Copper Supply Research Articles

Resource efficiency in the German copper cycle: Analysis of stock and flow dynamics resulting from different efficiency measures

In the context of the increasing depletion of finite natural resources and associated environmental and social problems, it is vital for societies to understand the drivers of resource demand and develop strategies to reduce its negative impacts. One such strategy is the move towards a circular economy, in which linear industrial systems are turned into circular systems where former waste streams from one part of the system can act as inputs in other parts. This includes the substitution of primary with secondary materials, thus reducing some of the negative impacts of primary production. The extent to which this is possible depends on the amount of retired material stocks that are made available for re-use. This article develops a methodology for analyzing material flows in relation to the wider economic system for the special case of copper. For this, a macroeconomic simulation model and a substance flow model are coupled to determine sectoral copper demand on the one hand, and the availability of secondary copper on the other hand. A number of scenarios aimed at reducing primary copper demand or increasing the supply of secondary copper are modeled. The results vary considerably between scenarios, depending on which material efficiency measure is analyzed. Due to delays in the retirement of copper stocks, trade-offs can be observed between reductions of original material demand and the availability of secondary material.

Mitochondrial copper homeostasis and its derailment in Wilson disease.

In mitochondria, copper is a Janus-faced trace element. While it is the essential cofactor of the mitochondrial cytochrome c oxidase, a surplus of copper can be highly detrimental to these organelles. On the one hand, mitochondria are strictly dependent on adequate copper supply for proper respiratory function, and the molecular mechanisms for metalation of the cytochrome c oxidase have been largely characterized. On the other hand, copper overload impairs mitochondria and uncertainties exist concerning the molecular mechanisms for mitochondrial metal uptake, storage and release. The latter issue is of fundamental importance in Wilson disease, a genetic disease characterized by dysfunctional copper excretion from the liver. Prime consequences of the progressive copper accumulation in hepatocytes are increasing mitochondrial biophysical and biochemical deficits. Focusing on this two-sided aspect of mitochondrial copper, we review mitochondrial copper homeostasis but also the impact of excessive mitochondrial copper in Wilson disease.

The impact of commodity price shocks in a copper-rich economy: the case of Chile

The present paper analyzes how shocks to the copper price affect the economy of Chile, the world’s largest producer of this metal. Chile is an interesting case study, it being an emerging commodity producing economy that has a fiscal rule, which explicitly takes into account the expected future copper price, and has adopted an inflation targeting monetary policy with a fully floating exchange rate. The empirical analysis consists in estimating structural vector autoregressive models where the shocks are identified by sign restrictions in order to make the distinctions of those caused by increasing world demand, decreasing copper supply, and specific copper demand, e.g., speculation in future price increases. Positive copper price shocks, independently of the source, result in an appreciated currency, whereas the effects on the other macroeconomic variables do depend on the source of the shock. While demand shocks affect the Chilean gross domestic product positively, this is not the case when the copper price increases because of a supply-side event or a specific copper demand. Particularly, the activity in the mining sector is affected, while the non-mining sector expands only when the shock is caused by increasing world demand. One explanation could be the stabilizing effect of the fiscal rule. The impacts on inflation and the interest rate are correlated because of the inflation targeting monetary policy.

Copper supply and fruit yield of young Citrus trees: fertiliser sources and application methods

ABSTRACT This study aimed to evaluate the fertiliser sources and application methods of copper (Cu) in citrus trees during the first years of fruit production. Two experiments were set up in an orchard with 3-year-old sweet orange trees, which were applied with three sources of Cu (nitrate, sulfate or EDTA) either via fertigation (Experiment 1) or via foliar sprays (Experiment 2). Regardless of the fertiliser source, Cu application via fertigation was not efficacious to increase the micronutrient concentration in leaves and, consequently, did not affect fruit yield. Conversely, foliar application of Cu, either as nitrate or sulfate, increased this nutrient level in leaves but when applied as copper nitrate, visual phytotoxicity symptoms were verified in leaves due to salt accumulation in the plant canopy, which reduced the fruit yield. Considering the plant growth and intensified phytosanitary management of the orchard with the application of copperbased products after the third year of the experiment, the effects of Cu treatments on fruit yield are expected to be negligible as the trees age.

