Fraction Of Cu Research Articles

Heavy metal distribution in Tiaoxi River's sediment.

According to current study, seven surface sediments and three sediment cores were collected from three typical areas of Tiaoxi River, which were living area, agricultural area, and industrial area. The water quantity into the Lake Taihu from the Tiaoxi River accounted for almost one third of the total water quantity by all rivers into the Lake Taihu. To study geochemical features and pollution history of heavy metals in three typical areas of Tiaoxi River, total content and chemical fractionations of Cu, Pb, Cd, Cr, Mn, Zn, Fe, As, and Hg were analyzed for surface and core sediments using the speciation extraction procedure, proposed by the Commission of the European Communities Bureau of Reference (BCR), together with grain size and organic carbon measurements. The results showed that the concentration of nine heavy metals and the variation characteristics of Zn, Cu, Fe, Mn, and Cr are different among five cores, which has shown that the river responses to natural and anthropogenic activities were dissimilar in various areas. BCR sequential extraction showed contents of Cr, Fe, and Cu were dominated in the remaining parts. Non-residual fractions for Zn and Mn contained major portions. Based on RAC (risk assessment core), the risk of Mn was high to very high in the three typical areas, and the risk of Zn was medium in the three typical areas.

Dynamics of copper and tetracyclines during composting of water hyacinth biomass amended with peat or pig manure.

Composting is one of the post-treatment methods for phytoremediation plants. Due to a high potential of water hyacinth to accumulate pollutants, the physicochemical parameters, microbial activity as well as fates of copper (Cu) and tetracyclines (TCs) were investigated for the different amended water hyacinth biomass harvested from intensive livestock and poultry wastewater, including unamended water hyacinth (W), water hyacinth amended with peat (WP), and water hyacinth amended with pig manure (WPM) during the composting process. Pig manure application accelerated the composting process as evidenced by an increase of temperature, electrical conductivity (EC), NH4-N, as well as functional diversity of microbial communities compared to W and WP treatments. Composting process was slowed down by high Cu, but not by TCs. The addition of peat significantly increased the residual fraction of Cu, while pig manure addition increased available Cu concentration in the final compost. Cu could be effectively transformed into low available (oxidizable) and residual fractions after fermentation. In contrast, less than 0.5% of initial concentrations of TCs were determined at the end of 60-day composting for all treatments in the final composts. The dissipation of TCs was accelerated by the high Cu concentration during composting. Therefore, composting is an effective method for the post-treatment and resource utilization of phytoremediation plants containing Cu and/or TCs.

Geochemistry of the Cretaceous Kaskanak Batholith and genesis of the Pebble porphyry Cu-Au-Mo deposit, Southwest Alaska

