Distribution Of Copper Research Articles

Trace element concentrations in the organs of fish along the southeast coast of India

Trace element pollution in the marine system is a global concern as the exposure of marine organisms to this pollution results in bioaccumulation and further transfer of the trace elements to humans through food chain. In the present study, the distribution of trace elements, namely chromium, cobalt, nickel, iron, copper, zinc, arsenic, cadmium, mercury, and lead, in gills, bone, liver, and muscle of eight commercially important fish collected along the southeast coast of India was analyzed using an inductively coupled plasma mass spectrometer. The liver was the main organ of accumulation for copper, zinc, arsenic, cadmium, and mercury; bone for chromium, cobalt, and lead; gills for copper; and muscle for arsenic and mercury. The concentration of toxic trace elements such as arsenic, cadmium, mercury, and lead in the edible portion of fish was lower than the recommended International Legislation limits, indicating that the fish of this region are safe for consumption.

Copper concentration simulation in a river by SWAT-WASP integration and its application to assessing the impacts of climate change and various remediation strategies

The present study aimed to investigate the copper distribution in a river through the integrated utilization of the soil hydrological assessment model and water quality model. The Erren River was selected as the investigated river system because an apparent heavy metal pollution was observed. The Soil and Water Assessment Tool (SWAT) was employed to estimate the soil flux. The Water Quality Analysis Simulation Program Model (WASP) was used for water quality simulation. The copper was selected as the model chemical and scenarios of various copper effluent control measures and impacts of the heavy rainfall by climate change on copper concentration were simulated. The results showed that the aqueous copper was adsorbed to suspended solids and the high aqueous copper concentration resulted in a high copper concentration in the sediment. In dry seasons, the aqueous copper concentration increased 215% comparing to the 2006–2016 average (baseline) concentration and a 20% decrease in copper concentration in the sediment was observed due to less wash-out solid. Under the impact of enhanced rainfall by climate change, the aqueous copper concentration decreased due to the increased river flow, which also reduced the copper deposition causing the copper concentration in the sediment lower than that in the baseline condition. In the middle and downstream river sections, the copper concentration in the water and sediment phases decreased around 66% by implementing a more-stringent effluent standard. The suspended solid played a key role for copper movement in a river. The copper accumulation in the sediment might be alleviated by reducing its aqueous concentration.

Characteristics of heavy metals in surface water and assessment of water environment quality in the upper reaches of the Yellow River in recent 10 years

With the rapid development of economy, the load-bearing pressure of ecological environment is increasing, and human activities have brought tremendous challenges to surface water. In this paper, the surface water of 17 cities and counties in the upstream watershed of the reservoir in the source area of the Yellow River was taken as the research object. Based on the monitoring of the surface water quality section of the ecological transfer payment work in the national key ecological functional areas, surface water samples were collected quarterly from 2009 to 2018. Six heavy metal elements (cadmium, mercury, hexavalent chromium, lead, arsenic and copper) in surface water were analyzed in laboratory, and ArcGIS Kriging spatial interpolation method was used to study the spatial distribution characteristics of heavy metals in surface water in the upstream basin of the reservoir in the source area of the Yellow River. Meanwhile, the maximum membership degree method was used to evaluate the quality of water environment. The results showed that the spatial distribution of cadmium, mercury, hexavalent chromium, lead, arsenic and copper in the upstream of the reservoir in the source area of the Yellow River presented a dynamic change, and the high value of cadmium concentration appeared in the northeastern region of the evaluation area as a whole, showing a planar and strip distribution characteristics; the concentration values of mercury in the southwestern region of Maqu County and Luqu County were the highest, and in each county of the northeastern region were relatively lower. In the past 10 years, the average concentration of heavy metals in lead was 0.004 27 mg/L, and that in mercury was 0.000 4 mg/L. According to the maximum membership principle, the environmental quality of heavy metals in surface water in the upstream basin of the reservoir in the source area of the Yellow River in recent 10 years was superior.