Mining linkages in the Chilean copper supply network and regional economic development

The geographical expansion and increasing complexity of extractive production imply that the effect of mining linkages on economic development is unevenly felt inter- and intra-nationally. This article uses the linkages-based approach to understand from a multi-scalar perspective the uneven development patterns that could arise within a country related to the mining activity. For this purpose, we analyze the strength and potential quality of the mining linkages in the Chilean regions using information from input-output tables between 1995 and 2011 and a sample of almost 4000 mining services suppliers. Results show that the potential for high quality win-win mining linkages in the Chilean mining regions is very weak something that strongly constrains their possibility of achieving sustainable forms economic development.

Assessing environmental implications associated with global copper demand and supply scenarios from 2010 to 2050

Abstract Utilisation of resources is closely linked to population growth and economic and technological development. Hence, it is expected that global resource demand will increase substantially over the next decades. This resource challenge is currently partly addressed by the UNEP-IRP resource scenario activity, where metals, non-metallic minerals, and biomass resource availability and consumption scenarios are being developed. Advancements in the understanding of environmental impacts induced by anthropogenic activities indicate that large-scale exploitation of metal resources adversely affects the natural environment. Global copper demand is expected to grow significantly over the next decades, which is likely to result in increasing environmental stress and can be problematic for efforts to reduce the global environmental footprint. This research aims to estimate environmental implications of copper demand scenarios from present to mid-century by applying a life cycle sustainability analysis (LCSA) methodology. The results indicate that the environmental impacts related to global copper supply are expected to increase substantially between 2010 and 2050 – e.g., the carbon footprint is estimated to increase by 100% to 200%, depending on the scenario. This research discusses the main drivers of growing environmental implications of global copper supply scenarios and shows potential focus areas for mitigation policies.

Nutritional Assessment and Management for Patients with Chronic Liver Disease

When liver disease is severe, the prognosis can be worse if the patient is malnourished. Adequate nutritional support for patients with liver diseases can improve the patient's condition and prognosis. In the case of liver cirrhosis, malnutrition can occur due to a variety of causes, including poor oral intake, maldigestion, malabsorption, associated renal disease, and metabolic abnormalities. For a nutritional assessment, it is important to check the dietary intake, change in body composition, including anthropometry, and a functional assessment of muscle. Counselling and oral or enteral nutrition is preferred over parenteral nutrition as in other diseases. If esophageal varices are present, care should be taken when installing a feeding tube, but if there are ascites, percutaneous endoscopic gastrostomy is contraindicated because of the risk of complications. Calories of 30-35 kcal/kg/day and protein from 1.2 to 1.5 g/kg/day are appropriate. Protein restriction is unnecessary unless the hepatic encephalopathy is severe. A late evening snack and branched chain amino acids can be helpful. In the case of cholestasis, the supply of manganese and copper should be restricted. Sarcopenia in patients with liver cirrhosis is also prevalent and associated with the prognosis.

Copper-Induced Modulation of Biomass Growth, Physiological Parameters, Bioactive Centellosides, and Expression of Biosynthetic Pathway Genes in an Important Medicinal Herb, Centella asiatica

Hydroponically established Centella asiatica plants were studied under different concentrations of copper (0, 0.32,1.6, and 3.2 µM) for their morphological, physiological, and biochemical characteristics. The plants grown in the medium without any exogenous supply of copper showed improved biomass accumulation with maximum fresh weight (FW = 24.7 g plant−1) and dry weight (DW = 2.35 g plant−1). The total chlorophyll content, leaf number, and the leaf area were higher (0.27 mg g−1 DW, 20 and 100.54 cm2) in the plants grown under copper-deficient conditions. The toxic effects of increased levels of copper were evident by significant inhibition in growth and other morphological parameters. Copper treatment showed an increase in malondialdehyde (MDA) content and SOD activity. Bioactive phytochemical profiling using HPLC analysis revealed that higher levels of copper (1.6 and 3.2 µM) inhibit the accumulation of total centelloside content. The differential accumulation of centelloside content was further validated by the consistent pattern of expression of key pathway genes related to centelloside production in copper-treated C. asiatica plants. The study unveiled some of the important facts associated with the mechanism of copper tolerance in this important medicinal herb C. asiatica. The findings of the present study can be further used to provide better production of high value, in demand centellosides.