The key magmatic processes that lead to the formation of large magmatic-hydrothermal porphyry copper mineral deposits remain uncertain, and a particular question is why a few of these deposits, such as the Pebble porphyry Cu-Au-Mo deposit, are strongly enriched in both gold and molybdenum. This study investigated the igneous rocks of the Pebble district and obtained major and trace element compositions, Sr and Nd isotopic compositions, and zircon age and trace element data to model the origin of the ore-forming magmas. The Pebble porphyry Cu-Au-Mo deposit, one of the world’s largest Cu-Au resources, formed during the final stages of regional Late Cretaceous arc magmatism (101–88 Ma) in the Southwest Alaska Range. Local pre-mineral intrusions (99–95 Ma) are dominated by alkaline compositions including monzodiorite stocks, shoshonite dikes, and monzonite porphyries, but also include lesser volumes of high-K calc-alkaline diorite and granodiorite sills. The occurrence of early alkaline magmas has been noted at other gold-rich porphyry systems, including Bingham and Kerr-Sulfurets-Mitchell. Mineralization at Pebble is associated with granodiorite to granite porphyry dikes related to the >165 km 2 high-K calc-alkaline Kaskanak granodiorite batholith (91–89 Ma). Over a period of 10 m.y., Late Cretaceous melts evolved from high temperatures (930–730 °C) and modestly hydrous and oxidized conditions to relatively low temperatures (760–680 °C) and very hydrous and oxidized conditions. Collectively, all Late Cretaceous igneous rocks at Pebble contain magnetite and little or no ilmenite, are metaluminous to weakly peraluminous, and have typical arc trace element enrichments and depletions. They have moderate Sr/Y ratios (20–55) and gently sloped REE profiles (La/Yb = 5–20) that are not adakitic, which supports a source area lacking garnet that is consistent with a thin crust in southwest Alaska. Radiogenic isotopes for Late Cretaceous intrusions at Pebble have a restricted range of primitive Sr and Nd isotopic compositions ( 87 Sr/ 86 Sr i = 0.70329–0.70424; ɛNd i = 4.9–6.1), which overlap with volcanic and plutonic basement rocks of the Jurassic Talkeetna Arc along the Alaska Peninsula. The Kaskanak batholith intrudes the Late Jurassic–Early Cretaceous Kahiltna flysch, and mixing models using Sr and Nd isotopes indicate that the Kaskanak batholith assimilated ≤10 wt% Kahiltna flysch in amounts that did not likely affect magma fertility. Xenocrystic zircon samples are abundant in Cretaceous pre-mineral intrusions and have U-Pb ages similar to detrital zircon samples in the Kahiltna flysch. These data support some assimilation of upper crustal Kahiltna flysch, but the dominance of Devonian–Mississippian xenocrystic zircon populations in some intrusions suggests derivation from unexposed older basement. The extraordinary endowment of Cu and Au at Pebble is inferred to result from primitive calc-alkaline and alkaline arc magmas and the hydrous and strongly oxidized conditions that suppressed the formation and fractionation of Cu- and Au-enriched sulfide melts. Furthermore, differentiation to silicic compositions was a product of extensive crystal fractionation of parental melts accompanied by minor crustal assimilation. The trace element content of the intermediate composition intrusions indicates that both hornblende and titanite fractionation processes in the mid- to shallow-crust were both required to produce the more evolved granodiorite and granite porphyry compositions. Despite the apparent lack of Mo-enriched continental crust in the region, primitive hydrous melts were produced by protracted arc magmatism and were modified by minor crustal assimilation including early alkaline magmatism, periodic recharge of mafic hydrous basalts and hybrid andesites, and fractional crystallization, which was apparently sufficient to enrich Mo in late stage felsic melts.

Leaching of Cu, Cd, Pb, and phosphorus and their availability in the phosphate-amended contaminated soils under simulated acid rain.

Phosphate amendments have been used to immobilize heavy metal-contaminated soils. However, phosphate amendments contain large amounts of phosphorus, which could leach out to potentially contaminate groundwater and surface water. A laboratory column leaching experiment was designed to study the effects of simulated acid rain (SAR) on the potential release of copper (Cu), lead (Pb), cadmium (Cd), and phosphorus (P), and their availability after immobilizing with hydroxyapatite (HAP) and potassium dihydrogen phosphate (PDP). The application of HAP and PDP enhanced the leachate electrical conductivity, total organic carbon, and pH. Higher P was found in the PDP- (>4.29mgL-1) and HAP-treated (>1.69mgL-1) columns than that in untreated (<0.2mgL-1) columns, and they were both over the class V limit (0.4mgL-1) mandated by the Chinese National Quality Standards for Surface Waters (GB 3838-2002). PDP application decreased the leachate Cu, Pb, and Cd effectively; however, HAP addition increased leachate Cu and Pb. HAP and PDP applications decreased the soil CaCl2-extractable and exchangeable fraction of Cu, Pb, and Cd, and increased resin P. However, eluviations transformed the heavy metals from inactive to active fractions and reduced soil labile P. These findings showed that HAP and PDP had a potential risk of excessive P-induced eutrophication. Meanwhile, more attention should be paid to the leaching loss of multiple metals because phosphate amendments might promote the leaching of some metals while immobilizing others.

