Academic literature on the topic 'Copper isotope'

The natural copper isotopic compositions of superoxide dismutase and metallothionein from six post-mortem human frontal cortices were determined using a combination of size exclusion protein liquid chromatography, followed by anion exchange chromatography and multiple collector inductively-coupled plasma mass spectrometry. Superoxide dismutase was enriched in the heavier 65Cu relative to the metallothionein fraction in all specimen pairs. The isotopic compositions were independent of copper content. This finding provides evidence that nitrogen ligands in protein copper binding sites will be enriched in heavy metal isotopes, and sulphur ligands will preferentially incorporate lighter isotopes in vivo. This in turn has implications for understanding isotopic distributions within different components in the body and the dominant ligands in different tissues. Differences in Cu isotope distributions between the two proteins were seen between Alzheimer’s disease and healthy control samples, when normalised for sex.

The separation coefficient of copper isotopes, 63Cu and 65Cu, in the electromigration process through cation exchange m em brane was experimentally determined as 3.2 x l0- 4. The appropriate heating condition of low ionizing filament current for thermo-ionization mass spectrometry was developed and this method was applied to the copper isotope analysis in the present work.

1. 65Cu/63Cu stable-isotope ratios have been measured in blood serum after oral administration of the stable isotope 65Cu. The incorporation of the isotope into the plasma protein pool was followed at various times for up to 3 days. The resulting patterns of enrichment in healthy control subjects, in Wilson's disease patients and in heterozygotes for the Wilson's disease gene, were similar in appearance to those found by others using copper radioactive isotopes. After an initially high enrichment at 2h after dosage, the Wilson's disease cases, in contrast to the control subjects, did not show a secondary rise in isotope enrichment of the plasma pool after 72 h, demonstrating a failure to incorporate copper into caeruloplasmin. The Wilson's disease heterozygotes had variable degrees of impairment of isotope incorporation, not always distinguished from those of control subjects. 2. The stability of the isotope also permits the copper tracer to be followed for a longer period. Ten healthy subjects were studied for over 40 days, allowing the biological half-time of an oral dose of copper to be determined (median 18.5 days, 95% confidence interval 14–26 days). Known heterozygotes for the Wilson's disease gene were found to have a significantly increased biological half-time for removal of copper from the plasma pool (median 43 days, 95% confidence interval 32–77 days). 3. The incorporation of 65Cu in patients with diseases of the liver (other than Wilson's disease) was found to be similar to that in control subjects, aiding differential diagnosis.

The current consensus is outlined about the application of lead isotope analyses to metal provenance studies and to the unravelling of the Mediterranean Bronze Age copper trade, with special reference to copper oxhide ingots. Various misconceptions, especially some of those contained in Knapp (1999, 2000), are corrected. It is shown that there is no need to fall back on hypotheses based upon the Mediterranean-wide mixing/recycling of copper metals to explain the lead isotope characteristics of post-1250 BC copper oxhide ingots, since there is a good isotopic coincidence between these ingots and the Apliki region ore deposits in Cyprus. Weaknesses are exposed in the hypotheses of direct or indirect pooling of Cypriot ores, and of the proposed widespread recycling of metals in a Mediterranean-widekoine, particularly since there is no evidence for a homogeneity of lead isotope composition in artefacts and no tin in the oxhide ingots.

The objective of the present study was to investigate the validity of using holmium as a faecal marker in a copper absorption study using a highly enriched 65Cu stable isotope label. Ten volunteers (nine female, one male) aged 24-55 years were recruited from the Norwich area to take part in a free-living study. The study was conducted in the Human Nutrition Unit at the Institute of Food Research, Norwich, U.K., and involved feeding breakfast test meals containing foods labelled intrinsically or extrinsically with a highly enriched 65Cu stable isotope label. A 1mg oral dose of the rare earth element holmium was administered to volunteers simultaneously with an oral dose of highly enriched 65Cu stable isotope as a label in the breakfast test meal. Complete faecal collections were made for 10 days after dosing, and the mean percentage holmium recovery (±S.D.) was 105±15%. After correcting for re-excreted copper label, the labelled copper and holmium had similar excretory profiles. It was concluded that holmium is a valid faecal marker in adult human copper absorption studies using stable isotopes.

Copper is a critical enzyme cofactor in the body but also a potent cellular toxin when intracellularly unbound. Thus, there is a delicate balance of intracellular copper, maintained by a series of complex interactions between the metal and specific copper transport and binding proteins. The gastrointestinal (GI) tract is the primary site of copper entry into the body and there has been considerable progress in understanding the intricacies of copper metabolism in this region. The GI tract is also host to diverse bacterial populations, and their role in copper metabolism is not well understood. In this study, we compared the isotopic fractionation of copper in the GI tract of mice with intestinal microbiota significantly depleted by antibiotic treatment to that in mice not receiving such treatment. We demonstrated variability in copper isotopic composition along the length of the gut. A significant difference, ∼1.0‰, in copper isotope abundances was measured in the proximal colon of antibiotic-treated mice. The changes in copper isotopic composition in the colon are accompanied by changes in copper transporters. Both CTR1, a copper importer, and ATP7A, a copper transporter across membranes, were significantly down-regulated in the colon of antibiotic-treated mice. This study demonstrated that isotope abundance measurements of metals can be used as an indicator of changes in metabolic processes in vivo. These measurements revealed a host–microbial interaction in the GI tract involved in the regulation of copper transport.

