Copper Isotope Ratios Research Articles

Copper isotope ratios in serum do not track cancerous tumor evolution, but organ failure.

Relative to healthy controls, lighter copper isotopic compositions have been observed in the serum of breast cancer and end-stage liver disease patients, raising the possibility that Cu isotope ratios could be used as a tracer for disease progression. Here, we assess the potential of natural Cu isotopic variations (expressed as δ65Cu) as diagnostic tools for cancer progression and/or liver failure by performing a first-order analysis of Cu isotopic cycling in the human body. Using a box model, we simulate the kinetics of Cu mass transfer throughout significant reservoirs in the body, allowing isotopic fractionation to occur during Cu uptake/release from these reservoirs. With this model, we determine under which conditions the serum δ65Cu values would reflect perturbation related to cancer growth and/or liver failure at a level resolvable with modern mass spectrometry. We find that tumor growth alone is unable to explain the light isotopic signature observed in serum. Instead, we find that metabolic changes to the liver function resulting in a ∼1‰ isotope fractionation during Cu uptake from the blood into the liver can readily explain the long-term serum isotopic shift of ∼0.2‰ observed in cancer patients. A similar fractionation (∼1.3‰) during Cu uptake into the liver also readily explains the -1.2‰ shift observed in the serum of cirrhosis patients with ascites, suggesting a potentially common driver of isotopic fractionation in both cases. Using this model, we then test hypotheses put forward by previous studies and begin to probe the mechanisms behind the measured isotopic compositions.

Investigation of metasomatism using Cu, Zn and Fe stable isotopes: Rodingitization of mafic and ultramafic rocks in ophiolites from northern Greece

Rodingites, a high-Ca content variety of metasomatic rocks, have been found in the Veria-Naousa and Edessa ophiolites, in northern Greece. The rodingites from both areas are characterized by a substantial overprint of primary textures. Coupled field and petrographic observations reveal derivation from ultramafic and mafic protoliths. The mineral phases in the ultramafic-derived rodingites (UDR) include mainly diopside, garnet, chlorite, tremolite, and FeTi oxides whereas mafic-derived rodingites (MDR) contain diopside, garnet, vesuvianite, chlorite and quartz. Here we present, for the first time, whole rock Cu, Zn and Fe isotopic data for the UDR and MDR from the Veria-Naousa and Edessa ophiolites, to investigate the evolution of this peculiar metasomatic lithotype. All the studied rodingites present δ65Cu values varying from −0.17 ± 0.03‰ to +0.62 ± 0.05‰ and δ66Zn ranging from −0.06 ± 0.03‰ to +0.74 ± 0.06‰. 0.0. Copper isotope ratios are systematically heavier in rodingites compared to their respective protoliths whereas Zn shows a diverse behavior with enrichment in its light isotopes (group 1: comprising all the UDR and a MDR sample) or in its heavy isotopes (group 2, the rest MDR samples). The same gabbroic protolith can lead to both group 1 and 2 rodingites with respect to their Zn isotopic ratios. Alkaline conditions of the hydrothermal metasomatic fluids and the inferred sulfide and bisulfide ligands promoted mobility of Cu and Zn and have likely played a major role to their isotopic behavior in the rodingites. In contrast, Fe isotopes have not fractionated during rodingitization. Complex metasomatic processes, such as rodingitization, have a clear impact on stable isotope fractionation, which is decoupled between the Cu, Zn and Fe isotope systems. The lack of correlation between isotope ratios and any mineralogical or elemental indicator highlights the absence of any profound relationship between isotope fractionation and mineral phases, which could reflect the stage and evolution of rodingitization. The consistent isotopic behavior of Cu indicates a promising geochemical tool to distinguish metasomatized and non-metasomatized samples within different observed groups, and define conditions and parameters during Ca-metasomatism, regardless the degree of rodingitization, prior alteration and various protoliths compositions. Additionally, Zn isotopes give a useful insight on the metasomatic conditions for both ultramafic and mafic precursors defining local pH changes coupled with available ligands, HS−, where Cu isotopes alone would not be able to describe.