Comparison between the effectiveness of regional BLEG and −80# stream sediment geochemistry in detection of precious and base metal mineral deposits in Western Turkey

Stream sediments remain the preferred sampling media for regional mineral exploration programs in most parts of the world where there is a well-defined drainage system. In Au exploration the analysis of either BLEG (bulk leach extractable gold) or acid-extractable Au in the −80# (<180μm) stream sediment fraction are the two most common approaches. Western Turkey contains a variety of mineral deposit types and geological settings. Using a large geochemical database derived mainly from company exploration programs (5149 BLEG, 11,692 −80# stream sediment analyses and 7732 rock chip samples), a comparison is made between the efficiency of these two approaches in detecting the known mineral deposits or occurrences. There is only limited variation between the median or 95th percentile values for Au or Cu across the different lithologies, although Cu is higher in BLEG in basaltic areas and Au higher in the ultramafic and metamorphic dominated terranes. Element distributions were examined using both quantile-quantile (Q-Q) and concentration-area (C-A) multifractal plots to establish the major breaks between regional geochemical populations. The C-A fractal plots generated clearer breaks than the Q-Q plots between populations and lower thresholds to the dominant “background” populations (e.g. 2ppb Au for Q-Q and 0.9 ppb for C-A in BLEG). Overall geochemical patterns in the −80# delivered clearer spatial correlations with known mineral deposits and occurrences than BLEG. Comparing the observed population breaks with the distribution of catchments containing known mineralization, based on the proportion of “true positives” and “false negatives”, C-A was more effective at separating populations related to catchments containing Au or Cu mineralization with little difference between BLEG and −80# (~80% agreement) for Au but a superior response in the −80# fraction for Cu. Given ongoing improvements in analytical detection limits for most elements, the use of the −80# (or possibly finer fractions) is recommended over BLEG for regional reconnaissance stream sediment survey in terrains similar to Western Turkey.

Pine Bark Amendment to Promote Sustainability in Cu-Polluted Acid Soils: Effects on Lolium perenne Growth and Cu Uptake

The establishment of a complementary grass cover on vineyard soils can promote sustainability of the affected environment. In this work, we used an acid vineyard soil with total Cu concentration 188 mg kg−1 to study the influence of pine bark amendment on Lolium perenne growth and Cu uptake. The results indicate that the pine bark amendment did not cause a significant increase in the mass of the shoots of Lolium perenne, but favored the root biomass: 0.034 g for control and 0.061 g for soil samples amended with 48 g kg−1 of pine bark. Moreover, the pine bark amendment decreased Cu concentration in both, shoots (50 mg kg−1 for control soil and 29 mg kg−1 for soil amended with 48 g kg−1 pine bark) and roots (250 mg kg−1 for control soil and 64 mg kg−1 for soil amended with 48 g kg−1 pine bark). The main factor responsible for these results was a significant decrease of the most mobile fractions of Cu in the soil. Those fractions were extracted using ammonium acetate, ammonium chloride, sodium salt of ethylene-diamine-tetraacetic acid (EDTA-Na), and diethylene-triamine-pentaacetic acid (DTPA).

Compost and biochar interactions with copper immobilisation in copper-enriched vineyard soils

Applications of Cu-based fungicides against downy mildew of grapevines have led to Cu accumulation in the topsoil of vineyards. In such soils, Cu may reach levels high enough to exert adverse effects on soil microorganisms, soil fauna and plant roots. This study aimed to test combinations of compost and biochar for their potential to decrease the bioavailability of Cu in Cu-enriched vineyard soils.Grapevine plants (Vitis vinifera L. cv. Grüner Veltliner) were cultivated in soil columns equipped as microlysimeters during two vegetation periods under greenhouse conditions. The two experimental soils differed in pH (6.2 and 7.2, resp.), organic carbon (2.7 and 0.9%, resp.) and EDTA-Cu (97 and 198 mg kg−1, resp.). Treatments differed in the mixing ratio of compost and biochar, feedstock for biochar and post-pyrolysis modification of biochar. Standard addition rates amounted to 4 kg additive m−2.Cu uptake into the grapevine shoots and leaves hardly responded to the different soil additive treatments. The roots buffered different Cu availability with increased Cu accumulation and largely prevented excessive translocation to aerial plant parts. The soil with lower pH and higher organic carbon content showed more vigorous shoot growth and higher leaf Cu concentrations than the soil of neutral pH in spite of lower EDTA-Cu concentrations of the soil. Soil analyses at the end of the experiment showed that the CaCl2-extractable fraction of Cu was lower in the neutral soil (3% of EDTA-Cu) than in the more acidic soil richer in Corg (8%).The novelty of this study is the inclusion of Cu speciation for investigating the effects of the soil additives. Differences between treatments were more pronounced for Cu2+ than for CaCl2-extractable Cu. All tested additive treatments in the acidic soil showed clear reductions of Cu2+ compared to the control without additives whereas this effect was less expressed but still recognizable in the neutral soil. In the soil pore water the Cu concentrations showed a Cu-mobilizing effect of the additives in the neutral soil, a mostly not significant effect in the acidic soil and a clear decrease of the Cu2+ fraction that was more distinct in the acidic than in the neutral soil. Although the Cu2+ fraction that was successfully reduced by the tested additives usually constitutes only <1% of total Cu in soil, this fraction is ecotoxicologically more relevant than the prevailing organically bound fraction.

