Differences In Cu Research Articles

Portable XRF and wet materials: application to dredged contaminated sediments from waterways

The sustainable management of dredged waterway sediments requires on-site determination of the main pollutants to facilitate their safe reuse or treatment. Portable X-ray fluorescence (pXRF) is commonly used for similar applications with contaminated soil, but the high water content of dredged sediments precludes any application of standard methods. Measurements for Pb, Zn, Cu and As were performed on-site on raw wet sediments with 50 to 70 % water contents during dredging or mapping operations. These results, although two or three times lower than laboratory analyses on the same samples, were found to be related to absolute concentrations closely enough to rank samples. In order to investigate further the feasibility of field analyses on wet sediments, partial dehydration methods were tested. The most efficient technique is based on a hand press. It is simple and quick enough to be used on dredging boats during operations and produces sample pellets with 30 to 50 % water contents. The relationship between pXRF measurements on these pellets and laboratory analyses was found to be sufficiently linear to calculate estimated concentrations. Potential differences were found to be less than 20 % for Pb and Zn. Higher differences for Cu were due to very low concentrations, within twice the limit of detection (LOD). Some limitations were observed. The water content in pellets is variable depending on the sediment type or matrix. The correction factors vary between the measured elements and they may also vary with matrix chemistry. However, Pb-Zn-Cu-As concentrations were ranked and evaluated accurately and the geochemical signatures of the samples were preserved. We demonstrated that, with a simple partial dehydration procedure, pXRF measurements can be reliably related closely enough to absolute concentrations to make field decisions for sediment management. Since the approximately linear relationships between measurements on semi-wet samples and laboratory analyses are matrix- and site-dependent, they must be recognised before using pXRF on wet samples for decision-making.

Accumulation of heavy metals in agricultural soils of Mediterranean: Insights from Argolida basin, Peloponnese, Greece

Excessive application of chemical products for promoting crop growth is a significant contributor for elevated concentrations of heavy metals in agricultural soils potentially threatening human health through the food chain. In this study, a series of heavy metals were quantified in 132 agricultural soils of Argolida basin, Peloponnese, Greece, with the aim to characterize their accumulation patterns. Median concentrations of Cu, Pb, Zn, Ni, Co, Mn, As, Cd, Cr and Fe were 65.23, 20.1, 72.75, 120.3, 20.6, 956.5, 7.1, 0.45, 72.3 and 27,100mg/kg respectively. Statistically significant differences for Cu, Zn, Pb and Cd content were found between agricultural and background soils in the same region. Implementation of principal component analysis and cluster analysis successfully grouped the investigated chemical elements according to their anthropogenic or natural origin. The prolonged application of large amounts of fertilizers and pesticides–fungicides has resulted to Cu, Zn, Cd, Pb and As accumulation in the agricultural fields whereas Ni, Cr, Co and Fe amounts are controlled by parent material influences. Contrary to results commonly reported in the literature that characterize Mn as a geogenic element, this metal was found to exhibit a mixed source in the study agricultural system. Geographical information system techniques were used to illustrate the spatial distribution trends of the investigated elements confirming the clear contribution of agrochemicals to soil chemistry and highlighting the citrus soils around Argos town to have received large anthropogenic inputs. The agricultural area represented by olive groves does not demonstrate significant anthropogenic soil metal enrichment indicating that accumulation phenomena are restricted to the soils cultivated for oranges and mandarins. This study is the first detailed report on metal accumulation in citrus soils from Argolida basin, and results promote the care for the environment by reducing application rates of fertilizers and pesticides–fungicides and monitoring heavy metals levels in receiving soils. Future studies should pay attention to characterize the fractionation and reactivity of metals in citrus soils by utilizing selective chemical extractions with the aim to assess the actual risks for the environment.