Copper isotope delta measurements in high purity materials: CCQM-P213 pilot study

Main textAccurate and precise isotope ratio measurements of heavy elements are playing an increasingly important role in modern analytical sciences and have numerous applications. Today, isotope ratio measurements are typically performed with two principal techniques: thermal ionization mass spectrometry (TIMS) and multiple collector-inductively coupled plasma mass spectrometry (MC-ICP-MS). To obtain accurate results by mass spectrometry, isotopic certified reference materials (iCRMs) are needed for mass bias correction and for the validation of the method used for analysis. Thus, it is of paramount importance to achieve measurement comparability of all data reported, and to assess measurement capability of each CRM producer/National Metrology Institute (NMI). Therefore, the international comparison (CCQM-P213) was performed to assess the analytical capabilities of NMIs for the accurate determination of copper isotope ratio delta values in high purity materials. The study was proposed by the coordinating laboratories National Research Council Canada (NRC), National Institute of Standards and Technology (NIST), Bundesanstalt für Materialforschung und -prüfung (BAM) and Physikalisch-Technische Bundesanstalt (PTB) as an activity of the Isotope Ratio Working Group (IRWG) of the Consultative Committee for Amount of Substance - Metrology in Chemistry and Biology (CCQM). Participants included six NMIs and one designated institute (DI) from the six countries. Although no measurement method was prescribed by the coordinating laboratories, MC-ICP-MS with either standard-sample bracketing (SSB) or combined SSB with internal normalization (C-SSBIN) models for mass bias correction were recommended. Results obtained from the six NMIs and one DI were in good agreement.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Determination of the isotopic composition of copper in a certified reference material HICU-1 by MC-ICP-MS using gravimetric isotope mixture calibration

An independent and fully calibrated copper isotope ratio measurement of a high-purity copper certified reference material, HICU-1, was achieved by MC-ICP-MS with use of gravimetric isotope mixture calibration.

Copper isotope ratios allowed for quantifying the contribution of coal mining and combustion to total soil copper concentrations in China

The most prominent source of Cu contamination in soils is metal mining and processing, partly since the Middle Age. However, coal mining and combustion can also cause (some) Cu contamination. We studied the distribution of Cu concentrations and isotope ratios in soils of the Huaibei coal mining area. The contribution of the coal mining and combustion to total Cu concentrations in soil was determined with a two-end-member mixing model based on the distinct δ65Cu values of the Cu emitted from coal mining and combustion and in native soil. The mean Cu concentration of 75 mg kg−1 exceeded the local soil background value (round to 22.13 mg kg−1). The similar δ65Cu value of grass near the coal mining and combustion operation as in gangue and flying ash indicated a superficial Cu contamination. Mining input was the dominant source of Cu in the contaminated soils, contributing up to 95% and on average 72% of the total Cu in the topsoils. The mining-derived Cu was leached to a depth of 65 cm, where still 29% of the Cu could be attributed to the mining emissions. Grasses showed lower δ65Cu values than the topsoils, because of the preferential uptake of light Cu isotopes. However, the Δ65Cugrass-soil was lower in the contaminated than the uncontaminated area because of superficial adsorption of isotopically heavy Cu from the mining emissions. Overall, in this study the distinct δ65Cu values of the mining-derived Cu emissions and the native soil allowed for the quantification of the mining-derived Cu and had already reached the subsoil and contaminated the grass by superficial adsorption in only 60 years of mining operation.