The widespread hypoxic conditions of the tumor microenvironment can impair the metabolism of bioessential elements such as copper and sulfur, notably by changing their redox state and, as a consequence, their ability to bind specific molecules. Because competing redox state is known to drive isotopic fractionation, we have used here the stable isotope compositions of copper (65Cu/63Cu) and sulfur (34S/32S) in the blood of patients with hepatocellular carcinoma (HCC) as a tool to explore the cancer-driven copper and sulfur imbalances. We report that copper is 63Cu-enriched by ∼0.4‰ and sulfur is 32S-enriched by ∼1.5‰ in the blood of patients compared with that of control subjects. As expected, HCC patients have more copper in red blood cells and serum compared with control subjects. However, the isotopic signature of this blood extra copper burden is not in favor of a dietary origin but rather suggests a reallocation in the body of copper bound to cysteine-rich proteins such as metallothioneins. The magnitude of the sulfur isotope effect is similar in red blood cells and serum of HCC patients, implying that sulfur fractionation is systemic. The 32S-enrichment of sulfur in the blood of HCC patients is compatible with the notion that sulfur partly originates from tumor-derived sulfides. The measurement of natural variations of stable isotope compositions, using techniques developed in the field of Earth sciences, can provide new means to detect and quantify cancer metabolic changes and provide insights into underlying mechanisms.

Abstract The E-trending Gangdese porphyry copper belt in southern Tibet is a classic example of porphyry mineralization in a continental collision zone. New zircon U-Pb geochronological, zircon Hf-O, and bulk-rock Sr-Nd isotope data for the Miocene mineralizing intrusions from the Qulong, Zhunuo, Jiru, Chongjiang, and Lakange porphyry copper deposits and Eocene igneous rocks from the western Gangdese belt, together with literature data, show that both Paleocene-Eocene igneous rocks and Miocene granitoids exhibit coupled along-arc isotopic variations, characterized by bulk-rock ɛNd(t) and zircon ɛHf(t) values increasing from ~84° to ~92°E and then decreasing toward ~95°E. These are interpreted to reflect increasing contributions of subducted Indian continental materials from ~92° to ~84°E and from ~92° to ~95°E, respectively. The Miocene mineralizing intrusions were derived from subduction-modified Tibetan lower crust represented isotopically by the Paleocene-Eocene intrusions, with contributions from Indian plate-released fluids and mafic melts derived from mantle metasomatized by subducted Indian continental materials. Involvement of isotopically ancient Indian continental materials increased from east (Qulong) to west (Zhunuo), which is interpreted to reflect an increasingly shallower angle of the downgoing Indian slab from east to west, consistent with geophysical imaging. Exploration of Gangdese Miocene porphyry copper deposits should focus on the Paleocene-Eocene arc where the subarc mantle was mainly enriched by fluids from the subducted Neo-Tethyan oceanic slab. Neodymium-Hf isotope data for mineralizing igneous rocks from porphyry copper deposits globally show no obvious correlations with Cu endowment. Although Nd-Hf isotopes are useful for imaging lithospheric architecture through time, caution must be taken when using Nd-Hf isotopes to evaluate the potential endowment of porphyry copper deposits, because other factors such as tectonic setting, crustal thickening, magma differentiation, fluid exsolution, and ore-forming processes all play roles in determining Cu endowments and grades.

The article considers the results of the study of lead isotope composition of 38 non-ferrous artifacts discovered at medieval rural sites of the Suzdal Region (Kievan Rus’). The copper-alloy, silver and pewter artifacts were compared with reference data from geographically and temporally diverse medieval artifacts and ore deposits and revealed differing source regions and supply networks within and between metal types. The identification in some cases was difficult due to the conformity of the lead isotopic composition of deposits of some regions. The copper-alloys, represented mostly by crosses made of high-tin bronze, show close isotopic parallels to contemporary copper alloys from Southern Scandinavia, Westphalia and Lower Saxony. Since the copper alloys contain significant quantities of lead, this lead may have entered the metal by alloying with lead-tin alloys, by smelting mixed copper-lead ore, or through haphazard alloying with lead. The lead isotope ratios for nearly all copper alloys are consistent with deposits in Cornwall and Devon and remobilized ore from the Rhenish Massif. For silver and lead-tin alloy objects, lead isotope analyses point to wide ranging sources. Most silver objects are consistent with mid-to-late 10th century silver stocks circulating in the Baltic area and 10th century Volga-Bulgar silver dirham imitations probably representing mixtures of 9th-10th century Islamic silver. The silver shows a heavy reliance on 10th century mixed stocks and there are little indications of Central and Western European silver, which was common in the 11th century Baltic region. The pewter and lead, however, indicate other sources. Lead isotope ratios are consistent with sources connected to Mediterranean and Baltic networks, some being consistent with sources in England, but it is possible that the lead found in some pewter objects could come from the Olkusz lead district in southern Poland.

We present data on the chemical and lead isotope composition of copper and bronze objects from Nuragic Sardinia. The sample suite comprises, inter alia, objects from the hoard finds at Arzachena (21 objects), Bonnanaro (10), Ittireddu (34), and Pattada (20), all in northern Sardinia. With one exception, all ingot fragments (49) consist of unalloyed copper; the exception comes from Ittireddu and contains 11 per cent tin. In contradistinction, all implements (21) are made from standard bronze with a mean tin content of 10.8 per cent. A dozen sword fragments from the Arzachena hoard, all of fairly uniform small size, are pieces of a large number of different swords. The low tin content of only about 1 per cent would have made for poor weapons, confirming the archaeological identification of the fragments as pieces of votive swords. Scrap metal from Arzachena is remarkable for its wide range of trace element contents and lead isotope abundance ratios. It is dissimilar to all other metal samples investigated, possibly representing metal from local smelting experiments using a variety of different copper ores. Lead isotope data and trace element patterns, alone or in conjunction, do not allow us to tell oxhide ingots from plano-convex (bun) ingots. Most ingot fragments have a lead isotope signature similar to those of Cypriot copper ores but there are also a number of ingots whose lead isotope fingerprints are fully compatible with them being local products. Of the bronzes, none has lead with an isotopic composition characteristic of copper ingots from Cyprus. All contain local lead, suggesting the bronze implements were manufactured locally. Isotopically-fitting lead is found in copper and lead ore deposits from the Iglesiente-Sulcis district in south-west Sardinia and from Funtana Raminosa in central Sardinia.