Copper Accumulation and Availability in Sandy, Acid, Vineyard Soils

ABSTRACTThe use of copper (Cu)-based fungicides to control diseases in vineyards can cause excessive Cu accumulation in soils. Greater Cu availability is expected in acid sandy soils with low organic matter (OM), where the risk of toxicity to plants and environment contamination is high. This study aimed to study the evolution of Cu in acid, sandy soils planted with grapevines for a period of time between 2 and 32 years. Two studies were carried out in South Brazil: in the first study, soil samples, from 19 vineyards were collected and analyzed in the first 0.2 m depth-layer for the total and available Cu. In the second study, 3 soils were selected among the previous 19 according to the age of vineyard (5, 11, and 30 year-old), and their 0.60 m-depth profile was analyzed for 5 fractions of Cu (soluble, exchangeable, mineral, organic, and residual). All the soils were classified as Ultisols. The vineyards with more than 25 years under cultivation had a mean total Cu concentration of 90 mg kg−1 in the 0–0.10 m layer. Approximately 80% of it was potentially available to plants. The greatest total and available Cu were found in the soil surface layers (0.2 m depth), where up to 75% of the total Cu is adsorbed in clay minerals and only 20% is complexed in the OM.

Silver contents and Cu/Ag ratios in Martian meteorites and the implications for planetary differentiation

Silver and Cu show very similar partitioning behavior in sulfide melt-silicate melt and metal-silicate systems at low and high pressure-temperature (P-T) experimental conditions, implying that mantle melting, fractional crystallization and core-mantle differentiation have at most modest (within a factor of 3) effects on Cu/Ag ratios. For this reason, it is likely that Cu/Ag ratios in mantle-derived magmatic products of planetary bodies reflect that of the mantle and, in some circumstances, also the bulk planet composition. To test this hypothesis, new Ag mass fractions and Cu/Ag ratios in different groups of Martian meteorites are presented and compared with data from chondrites and samples from the Earth’s mantle.Silver contents in lherzolitic, olivine-phyric and basaltic shergottites and nakhlites range between 1.9 and 12.3ng/g. The data display a negative trend with MgO content and correlate positively with Cu contents. In spite of displaying variable initial Ɛ143Nd values and representing a diverse spectrum of magmatic evolution and physiochemical conditions, shergottites and nakhlites display limited variations of Cu/Ag ratios (1080±320, 1s, n=14). The relatively constant Cu/Ag suggests limited fractionation of Ag from Cu during the formation and evolution of the parent magmas, irrespectively of whether sulfide saturation was attained or not. The mean Cu/Ag ratio of Martian meteorites thus reflects that of the Martian mantle and constrains its Ag content to 1.9±0.7ng/g (1s).Carbonaceous and enstatite chondrites display a limited range of Cu/Ag ratios of mostly 500–2400. Ordinary chondrites show a larger scatter of Cu/Ag up to 4500, which may have been caused by Ag redistribution during parent body metamorphism. The majority of chondrites have Cu/Ag ratios indistinguishable from the Martian mantle value, indicating that Martian core formation strongly depleted Cu and Ag contents, but probably did not significantly change the Cu/Ag ratio of the mantle compared to bulk Mars. Bulk Mars is richer in moderately volatile elements than Earth, however, the Martian mantle displays a much stronger depletion of the moderately volatile elements Cu and Ag, e.g., by a factor of 15 for Cu. This observation is consistent with experimental studies suggesting that core formation at low P-T conditions on Mars led to more siderophile behavior of Cu and Ag than at high P-T conditions as proposed for Earth. In contrast, Cu/Ag ratios of the mantles of Mars and Earth (Cu/AgEarth=3500±1000) display only a difference by a factor of 3, which implies restricted fractionation of Cu and Ag even at high P-T conditions. The concentration data support the notion that siderophile element partitioning during planetary core formation scales with the size of the planetary body, which is particularly important for the differentiation of large terrestrial planets such as Earth. Collectively, the Ag and Cu data on magmatic products from the mantles of Mars and Earth and the data on chondrites confirm experimental predictions and support the limited fractionation of Cu and Ag during planetary core formation and high-temperature magmatic evolution, and probably also in early solar nebular processes.