The Great War and the transformation of the Atlantic copper trade

ABSTRACT Just before the First World War, 70% of the globe’s copper was mined or processed in the U.S. At that time, nearly the same percentage of copper was consumed in Europe – the vast majority of which originated from American mines. At first glance, a trade dynamic of this sort would appear to strongly favour the position of U.S. producers; surprisingly, sources indicate that control of the world’s copper trade was largely the prerogative of a select group of German metal trading companies – the largest and most influential among them was Metallgesellschaft (MG). The following essay explores the competitive dynamics among producers, consumers, and intermediary groups. It argues that U.S. producers were only able to gain substantive control over the supply and marketing of copper in the wake of the economic disruption caused by the Great War.

(Invited) Fabrication and Characterization of Copper-Silica-Metal Resistive Switching Devices

Switching in metal-oxide-metal devices has been studied since the late 1960s. A number of mechanisms have been identified to explain the change in resistance in such structures, including the formation of metallic filaments which bridge the insulating layer and provide a low resistance pathway between the electrodes. The low power “cationic” switching of copper-silica-metal devices, where the metal is a relatively inert conductor (e.g., tungsten), has gained attention in recent times as these materials are already present in the back-end-of-line (BEOL) of integrated circuits, making device integration simpler and less expensive than in the case of more “exotic” resistive switching systems. This technology is a variant of programmable metallization cell (PMC) or conductive-bridging random access memory (CBRAM). The switching mechanism involves the transport of copper ions in the oxide and their subsequent reduction to form the conducting metallic pathway. The oxidizable electrode provides ions into the reaction environment to maintain the supply of copper for the growing filament. The switching process is bipolar, in that a bias opposite to that used for writing is required to reverse the filament formation process to return the device to its high resistance state. The copper-silica-metal structures exhibit similar switching characteristics to previously-commercialized devices based on higher chalcogenide glasses, albeit at somewhat lower switching speed for the same programming voltage, while possessing inherently greater CMOS compatibility. Devices have been fabricated using either physical vapor deposition (PVD) or chemical vapor deposition (CVD) of the silica under conditions that allow the film to have a slightly lower density than a typical deposited oxide to promote ion transport and facilitate filament formation. A forming step is required to form a switchable region in the oxide and following this, sub-µs switching at low voltage and current is readily attainable. In this talk we will report on the operational characteristics of these copper-silica-metal devices and the effect of different processing approaches on individual structures as well as crossbar arrays. We will also show the results of impedance spectroscopy analysis as they pertain to the physical structure of the devices. The applications of this technology range from active and passive non-volatile memories to neuromorphic elements and physical unclonable functions (PUFs) for physical and cyber security and these uses will be highlighted in the talk.

Mitochondrial Ferredoxin Determines Vulnerability of Cells to Copper Excess

SummaryThe essential micronutrient copper is tightly regulated in organisms, as environmental exposure or homeostasis defects can cause toxicity and neurodegenerative disease. The principal target(s) of copper toxicity have not been pinpointed, but one key effect is impaired supply of iron-sulfur (FeS) clusters to the essential protein Rli1 (ABCE1). Here, to find upstream FeS biosynthesis/delivery protein(s) responsible for this, we compared copper sensitivity of yeast-overexpressing candidate targets. Overexpression of the mitochondrial ferredoxin Yah1 produced copper hyper-resistance. 55Fe turnover assays revealed that FeS integrity of Yah1 was particularly vulnerable to copper among the test proteins. Furthermore, destabilization of the FeS domain of Yah1 produced copper hypersensitivity, and YAH1 overexpression rescued Rli1 dysfunction. This copper-resistance function was conserved in the human ferredoxin, Fdx2. The data indicate that the essential mitochondrial ferredoxin is an important copper target, determining a tipping point where plentiful copper supply becomes excessive. This knowledge could help in tackling copper-related diseases.