Copper Redox Transformation and Complexation by Reduced and Oxidized Soil Humic Acid. 2. Potentiometric Titrations and Dialysis Cell Experiments

Cation binding and electron transfer reactions of humic substances determine copper speciation in redox-dynamic systems, but quantitative studies for Cu+ binding to humic substances are lacking. We investigated reduction of Cu2+ and binding of Cu+ at pH 7.0 in a dialysis cell experiment using reduced and reoxidized soil humic acid (HA) as reductant and sorbent at copper loadings of 9.5-600 mmol kg(-1). The data were used to quantitatively explain the interaction between cation binding and electron transfer processes that determine copper speciation in the presence of HA under anoxic and oxic conditions. Addition of Cu2+ to reduced HA resulted in almost complete reduction to Cu(I) within 1 h. Reduction was also significant under oxic conditions. The slow decrease of the Cu(I) fraction was attributed to formation of Cu(0) based on thermodynamic consideration. Cu+ binding to HA was found to be strong compared to other chalcophile cations like Ag+ or Cd2+. Our results indicate that Cu+ and Cu2+ isotherms exhibit a redox potential-dependent intersection point. According to the differences in Cu+ and Cu2+ binding, the presence of HA was found to extend the stability field of Cu(II) to moderately reducing conditions and to reduce the stability field of Cu(0) due to the formation of Cu(I) complexes.

Trace element, oxidant, and antioxidant enzyme values in blood of children with refractory epilepsy

Purpose: The aim of this study is to evaluate the serum levels of some trace elements, oxidants, and antioxidants in children with intractable epilepsy compared to healthy children. Patients and Methods: In a case–control study, 40 children (24 males and 16 females) suffering from refractory generalized epileptic seizures were compared with 40 sex- and age-matched healthy children serve as a control group. Serum selenium (Se), zinc (Zn), copper (Cu), and plasma malondialdehyde (MDA) as well as erythrocyte glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) values were measured in the patients and controls. Results: Plasma MDA values of the patient group were significantly ( p < 0.001) higher than those in control. Serum Zn, Se, and erythrocyte GSH-Px values of the patient group are significantly ( p < 0.001) lower than those in control, although there is no statistical difference in Cu and SOD values. Conclusion: Plasma MDA, erythrocyte GSH-Px, and trace elements Zn and Se may play an important role in the pathogenesis of intractable epilepsy in children.

Parity-related changes in body weight may influence the zinc and copper status of urban pregnant women: A report from south eastern Nigeria

Background: Micronutrient replacement is done indiscriminately, without recourse to peculiar socioeconomic and sociodemographic variables. Particularly, the relationship between parity, body weight, and some micronutrients has received minimal attention in Nigeria. Aim: To determine the relationship between parity, body weight, and some micronutrients during pregnancy. Subjects and Methods: This is a cross-sectional study involving 130 pregnant women and 30 nonpregnant control. They were recruited from two health care facilities in Nigeria and grouped into nulliparous and multiparous. After a 24-h dietary recall, the weight (W) and height (H) were measured. The body mass index (BMI) (W in kg/H in m 2 ) was calculated. Serum copper and zinc were estimated using flame atomic absorption spectrophotometer. Results: Multiparous nonpregnant subjects parity=3.0 (0.58) had higher weight ( P =0.037) and BMI ( P =0.035) than their nulliparous counterparts (parity=0). In addition, there were no significant difference in Cu and zinc levels between the two groups ( P =0.243 and 0.402, respectively). Expectedly, weight and BMI increased as pregnancy progressed. There was no significant difference in Cu levels between the three trimesters in the nulliparous pregnant and multiparous pregnant subjects. In the pregnant nulliparous subjects, the Zn levels of the 2 nd and 3 rd trimesters were significantly lower than that of the nonpregnant nulliparous subjects ( P rd trimester Zn level was significantly lower than that of the nonpregnant controls ( P =0.017). Conclusion: Pregnancy weight gain is more pronounced in multiparous than nulliparous women. This parity-related pattern only affects the serum zinc levels, a situation that should be taken into consideration when formulating policies for nutritional replacement.