Assessment of heavy metal pollution in soils around a paper mill using metal fractionation and multivariate analysis

Effects of paper mill wastes on the status of soil copper (Cu), manganese (Mn) and zinc (Zn) in and around 16 sites near a paper mill in Assam, North East India (26°07.485′ to 26°07.915′ N latitude and 92°12.706′ to 92°15.065′ E longitude), have been investigated in the present study. The six-step sequential extraction techniques revealed that the water-soluble fraction had the least contribution (below detectable limit to 3.24 mg kg−1 of Cu, 13.87 mg kg−1 of Mn and 1.25 mg kg−1 of Zn) towards soil contamination, irrespective of the metals evaluated. Chemical fractionation of Cu, Mn and Zn in majority of the sampling locations showed non-homogenous orders of contamination. Comparison of the magnitude of local and individual heavy metal contamination factors against global values showed that the places near the paper mill waste disposal site displayed higher potential risk from metal contamination. Furthermore, the mobility factor related to ecotoxicity of soil environment was found to be metal specific and depended not only on total metal concentration but also on the nature of metal in the order Mn > Cu > Zn.

Increasing copper alters cellular elemental composition (Moand P) of marine diatom.

The elemental composition (surface adsorbed and internalized fraction of Cu, Mo and P) in marine phytoplankton was first examined in cultures of the diatom Phaeodactylum tricornutum which were exposed to various levels of Cu concentrations ranging from 0.25 to 16 μmol/L with equivalent free [Cu2+] concentrations of 0.4–26 nmol/L. We observed an acceleration of algal growth rates (20–40%) with increasing ambient Cu levels, as well as slightly increased levels of internalized Cu in cells (2–13 × 10−18 mol/cell) although cellular Cu mostly accumulated onto the cell surface (>50% of the total: intracellular + surface adsorbed). In particular, we documented for the first time that the elemental composition (Mo and P) in algal cells varies dynamically in response to increased Cu levels: (1) Cellular P, predominantly in the intracellular compartment (>95%), shows with a net consumption as indicated by a gradual decrease with increasing [Cu2+] (120→50 × 10−15 mol P/cell) probably due to the fact that P, a backbone bioelement, is largely required in forming biological compartments such as cell membranes; and (2) cellular Mo, predominantly encountered in the intracellular compartment, showed up to tenfold increase in concentration in the cultures exposed to Cu, with a peak accumulation of 1.1 × 10−18 mol Mo/cell occurring in the culture exposed to [Cu2+] at 3.7 nmol/L. Such a net cellular Mo accumulation suggests that Mo might be specifically required in biological processes, probably playing a counteracting role against Cu.

Influences of hydrological regime on heavy metal and salt ion concentrations in intertidal sediment from Chongming Dongtan, Changjiang River estuary, China

The tidal flat along the Changjiang (Yangtze) River estuary has long been reclaimed for the agricultural purposes, with the prevailing hydrological conditions during such pedogenic transformations being of great importance to their successful development. In this study, samples of surface sediment from Chongming Dongtan, situated at the mouth of the Changjiang River estuary, were collected and analyzed in order to understand how hydrological management can influence the concentrations of heavy metals and salt ions in pore water, and chemical fractionation of heavy metals during the reclamation process. We performed a series of experiments that simulated three different hydrological regimes: permanent flooding (R1), alternative five-day periods of wetting and drying (R2), continuous field capacity (R3). Our results exhibited good Pearson correlations coefficients between heavy metals and salt ions in the pore water for both R1 and R2. In particular, the concentrations of salt ions in the pore water decreased in all three regimes, but showed the biggest decline in R2. With this R2 experiment, the periodic concentration patterns in the pore water varied for Fe and Mn, but not for Cr, Cu, Pb and Zn. Neither the fractionation of Ni nor the residual fractions of any metals changed significantly in any regime. In R1, the reducible fractions of heavy metals (Cr, Cu, Zn and Pb) in the sediment decreased, while the acid extractable fractions increased. In R2, the acid extractable and the reducible fractions of Cr, Cu, Zn and Pb both decreased, as did the oxidizable fraction of Cu. These data suggest that an alternating hydrological regime can reduce both salinity and the availability of heavy metals in sediments.