Weld formation mechanism of fiber laser oscillating welding of dissimilar aluminum alloys

The development of high power galvanometer provides an opportunity to improve the weld formation of dissimilar aluminum alloys. In this paper, the influence of oscillating frequency and amplitude on weld formation of 6061/2A12 aluminum alloys was studied. Laser induced breakdown spectroscopy (LIBS) was used to detect the distribution of copper in weld section to explore the flowing of melting pool. The results showed that weld morphology became smooth and uniform with the increase of oscillating frequency and amplitude, reaching the optimized at frequency of 200 Hz and amplitude of 0.4 ∼1.2 mm. The front weld width increased and the backside weld width decreased gradually with the oscillating frequency and amplitude increased. The weld segregation was improved in laser oscillating welding, expressed by the mixing uniformity. It was mainly depended on oscillating frequency, and increased with the oscillating frequency increased. When increasing oscillating frequency or amplitude, the stirring intensity of the melting pool was increased. The melting pool was accelerated and mixed more evenly. Thus, the Cu is evenly distributed in the weld, and it can be detected on the side near 6061 base material.

Differing effects of inorganic and organic arsenic on uptake and distribution of multi-elements in Rice grain.

Arsenic (As) pollution can lead to an element imbalance in rice. A hydroponic study was carried out to examine the influence of inorganic (arsenate) and organic (dimethylarsinic acid (DMA)) arsenic compounds on the concentration and distribution of iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), nickel (Ni), carbon (C), nitrogen (N), and sulfur (S) in rice caryopsis at maturity using laser confocal microscopy and synchrotron X-ray fluorescence (SXRF). Results showed that treatments with inorganic (iAs) and organic (DMA) arsenic did not change the distribution characteristics of the above elements in rice grains. Fe, Mn, and iAs were mainly limited to the ventral ovular vascular trace, while Cu, Zn, and DMA extended into the endosperm. This implies that milling processes are likely to remove a majority of Fe, Mn, and iAs, but not Cu, Zn, and DMA. With regard to the average fluorescent intensity of the rice endosperm, iAs exposure caused significant reductions in Mn (53%), Fe (40%), Cu (27%), and Zn (74%) while DMA treatments decreased Mn (49%), Fe (37%), and Zn (21%). Compared with DMA, iAs exerted more influence on the reduction of these elements in rice caryopsis. In addition, the elemental analysis revealed a significant 12.7% increase for N and 8% reduction for S in DMA-treated rice caryopsis while a significant decrease of 24.0% for S in iAs-exposed rice caryopsis. These findings suggest that Cu, Zn, and S are more easily impacted by iAs, while N is mostly affected by DMA.

Crystal structures and charge distribution of partially-fluorinated β-diketonate copper(II) complexes based on Hirshfeld surface analysis and DFT calculations

Two partially-fluorinated coordination complexes, C30H20CuF2O4 (1) and C30H18CuF4O4 (2), were prepared and the corresponding crystals, 1 with a benzene solvate (1•C6H6) and 2, were obtained from a benzene-dichloromethane solution. The crystallographic studies and the Hirshfeld surface analysis of the crystals showed the metal⋯π interactions through an electrophilic property of the Cu ions and the remarkable CH⋯π interactions between the phenyl substitutions; the most important contributions for the crystal packing for 1 in 1•C6H6 are from the C⋯H/H⋯C (36.8%), H⋯H (34.0%), and F⋯H/H⋯F (10.4%) interactions but those for 2 are from the H⋯H (28.8%), F⋯H/H⋯F (22.9%), and C⋯H/H⋯C (19.2%). A density functional theory (DFT) calculation using the optimized structures from the crystal data clearly showed the proportion of the electron-withdrawing effects of the fluorine substitution and the corresponding effects on the central metal ions and the other aromatic rings.

Characterization of metal element distributions in the rat brain following ischemic stroke by synchrotron radiation micro-fluorescence analysis

Ischemic stroke is one of the leading causes of death worldwide, and effective treatment strategies in the chronic phase of this disease remain insufficient. Homeostasis of metals in the brain plays an important role in maintaining normal brain function. However, the dynamic spatial distributions of iron, zinc, calcium, potassium, and copper in a rat brain following ischemic stroke and the association between structural distribution and function remain to be elucidated. In this study, we used a synchrotron radiation-based micro-X-ray fluorescence technique to image element mapping changes in special rat brain regions after ischemic stroke, showing the distribution characteristics of iron, zinc, calcium, potassium, and copper. We demonstrated, for the first time, the consistent dynamic spatial distributions of metal elements at a series of time points (3 h, 4.5 h, 6 h, 12 h, 1 d, 3 d, 5 d, 7 d, 10 d, 14 d, 28 d) after brain ischemia, which revealed that the homeostasis of iron, zinc, calcium, potassium, and copper in the brain was disturbed with distinctive change trends, providing clear insights in understanding the underlying pathogenesis of stroke from a novel perspective, thus laying the foundation of further developing new drug targets for stroke treatment.