Depuis la fin du 19ème siècle, le traitement des vignes par des fongicides cupriques a engendré une augmentation de la teneur en cuivre (Cu) dans les sols viticoles, ainsi que dans les écosystèmes aquatiques en aval. Cette thèse vise à mieux comprendre le devenir de ce Cu dans un agrosystème basé sur l’étude du fractionnement isotopique du 65Cu/63Cu. Les résultats montrent que durant 4 à 5 décennies de culture de vignes, les sols en surface se sont enrichis en Cu de 9 à 28 fois par rapport au fond géochimique et que les minéraux argileux jouent un rôle important dans l’accumulation du Cu. Lors des événements pluvieux, ~1% du Cu appliqué est mobilisé, essentiellement lié à des argiles. Le bassin d’orage récoltant les lames ruisselantes retient en moyenne 68% du Cu dissous et plus de 92% du Cu particulaire. Les ratios isotopiques du Cu dans le bassin indiqueraient la sorption du Cu dissous dans les sédiments, ainsi que la réduction du Cu(II) in situ due à des processus biogéochimiques
Since the end of the 19th century, the use of copper (Cu)-based fungicides has resulted in increased Cu concentrations in vineyard soils, but also in downstream aquatic ecosystems. The aim of the thesis was to better understand the fate of this Cu in an agrosystem based on assessing Cu isotope fractionation (65Cu/63Cu). The results have shown that the surface vineyard soils have become enriched in Cu from 9 to 28 times compared to the background level during 4 to 5 decades of vine-growing and that clay minerals were the major Cu sorbing phases in the soils. During rainfall, runoff mobilized ~1% of the applied Cu during the, mainly associated with clays. The stormwater wetland collecting the runoff retained in average 68% of the dissolved and more than 92% of particulate Cu. Cu isotope ratios measured in the wetland suggested dissolved Cu sorption to the sediments and in situ reduction of Cu(II) due to biogeochemical processes

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IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

The nature of Cu isotope fractionation in natural Cu-Fe-S minerals was investigated through acid ferric sulfate leaching of copper ore from Morenci, Arizona. Copper isotope composition of the derived solutions varies from δ⁶⁵Cu = 0.47‰ to 5.21‰ over the course of progressive copper extraction. High δ⁶⁵Cu values characterize solutions collected in the first half of the leach, while the solutions collected between 35% and 45% copper recovery exhibit lower δ⁶⁵Cu values. This general pattern was observed for both bacterially-mediated and abiotic leaching. Sulfate solutions derived from dissolving pure djurleite show variable Cu isotope compositions as well, although the range is protracted from δ⁶⁵Cu = 0.01‰ to 1.21‰. As the Cu:S ratio of the remaining sulfide decreases, crystal structure parameters change as mineralogy passes through a series of nonstoichiometric copper sulfides. Mineralogy converges to yarrowite near 44% copper dissolution. Crystal chemical studies show that distribution of the two copper-sulfur bond coordination geometries, triangular planar and tetrahedral, in the copper sulfides, approximately corresponds to changes in δ⁶⁵Cu of the leachates. In particular, the proportion of CuS3 relative to CuS4 groups decreases from Cu/S = 2.00 (chalcocite) to 1.40 (geerite). Between Cu/S = 1.40 to 1.00 (covellite), the relative proportion of CuS3 groups increases slightly. Connection between coordination number and Cu isotope fractionation implies affinity of CuS₃ groups for the heavier, ⁶⁵Cu, isotope. This can be justified through bond length-bond strength arguments. Solutions from bornite dissolution vary from δ⁶⁵Cu = -0.79‰ to 1.14‰, with the largest values associated with solutions from early stage of reaction (up to 15% copper removal). Around 25% dissolution, δ⁶⁵Cu of the solution approaches that of the original bornite (δ⁶⁵Cu = 0.02‰). This is explained by disappearance of all remaining CuS₃ groups. Sulfur isotope compositions of solutions and sulfides derived from djurleite leaching were determined to investigate the possibility of intra-mineral fractionation. Very soon after reaction initiation, δ³⁴S of both sulfur reservoirs reach a steady-state with sulfate solutions about 2‰ enriched in ³⁴S relative to residual sulfide. Unlike the case of Cu isotopes, the main partitioning affecting S isotopes is exchange between sulfate and sulfide.