Forage enrichment with copper and zinc in beef grazing systems in Argentina

The presence of trace elements in water and soils, their absorption by plants, and their transfer to the food chain, is a phenomenon that has been studied in different regions around the world. In Argentina, few studies exist regarding trace element content in soils, and the studies on forages are furthermore scarce. The interest to quantify the levels of trace elements in cattle forage lies in the intrinsic connection between the quality of forage and the nutritional (i.e. Cu and Zn) aspects of cattle health and products for human consumption. Feed lots use feed, which incorporates core minerals whose basic components are Fe, Se, I, Mn, Co, Cu, and Zn. The excess of these trace elements are eliminated through the feces into the environment, therefore, the use of manure from these systems, as a source of organic fertilizer, could reduce environmental contamination, and supplement soils, in areas which are naturally deficient in these micronutrients, for forage growth intended for livestock consumption. Soils from different areas in Argentina were characterized, mainly for their Cu and Zn content. Soil–plant transfer of these trace elements to natural forage was analyzed for agricultural soils with higher content of micronutrients. On the other hand, pot experiments were performed for the enrichment of the forage species, Lolium perenne (ryegrass), with Cu and Zn through fertilization with bovine feces spiked with known concentrations of these trace elements. Soils from copper‐deficient areas used for livestock breeding were used in these experiments. Differences in Cu and Zn concentrations were observed between the fertilized and non-fertilized reactors, while there were no differences found in the Cu and Zn concentrations considering the method of fertilization (homogenization or superficial). These results show that manure from feed lots may be used for forage enrichment with micronutrients.

Provenance of the gold of the Early Bronze Age Nebra Sky Disk, central Germany: geochemical characterization of natural gold from Cornwall

The Early Bronze Age Nebra Sky Disk, central Germany, comprises different types of gold inlays which have been plated and punched onto a bronze disk in three phases. The present study aims at provenancing the gold, used for the first phase, which includes gold sheets in the shape of a sun or full moon, a crescent-shaped moon, and 32 stars. The geochemical composition, determined by LA-ICP-MS, of one fragment of the sun sheet is compared with 66 native gold particles from six placer deposits and one lode gold deposit in Cornwall. The focus on Cornish gold deposits is based on results of previous provenance and tin isotope studies. The geochemical survey is performed using distinctive geochemical tracers ( e.g., Co, Ni, Cu, Ru, Pd, Ag, Sn, Sb, Ir, and Pt) which are characterized by high stability during geological and metallurgical processes. For Cornwall, the Carnon gold placers at the localities Devoran and Feock show different variations in Co, Ni, Pd, Ag, Sn, and Sb which correlate with the variation found in the gold from the sun sheet when mixed. This mixture would have been easily possible as both localities are located about three km apart from each other. Similar geochemical comparisons with natural gold from central and southeastern Europe, carried out in a previous provenance study, showed no similarity with the sun sheet. Differences in Cu and Pt contents between the Carnon gold placers and the sun sheet, which have also been detected for the previously studied gold deposits, question the relevance of mineral (micro) inclusions and accretions or unintended contamination with heavy minerals during processing. The results on the gold further led to the comparison of 18 Cornish copper ores with the bronze of the Nebra hoard using lead isotope ratios, which showed no correlation, excluding Cornwall as copper source. With the gold of the first phase of the Nebra Sky Disk being likely to originate from Cornwall, substantial metal trade from the British Isles towards central Germany during the Early Bronze Age must be assumed.

Heavy-Metal Concentrations in Soft Tissues of the Burrowing Crab Neohelice granulata in Bahía Blanca Estuary, Argentina

