessment of Urban Source Metal Levels in Influent,Effluent, and Sludge of Two Municipal Biological Nutrient Removal Wastewater Treatment Plants of Bursa,an Industrial City in Turkey

Removal of Al, As, Cd, total Cr (Tot. Cr), Cu, Total Fe (Tot. Fe), Mn, Ni, Pb, Sb, Sn, and Zn from urban effluent by wastewater treatment plants (WWTPs) operated under five‐stage Bardenpho® process were investigated and water soluble metals in the dewatered sludge were quantified. Samples were collected from two WWTPs on a weekly basis over an approximately 2.5‐year time span. Tot. Fe and Al were the most abundant, As, Pb, Ni, Cu, and Cd were the least abundant metals in the influents of both WWTPs. Removal efficiencies above 75% were achieved for Tot. Cr, Tot. Fe, Al, and Cu, whereas, no significant removal was observed for As, Cd, Pb, Sb, and Sn. Removal of Tot. Cr, Cu, Tot. Fe, Zn, Al, Mn, and Ni were influenced by influent suspended solids concentrations, and of Tot. Cr, Zn, and Cd were influenced by their initial content in the influent. Zn removal efficiency of biological nutrient removal (BNR) system in this study was higher and Cd removal efficiency was lower than that of conventional activated sludge reported in the literature. No remarkable difference for metals such as Cu, Mn, Ni, and Pb was observed between the removal efficiencies of conventional system and BNR system.     

A new kind of primitive chondrite, Allan Hills 85085

Allan Hills 85085 is a chemically and mineralogically unique chondrite whose components have suffered little metamorphism or alteration. This chondrite is unique because it has fewer and smaller chondrules (4 wt. %; mean diameter 16 μm) than any other chondrite, more metallic Fe,Ni (36%) and lithic and mineral silicate fragments (56%), and a lower abundance of troilite (2%) and volatiles. Most chondrules are cryptocrystalline or glassy and are depleted in volatiles, some small chondrules are also very depleted in refractory lithophiles. Matrix lumps (4%) partly resemble CI and CM matrices and may be foreign to the parental asteroid. Despite these differences, the components of ALH 85085 have some features common to most type 2 and the least metamorphosed type 3 chondrites: metallic Fe,Ni grains that contain 0.1–1 wt.% Cr, Si and P; Fe/(Fe + Mg) values of olivines, pyroxenes and chondrules are concentrated in the range 1–6 at.% with a few percent in the range 7–30%; porphyritic chondrules are chondritic in composition (except for their low volatile abundances). Thus the components of ALH 85085 probably have similar origins to those of components in other chondrites, and their properties largely reflect nebular, not asteroidal, processes.The bulk composition of ALH 85085 fits none of the nine groups of chondrites: it is richer in Fe (1.4 × CI levels when normalized to Si) and poorer in Na and S (0.1–0.2 × CI) than other chondrites. Low volatile concentrations are due to a low matrix abundance and loss of volatiles during or prior to chondrule formation, not to volatile loss during metamorphism. Chondrule textures imply extensive heating of chondrule melts above the liquidus, consistent with loss of volatiles from small volumes of melt during chondrule formation. The small size of chondrules is partly due to extensive fragmentation by impacts, which may have occurred on the parent asteroid or in the solar nebula. Collisions between chondrule precursor aggregates in the nebula could also be responsible for the small sizes of chondrules.Assuming that ALH 85085 is a representative sample of an asteroid, its properties lend support to models for the origins of the Earth, eucrite parent body and volatile-poor iron meteorites that invoke chondritic planetesimals depleted in volatiles. The existence of ALH 85085 and Kakangari suggests that the nine chondrite groups may provide a remarkably poor sample of the primitive chondritic material from which the asteroids formed. Certain similarities between ALH 85085 and Bencubbin and Weatherford suggest that the latter two primitive meteorites may actually be chondrites with even higher metal abundances (50–60 wt.%) and very large, partly fragmented chondrules.     

Element partitioning between metallic liquid, silicate liquid, and lower-mantle minerals: implications for core formation of the Earth

We determined the partition coefficients of 19 elements between metallic liquid and silicate liquid at 20 GPa and 2500°C, and between metallic liquid and silicate perovskite at 27 GPa and 2200°C. Remarkable differences were observed in the partitioning behaviors of Si, P, W, Re, and Pb among the silicate liquid, perovskite, and magnesiowüstite coexisting with metallic liquid, reflecting incompatibility of the elements in the silicate or oxide phase. We could not observe any significant difference in the partitioning behaviors of V, Cr, Mn, Co, Ni, and Cu among the phases coexisting with metallic liquid.