Master of Science
Department of Geology
Matthew E. Brueseke
Mid-Miocene epithermal Au-Ag ores of the northern Great Basin USA are related to magmatism associated with the inception of the Yellowstone hotspot. The geochemical chemical connection between these ores and spatially and temporally related volcanism is not well understood, but has been suggested (Kamenov, 2007; Saunders et al., 2015). These Cu- and Pb- isotope studies show that the ore and associated gangue minerals have different sources of Pb, which supports evidence that the metal(loids) originate from a deep magmatic source (Saunders et al., 2008). Cu isotopes as a tool for exploring linkages between ore deposits and related volcanic rocks is a new and evolving field. A suite of mid-Miocene Northern Great Basin (NGB) and Snake River Plain (SRP) volcanic rocks was analyzed by aquaregia leach for their δ⁶⁵Cu compositions. These samples have all been previously characterized and include basalts, trachybasalt, basaltic andesites, and basaltic trachyandesites that are representative of regional flood basalt magmatism and younger basalt eruptions in central Idaho. Included are rocks from the Santa Rosa-Calico volcanic field, NV (e.g., Buckskin-National district); Owyhee Mountains, ID (Silver City District); Midas, NV region, near Jarbidge, NV; and a locality proximal to Steens Mountain, OR. Also included are two Pleistocene basalts from the central Snake River plain unequivocally related to the Yellowstone hotspot volcanism (McKinney Basalt and Basalt of Flat Top Butte), and one Eocene basalt from the Owyhee Mountains that is related to pre-hotspot arc volcanism. International rock standards ranging from ultramafic to intermediate were also analyzed in this study for comparison. Our new δ⁶⁵Cu data greatly expands the range of known Cu isotopic compositions for basalts, with values ranging from -0.84‰ to +2.61‰. These values overlap with the δ⁶⁵Cu of regional ores, further suggesting a link between the source(s) of the ores and the NGB rocks. The range of δ⁶⁵Cu values also overlaps with mantle rock values, suggesting that the Cu isotopic composition may be a signature derived from the mantle source. Fractionation mechanisms that cause such a broad range in Cu isotopes are still unclear but liquid-vapor transitions and mantle metasomatism are being explored. Furthermore, δ⁶⁵Cu values of international rock standards reported in this study did not agree with previously reported data (Archer and Vance, 2004; Bigalke et al., 2010; Moeller et al., 2012; Liu et al., 2014, 2015) suggesting that aquaregia leach may not be a preferable technique when analyzing volcanic rocks.