Cu and Ni Isotope Variations of Country Rock-Hosted Massive Sulfides Located Near Midcontinent Rift Intrusions

Abstract Previous Cu isotope work has documented a clear disparity between δ65Cu values of sheet-style (–0.5 to 0.5‰) and conduit-style (0.5–2.0‰) intrusions associated with the Midcontinent rift system. The application of metal isotopes to the study of magmatic Ni-Cu-platinum group element (PGE) deposits is in an early stage, and very little is known regarding isotope distributions and mechanisms of fractionation at high temperatures. In order to resolve the previously mentioned Cu isotope disparity, to determine metal sources for the intrusions, and to assess sources of high-temperature metal isotope fractionation, we have measured Cu and Ni isotope ratios from a suite of exceptionally well characterized Ni-Cu-PGE massive sulfides that occur in sedimentary country rocks near intrusions within the Midcontinent rift system in Michigan and Minnesota. Previous mineralogic and S, Pb, and Os isotope measurements indicate that the massive sulfides are of magmatic origin and provide a framework for the interpretation of the Cu and Ni isotope data in terms of magmatic processes, including assimilation of Proterozoic country rocks. Copper and Ni isotope ratios were determined for massive sulfides as well as local sedimentary sulfides, and these results were compared with available Cu and Ni isotope results of magmatic and sedimentary sulfides in the Midcontinent Rift and elsewhere. Nickel isotope ratios of the sulfides have been modeled in terms of the effects of variable silicate/sulfide ratios, or R-factors (the mass ratio of silicate magma to sulfide magma), crustal contamination, and olivine fractional crystallization. The near-zero and slightly negative δ60Ni values of country rock-hosted magmatic sulfides (–0.45 to 0.17‰) near Tamarack and Eagle can be explained by minor degrees of crustal contamination of a mantle-derived melt at variable R-factors. Igneous-sourced, Cu-poor sulfides from below the Partridge River intrusion generally have lower δ60Ni values (−0.77 to –0.52‰) that require substantially more contamination from a low δ60Ni source, similar to some of the local sedimentary rocks. Copper isotope ratios of country rock-hosted massive sulfides near Eagle and Tamarack are lower than those reported by previous workers and are mostly about 0‰, similar to those expected for unaltered mantle. Tamarack samples require very little crustal contamination to explain their isotope ratios, whereas Eagle samples require no contamination from local sedimentary rocks to explain their Cu isotope compositions. Copper isotope ratios of samples beneath the Partridge River intrusion are similar to those from previous analyses of igneous-hosted sulfides, supporting their origin from a magmatic sulfide liquid. The low δ65Cu values (–1.14 to 0.25‰) from samples below the Partridge River intrusion cannot be explained by contamination from the Virginia and Thomson Formations, which are characterized by mostly positive δ65Cu values (–0.33 to 3.12‰), unless a lighter reservoir remains to be discovered in the local Proterozoic rocks. We suggest these values may have been produced by a combination of incomplete sulfide melting during partial melt generation and fractionation related to sulfide segregation at variable R-factors.

Stable isotope evidence (Fe, Cu) suggests that sex, but not aging is recorded in rhesus macaque (Macaca mulatta) bone.

Here, we examine (1) if the sex-related differences in iron (Fe) and copper (Cu) isotope ratios, represented as δ56 Fe and δ65 Cu values, respectively observed in humans exist in bulk occipital bone and incisors of male and female non-human primates, and (2) if the variation of Fe and Cu isotope ratios, known to vary in human blood as a factor of age are similar in non-human primate bone. Isotope ratios were measured from the skeletal elements of 20 rhesus macaques (Macaca mulatta) with known life history traits. The metals were purified by column chromatography and their isotope ratios measured by MC-ICP-MS. Data were analyzed using generalized additive models (GAM). When accounting for age and sex independently, we found a significant relationship between δ65 Cu values and occipital bone, but not in incisors. There were no significant relationships observed between δ56 Fe values, occipital bone, or incisors. Similarly, there were no significant relationships observed between δ56 Fe values, δ65 Cu values, and age. We suggest that Cu and Fe isotope ratios have the potential to be useful supplementary tools in future research in biological anthropology, but additional studies are needed to further verify the relationship between sex, age, δ65 Cu, and δ56 Fe values in primates.