Comparison of the present partitioning data with those obtained previously at lower pressure and temperature suggests that the exchange partition coefficients, K_met/sil, of Co, Ni, Mo, and W decrease, whereas those of V, Cr, and Mn increase and tend to approach unity with increasing pressure and temperature. We also made preliminary experiments to clarify the effect of sulfur on the partitioning behaviors. Sulfur lowers the exchange partition coefficients, K_met/sil, of Mo and W between metallic liquid and silicate liquid significantly at 20 GPa and 2300°C.

The mantle abundances of Co, Ni, Cu, Mo, and W calculated for the metal-silicate equilibrium model are lower than those of the real mantle, whereas P, K, and Mn are overabundant in the calculated mantle. The discrepancies in the abundances of Co and Ni could be explained by the chemical equilibrium at higher pressure and temperature. Large discrepancies in Mo and W between the calculated and real mantles could be accounted for by the effect of sulfur combined with the effects of pressure and temperature on the chemical equilibrium. The mantle abundances of P, K, and Cu could be accounted for by volatile loss in the nebula, perhaps before accretion of the Earth, combined with the chemical equilibrium at higher pressure and temperature. Thus the observed mantle abundances of P, K, Co, Ni, Cu, Mo, and W may be consistent with a model of sulfur-bearing metal-silicate equilibrium in lower-mantle conditions.     

Evidence of the impacting body of the Ries crater — the discovery of Fe-Cr-Ni veinlets below the crater bottom

Fe-Cr-Ni particles and veinlets have been discovered in the top 15 m of the compressed zone with abundant shatter cones below the bottom of the Ries crater. The metallic particles are less than a few microns across. They occur in various minerals along healed intergranular and locally in intragranular microfractures in quartz diorite, amphibolite and chloritized granite of the basement crystalline rocks.The particles consist of major Fe, Cr, and Ni with minor Si and Ca. Origin due to contamination is absolutely ruled out. We believe that these Fe-Cr-Ni particles are probably condensed from the vaporized impacting body which produced the Ries crater. These particles were injected with high velocity into microfractures near the top of the compressed zone, implanted in and across various minerals before these microfractures were resealed. The presence of Si and Ca as well as the fact that the Cr content is nearly twice that of Ni, led us to conclude that the Ries impacting body is very likely not an iron meteorite but a stony meteorite.     

Dechlorination of 3,3′,4,4′-tetrachlorobiphenyl (PCB77) in water,by nickel/iron nanoparticles immobilized on L-lysine/PAA/PVDF membrane

In this study, the dechlorination of chlorinated hydrocarbon 3,3′,4,4′-tetrachlorobiphenyl (PCB77) by bimetallic Ni/Fe nanoparticles immobilized on L-lysine/PAA/PVDF membrane was investigated at ambient conditions through the batch mode operation. The membrane support polyvinylidene fluoride (PVDF) was modified by in situ polymerization of acrylic acid in aqueous phase, then L-lysine was covalently bonded to the polymerized acrylic acid chains with the aid of a water-soluble carbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC). The modification procedure involved cationic ion exchange with Fe²⁺, reduction to Fe⁰ with NaBH₄ and finally deposition of Ni⁰. The scanning electron microscopic images showed that the Ni/Fe nanoparticles were successfully immobilized inside the membrane using the polyacrylic acid (PAA) as an inter-linkage between PVDF and L-lysine. A systematic characterization of the composite was performed using ATR-FTIR, HRSEM, EDX, HRTEM, XRD, and contact angle measurement studies and a relatively uniform distribution of Ni/Fe was found in L-lysine/PAA/PVDF membrane because of its hydrophilic nature. The obtained Ni/Fe nanoparticles consist of Fe⁰ core surrounded by the Ni⁰ shell. The diameter of Ni/Fe nanoparticles was predominantly within the range 20–30 nm. The immobilized Ni/Fe nanoparticles exhibited a good reactivity towards the dechlorination of the chlorinated hydrocarbon since the concentration of the PCB77 was decreased by catalytic dechlorination with Ni/Fe nanoparticles inside the L-lysine/PAA/PVDF membrane. Dechlorination efficiency of 98% was achieved within 9 h.     

