Weathering of Copper Deposits and Copper Mobility: Mineralogy, Geochemical Stratigraphy, and Exploration Implications

Weathering of pyrite and copper sulfide-bearing rocks produces a consistent series of iron- and copper-bearing minerals that reflect vertical and lateral geochemical changes as supergene solutions react with rock and experience loss of oxidizing capacity. Reactive host rocks, comprising feldspars, mafic minerals, chlorite, and carbonates, buffer pH values that limit copper mineral destruction, thus restricting the supergene transport of copper. Generally, rocks that have undergone well-developed hypogene or supergene hydrolysis of aluminosilicates promote copper mobility because they do not react substantially with low-pH supergene solutions generated by oxidation of pyrite and associated copper sulfides. Development of geochemical stratigraphy is characterized by physical and geochemical parameters that determine the maturity of a supergene profile, with cyclical leaching and enrichment periods critical for the production of economically significant copper accumulation. Evidence for multicycle enrichment is recorded by hematite after chalcocite, hanging zones of copper oxides that replace chalcocite, and hematitic capping overlying immature goethitic-pyritic capping. Because pyrite is the most refractory sulfide with respect to chalcocite replacement, geochemically strong supergene enrichment is independent of total copper added to protore and instead is indicated qualitatively by the degree to which chalcocite replaces pyrite. Covellite replacement of chalcopyrite indicates weak copper addition to protore and generally represents the base and lateral extent of supergene enrichment; covellite replacement of chalcocite indicates incipient copper removal by copper-impoverished supergene solutions. Exploration for, and delineation of, mature supergene enrichment profiles benefits from the recognition of paleoweathering cycles and consequent development of mature geochemical stratigraphy.

Total and Exchangeable Copper Assay Using Inductively Coupled Plasma Mass Spectrometry and Establishment of a Pediatric Reference Interval

Context.— Recently, an exchangeable copper (CuEXC) assay has been suggested as a robust and feasible diagnostic tool for Wilson disease (WD). Although WD is a disorder that requires lifelong treatment and monitoring, few data are currently available regarding the status of copper levels in children. Objective.— To evaluate the performance of copper assays and establish a reference interval for total copper and CuEXC in the pediatric population. Design.— Serum samples from children aged 1–5 (n = 122), 6–12 (n = 125), and 13–18 years (n = 120) were analyzed. Total copper and CuEXC concentrations were directly measured using inductively coupled plasma mass spectrometry, and relative CuEXC levels were calculated. Total copper reference intervals, CuEXC levels, and relative CuEXC levels were determined based on the 2.5th and 97.5th percentiles of the data with 90% confidence intervals. Results.— There were significant differences in the median concentrations of total copper and relative CuEXC among the age groups. Reference intervals determined for total copper were 82 to 167, 75 to 139, and 64 to 133 μg/dL for children aged 1 to 5, 6 to 12, and 13 to 18 years, respectively. The reference intervals for CuEXC were 4.29 to 9.79, 4.02 to 9.09, and 3.55 to 8.25 μg/dL for children aged 1 to 5, 6 to 12, and 13 to 18 years, respectively. Among 11 patients with suspected WD, relative CuEXC values were elevated in all 3 diagnosed with WD. Conclusions.— The pediatric reference intervals derived in this study are expected to be useful for the diagnosis, differential diagnosis, treatment, and monitoring of pediatric patients with WD.

The variability and covariability of dissolved and particulate metal concentrations in the Rhine River

<p>To predict the transfer and fate of metal contaminants in river systems, a thorough understanding of the factors controlling metal concentrations is essential. This study examines the variability and covariability of dissolved and particulate metal concentrations in the Rhine River at the Lobith monitoring station in the Netherlands in the period 2009 -2017. The data analysis concentrated on copper and zinc as these metals were not affected by limits of detection. The total copper and zinc concentrations are significantly linearly related to the suspended sediment concentrations. The intercept of this relation represents the mean dissolved metal concentration and the gradient the mean particulate metal concentrations. The thus estimated mean dissolved and particulate concentrations of zinc and copper resemble mean measured concentrations. For both metals, the particulate concentrations are only weakly positively correlated to the dissolved concentrations. This correlation can be attributed to the fact that both the dissolved and the particulate concentrations of copper and zinc are negatively related to river discharge, where the decline of the particulate concentrations in response to increasing discharge is relatively larger than that of the dissolved concentrations. When the particulate metal concentrations are standardised for the diluting effect of discharge, the standardised particulate metal concentrations do not correlate significantly with the dissolved concentrations. This may indicate that the sediment solid/liquid partition coefficients (Kd-values) for the considered metals vary considerably in time, although this hypothesis requires further investigation.</p>

The Influence of Olive Orchards Copper-Based Fungicide Use, in Soils and Sediments—The Case of Aetoliko (Etoliko) Lagoon Western Greece

In this study, soil and aquatic sediments were sampled in the Aetoliko Lagoon and its catchment area, which is exclusively dominated by olive orchards. For the first time in Greece, soil as well as sediments samples of one coherent protected aquatic ecosystem were directly compared. In order to determine the influence that the usage of copper-based fungicides have on the lagoon sediments and on the soils of the surrounding area, twenty five (25) soil samples from different olive orchards that are bordering the water body and ten (10) sediment samples from the bottom of the lagoon were taken. The samples were analyzed for total copper content (total digestion) and extractable copper (diethylenetriaminepenta acetic acid, DTPA, extraction method). Furthermore, soil/sedimentological and geochemical analyses such as pH, grain size, total organic carbon, total sulfur, total nitrogen, and calcium carbonate content were carried out. The results show that the total copper in soils ranges from 58.37 to 671.33 mg kg−1. In addition the DTPA-extractable copper in soils has an average value of 45.00 mg kg−1. The average value of total copper in soils (286.24 mg kg−1) is higher than the threshold value for the Cu concentration (100 mg kg−1) set by the EU countries. Total copper content in the lagoon sediments is lower than in soils and varies between 43.85 mg kg−1 and 71.87 mg kg−1. The DTPA-extractable copper in sediments is in low ranges from 0.14 to 0.60 mg kg−1. On average, the total copper value for the lagoon sediments (55.93 mg kg−1) exceeds the Toxicity Screening Value (25.20 mg kg−1) for Cu in freshwater sediments. From the present study, it is clear that, although the copper in soils of the surrounding lagoon area exceeds the threshold limit for ecological risk, the lagoon sediments are influenced in a smaller degree. Our study can be used as a valuable reference and baseline for future studies on the environmental monitoring of the Aetoliko lagoon, as well as for studies in similar ecosystems.

Copper Availability from the Recycling of Electric Vehicles in Europe, North America and China: A Model Based Estimation until 2050

The expected increase in electric mobility is accompanied by an additional demand for copper, which is needed for the electric drivetrain consisting of the electric motor and auxiliary components. Key of the presented work is a simulation model to assess the implications of this additional copper demand on stocks and scrap flows of copper in the EU28, North America and China until the year 2050. The calculation results indicate that in the mid 2030s the copper used for electric vehicles starts having a considerable influence on both stocks and scrap flows. With 3 million tonnes of additional copper scrap in 2050, scrap from electric vehicles accounts for ~17% of China's total copper scrap. In absolute terms, this scrap flow is five times higher than the corresponding flows in Europe and North America. Therefore, China seems to be particularly promising as a location for recyclers and (secondary) copper smelters to expand their businesses.