Copper, Zinc and Lead Isotopic Delta Values and Isotope Ratios of Various Geological and Biological Reference Materials

Copper, Zn and Pb isotope ratios are important tracers for understanding geological and biological processes. We present optimised column separation methods using an anion exchange resin for Cu and Zn, and a Pb‐specific resin for Pb, and provide Cu, Zn and Pb isotope data for thirty‐three commercially available geological and biological reference materials (RMs) using MC‐ICP‐MS. Our measurement procedures can be applied to various environmental samples. The Cu, Zn and Pb yields were higher than 99.2%, and isotopic fractionation did not occur during column separation. Copper and Zn delta values of AGV‐2, BCR‐2, BIR‐1a, BHVO‐2, GSP‐2, NOD‐A‐1, NOD‐P‐1, DOLT‐4, BCR‐414, BCR‐279 and NIST SRM 1573a were in good agreement with previously reported values. The intermediate measurement precision for Cu and Zn delta values was better than ± 0.02‰ (2s). The δ65CuNIST976, δ66ZnJMCand206Pb/207Pb values determined in this study ranged from −0.19 to +0.73‰, −0.96 to +1.00‰ and 1.1172 to 1.2263, respectively. The δ66ZnJMCvariability (Δ66Znmax–min) in this study was relatively larger than that of δ65CuNIST976variability (Δ65Cumax–min). A combination of Cu, Zn and Pb isotopes can be used as potential environmental tracers to track the origins of these elements in the environment as well as to understand their influence on organisms.

Copper Isotope Ratio Measurements of Cu-Dominated Minerals Without Column Chromatography Using MC-ICP-MS.

This study performed a series of comparable experiments (with or without column chromatography) to evaluate whether non-deviated Cu isotope ratios can be obtained directly by Nu Plasma II multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS) using standard-sample bracketing with Ga as internal mass bias correction model (C-SSBIN) without column chromatography. Twelve Cu-dominated minerals (copper plate, native copper, chalcopyrite, bornite, chalcocite, digenite, covellite, tetrahedrite, azurite, malachite, atacamite, and cyanotrichite) displayed little drift in δ65Cu values compared with those of minerals with column chromatography, with Δδ65Cuwithout−with ranging from −0.04 to +0.02‰. This means that Cu isotope ratios in Cu-dominated minerals can be achieved without column chromatography, due to the simple matrix and the stability of the machine by using C-SSBIN mode. The acidity and internal standard concentration mismatch effects, as well as the matrix effect, were strictly assessed by Nu Plasma II MC-ICP-MS in a wet-plasma mode in the State Key Laboratory of Continental Dynamics (SKLCD). Finally, a long-term reproducibility of better than ±0.03‰ [n = 38, 2 standard deviations (2s)] were achieved by repeatedly measuring chalcopyrite without column chromatography over 4 months.

A Triple‐Stack Column Procedure for Rapid Separation of Cu and Zn from Geological Samples

We present a new procedure for the separation and purification of Cu and Zn from geological samples. Our procedure employed a single pass, triple‐stack column set‐up. The first column, filled with TRU resin (TrisKem International), quantitatively removed Fe and Ti from sample matrices. A second column, filled with pre‐filter resin (TrisKem International), removed organic compounds. Finally, a third column, filled with anion exchange resin (AG1‐X8, 200–400 mesh, Bio‐Rad), was used to separate Cu and Zn from the remaining matrix. Our procedure required about 50% less acid volume than previously reported methods for Cu and Zn separation, thereby minimising analytical blanks and column running times. Copper and Zn stable isotope ratios were determined by a Thermo Neptune Plus MC‐ICP‐MS using Zn and Cu external normalisation, respectively, in addition to sample‐standard bracketing to correct for instrumental mass bias. We explore the inter‐calibration of Cu and Zn isotope fractionation coefficients during analysis by measuring mixed Cu–Zn solutions with enhanced mass bias variation generated by varying sample gas flow rates. Our results demonstrate that this procedure is useful when variation in instrumental mass bias throughout analytical sequences is insufficient to inter‐calibrate Cu and Zn fractionation coefficients.