The provenance of metal artifacts in the early history of metallurgy has been a major question in archaeology for many decades. Pb isotope ratios (206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb) are commonly used for provenancing in archaeometry, but interpretations are hardly debated and sometimes ambiguous because natural ore deposits frequently show overlapping Pb isotopic compositions. The first way to reduce observed overlaps is by improving the analytical precision. The second way to reduce ambiguities is to combine the lead isotopic signature with other geochemical indicators, e.g. minor and trace elements or other isotopic data. Extraction of reliable provenance information from a combination of several geochemical tracers, however, requires sophisticated statistical analysis. Here, more than 350 samples were collected from 50 mining areas. Some of the most important copper districts in the central-eastern Southern Alps (Variscan basement and Permian-Triassic cover, Carnic Alps), in the Western Alps (Piedmont Zone, Ligurian Briançonnais, Gran Paradiso nappe, Argentera), in the Ligurian Apennines (Libiola, Monte Loreto) and the Southern Tuscany (Isola d’Elba, “Colline metallifere” and Montecatini Val di Cecina). About 270 samples of primary (copper and copper-iron sulfides and copper sulphosalts) and secondary (supergenic copper carbonates and oxides and native copper) raw minerals and archaeological finds (slags, copper and bronze artifacts of Chalcolithic to Late Bronze Age) were analyzed for lead isotopes and minor and trace elements (including most transition metals and chalcophile elements and the REE). Moreover, the feasibility of the routine measurement of the 65Cu/63Cu isotope ratio and its use as a possible ore tracer was also tested. An advanced statistical investigation (PCA, PLS-DA, NPC) has been carried out on the database to provide discriminant statistic tools for metal provenancing. The samples were first characterized mineralogically and petrologically (XRD, RL-OM), and then analysed by ICP-QMS (Inductively Coupled Plasma-Quadrupolar Mass Spectrometry) for trace elements and 65Cu/63Cu isotopic ratios. Multicollector ICP mass spectrometry (MC-ICP-MS) was used to determine precise Pb isotopic ratios (206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb). The chemical/isotopic dataset of the mines was analysed with Principal Component Analysis (PCA) and Partial least Square-Discriminant Analysis (PLS-DA). The chemical and isotopic data were arranged into a bidimensional matrix characterized by samples (objects) in the rows and the chemical measurement as the variables in the columns. The dataset was also analysed with the Nonparametric Combination (NPC) test, which is an inferential multivariate nonparametric method that frees from the stringent assumptions of parametric methods (such as t and F test) and allows a more flexible analysis both in terms of specification of multivariate hypotheses and in terms of the nature of the variables involved. One of the most important advantages of applying nonparametric statistics like permutation tests, is that it allows one to relax the assumption of normality of response variables. Moreover, the NPC Test does not requires modelling of dependence among variables and is not affected by the problem of loss of degrees of freedom when the number of variables is large compared to sample size. Results of NPC Test analysis were obtained using the free software NPC Test R10, where as test statistic we used the F-test and as combining function we used the Fisher combining function (Pesarin, 2001). The results can be graphically represented by PCA. The availability of an unprecedented and comprehensive amount of geochemical data for Alpine copper deposits yielded information relevant to their metallogenic interpretation. In particular, the isotopic compositions of trace lead in copper-bearing hydrothermal sulphide deposits from the central-eastern Southalpine region were combined with existing lead isotope data for hydrothermal polymetallic deposits in the same area and compared with the isotopic compositions of potential lead sources. Copper and polymetallic pre-Variscan (Late Ordovician–Early Silurian) stratiform, post-Variscan (Permian to Triassic) vein, and stratabound sediment-hosted (Permian to Early Triassic) deposits, are characterized by highly variable ratios of radiogenic to non-radiogenic lead, but show very similar, high, time-integrated  (= 238U/204Pb) and W (= 232Th/204Pb) values. A progressive relative increase in radiogenic lead is observed from (i) pre-Variscan deposits to (ii) post-Variscan sulphide-rich veins in the Variscan metamorphic basement and in the lower–intermediate units of the Early Permian volcanic sequence to (iii) post-Variscan sulphide-rich and fluorite-rich veins in the upper units of the Early Permian volcanic sequence to (iv) post-Variscan fluorite-rich veins cutting the overlying Late Permian sediments and mid-Triassic mafic dikes. The dominant lead sources for all these deposits were Cambrian–Devonian (meta)sediments of the Variscan basement. Contributions from Permian and Triassic igneous rocks were of minor importance, if any, even for vein deposits which were evidently related to Permian magmatism While Pb isotopic fingerprinting could potentially help identify the likely provenance of an archeological object, there are a number of related difficulties. First of all, natural ore deposits frequently have overlapping Pb isotopic compositions. So, trace elements, Rare Earth Elements and 65Cu/63Cu isotopic ratios were investigated in addition to lead isotopes. Copper 63Cu/65Cu isotopic ratio is sensitive to the temperature of mineral segregation; therefore, it provides information on the nature of the mineral used for the object manufacturing. A statistical selection was carried out to detect the variables that more effectively distinguish the investigated ores. This was achieved using a PLS-DA strategy. This technique is a classification method that models the differences between two classes. The PLS method calculates a linear regression model between the predictors matrix (X) and the response vector (Y): in this particular case the Y vector is expressed with the binary code. The model provides scores and loading plots as well as the regression coefficient for each variable. An estimate of the statistical significance of these regression coefficients is also provided. The statistical relevance of the variables was tested through the Martens Uncertainty test. The study of the correlation loadings and the model coefficients led to the definition of a variable subset capable to discriminate the samples coming from the different mining sites/areas. A single model was not sufficient and a multi-step exclusion strategy was required to attain a satisfactory discrimination. The procedure adopted can be summarized as follows: 1) the whole data set is taken into account and a PCA model is built. Through the study of the score plots generated by the combination of the first principal components (usually PC1 to PC4) the most effectively discriminated locality is chosen for the exclusion process; 2) the next step is the variable selection in order to emphasize the differences between the selected locality and all other localities: the aim is to build a simple discriminant model using only PC1 or no more than two PCs; 3) the data related to the selected locality are excluded from the original matrix and the whole process is then repeated on this reduced matrix initially considering again all the variables. The discriminating power of the database was tested for the provenancing of copper metals and slags from the Agordo area (BL) and of prehistoric copper fragment and slags from Millan (Bressanone, BZ). The samples were projected onto an existing PCA model, and their position compared with the position of the samples used to build the model. The same projection method was also used for the validation of the multiple step exclusion strategy. Data for copper artifacts and slags from the Agordo area show that the discriminant model that best identifies the Agordo ores is perfectly applicable to the objects, clearly indicating that the metal was extracted from the local ores. For the Millan case, the discriminating model of the deposits that best describes the copper fragment is the one that identifies the Val Venosta area (Oris, Val Martello, and Stelvio mines), located 80 km to the west of the archaeometallurgical site of Millan. This result suggests that the copper sample is genetically unrelated to the large amount of associated slags produced during the smelting of copper from local sphalerite/galena-rich chalcopyrite ores, which have a significantly different mineralogical and geochemical character. A successful strategy to characterize copper ores and to trace the provenance of copper minerals and ancient copper objects was presented. A whole analytical protocol starting from the sampling to the quantitative analysis was developed to ensure geologically sound and good quality analytical data. The measurements of a wide group of elements including the Rare-Earth Elements (REE) together with the lead and copper isotopic ratio in Cu minerals allowed a full geochemical characterization of the investigated Cu-ores. The data collected were used to build a database that can be used as the fundamental reference frame for tracing of metal extraction and diffusion in the past. Application of advanced statistical techniques to the geochemical and isotopic data proved to be a powerful tool to discriminate the ore source areas. The presented applications to copper metal samples and slags seem to confirm that the analysis can be successfully performed on archaeometallurgical specimens. The availability of such an unprecedented and comprehensive amount of data for Alpine copper deposits also yield interesting information for their geochemical and metallogenic interpretation. In particular, the high  and W values of the deposits from the central-eastern Southalpine are consistent with regional isotopic patterns of Pb–Zn-rich deposits in more northerly and easterly sectors of the Eastern Alps (Austroalpine, eastern Southalpine) and of several circum-Mediterranean Pb–Zn and polymetallic deposits of Paleozoic to Triassic age (Sardinia; Betic Cordillera) or derived from remobilization of Paleozoic deposits (Tuscany). This isotopic uniformity suggests the existence of an isotopic province characterized by the dominance of old (Early Proterozoic to Archean) detrital source material, extending across a relatively wide portion of the former north-Gondwanan margin.