Copper (Cu), cadmium (Cd), and chromium (Cr) in soft tissues of male and female burrowing crab Neohelice granulate, as well as their eggs, were measured in two different locations in the Bahía Blanca estuary, a moderately polluted ecosystem, from October 2008 to August 2009. Differences between sexes, sites, and seasonality were assessed. Furthermore, metal levels in eggs were compared with metal levels in female crabs. The results showed no significant differences for Cu and Cd between sexes (Student t test p > 0.25 for both sites) and sites (two-way analysis of variance: Cu p = 0.82 and Cd p = 0.29). Nevertheless, seasonality was found, with winter having significantly lower concentrations for both metals. The range of Cu concentrations was between 96.92 and 152.18 μg g(-1) dry weight (dw), and the range of Cd concentrations was between 6.09 and 10.41 μg g(-1) dw. Cr concentrations could not be assessed because most of the values were lower than the detection limit. Although heavy metals in sediments were not measured in this study, a bioaccumulation process may be occurring for Cd because levels found during the entire sampling period were greater than levels in sediment from previous years. For Cu, a regulation process may be occurring considering that this is an essential metal and levels of Cu in N. granulata found in this study were between 1 and 2 orders of magnitude greater than levels in sediments. Finally, Cu and Cd levels in eggs were detectable, but they were lower than levels in female crabs. The importance of these findings is linked to the fact that metal accumulation seems to be occurring before hatch. The presence of heavy metals in soft tissues as well as in eggs of N. granulata is of great importance considering that this is a key species within the Bahía Blanca estuary; therefore, it plays a major role in the transference of pollutants to greater trophic levels.

Direct and simultaneous determination of Co and Cu on a silicon wafer using a chemiluminescence system

In this work, we developed a drop-type chemiluminescence (CL) system with a partial least squares (PLS) calibration in which the coaxial optical fiber sensing head was developed for sampling and detection to determine Cu(2+) and Co(2+) on a silicon wafer directly. The use of time-resolved signal generation and PLS calibration in addition to CL allowed us to determine the metal ions simultaneously and selectively, based on the kinetic difference of Cu and Co ions in the luminol-H(2)O(2) system. Two component mixtures with a set of 15 wafer fragments were orthogonally calibrated. After prediction test, the method was applied to an intentionally contaminated silicon wafer and validated by inductively coupled plasma-mass spectrometer (ICP-MS) measurement with a HF-HNO(3) scanning solution. The average concentrations of Cu(2+) and Co(2+) of 3.45 (±0.95) × 10(13) and 2.30 (±1.18) × 10(11) atoms per cm(2), respectively, were obtained, which were very close to the ICP-MS results of 3.70 × 10(13) for Cu(2+) and 2.46 × 10(11) atoms per cm(2) for Co(2+). In conclusion, this drop mode CL showed almost more than 10 times better reproducibility than the typical batch mode for the profile measurement. Moreover, the adoption of PLS calibration added the function of selectivity for the simultaneous determination to this CL system, in addition to the direct mapping capability for the solid surface analysis.

Influence of natural organic matter (NOM) quality on Cu–gill binding in the rainbow trout ( Oncorhynchus mykiss)

Natural organic matter (NOM) in aquatic environments reduces metal toxicity to fish by forming metal–NOM complexes, which reduce metal bioavailability, metal–gill binding and toxicity. However, differences in the chemical composition of different types of NOM (quality) could also affect metal–NOM binding and toxicity. We predicted that Cu–gill binding would vary in trout exposed to Cu in the presence of NOM of different qualities. NOM was collected from three sources: Luther Marsh (terrigenous ∼ allochthonous), Bannister Lake (nominally autochthonous), and from a local sewage treatment plant (designated Preston effluent). Excitation–emission matrix spectroscopy (EEMS) revealed that terrigenous Luther Marsh NOM was primarily humic acid-like material (74%), whereas Bannister Lake and Preston sewage effluent NOM had lower humic acid-like material but greater fulvic acid-like material (30% and 50%, respectively). The specific absorption coefficient (SAC) of Luther Marsh NOM was also much higher (SAC = 37.8), consistent with its darker color, compared to more autochthonous, lightly coloured Bannister Lake (SAC = 12.4) NOM, and Preston effluent NOM (SAC = 9.2). At low-moderate waterborne Cu (0–2,000 nmol L −1), all NOM isolates reduced Cu–gill accumulation by 70–90%. Surprisingly, there were no measurable differences in Cu–gill binding amongst the three NOM treatments when fish were exposed to Cu in the low-moderate range. Only at higher Cu (>2,000 nmol L −1) were differences observed, where terrigenous Luther Marsh and Preston effluent NOM reduced Cu–gill binding by 40–50% more than the more autochthonous Bannister Lake NOM. Although Cu–gill binding estimates using the HydroQual BLM showed similar trends, the BLM consistently underestimated Cu–gill binding. We conclude that differences in Cu toxicity at lower-moderate Cu concentrations in the presence of different types of NOM are not necessarily related to measurable differences in Cu–gill accumulation. Rather, we suggest that differences in Cu toxicity reported in the presence of different types of NOM might be explained by direct actions of NOM on the gills, which are quality dependent.