Copper and zinc isotope variation of the VMS mineralization in the Kalatag district, eastern Tianshan, NW China

The copper and zinc isotope ratios of massive sulfide and stockwork ores of Honghai volcanogenic massive sulfide (VMS) deposits in eastern Tianshan Orogen, NW China, were measured by multiple collector-inductively coupled plasma-mass spectrometry (MC-ICP-MS). The overall range of δ65Cu (where δ65Cu = [{(65Cu/63Cu)sample / (65Cu/63Cu)NIST976} − 1] × 1000) values of 16 mineral separates from Honghai deposit varies from −0.28 to 0.70‰, with near-surface massive Zn ores having isotopically heavy values compared to massive Cu ores from deeper levels. This suggests that a kinetic fractionation of copper isotopes could be encouraged during precipitation of chalcopyrite. However, the δ65Cu values of mineral separates from Massive Zn ores in drill hole ZK0302 are considerably higher than those of other mineral separates, which might be associated with the development of secondary mineralization. We also obtained zinc isotope data from 6 sphalerite-bearing samples. The range of δ66Zn (where δ66Zn = [(66Zn/64Zn)sample / (66Zn/64Zn)JMC 3-0749L − 1] × 1000) values varies from 0.05 to 0.17‰, with central parts of mineral separates having isotopically light values (δ66Zn = 0.05‰) compared with that from distal (δ66Zn = 0.12–0.17‰) of VMS system. The results suggest that Cu and Zn isotopes could provide a valuable tool for tracing flow paths toward the center of hydrothermal systems.

Determination of the copper isotope composition of seawater revisited: A case study from the Mediterranean Sea

A new technique for the determination of dissolved copper isotope composition (δ65Cu) of seawater was applied to examine copper sources and internal cycling in the Mediterranean Sea along the GEOTRACES GA04N transect. A succession of chelating resin with nitrilotriacetic acid functional groups and strong base anion exchange resin, together with optimization of the multi-collector inductively coupled plasma mass spectrometry set-up allowed to isolate copper from seawater matrix and to measure the 65Cu/63Cu ratios in seawater with an external precision of 0.06‰ (2 s.d.). This method was first applied for inter-comparison measurements to surface and deep waters sampled at the Bermuda Atlantic Time-Series station (BATS) in the North Atlantic Ocean during the GEOTRACES Intercalibration Cruise 1. Disparities in δ65Cu reported here and in the literature over these samples showed a need to investigate whether a new inter-comparison sample should be decided upon, or whether the use of UV-oxidation can also affect the measurement of δ65Cu. We also measured total dissolved Cu concentration ([dCu]T) and δ65Cu for 12 stations in the Mediterranean Sea. The δ65Cu distribution showed significant variations in the euphotic zone, at the Chl a maximum and at bottom depths. Copper isotope ratios ranged from +0.21‰ to +0.76‰ (±0.06‰, 2 s.d.), yielding an average of +0.51‰ (±0.20‰, 2 s.d.; n = 96) for the Mediterranean Sea. A strong zonation between natural aerosol deposition to the South and anthropogenic aerosol deposition to the North was seen in the sample set (Dulaquais et al. 2017; Gerringa et al. 2017; Rolison et al. 2015). Natural dust deposits seemed to draw δ65Cu toward lower values and deeper in the euphotic zone whereas the impact of anthropogenic aerosols seemed restricted to an increase in [dCu]T. At the Chl a maximum, δ65Cu showed significant increase which we attributed to scavenging on and/or uptake by phytoplankton. The isotope signature of Cu sources to the Mediterranean Sea was also investigated and we inferred a significant source of isotopically heavy Cu in the Gibraltar area, potentially originating from a release of Cu sulfide leached in the mining area of Southern Spain (i.e. Iberian Pyrite Belt) in rivers and transported to the Mediterranean Sea in surface by seasonal water mass circulation. Conversely, marine sediments appear to be a source of isotopically-light Cu to deep waters. This study provides new hints on the use of copper isotopes to study sources and sinks of Cu in seawater. This article is part of a special issue entitled: “Cycles of trace elements and isotopes in the ocean – GEOTRACES and beyond” - edited by Tim M. Conway, Tristan Horner, Yves Plancherel, and Aridane G. González.