La provenienza di manufatti metallici nella prima storia della metallurgia è stata il maggiore problema in archeologia per molte decadi. I rapporti isotopici del Pb (206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb) sono comunemente usati per definire la provenienza dei manufatti in archeometria, ma le interpretazioni sono fortemente dibattute e qualche volta ambigue dal momento che i depositi naturali mostrano di frequente composizioni isotopiche del Pb sovrapposte. Il primo modo di ridurre le sovrapposizioni osservate è di aumentare la precisione analitica. Il secondo modo di ridurre le ambiguità è di combinare la segnatura isotopica del piombo con altri indicatori geochimici, ad esempio con altri dati isotopici o di elementi minori e in traccia. L’estrazione di un’informazione di provenienza affidabile dalla combinazione di numerosi traccianti geochimici, tuttavia, richiede analisi statistiche sofisticate. Qui più di 350 campioni sono stati raccolti da 50 aree minerarie. Alcuni dei più importanti distretti di rame nella porzione centro-orientale delle Alpi meridionali (Alpi Carniche, copertura Permo-Triassica e basamento Varisico), nelle Alpi occidentali (Zona Pedemontana, Brianzonese Ligure, nappe del Gran Paradiso, Argentera), negli Appennini Liguri (Libiola, Monte Loreto) e nella Toscana meridionale (Isola d’Elba, “Colline metallifere” and Montecatini Val di Cecina). Sono stati analizzati circa 270 campioni di minerali grezzi primari (rame, solfuri di rame-ferro e solfo-sali di rame) e secondari (carbonati e ossidi di rame supergenico e rame nativo) e ritrovati archeologici (scorie, manufatti di rame e bronzo di età da Calcolitica a Tardo Bronzo) per analisi degli isotopi del piombo e degli minori e in tracce (inclusi la maggior parte dei metalli di transizione, elementi calcofili e terre rare). Inoltre è stata testata la fattibilità di misure di routine del rapporto isotopico del Cu (65Cu/63Cu) e del suo possibile uso come tracciante delle miniere. E’ stata eseguita un’avanzata analisi statistica (PCA, PLS-DA, NPC) su un database per ottenere strumenti statistici discriminanti per la provenienza dei metalli. I campioni sono stati prima caratterizzati mineralogicamente e petrologicamente (XRD e RL-OM) e successivamente analizzati mediante tecnica ICP-QMS (Spettrometri di Massa Quadrupolare mediante Plasma accoppiato induttivamente) per gli elementi in tracce e i rapporto isotopico 65Cu/63Cu. E’ stata usata la spettrometria di massa multicolletore (MC-ICP-MS) per la determinazione precisa dei rapporti isotopici del piombo (206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb). L’insieme di dati chimico/isotopico delle miniere è stato analizzato con l’Analisi delle Componenti Principali (PCA) e con l’Analisi Discriminante dei minimi quadrati parziali (PLS-DA). I dati chimici e isotopici sono stati inseriti in una matrice bidimensionale caratterizzata dai campioni (manufatti) nelle righe della matrice e le analisi chimiche come variabili nelle colonne. L’insieme dei dati è stato inoltre analizzato con il test della Combinazione non-parametrica (NPC), che è un metodo non-parametrico multivariato inferenziale che libera dalle stringenti assunzioni dei metodi parametrici (come il t e F test) e permette un’analisi più flessibile sia in termini della specificazione di ipotesi multivariate, sia in termini della natura della variabili in causa. Uno dei più importanti vantaggi dell’applicare statistiche non-parametriche come i test di permutazione, è che permette di lasciare libera l’assunzione di normalità delle variabili di risposta. Inoltre, il Test NPC non richiede la modellazione della dipendenza tra le variabili e non è affetta da problemi di perdita di gradi di libertà quando il numero di variabili è grande comparato al numero dei campioni. I risultati dell’analisi del Test NPC sono stati ottenuti usando il programma libero NPC Test R10, dove abbiamo usato l’F-test come test statistico e la funzione di combinazione Fisher come funzione combinante. I risultati possono essere rappresentati graficamente mediante la PCA. La disponibilità di una comprensiva e senza precedenti quantità di dati geochimici per i depositi Alpine di rame ha dato informazioni rilevanti per la loro interpretazione metallo genica. In particolare, le composizioni isotopiche delle tracce di piombo nelle mineralizzazione a rame in depositi di solfuri idrotermali della regione sudalpina centro-orientale sono state combinate con i dati degli isotopi del piombo di depositi poli-metallici idrotermali esistenti nella stessa area, e comparati con le composizioni isotopiche di potenziali sorgenti di piombo. Depositi stratiformi di rame e poli-metallici pre-Varisici (tardo Ordoviciano - primo Siluriano), depositi a vene post-Varisiche (da Permiano a Triassico) e depositi a stratabound ospitati in sedimenti (da Permiano al primo Triassico) sono caratterizzati da rapporti altamente variabili di piombo radiogenico e non, ma mostrano valori di  (= 238U/204Pb) e W (= 232Th/204Pb) molto simili e alti. Si osserva un relativo progressivo aumento in piombo radiogenico dai (i) depositi pre-Varisici alle (ii) vene ricche di solfuri post-Varisiche presenti nel basamento metamorfico Varisico e nelle unità inferiori-intermedie della sequenza vulcanica per primo Permiano alle (iii) vene post-Varisiche ricche in fluorite e solfuri nelle unità superiori della sequenza vulcanica del primo Permiano alla (iv) vene post-Varisiche ricche in fluorite che tagliano i sovrastanti sedimenti tardo-permiani e i dicchi mafici medio-triassici. Le sorgenti di piombo dominanti per tutti questi depositi sono i (meta)sedimenti del Cambriano-Devoniano del basamento Varisico. Contributi da rocce ignee permiane e triassiche sono di minore importanza, se presenti, anche per depositi di vena che sono evidentemente correlati con il magmatismo permiano. Mentre l’impronta isotopica del Pb potrebbe potenzialmente aiutare la probabile provenienza del manufatto archeologico, ci sono numerose difficoltà correlate. Prima di tutto, i depositi naturali hanno frequentemente composizioni isotopiche del Pb sovrapposte. Così in aggiunta agli isotopi del Pb sono stati analizzati gli elementi in tracce, terre rare e rapporti isotopici del rame (65Cu/63Cu). Il rapporto isotopico del rame 65Cu/63Cu è sensibile alla temperature di segregazione del minerale; quindi fornisce informazioni sulla natura del minerale usato per la produzione del manufatto. E’ stata operato una selezione statistica per identificare le variabili che più effettivamente distinguono le miniere investigate. Questo è stato raggiunto usando una strategia PLS-DA. Questa tecnica è un metodo di classificazione che modella le differenze tra due classi. Il metodo PLS calcola un modello di regressione lineare tra la matrice dei predittori (X) e il vettore risposta (Y): in questo particolare caso il vettore Y è espresso con un codice binario. Il modello restituisce scores and loading plots così come il coefficiente di regressione per ogni variabile. Viene inoltre fornito una stima del significanza statistica di questo coefficienti di regressione. La rilevanza statistica delle variabili è stata testata attraverso il Martens Uncertainty test. Lo studio delle matrici di correlazione e dei coefficienti del modello permette di definire un sotto-insieme di variabili in grado di discriminare i campioni provenienti dalla differenti aree/siti. Un singolo modello non è stato sufficiente ed è stata richiesta una strategia di esclusione a più passaggi per ottenere una discriminazione soddisfacente. La procedura adottata può essere schematizzata come segue: 1) l’intero insieme di dati è preso in considerazione e viene creato un modello PCA. Attraverso lo studio dei score plots generato dalla combinazione delle prime componenti principali (in genere da PC1 a PC4) la località maggiormente discriminante viene scelta per il processo di esclusione; 2) il passo successivo la selezione della variabile con l’intento di enfatizzare le differenza tra la località selezionata e tutte le altre località: l’obiettivo è costruire un semplice modello discriminante usando solo PC1 o non più di due PCs: 3) i dati correlati alla località selezionata sono esclusi dalla matrice originale e l’intero processo è quindi ripetuto su questa matrice ridotta inizialmente considerando di nuovo tutte le variabili. Il potere discriminante del database è stato testato sulla provenienza di metalli e scorie di rame provenienti dall’area di Agordo (Belluno) e di frammenti e scorie di rame preistorici provenienti da Millan (Bressanone, Bolzano). I campioni sono stati proiettati in un modello PCA esistente, e la loro posizione comparata con la posizione dei campioni usati per costruire il modello. Lo stesso metodo di proiezione è stato inoltre usato per la validazione della strategia di esclusione a passaggi multipli. I dati per manufatti e scorie di rame proveniente dall’area di Agordo mostrano che il modello discriminante che meglio identifica le miniere di Agordo è perfettamente applicabile ai manufatti, indicando chiaramente che il metallo è stato estratto dalle miniere locali. Per il caso di Millan, il modello discriminante dei depositi che meglio descrive il frammento di rame è quello che identifica l’area della Val Venosta (miniere di Oris, Val Martello e dello Stelvio), localizzate 80 km a ovest del sito archeometallurgico di Millan. Questo risultato suggerisce che il campione di rame è geneticamente non correlato alla grande quantità di scorie associate prodotte durante il processo di smelting del rame provenienti dalle locali miniere di calcopirite ricche di sfalerite e galena, che hanno un carattere mineralogico e geochimico significativamente differente. E’ presentata una strategia vincente per caratterizzare miniere di rame e per tracciare la provenienza di minerali e antichi manufatti di rame. E’ stato sviluppato un intero protocollo di controllo, che parte dal campionamento all’analisi quantitativa, per assicurare una corrispondenza geologica e una buona qualità dei dati analitici. Le misure di un vasto numero di elementi che include le terre rare (REE) insieme con i rapporti isotopici del rame e del piombo in minerali di rame ha permesso una completa caratterizzazione geochimica delle miniere a rame investigate. I dati raccolti sono stati usati per costruire un database che può essere usato come riferimento fondamentale per tracciare l’estrazione del metallo e la sua diffusione in passato. L’applicazione di avanzate tecniche statistiche ai dati geochimici e isotopici fornisce uno strumento potente per discriminare le aree delle miniere sorgenti. Le applicazioni presentate relativamente ai campioni e scorie di rame sembrano confermare che le analisi possono essere operate con successo su campioni archeometallurgici. La disponibilità di un tale ammontare di dati esaustivo e senza precedenti per i depositi di rame alpini inoltre da informazioni interessanti per la loro interpretazione geochimica e metallogenica. In particolare, gli alti valori di  e W dei depositi del sud-alpino centro-orientale sono consistenti con andamenti isotopici regionali dei depositi a Pb-Zn in settori più settentrionali e orientali delle Alpi orientali (Australoalpino, Sudalpino orientale) e di numerosi depositi metallici e a Pb-Zn dell’area mediterranea di età paleozoica fino a triassica (Sardegna, Cordigliera Betica) o derivati da rimobilizzazione di depositi paleozoici (Toscana). Questa uniformità isotopica suggerisce l’esistenza di una provincia isotopica caratterizzata da una preponderanza di vecchio materiale sorgente detritico (primo Proterozoico fino ad Archeano), che si estende attraverso una relativamente estesa porzione di un più recente margine nord-Gondwaniano.