Simultaneous quantification of dissolved organic carbon fractions and copper complexation using solid-phase extraction

Abstract Trace metal cycling in natural waters is highly influenced by the amount and type of dissolved organic C (DOC). Although determining individual species of DOC is unrealistic, there has been success in classifying DOC by determining operationally defined fractions. However, current fractionation schemes do not allow for the simultaneous quantification of associated trace metals. Using operational classifications, a scheme was developed to fractionate DOC based on a set of seven solid-phase extraction (SPE) cartridges. The cartridges isolated fractions based on a range of specific mechanisms thought to be responsible for DOC aggregation in solution, as well as molecular weight. The method was evaluated to determine if it can identify differences in DOC characteristics, including differences in Cu–DOC complexation. Results are that: (1) cartridge blanks were low for both DOC and Cu, (2) differences are observed in the distribution of DOC amongst the fractions from various sources that are consistent with what is known about the DOC materials and the mechanisms operative for each cartridge, (3) when present as a free cation, Cu was not retained by non-cationic cartridges allowing the method to be used to assess Cu binding, (4) the capability of the method to provide quantitative assessment of Cu–DOC complexation was demonstrated for a variety of DOC standards, (5) Cu was found to preferentially bind with high molecular weight fractions of DOC, and (6) estimated partitioning coefficients and conditional binding constants for Cu were similar to those reported elsewhere. The method developed describes DOC characteristics based on specific bonding mechanisms (hydrogen, donor–acceptor, London dispersion, and ionic bonding) while simultaneously quantifying Cu–DOC complexation. The method provides researchers a means of describing not only the extent of DOC complexation but also how that complex will be behave in natural waters.

Effect of copper- and zinc-methionine supplementation on bioavailability, mineral status and tissue concentrations of copper and zinc in ewes

The effect of feeding Cu- and Zn-methionine to ewes was studied in a 240d feeding trial. The plasma and tissue Cu and Zn concentrations and Cu/Zn-superoxide dismutase (Cu/Zn-SOD) activity were employed to assess the relative bioavailability from Cu- and Zn-methionine. The macro and micronutrient intake, utilization, plasma mineral status, tissue accumulation of Cu and Zn as well as wool concentration of Cu and Zn were studied in ewes ( n=12) fed a corn-soybean meal based basal diet with 50% more Cu and Zn supplementation over the basal diet either from Cu- and Zn-sulfate (Cu-Sulf+Zn-Sulf group) or Cu- and Zn-methionine (Cu-Meth+Zn-Meth group). The average daily feed intake and body weight gain of ewes did not differ due to dietary supplementation of Cu- and Zn-methionine. However, dry matter intake was comparatively lower and thus resulted in better feed: gain in Cu- and Zn-methionine group as compared to ewes fed Cu- and Zn-sulfate. Supplementation of Cu and Zn over the basal diet either from methionine-chelated or sulfate sources resulted in increased plasma Cu and Zn as well as Cu/Zn-SOD activity on d-30, which indicated a positive correlation between plasma Cu and Zn and Cu/Zn-SOD activity. The gut absorption, liver concentrations of Cu and Zn, and liver Cu/Zn-SOD activity were significantly ( P<0.01) higher in ewes supplemented with Cu- and Zn-methionine compared to Cu- and Zn-sulfate. Periodical analysis of wool samples indicated no significant difference in Cu and Zn content between Cu-and Zn-methionine and Cu- and Zn-sulfate groups. Feeding of Cu and Zn from methionine-chelated source resulted in reduced ( P<0.01) excretion of Cu and Zn in feces indicating their better utilization, and this will have positive implication on environment. The gut absorption values, plasma and liver tissue concentrations of Cu and Zn supported the hypothesis that Cu- and Zn-methionine supplements have better bioavailability compared to Cu- and Zn-sulfate and Cu- and Zn-dependent enzyme (Cu/Zn-SOD) could be used to determine the bioavailability of Cu and Zn.