Copper and sulfur isotope ratios in Paleozoic-hosted Mississippi Valley-type mineralization in Wisconsin, USA

We provide the first Cu-isotope data for chalcopyrite in Paleozoic carbonate-hosted Mississippi Valley-type (MVT) mineralization, along with corresponding sulfur isotopes, for eastern Wisconsin, USA. Chalcopyrite in this region occurs mainly as disseminated crystals and is associated with regionally extensive dolomite-hosted subeconomic MVT mineralization on the western edge of the ancestral Michigan Basin. A narrow range in δ65Cu values (0 ± 0.5‰) for chalcopyrite is observed along a large region (125 km) of the western margin of the basin that is consistent with a homogeneous Cu-source in the crust with a δ65Cu composition near 0‰, along with limited redox modification during regional flow or hydrothermal precipitation processes. Cu and S-isotope values, in conjunction with existing lead, strontium, and sulfur isotope data from other sulfide minerals in the region, are consistent with a Precambrian source similar to parts of the Midcontinent Rift System, but distinct from some other Precambrian deposits in the region.

The potential of stable Cu isotopes for the identification of Bronze Age ore mineral sources from Cyprus and Faynan: results from Uluburun and Khirbat Hamra Ifdan

Copper isotope ratios differ between hypogene sulfidic, supergene sulfidic and oxidized ore sources. Traditional lead isotope signatures of ancient metals are specific to deposits, while Cu isotope signatures are specific to the types of ore minerals used for metal production in ancient times. Two methodological case studies are presented: First, the mining district of Faynan (Jordan) was investigated. Here, mainly oxidized copper ores occur in the deposits. The production of copper from Fayan’s ore sources is confirmed by the measurement of the Cu isotope signature of ingots from the Early Bronze Age metal workshop from Khirbat Hamra Ifdan. Based on our results illustrating differences in the Cu isotope composition between the ore mineralizations from Timna (Israel) and Faynan, it is now possible to determine these prehistoric mining districts from which copper artifacts originated by combining trace elements and Pb isotopes with Cu isotopes. The second case study presents data on Late Bronze Age copper production in Cyprus. Oxhide ingots from the shipwreck of Uluburun (Turkey) were tested for their lead isotope signatures and assigned to Cypriot deposits in the recent decades. The oxhide ingots from Uluburun show a Cu isotope signature which we also found for oxidized copper ores from Cyprus, while younger oxhide ingots as well as metallurgical slag from the Cypriot settlements Kition and Enkomi show a different signature which might be due to the use of sulfidic ore sources from a greater depth of deposits. We assert that there could be a chronological shift from oxidized to sulfidic ore sources for the copper production in Cyprus, requiring different technologies. Therefore, Cu isotopes can be used as a proxy to reconstruct mining and induced smelting activities in ancient times.