The distribution of the stable isotopes of Cu and Fe in nature is susceptible to isotope fractionation processes during the biogeochemical cycle. Since Cu and Fe are redox sensitive metals, differences in their oxidation states can lead to variations in the stable isotope composition of the aquatic species or compounds that they form. Stable isotopes of Cu and Fe have recently been used to trace metal redox cycles, nutrient pathways, metal contaminant sources and to develop isotopic biosignatures. The objective of this project was to study the geochemical processes governing the isotopic fractionation of Cu and Fe in mine impacted sites, including processes related to mineral processing. One of the key questions was to explain the role of bacteria in the variations of the isotopic composition of Cu and Fe. First, bioleaching and electroleaching of a chalcopyrite concentrate were performed. During the chalcopyrite leaching in both experiments the first release of Cu to the leachate is enriched in the heavier Cu isotope as a product of oxidative dissolution. At the later stages of leaching, the δ65Cu values for the leachate are similar to the initial material, confirming an equilibrium fractionation in a closed system. In the case of Fe isotope fractionation the dissolution of pyrite at redox potentials higher than 600mV leads to an enrichment of the heavier Fe isotope in the leachate in the bioleaching experiment, mainly regulated by the formation of secondary minerals such as jarosite. Soil bacteria were studied in three different experimental scales using pot, lysimeters and field experiments, amended with autochthonous plant growth promoting bacteria. Roots and plants from pots showed no variation in their Fe and Cu isotope composition compared to non-amended samples. However, plants growing in the amended substrates regardless of their experimental scale, showed variations in the Fe and Cu isotope composition of their roots with an increase in the heavier Cu isotope. Siderophores released either by bacteria or the plant can complexate available Cu and Fe in the soil, causing a change in the isotope fractionation of those metals. The second question is related to the biogeochemical cycle of Cu and Fe. In mine tailings the sulphide oxidation resulted in an enrichment of the lighter Cu isotope in secondary phases in the oxidized zone of the tailings compared to the original isotope composition in the unoxidised mineral. Precipitation of covellite at the oxidation front of the tailings profile resulted in a significant enrichment of the lighter Cu isotope in the bulk soil with a δ65Cu value as low as -4.35 ±0.02 ‰. Fe isotope fractionation in the Kristineberg test cell varied due to processes such as Fe(II)-Fe(III) equilibrium and precipitation of Fe-(oxy)hydroxides at the oxidation front, where δ56Fe values were higher than in the initial material. As a way to link the obtained results from this thesis, a self-restored mine site was studied. A variation towards higher δ65Cu values was seen from rocks, to water and biofilms. Cu absorption mainly by extrapolymeric substances and secondary mineral precipitation regulates the isotopic composition of the biofilm. Oxidative weathering of sulphide minerals and further precipitation of Fe-(oxy)hydroxides are considered to be the main causes for Fe isotope fractionation in this area. Summing up, this thesis provides several field studies to corroborate the data observed in the lab regarding processes that are important for the biogeochemical cycling of metals and could be further applied to the extraction of metals or for remediation purposes.
Godkänd; 2013; 20131028 (natper); Dissertation to be held in public in room E632 on Tuesday 17th of December at 10:00 am. External examiner: Dr. Dominik Weiss, Department for Earth Sciences and Engineering, Imperial College London. Chairman: Professor Björn Öhlander, Division of Geosciences and Environmental Engineering, Luleå University of Technology. --- Tillkännagivande disputation 2013-11-22 Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Nathalie Pérez Rodríguez Ämne: Tillämpad geologi/Applied Geology Avhandling: Biotic and Abiotic Isotope Fractionation of Copper and Iron. From the Lab to the Field Scale Opponent: Dr Dominik Weiss, Reader, Department of Earth Science & Engineering, Imperial College of London, UK Ordförande: Professor Björn Öhlander, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Tid: Tisdag den 17 december 2013, kl 10.00 Plats: E632, Luleå tekniska universitet