Surface chemical mechanisms of inadvertent recovery of chromite in UG2 ore flotation: Residual layer identification using statistical ToF-SIMS analysis

In the UG2 ore (Bushveld Complex, South Africa) flotation, normally more than 3% of the gangue minerals, principally chromite with talc and pyroxene, report to the concentrate diluting the PGM recovery and contributing to subsequent processing costs. Previous studies have identified residual talc-like layers on orthopyroxene surfaces in Merensky ore flotation contributing to inadvertent flotation of relatively large particles (20–150 µm) of this mineral. Chromite (75–150 µm) from flotation of UG2 ore has been similarly examined. Statistical comparison of ToF-SIMS analysis of particles from concentrate and tails reveals no significant difference in Cu, Pb, Ni and collector (IBX and DTP) signals between these streams but surface exposure of Mg and Si is favoured in the concentrate. The flotation rate of coarse chromite correlates with the exposures of magnesium and silicon in patches on the chromite surface; higher exposures give earlier flotation. Conversely, there is a negative correlation with signals corresponding to the chromite surface, i.e. Cr, Fe, Al. Flotation of chromite without collector has confirmed this statistical discrimination. Hydrophobic talc-like residual layers, similar to those found on orthopyroxene surfaces, probably from partial alteration, explain this flotation mechanism.

Collectorless flotation of pyroxene in Merensky ore: Residual layer identification using statistical ToF-SIMS analysis

In Merensky (Bushveld Complex, South Africa) ore flotation, normally more than 2% of the gangue minerals, principally pyroxene with minor chromite, reports to the concentrate diluting the PGM recovery and contributing to subsequent processing costs. Understanding and controlling the mechanisms that cause this misreporting remains a primary target in PGM flotation. The orthopyroxene in Merensky ore can develop floatable properties through chemical interactions in the flotation system, principally through inadvertent copper-collector complexation, but this paper shows that this mechanism does not fully account for the true flotation of large pyroxene (20–150 µm) particles. Statistical comparison of ToF-SIMS analysis of particles from concentrate and tails reveals no significant difference in Cu and collector (IBX, DTP) signals between these streams but surface exposure of Mg and Si is favoured in the concentrate. Flotation of pyroxene without collector has confirmed this statistical discrimination. Hydrophobic talc-like residual layers, probably from partial serpentinisation of the pyroxene, seen in XRD differences between the concentrate and tails, explain this flotation mechanism.

Heavy Element Abundances in Giant Stars of the Globular Clusters M4 and M5

We present a comprehensive abundance analysis of 27 heavy elements in bright giant stars of the globular clusters M4 and M5 based on high-resolution, high signal-to-noise ratio spectra obtained with the Magellan Clay Telescope. We confirm and expand on previous results for these clusters by showing that (1) all elements heavier than, and including, Si have constant abundances within each cluster, (2) the elements from Ca to Ni have indistinguishable compositions in M4 and M5, (3) Si, Cu, Zn, and all s-process elements are approximately 0.3 dex overabundant in M4 relative to M5, and (4) the r-process elements Sm, Eu, Gd, and Th are slightly overabundant in M5 relative to M4. The cluster-to-cluster abundance differences for Cu and Zn are intriguing, especially in light of their uncertain nucleosynthetic origins. We confirm that stars other than Type Ia supernovae must produce significant amounts of Cu and Zn at or below the clusters' metallicities. If intermediate-mass AGB stars or massive stars are responsible for the Cu and Zn enhancements in M4, the similar [Rb/Zr] ratios and (preliminary) Mg isotope ratios in both clusters may be problematic for either scenario. For the elements from Ba to Hf, we assume that the s- and r-process contributions are scaled versions of the solar s- and r-process abundances. We quantify the relative fractions of s- and r-process material for each cluster and show that they provide an excellent fit to the observed abundances.