Compressibility of the calcium aluminosilicate, CAS, phase to 44 GPa

In situ X-ray diffraction measurements on a calcium aluminosilicate (CAS) phase have been carried out using a laser-heated diamond anvil cell up to a pressure of 44 GPa, employing a synchrotron radiation source. CAS is the major mineral formed from sediments subducted into the Earth's mantle. The sample was heated using a YAG laser after each pressure increment to relax the deviatoric stress in the sample. X-ray diffraction measurements were carried out at T = 300 K using an angle-dispersive technique. The pressure was calculated using an internal platinum metal pressure calibrant. The Birch–Murnaghan equation of state for the CAS phase obtained from the experimental unit cell parameters showed a density of ρ₀ = 3.888 g/cm³ and a bulk modulus of K₀ = 229 ± 9 GPa for K^′₀ = 4.7 ± 0.7. When the first pressure derivative of the bulk modulus was fixed at K^′₀ = 4, then the value of K₀ = 239 ± 2 GPa. From the experimental compressibility, the density of the CAS phase was observed to be lower than the density of co-existing Al-bearing stishovite, calcium perovskite, calcium ferrite-type phases, and (Fe,Al)-bearing Mg-perovskite in subducted sediments in the lower mantle. Therefore, the density of subducted sediments in the lower mantle decreases with increasing mineral proportion of the CAS phase.     

Concentration of 7 Heavy Metals in Sediments and Mangrove Root Samples from Mai Po, Hong Kong

Concentration of 7 heavy metals, Zn, Fe, Cu, Cr, Cd, Pb and Ni in mudflat sediments, mangrove root sediments and root tissues of Acanthus ilicifolius, Aegicerus corniculatum and Kandelia candel from the Mai Po Nature Reserve, Northwest Hong Kong, were measured. Metal concentrations in the upper 0–10 cm of the sediment cores from the mudflat were 4–25% higher than those found in the bottom 21–30 cm. Relative Topsoil Enrichment Index approximated 1.0 for all the metals. Mudflat sediment concentrations of Fe, Ni, Cr, Cd and Cu were greater than those found in the mangrove sediments. Except for Fe, concentrations of the other 6 heavy metals were more elevated in the mangrove root sediments than in the corresponding root samples. Higher concentration factors for Zn, Fe and Cu may indicate bioaccumulation. Mean metal concentrations in both mudflat and mangrove sediments decreased in the order Fe > Zn > Pb > Ni > Cu > Cr > Cd. Mangrove root tissues also showed the same pattern except that Pb > Cu > Ni     

Ecological-geochemical assessment of the state of the Volga source of water supply to Moscow

Long-term observational data (1992?C2009) on heavy metal (Cu, Zn, Pb, Cr, Ni, V, Mo, Co, Fe, and Mn) content of different links in the Ivankovo Reservoir ecosystem are used to consider the regularities in the distribution and behavior of heavy metals in the system anthropogenic pollution sources-reservoir and its drainage area, thus enabling the assessment of the pollution level of the Volga Source of water supply to Moscow.     

Evaluation of metal contamination in coastal sediments of the Bay of Bengal, India: geochemical and statistical approaches

Surface sediment samples collected from the inner shelf region of the Bay of Bengal, were analysed for the major elements and total and acetic acid available trace elements (Al, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, Si, Zn) to evaluate geochemical processes influencing their distribution. Major elemental analysis showed that the sediments had high concentrations of Si and relatively low concentrations of Al and Fe. Both major elemental and trace metal concentrations indicated that the sediments represent weathered products of granite and charnockite. Normalization of metals to Al indicated relatively high enrichment factors for Pb, Cd, Zn and Cr. The higher proportions of nondetrital Pb (66%), Cd (41%) and Co (28%) reveal metal contamination due to anthropogenic inputs. Factor analysis (FA) identified six possible types of sedimentological and geochemical associations. The dominant factor accounting for 26.9% of the total variance identifies an anthropogenic input and accumulation of nondetrital Cd, Co, Cr, Ni and Pb. Association of these metals with CaCO3 reveals that shell fragments in the surface sediments are likely act as a carrier phase for nondetrital metals. The results are discussed in the context of the sources and pathways of elements in the Bay of Bengal.