The partitioning of Cu, Au and Mo between liquid and vapor at magmatic temperatures and its implications for the genesis of magmatic-hydrothermal ore deposits

The partition coefficients of Cu, Au and Mo between liquid and vapor were determined at P=130MPa and T=900°C, and P=90MPa and T=650°C and redox conditions favoring the dominance of reduced S species in the fluid. The experiments at 900°C were conducted in rapid-quench Molybdenum-Hafnium Carbide externally-heated pressure vessel assemblies, whereas those at 650°C were run in René41 pressure vessels. The fluids were sampled at run conditions using the synthetic fluid inclusion technique. The host quartz was fractured in situ during the experiments ensuring the entrapment of equilibrium fluids. A new method was developed to quantify the composition of the vapor inclusions from LA-ICPMS analyses relying on the use of boron as an internal standard, an element that fractionates between vapor and liquid to a very small degree. The bulk starting fluid compositions closely represented those expected to exsolve from felsic silicate melts in upper crustal magma reservoirs (0.64m NaCl, 0.32mKCl, ±0.2mHCl and/or 4wt% S). The experiments were conducted in Au97Cu3 alloy capsules allowing the simultaneous determination of apparent Au and Cu solubilities in the liquid and the vapor phase. Though the apparent metal solubilities were strongly affected by the addition of HCl and S in both phases, all three elements were found to preferentially partition to a liquid phase at all studied conditions with an increasing degree of preference for the liquid in the following order Au<Cu<Mo. The presence of HCl and S did not have a significant effect on the liquid/vapor partition coefficients of either Au or Cu, whereas the presence of HCl slightly shifted the partitioning of Mo in favor of the vapor. Ore metal partition coefficients normalized to that of Na (Ki-Naliq/vap=Diliq/vap/DNaliq/vap) fall in the following ranges respectively for each studied metal: KAu-Naliq/vap=0.20±0.07–0.50±0.19 (1σ); KCu-Naliq/vap=0.36±0.12–0.76±0.22; KMo-Naliq/vap=0.67±0.15–2.5±0.8. Decreasing T from 900°C to 650°C slightly shifted KAu-Naliq/vap and KCu-Naliq/vap to the lower end of the reported ranges. A consequence of KAu-Naliq/vap and KCu-Naliq/vap being significantly smaller than 1 is that much of the Au and a significant fraction of Cu may be carried to shallower levels of magmatic-hydrothermal systems by residual vapors despite potentially extensive brine condensation.

Availability and fractionation of Cu, Pb and Zn in an acid soil from Galicia (NW Spain) amended with municipal solid waste compost

The potential availability and chemical fractionation of trace elements in soil after compost addition was studied in a laboratory incubation. An acid agricultural soil, developed on biotitic schists, was amended with two rates of a municipal solid waste compost (3% and 6% weight) or lime (2.5 g CaCO&lt;sub&gt;3&lt;/sub&gt; kg&lt;sup&gt;-1&lt;/sup&gt;, calculated to raise soil pH to values close to those of the compost-amended soil), and incubated in the laboratory for five months. Compost addition increased the availability of Cu, Pb and Zn (measured in DTPA extract) with respect to the control, whereas lime reduced it. Compost amendment increased soil total Cu, Pb and Zn concentrations, and their chemical distribution, assessed by means of the BCR (Bureau Communautaire de Reference) fractionation scheme, was different for each element. Compost addition increased Pb in the reducible (iron oxide-bound) fraction, Cu in the organic and iron oxide fractions, and Zn in the soluble and reducible fractions. Lime did not change the fractionation or total concentrations of the metals analysed. The most problematic element in the compost-amended soil from an environmental point of view is Zn, because it was found in highly mobile forms, while for Cu and Pb this risk is low.