Longitudinal assessment of metal concentrations and copper isotope ratios in the G93A SOD1 mouse model of amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a motor neuron disease, which involves progressive motor neuron degeneration in the central nervous system (CNS). The G93A SOD1 mouse model simulates one of the most common causes of familial ALS through the overexpression of a mutated form of the human gene encoding copper/zinc superoxide dismutase (SOD1). Transition metals, particularly Cu and Zn, have been shown to behave abnormally in the disease context and have been hypothesized to contribute to and potentially trigger the disease. In this study, concentrations of Cu, Zn and Fe, as well as Cu isotope ratios were assessed in keystone tissues of ALS, including the brain, spinal cord, muscle and whole blood, from transgenic mutant SOD1G93A mice and non-transgenic controls. While no consistent Cu isotope signal was found to be related to the disease state, concentrations of Cu, Zn and Fe were significantly elevated in muscle tissue of the transgenic mice, even at pre-symptomatic time points. In brain and muscle tissue, in both animal groups, a time-dependent Cu isotope signal was observed. We hypothesize that the early and significant elevation in metal concentration in muscle tissue from SOD1 transgenic mice could facilitate the development of ALS, without affecting the overall signal from well-buffered CNS tissues. Ageing may be recorded isotopically as a shift from a neonatal Cu pool as inherited from the mother, through dietary Cu and recycling processes.

Copper isotopic compositions of the Zijinshan high-sulfidation epithermal Cu–Au deposit, South China: Implications for deposit origin

The Zijinshan high-sulfidation epithermal Cu–Au deposit is located in the Zijinshan ore field of South China, comprising porphyry–epithermal Cu–Au–Mo–Ag ore systems. The Cu ore body is more than 1000m thick and is characterized by an assemblage of digenite–covellite–enargite–alunite. Digenite is the dominant Cu-bearing mineral, which makes this deposit unique, although the mechanisms of digenite formation remain controversial. To elucidate the genesis of digenite, this paper presents the Cu isotopic compositions of Cu-sulfides in the Zijinshan high-sulfidation Cu–Au deposit. The Cu isotopic values (65Cu relative to NIST 976) of all samples range from −2.97‰ to +0.34‰, and most values fall in a narrow range from −0.49‰ to +0.34‰, which is similar to the Cu isotopic signature of typical porphyry systems. Copper isotope ratios of each mineral decrease with increasing depth, a trend that is also typical of porphyry deposits. The variation tendency of δ65Cu values between sulfides is consistent with the sequence of mineral formation. These observations suggest that the Cu-sulfides in the Zijinshan Cu–Au deposit have a hypogene origin.

Cu-Zn isotope constraints on the provenance of air pollution in Central Europe: Using soluble and insoluble particles in snow and rime

Copper (Cu) and zinc (Zn) isotope ratios can be used to fingerprint sources and dispersion pathways of pollutants in the environment. Little is known, however, about the potential of δ65Cu and δ66Zn values in liquid and solid forms of atmospheric deposition to distinguish between geogenic, industrial, local and remote sources of these potentially toxic base metals. Here we present Cu-Zn deposition fluxes at 10 mountain-top sites in the Czech Republic, a region affected by extremely high industrial emission rates 25 years ago. Additionally, we monitored isotope composition of Cu and Zn in vertical and horizontal atmospheric deposition at two sites. We compared δ65Cu and δ66Zn values in snow and rime, extracted by diluted HNO3 and concentrated HF. Cu and Zn isotope signatures of industrial pollution sources were also determined. Cu and Zn deposition fluxes at all study sites were minute. The mean δ65Cu value of atmospheric deposition (−0.07‰) was higher than the mean δ65Cu value of pollution sources (−1.17‰). The variability in δ65Cu values of atmospheric deposition was lower, compared to the pollution sources. The mean δ66Zn value of atmospheric deposition (−0.09‰) was slightly higher than the mean δ66Zn value of pollution sources (−0.23‰). The variability in δ66Zn values of atmospheric deposition was indistinguishable from that of pollution sources. The largest isotope differences (0.35‰) were observed between the insoluble and soluble fractions of atmospheric deposition. These differences may result from different sources of Cu/Zn for each fraction. The difference in isotope composition of soluble and insoluble particles appears to be a promising tool for pollution provenance studies in Central Europe.

Use of Ga for mass bias correction for the accurate determination of copper isotope ratio in the NIST SRM 3114 Cu standard and geological samples by MC-ICPMS

The absolute determination of the Cu isotope ratio in NIST SRM 3114 based on a regression mass bias correction model is performed for the first time with NIST SRM 944 Ga as the calibrant.