Community structure of copper supply networks in the prehistoric Balkans: An independent evaluation of the archaeological record from the 7th to the 4th millennium BC

Complex networks analyses of many physical, biological and social phenomena show remarkable structural regularities, yet, their application in studying human past interaction remains underdeveloped. Here, we present an innovative method for identifying community structures in the archaeological record that allow for independent evaluation of the copper using societies in the Balkans, from c. 6200 to c. 3200 BC. We achieve this by exploring modularity of networked systems of these societies across an estimated 3000 years. We employ chemical data of copper-based objects from 79 archaeological sites as the independent variable for detecting most densely interconnected sets of nodes with a modularity maximization method. Our results reveal three dominant modular structures across the entire period, which exhibit strong spatial and temporal significance. We interpret patterns of copper supply among prehistoric societies as reflective of social relations, which emerge as equally important as physical proximity. Although designed on a variable isolated from any archaeological and spatiotemporal information, our method provides archaeologically and spatiotemporally meaningful results. It produces models of human interaction and cooperation that can be evaluated independently of established archaeological systematics, and can find wide application on any quantitative data from archaeological and historical record.

Impacts of coal fly ash on plant growth and accumulation of essential nutrients and trace elements by alfalfa (Medicago sativa) grown in a loessial soil

Coal fly ash (CFA) is a problematic solid waste all over the world. One distinct beneficial reuse of CFA is its utilization in land application as a soil amendment. A pot experiment was carried out to assess the feasibility of using CFA to improve plant growth and increase the supply of plant-essential elements and selenium (Se) of a loessial soil for agricultural purpose. Plants of alfalfa (Medicago sativa) were grown in a loessial soil amended with different rates (5%, 10%, 20% and 40%) of CFA for two years and subjected to four successive cuttings. Dry mass of shoots and roots, concentrations of plant-essential elements and Se in plants were measured. Shoot dry mass and root dry mass were always significantly increased by 5%, 10% and 20% CFA treatments, and by 40% CFA treatment in all harvests except the first one. The CFA had a higher supply of exchangeable phosphorus (P), magnesium (Mg), copper (Cu), zinc (Zn), molybdenum (Mo), and Se than the loessial soil. Shoot P, calcium (Ca), Mg, Mo, boron (B), and Se concentrations were generally markedly increased, but shoot potassium (K), Cu, and Zn concentrations were generally reduced. The CFA can be a promising source of some essential elements and Se for plants grown in the loessial soil, and an application rate of not higher than 5% should be safe for agricultural purpose without causing plant toxicity symptoms in the studied loessial soil and similar soils. Field trials will be carried out to confirm the results of the pot experiment.

Fusaric acid contributes to virulence of Fusarium oxysporum on plant and mammalian hosts.

Fusaric acid (FA) is amongst the oldest identified secondary metabolites produced by Fusarium species, known for a long time to display strong phytotoxicity and moderate toxicity to animal cells; however, the cellular targets of FA and its function in fungal pathogenicity remain unknown. Here, we investigated the role of FA in Fusarium oxysporum, a soil-borne cross-kingdom pathogen that causes vascular wilt on more than 100 plant species and opportunistic infections in humans. Targeted deletion of fub1, encoding a predicted orthologue of the polyketide synthase involved in FA biosynthesis in F. verticillioides and F. fujikuroi, abolished the production of FA and its derivatives in F. oxysporum. We further showed that the expression of fub1 was positively controlled by the master regulator of secondary metabolism LaeA and the alkaline pH regulator PacC through the modulation of chromatin accessibility at the fub1 locus. FA exhibited strong phytotoxicity on tomato plants, which was rescued by the exogenous supply of copper, iron or zinc, suggesting a possible function of FA as a chelating agent of these metal ions. Importantly, the severity of vascular wilt symptoms on tomato plants and the mortality of immunosuppressed mice were significantly reduced in fub1Δ mutants and fully restored in the complemented strains. Collectively, these results provide new insights into the regulation and mode of action of FA, as well as on the function of this phytotoxin during the infection process of F. oxysporum.

Thiol‐based copper handling by the copper chaperone Atox1

Human antioxidant protein 1 (Atox1) plays a crucial role in cellular copper homeostasis. Atox1 captures cytosolic copper for subsequent transfer to copper pumps in trans Golgi network, thereby facilitating copper supply to various copper-dependent oxidereductases matured within the secretory vesicles. Atox1 and other copper chaperones handle cytosolic copper using Cys thiols which are ideal ligands for coordinating Cu(I). Recent studies demonstrated reversible oxidation of these Cys residues in copper chaperones, linking cellular redox state to copper homeostasis. Highlighted in this review are unique redox properties of Atox1 and other copper chaperones. Also, summarized are the redox nodes in the cytosol which potentially play dominant roles in the redox regulation of copper chaperones. © 2016 IUBMB Life, 69(4):246-254, 2017.