Modelling the elastic properties of bi-continuous composite microstructures captured with TriBeam serial-sectioning

The elastic and physical properties of a tungsten-copper (W-Cu) bi-continuous composite were predicted from microstructural data captured using TriBeam serial sectioning. The reconstructed 3D volume was converted into a Finite Element (FE) mesh. The minimum representative volume elements (RVEs) required for calculating phase volume fraction, Young's modulus and Poisson’s ratio were determined. The predicted volume fraction of Cu and Young's modulus were found to be within 2.6%, and 3.6% of the respective experimentally determined values. The minimum RVE size is found to be dependent on the material property. The variability in the required RVE size must be considered for material properties of W-Cu and similar bi-continuous composite microstructures.

The impact of aging wine in high and low oxygen conditions on the fractionation of Cu and Fe in Chardonnay wine

Solid-phase extraction has previously been used to fractionate copper and iron into hydrophobic, cationic and residual forms. This study showed the change in fractionated copper and iron in Chardonnay wines with 1-year of bottle aging under variable oxygen and protein concentrations. Wines containing protein in low oxygen conditions induced a decrease (20-50%) in total copper and increased the proportion of the hydrophobic copper fraction, associated with copper(I) sulfide. In contrast, protein stabilised wines showed a lower proportion of the hydrophobic copper fraction after 1-year of aging. In oxidative storage conditions, the total iron decreased by 60% when at high concentration, and the concentration of the residual fraction of both copper and iron increased. The results show that oxidative storage increases the most oxidative catalytic form of the metal, whilst changes during reductive storage depend on the extent of protein stabilisation of the wine.

Investigations on electrical characteristics of (PbO)30(CuO)x(As2O3)(70-x) glass ceramics

This study is mainly focused on dielectric properties of lead arsenate glasses crystallized with different concentrations of CuO over continuous ranges of frequency (3Hz −100kHz) and temperature (300–633K). The glasses were prepared by melt quenching technique and were heat treated for prolonged time for ceramization. Prepared samples were characterized by XRD, SEM and DSC techniques. SEM studies indicated that the samples are composed of small crystal grains of the size varying from 0.2 to 1.0µm cemented with the residual glass phase. XRD studies indicated CuAs2O4, Pb2Cu7(AsO4)6 and Cu2O are the main crystal phases developed during the crystallization. Optical absorption studies confirmed the presence of copper ions in Cu+ valence state in addition to Cu2+ state and the fraction of Cu+ ions is found to increase with the content of CuO. The optical band gap exhibited increasing trend with CuO content. IR spectral studies indicated an increase of degree of polymerization of the glass network with the CuO content. The observed variations of dielectric parameters with frequency, temperature and CuO content are discussed using different polarization mechanisms. The dielectric relaxation effects exhibited by the loss tangent and the electric moduli are analyzed using graphical method and observed relaxation effects are attributed to the complexes of divalent copper ions with oxygens. The impedance diagrams indicated increase of bulk resistance of the samples with increase of CuO content. The ac conductivity exhibited a decreasing trend with increase of CuO content. The conduction phenomenon is explained using polaron hopping between Cu+ and Cu2+ ions. The temperature independent part of the conductivity is explained using quantum mechanical tunneling (QMT) model. Finally, it is concluded that the insulating strength of the material increased with CuO content and such materials may be useful as electrical insulators in the low temperature region

Longterm study of transformation of potentially toxic element pollution in soil/water/sediment system by means of fractionation with sequential extraction procedures