Matrix and energy effects during in-situ determination of Cu isotope ratios by ultraviolet-femtosecond laser ablation multicollector inductively coupled plasma mass spectrometry

Copper isotope compositions in Cu-bearing metals and minerals have been measured by deep (194nm) ultraviolet femtosecond laser ablation multi-collector inductively coupled plasma mass spectrometry (UV-fsLA-MC-ICP-MS). Pure Cu-metal, brass, and several Cu-rich minerals (chalcopyrite, enargite, covellite, malachite and cuprite) have been investigated. A long-term reproducibility of better than 0.08‰ at the 95% confidence limit on the NIST SRM 976 (National Institute of Standards and Technology) Cu-metal standard has been achieved with this technique. The δ65Cu values for all samples have been calculated by standard-sample-standard bracketing with NIST SRM 976. All analyses have been carried out using Ni as a mass discrimination monitor added by nebulization prior to entering the plasma torch. For further verification samples have been analysed by conventional solution nebulization MC-ICP-MS and the results obtained have been compared with those from UV-fsLA-MC-ICP-MS. Several potential matrix-induced molecular interferences on the mineral copper isotope ratio, such as (32S33S)+ and (32S-16O17O)+ do not affect the Cu isotope measurements on sulfides, while hydrides, such as Zn–H or doubly-charged Sn2+ that interfere Ni isotopes can be either neglected or stripped by calculation. Matrix independent Cu-isotope measurements are sensitive to the energy density (fluence) applied onto the sample and can produce artificial shifts in the obtained δ65Cu values which are on the order of 3‰ for Cu-metal, 0.5‰ for brass and 0.3‰ for malachite when using energy density of up to 2J/cm2 for ablation. A positive correlation between applied energy density and the magnitude of the isotope ratio shift has been found in the energy density range from 0.2 to 1.3J/cm2 which is below the ablation threshold for ns-laser ablation. The results demonstrate that by using appropriate low fluence it is possible to measure Cu isotopic ratios in native copper and Cu-bearing sulfides, carbonates and oxides in situ with a precision of better than 0.1‰ (2SD) without using a matrix-matched standard during laser ablation analyses. Thus, this is a suitable tool to resolve Cu isotopic zoning larger than 0.1‰ in Cu-sulfides, carbonates and oxides.

Challenges of Using Copper Isotope Ratios to Trace the Origin of Native Copper Artifacts: An Example from the Keweenaw Peninsula

In an effort to understand how and if Cu isotopes can be used to trace native copper artifacts to their mineral deposits of origin, this study presents Cu isotope measurements from weathered native Cu artifacts and ores known to be derived from the Precambrian native copper deposits of Michigan. The five weathered artifacts have Cu isotope compositions ranging from δ65Cu= 0.54 to -1.15%o. Weathered glacial till native copper nuggets range from δ65Cu= -0.12 to 0.54%o, non-weathered ores have δ65Cu= 0.33 ± 0.2%o (n= 42 from the literature and this study), a completely oxidized copper rind derived of large glacial boulder of native copper has -0.04%o. The oxidized rinds along with the weathered artifacts possess isotopically lighter signatures in comparison to the non-weathered ores and interiors of weathered copper nuggets.The copper isotope data indicate the interiors of oxidized nuggets correlate with the non-weathered ores. Copper from the artifacts was sampled as micro drill bits (0.001–0.0009g) and larger cut pieces of the artifacts (>0.5g). Only the larger sample artifacts have the same copper isotope composition as the non-weathered ores, and not the oxidized rinds, and non-weathered interiors of copper nuggets. Therefore, when considering the unreacted interior of the native copper artifacts, the copper isotopic composition matches that of the known copper ore source. In contrast, weathering clearly depletes 65Cu on the surfaces of artifacts and micro-sampling of the outer rims does not yield similar isotope results between sources and artifacts.