The role of insufficient copper in lipid synthesis and fatty-liver disease.

The essential transition metal copper is important in lipid metabolism, redox balance, iron mobilization, and many other critical processes in eukaryotic organisms. Genetic diseases where copper homeostasis is disrupted, including Menkes disease and Wilson disease, indicate the importance of copper balance to human health. The severe consequences of insufficient copper supply are illustrated by Menkes disease, caused by mutation in the X-linked ATP7A gene encoding a protein that transports copper from intestinal epithelia into the bloodstream and across the blood-brain barrier. Inadequate copper supply to the body due to poor diet quality or malabsorption can disrupt several molecular level pathways and processes. Though much of the copper distribution machinery has been described and consequences of disrupted copper handling have been characterized in human disease as well as animal models, physiological consequences of sub-optimal copper due to poor nutrition or malabsorption have not been extensively studied. Recent work indicates that insufficient copper may be important in a number of common diseases including obesity, ischemic heart disease, and metabolic syndrome. Specifically, marginal copper deficiency (CuD) has been reported as a potential etiologic factor in diseases characterized by disrupted lipid metabolism such as non-alcoholic fatty-liver disease (NAFLD). In this review, we discuss the available data suggesting that a significant portion of the North American population may consume insufficient copper, the potential mechanisms by which CuD may promote lipid biosynthesis, and the interaction between CuD and dietary fructose in the etiology of NAFLD. © 2016 IUBMB Life, 69(4):263-270, 2017.

Econometric modeling of recycled copper supply

The supply of recycled material depends on historic consumption, i.e. what constitutes scrap available today originates from previously made products. Analytical tools, such as materials flow analysis, use this observation to estimate scrap metal flows. The supply of recycled metal also depends on changing economic conditions, e.g. metal consumption rates correlate with changes in gross domestic product. We use an autoregressive distributed lag approach to model the supply of recycled copper as a complementary approach to material flow analysis. We find that both industrial activity and world GDP correlate with total scrap supply, with limited dependence on copper price. We also develop independent models for direct remelt (higher quality) and refined (lower quality) scrap. A 1% increase in industrial production leads to a 2.1% increase in higher quality scrap quantity, while a similar increase in world GDP leads to a 1.4% increase in lower quality scrap. Based on this model dependence, we suggest that a recycling policy aimed at increasing recycling through the use of subsidies, taxes or price incentives should be directed towards the low-end segment of the scrap market and there it may still only have limited impact.

Copper for the Pharaoh: Identifying multiple metal sources for Ramesses' workshops from bronze and crucible remains

The origin of copper used in Late Bronze Age (LBA) Egypt is very poorly understood despite its cultural and economic importance attested in archaeological and historical sources. Extensive literature discusses major LBA copper sources such as Cyprus (oxhide ingots), Oman (bun ingots) and Egyptian-controlled sites in the Sinai. This paper presents new chemical and lead isotope data for Egyptian copper alloys excavated in several bronze production workshops from the New Kingdom capital Pi-Ramesse, expanding on earlier data from Amarna. Supporting data is obtained from the analysis of crucible remains from the same context, for which the potential contribution of lead isotope analysis is critically evaluated.Diachronic changes in the provisioning of these Egyptian workshops are discussed, incorporating an extensive overview of currently known Egyptian mining and metallurgy. The results have major implications for our understanding of LBA copper circulation in the wider region, for the first time analysing a major Egyptian ‘consumer’ assemblage.The analytical results reveal a complex picture of variable copper supply to the Ramesside workshops, which involved both the recycling of existing bronzes and the use of freshly smelted copper from various origins to produce fresh alloys. Importantly, this includes crucial new evidence for the melting of (Cypriot) oxhide ingot fragments in crucibles for alloying.The royal, internationally connected nature of these workshops makes Pi-Ramesse an exceptional case study of LBA metal trade, and hypotheses raised in this paper highlight the need for more extensive analysis of ancient Egyptian copper artefacts to grasp metal circulation throughout Egypt's long history. More refined frameworks, incorporating the variety of private as well as royal contexts, will improve understanding of Egypt's ancient economic organisation. This paper offers new perspectives onto LBA metal supply and consumption networks, with broader archaeological interpretative models of economic and political interactions across the wider ancient Near East.