In first part of the paper a review is given on fractionation methodologies by sequential extraction methodologies applied for risk assessment of environmental pollution by potentially toxic elements (PTE). Main sources of PTE release are the mining-, industrial-, agri-food production-, traffic- and communal-waste. In this latter the medical and health care sources may emerge due to therapeutic and diagnostic applications (Ag, As, Au, Ba, Bi, Cd, Ga, Gd, 131I, Ir, Li, Mn, Fe, Os, Pd, Pt, Rh, Ru, Sb, Sn, Ti, V), to nanomedicines, to ayurvedic herbal medicines with possible contaminant PTEs and non-controlled dietary supplements. The magnitude of adverse effects caused by PTEs in the soil-water-sediment system depends on the various chemical species that can arise. Long-term biological impacts are strongly influenced by mobilization-immobilization processes in the aquatic environment. These can be studied through sequential extraction procedures modelling their pathways. In Europe the simplified extraction scheme proposed by BCR in 1993 and modified in 2001 is mostly used for this purpose. By this approach samples are gradually decomposed and four different fractions of PTEs can be identified, i.e.: i) water-soluble and carbonate-bound fraction; ii) fraction associated with reducible Fe- and Mn-oxides; iii) organic complexed fraction and sulphides; iv) fraction soluble in oxidative acids. The sediment-based Certified Reference Material (CRM) BCR 701 was produced to check the accuracy of the fractionation procedure. The standardization process was hindered by methodological problems, i.e.: i) the solvents used in the BCR system do not mirror completely the natural mobilization processes and partly modify the original chemical species; ii) the time demand of the batch leaching extraction steps is exceedingly long (4–5days); iii) the above CRM, certified for the fractionation of Cu, Cd, Cr, Ni, Pb and Zn, is available only for sediment and cannot be applied to other environmental matrices and other PTEs. The studies aimed at improving the BCR methodology are summarized, in particular to: i) develop continuous flow systems; ii) accelerate the BCR leaching steps by sonication; iii) extend the BCR procedure to other environmental matrices (soils, red mud, composts, biofilms) and further PTEs by multielemental (ICP-OES) detection.In second part of the paper a case study is presented for evaluation of long-term changes of the environmental mobility of PTE contaminations in the fish pond system of Gödöllő town. For vertical and horizontal mapping of PTE content of accumulated sediment layers core samples were taken in 1994, 1995 and 2013. In the sediment layers total soluble PTE content was related to the BCR fractionation. The Chernobyl origine radionuclides were detected by γ-spectroscopy. The BCR sequential extraction procedure for tracking the long-term fate of PTE contamination of different origine in surface water/sediment/systems showed a much potential. By repetition of fractionation of PTEs after 20years clearly reflects the change of PTE concentrations in different fractions. The decrease of PTE concentrations can be explained by leaching the most mobile fractions by water exchange over the sediment and/or by remediation activity.

Velocity and ion charge in a copper plasma plume ejected from 5 microsecond vacuum arcs

The charge state and velocity of ions extracted from the expanding plasma of 5 μs vacuum arc were measured using a Time of Flight mass spectrometer. The arc was sustained between the cylindrical copper cathode of 1 mm diameter and Kovar cylindrical anode. The distance between the two electrodes is 0.1 mm. The ion charge state and velocity were detected after the arc pulse at different times (in range 20–45 μs) by opening an electronic shutter. The arc current was 35 A. It was obtained that the ion velocities are decreasing with detection times from 3.75 to 1.75 cm/μs. The fastest ions are made of a large fraction of Cu+3 with some Cu+2 while the slowest ions are made of a larger fraction of Cu+2 with some Cu+.

Fractionation and Speciation of Cu in Different Processing Apricots

An analytical procedure was proposed to study the operational fraction of Cu in ripe-fresh, sun-dried and sulphited-dried apricots harvested from either treated Bordeaux mixture or unexposed trees. Based on the methods that consists pressurized liquid extraction procedure and solid phase extraction to separate diverse Cu fractions on different sorbents such as Dowex 50Wx8-40 and Amberlite XAD-7, and then flame atomic absorption spectrometry (FAAS) and ion selective electrode were used for off-line determination of Cu concentrations in the effluents obtained.Total copper concentrations in different processing the apricot samples exposed to Bordeaux mixture were 4.58, 4.48 and 4.25 μg/g in ripe fresh, sun-dried, sulphuring-sun drying, respectively. However, Cu concentrations in the organic apricot samples were determined 2.92; 2.97 and 2.25 μg/g. While circa 40-59% of total copper are extractable with water solvent including about 67-68% cationic copper, 25-33% organically bound copper and 26- 44% labile in Kabaasi apricot samples. Besides, while about 27-48% of total copper are extractable with methanol: water solvents containing about 40-23% cationic copper, 60-78% organically bound copper and 56-71% of copper was absorbed in the stomach.It was applied to analytical procedures for Cu speciation in the apricot samples were verified and validated.