Uptake of heavy metal ions from aqueous solution using Mg–Al layered double hydroxides intercalated with citrate, malate, and tartrate

Mg–Al layered double hydroxide (Mg–Al LDH) was modified with organic acid anions using a coprecipitation technique, and the uptake of heavy metal ions from aqueous solution by the Mg–Al LDH was studied. Citrate·Mg–Al LDH, malate·Mg–Al LDH, or tartrate·Mg–Al LDH, which had citrate 3− (C 6H 5O 7 3−), malate 2− (C 4H 4O 5 2−), or tartrate 2− (C 4H 4O 6 2−) anions intercalated in the interlayer, was prepared by dropwise addition of a mixed aqueous solution of Mg(NO 3) 2 and Al(NO 3) 3 to a citrate, malate, or tartrate solution at a constant pH of 10.5. These Mg–Al LDHs were found to take up Cu 2+ and Cd 2+ rapidly from an aqueous solution at a constant pH of 5.0. This capacity was mainly attributable to the formation of the citrate–metal, malate–metal, and tartrate–metal complexes in the interlayers of the Mg–Al LDHs. The uptake of Cu 2+ increased in the order malate·Mg–Al LDH < tartrate·Mg–Al LDH < citrate·Mg–Al LDH. The uptake of Cd 2+ increased in the order malate·Mg–Al LDH < tartrate·Mg–Al LDH = citrate·Mg–Al LDH. These differences in Cu 2+ and Cd 2+ uptake were attributable to differences in the stabilities of the citrate–metal, malate–metal, and tartrate–metal complexes. These results indicate that citrate 3−, malate 2−, and tartrate 2− were adequately active as chelating agents in the interlayers of Mg–Al LDHs.

Trace mineral status and liver and blood parameters in sheep without mineral supply compared to local roe deer ( Capreolus capreolus) populations

General health, clinical-chemical blood analysis and copper (Cu), zinc (Zn), selenium (Se) and vitamin E concentrations in plasma and liver tissue (wet weight, ww) of two extensive grazing sheep flocks without mineral supply were compared to the status of local roe deer ( Capreolus capreolus) populations (liver samples). Both sheep flocks were classified as healthy except for a remarkable variation in body weight and a slight foot rot infection in one flock. Hematology of sheep was normal, and total protein and creatinine as well as activities of creatin kinase, aspartat-amino-transferase, alkaline phosphatase and gamma-glutamyl-transferase in plasma were within reference levels. The mean of glutamate dehydrogenase (13.8 U/l) was slightly elevated in one flock. Mean liver concentrations of Zn (38.9 and 43.5 mg/kg ww) and Cu (111 and 87.5 mg/kg ww) in sheep flocks were higher compared to the respective roe deer populations (27.5 and 36.3 mg Zn/kg ww; 18.3 and 28.6 mg Cu/kg ww). This is supposed to be caused by differences in Cu and Zn metabolism in sheep and roe deer. Selenium deficiency was diagnosed in liver samples of both sheep flocks (0.21 and 0.23 mg/kg ww). There were neither significant differences compared to roe deer (0.21 and 0.27 mg Se/kg ww) nor differences depending on location. Correlations between plasma and liver concentrations of Cu, Zn and Se were not significant in sheep. Means of vitamin E in liver samples (30.6 and 41.8 mg/kg ww) were higher in roe deer populations. This may be caused by the opportunity of selective browsing for wild ruminants, which allows access to younger plants which are higher in vitamin E.