Future copper resources

Concerns about future supplies of raw materials demand careful examination of underlying assumptions and data. Flawed deposit information, ignored undiscovered resources and questionable assumptions about future consumption require a new look at copper resources.A careful compilation of 1978 copper-bearing mineral deposits totals 2700 million metric tons of copper including past production—considerably more than reported in previous studies. About 69% of the copper is in porphyry copper deposits and 12% in sediment-hosted copper, Magmatic sulfide (mostly intrusive Ni) deposits account for 5.1%, and IOGC adds about 4.7%. VMS deposits represent 45% of the 1978 deposits but only 4.9% of the copper.The largest 20% of the deposits account for over 92% of the total copper metal. In other words, total Cu content in the smaller 1600 deposits is only about 8% of all Cu known in all deposits. This is a consequence of highly skewed frequency distributions of deposit tonnages and contained metals in all kinds of mineral deposits. This relationship is critical if one is concerned about long-term supply of copper. Typically, distributions of contained metal can be modeled well by the lognormal distribution for individual types of deposits.Information used here and in many other studies on copper includes past production. Total past production through 2015 is about 667 million tons Cu. After subtracting past production from the total copper in known deposits, the remaining unproduced copper from known deposits is 2030 million tons. Known deposits inform us about undiscovered copper resources.Over 80% of known copper is in porphyry copper and sediment-hosted copper deposits. A reliable and robust USGS managed global assessment of 225 tracts for porphyry Cu and sediment-hosted Cu produced an expected value estimate of 3500 million tons Cu in undiscovered deposits. Deposit types not assessed such as IOGC are likely to have significant amounts of undiscovered copper. If the proportion of total Cu accounted for by the two major deposit types assessed is the same proportion in all undiscovered deposits, total Cu expected in these other deposit types would add an additional 850 million tons. The reasonable estimate of copper in undiscovered mineral deposits of 4350 million tons when added to the unmined 2030 million tons in known deposits provides an estimate of 6380 million of tons Cu, which far exceeds estimates published by other researchers.Growth in copper production appears to be exponential over time but appears to be linear with respect to population. Demand for copper is not driven by time, but rather by population and per capita income. Rates of population increases are slowing and incomes in many countries are increasing. Per capita consumption of copper will increase over the coming years as populous nations such as China and India develop increasing per capita incomes, but the demand will likely level off as their economies improve. The large estimated copper resources along with evidence of slowing demand for copper over the long term considerably extend the time of “peak copper” and the long mine life of large deposits means the decline in production after will not be rapid. The focus of copper supply concerns should be on important problems such as improving recovery rates, careful consideration of the benefits and costs of mining very large deposits, technologies to increase exploration success in covered areas and reducing costs of underground mining.

Butte And Anaconda, Montana: Preserving and Interpreting a Vast Landscape of Extraction

The mines of Butte, Montana led the world in the supply of copper from 1887 through the First World War. This period corresponds in human history with a new acceleration in the scale of the industrialized production of minerals, as the geography of extraction expanded. That scale of production required industrial infrastructure of tremendous size and complexity, creating cultural landscapes of extraction on a vast new scale, and leading to environmental impacts of a severity not previously seen. Such characteristics make the preservation of sites embodying the history of industrialized extraction daunting, as can be seen in the region embracing Butte and Anaconda, Montana. The legacy of environmental damage caused by the mining industry at Butte and Anaconda has created the largest Superfund site in the United States. Unfortunately, Superfund remediation is often incompatible with the preservation of some historic features of mining's industrial infrastructure. This article suggests how such a vast landscape of extraction around Butte and Anaconda can be interpreted through judicious attention to large historic landscape features that survive, that are compatible with and often integrated into the Superfund remediation, and that help to convey the complexity and scale of historical industrialized mineral extraction.