Gas chromatography mass spectrometry (GCMS) and inductively coupled plasma mass spectrometry (ICPMS) were evaluated for the measurement of selenium (Se) and Se stable isotope ratios. GCMS and ICPMS were found to be accurate for quantitative Se analysis in biological matrices by isotope dilution using Se-78 and Se-76 as internal standards, respectively. A higher precision was obtained for ICPMS than GCMS enabling a smaller quantity of the tracer to be administered to subjects in labelling experiments. The isotopes of choice for metabolic tracers were Se-76 when sample analysis was by GCMS and Se-77 and Se-82 when analysis was by ICPMS. The influence of copper (Cu) on endogenous fecal Se excretion and true absorption of Se in nonlactating Holstein cows was examined by the use of Se stable isotopes as tracers. The method involved the application of conventional balance techniques in conjunction with isotopic enrichment of the body Se pools. Selenium in several tissues following oral and intravenous routes of isotope administration were evaluated as the precursors of endogenous fecal Se. Two cows fed a Se deficient diet (0.035 mg kg⁻¹) were administered 4 mg Se-76 orally, daily, for 5 d. After a 10-d equilibration period total collection of feces was made daily for two 5-d periods. The animals were then sacrificed and samples obtained from all major tissues and fluids. Se-7 6 enrichment (tracer/tracee mass percent, TTMP) in tissues was variable (< 0.56 - 13.4). However, enrichment was similar (9.8 - 12.9) in the tissues considered as potential contributors to endogenous fecal Se (serum, epithelium of the stomach, liver, bile, pancreas, small intestine and colon). Enrichment in serum and liver was used to calculate endogenous fecal Se. Apparent absorption of Se in the two cows was negative (-37 and -147 µg d⁻¹). Correction of apparent absorption for the fecal Se of endogenous origin gave a true Se absorption (% of intake) of 10 and 16%. The percentage of total fecal Se of endogenous origin was 23 and 36%. In two trials, 5 or 6 cows were assigned to one of two Cu-supplemented treatment diets: 0 mg kg⁻¹ or 17 mg kg⁻¹. The basal diet contained 0.19 mg Se kg⁻¹ and 13 mg Cu kg⁻¹. To each cow ~4.6 mg Se-77 and ~1.3 mg Se-82 were administered by oral and intravenous routes, respectively. After a 14-d equilibration period, total collection of feces and urine were made daily for two 5-d periods. Serum was collected on the first, third and fifth days of each period. Liver biopsies were taken 2 d following the completion of the balance periods. The estimates of endogenous fecal Se ( d⁻¹) from enrichment in the serum (256) and liver (235) following oral administration of the tracer and from enrichment in serum (241) following intravenous administration were not significantly different (P>0.05) but were higher than the estimate from the enrichment in liver (197) (P<0.05). No significant differences (P>0.05) were present when true absorption ( µg d⁻¹) was determined from enrichment in serum (290) or liver (268) following oral administration or from enrichment in serum (274) or liver (230) following intravenous administration. It was concluded the analysis of serum or liver with oral administration or the analysis of serum with intravenous administration of the tracer would provide reliable methods for estimation of endogenous fecal Se and true absorption. There was no effect of Cu on endogenous fecal Se excretion or true absorption of Se. Apparent and true absorption were 3.2 and 11%, respectively. Approximately 90% of the total Se excreted was in the feces, of which, 9.7% was of endogenous origin. The use of Se stable isotopes as metabolic tracers in dairy cattle provided a safe alternative to the use of radioactive tracers and enabled experiments requiring multi-isotopic enrichment to be performed.
Land and Food Systems, Faculty of
Graduate