Structural Investigations of Silica Polyamine Composites: Surface Coverage, Metal Ion Coordination, and Ligand Modification

Silanization of the silica gel surface in the synthesis of silica gel polyamine composites uses (chloropropyl)trichlorosilane (CPTCS). It is possible to substitute a molar fraction of reagent CPTCS with methyltrichlorosilane (MTCS), creating a mixed silane surface layer. Two types of silica gels were modified with a series of MTCS:CPTCS molar ratios. Solid-state CP/MAS 29Si and 13C NMR spectroscopies were used to evaluate the surface silane composition. Surface silane coverage was markedly improved for the resulting gels. When polyamines were grafted to the resultant MTCS:CPTCS silane layers, it was shown that the decrease in the number of propyl attachments to the polyamine resulted in increased quantities of “free amines”. Optimum MTCS:CPTCS ratios were determined for three polyamines grafted onto one silica gel. A substantial free amine increase was observed for poly(allylamine) (PAA). Metal uptake studies show increases in Cu(II) capacity and/or an improvement in Cu(II) mass-transfer kinetics. The effect of polymer molecular weight upon Cu(II) capacity was investigated for each polyamine. Substantial differences in Cu(II) capacity between 50 000 MW poly(vinylamine) (PVA) and >1000 MW PVA were evident. Similar differences between 25 000 MW poly(ethyleneimine) (PEI) and 1200 MW PEI were found. The mass-transfer kinetics was shown to be improved for composites prepared using a large fraction of MTCS in the reagent silane mixture. This resulted in substantial improvements in the 10% breakthrough Cu(II) capacity for PVA (50 000 MW). PEI composites were further modified to form an amino−acetate ligand. The impact of the MTCS:CPTCS silane ratio on the acetate ligand loading and ultimately on the Cu(II) capacity at pH = 2 was investigated. A ratio of 12.5:1 was shown to result in an acetate modified PEI composite with a Cu(II) capacity 140% of the Cu(II) capacity of the same composite prepared with “CPTCS only”.

Gender and genetic background effects on brain metal levels in APP transgenic and normal mice: Implications for Alzheimer β-amyloid pathology

The incidence of Alzheimer’s disease (AD) is greater in women than men at any age, as is the development of amyloid pathology in several transgenic mouse models of AD. Due to the involvement of metals in AD pathogenesis, variations between the sexes in metal metabolism may contribute to the sex difference in AD risk. In this study, we investigated sex differences in brain metal levels across the lifespan in mice of two different background strains, as well as in mice overexpressing the human amyloid precursor protein (APP) and amyloid-β protein (Aβ). We demonstrate consistently lower Cu and higher Mn levels in females compared with males at any age studied. The sex differences in Cu and Mn levels are independent of APP/Aβ expression. AD brain exhibits decreased Cu and increased Mn levels, as do transgenic mice overexpressing APP or Aβ. The age-dependent elevations of Cu, Fe and Co levels were found to be significantly greater in mice of B6/SJL background compared with B6/DBA. If depleting Cu and/or rising Mn levels contribute to AD pathogenesis, natural sex differences in these brain metal levels may contribute to the increased propensity of females to develop AD.

Mutants of Saccharomyces cerevisiae defective in vacuolar function confirm a role for the vacuole in toxic metal ion detoxification.

To directly define vacuolar role(s) in metal detoxification, we have examined the responses of vacuole-deficient mutants of Saccharomyces cerevisiae to several potentially toxic metals known to be mainly detoxified in the cytosol (Cu, Cd) or the vacuole (Co, Mn, Ni, Zn). Three mutants, deficient in targeting of vacuolar proteins, were used with JSR18 delta 1 being devoid of any vacuole-like structure while ScVatB and ScVatC were deficient in specific protein subunits of the V-ATPase. The results obtained show that the absence of a vacuole or a functional vacuolar H(+)-ATPase was associated with increased sensitivity and a largely decreased capacity of the vacuole-deficient strains to accumulate Zn, Mn, Co and Ni, confirming an essential role for the vacuole in detoxification of these metals. In addition, the lack of vacuolar involvement in detoxification of Cu and Cd was confirmed since these metals did not exhibit increased toxicity towards the vacuolar mutants nor were there significant differences in Cu or Cd accumulation between parental and mutant strains.