Spatial Distribution and Contamination Status of Copper and Chromium in Transshipment Area, Sichang Island, Thailand

Surface sediments were sampled at 22 locations in marine transshipment area in order to evaluate the distribution pattern, contamination status and ecological risk of Cu and Cr. The results of the metals distribution demonstrated that high concentrations of both Cu and Cr were found in the transshipment area, while lower concentrations were observed at the reference sites. Likewise, there were significant differences between the transshipment area and the reference site, indicating these were consequences of different outputs and activities. For comparison of the guidelines, concentrations of Cu and Cr were in a range that biological effects occasionally occur. Based on EF, concentrations of Cu and Cr indicated minor contamination. Also, all of the entire study area had low ecological risk.

Risk assessment via oral and dermal pathways from heavy metal polluted water of Kolleru lake - A Ramsar wetland in Andhra Pradesh, India.

The Kolleru Lake, India is a famous wetland of international significance. Analyses of certain potentially toxic heavy metal ions in water indicate that this freshwater lake is characterized by highly heterogeneous distribution of chromium (Cr; 4.5–80 μg/L), copper, iron (Cu, Fe; below detection limit), manganese (Mn; 1–313 μg/L) and zinc (Zn; below detection limit). Non-carcinogenic health risk assessment indices like hazard quotients (HQ) and hazard indices (HI) are estimated following the guidelines recommended by the US Environmental Protection Agency (USEPA). These indices are found to be within the acceptable limit (<1), indicating negligible potential health risk via ingestion and dermal routes. However, when the average values of these indices pertaining to the Kolleru lake are normalized with similar estimates from clean and uncontaminated global surface water, both high and low ratios are obtained. While Cr (12.5), Cu (2.3) and Mn (3.7) exhibit high ratios, those of Fe (0.09) and Zn (0.99) show respectively low and comparable values. The significance of such heterogeneous distribution of hazard indices and their ratios are discussed. Further, average carcinogenic risk levels of the adults and children due to Cr ingestion are estimated to be 0.00154 and 0.0022, respectively. Both values are higher than the permissible levels recommended by the USEPA. As a remediation measure, it is recommended that monitoring the levels of heavy metal in water and other items like fish in the lake or rice and vegetables grown in the area is needed to be carried out at regular intervals. This study therefore offers requisite perception to the local government and health officials to evolve their plan of action so that effective management and mitigation of water quality of the Kolleru lake can be administered.

Distribution of copper and zinc fractions in a Regosol profile under centenary vineyard

Phytosanitary treatments using Bordeaux mixture or zinc (Zn) fungicides are often used in vineyards, which increase soil copper (Cu) and Zn contents. In this study, the accumulation and distribution of Cu and Zn fractions (water soluble, exchangeable, oxidic, organic and residual fractions) was evaluated along a Regosol profile cultivated with vine since 1890 and treated with Bordeaux mixture. Copper and Zn contents of the superficial layer were around 2000 mg kg−1 and 170 mg kg−1, respectively, and decreased through depth profile. However, accumulation of these metals was also observed in deeper layers of the soil, until 50 cm depth. Most of the total Cu was bound to the mineral fraction, whereas Zn was predominantly in the residual one. In the superficial layer, the desorption potential was 25% for Cu and 46% for Zn of these metals total content. Although the dominance of chemical forms with low geochemical mobility, desorption of Cu and Zn occurs easily, representing a high risk of transference in the environment.

Mobility of Chromium, Copper and Arsenic in Amended Chromated Copper Arsenate Contaminated Soils

Aim: The use of copper-based preservatives such as chromated copper arsenate (CCA) and creosote to prolong the life of lumber present environmental concerns because they contain heavy metals and polycyclic aromatic hydrocarbons which are toxic to humans. The aim of this study was to investigate the effects of sewage sludge biosolid amendment on the distribution and mobility of chromium, copper and arsenic in chromated copper arsenate contaminated soils subjected to phytoremediation using maize (Zea mays L.).&#x0D; Place and Duration of the Study: Random composite soil samples from Kitetika wood factory, Wakiso, Uganda and sewage sludge biosolid from National Water and Sewerage Corporation plant in Bugolobi, Kampala, Uganda were collected and prepared. Maize grains were obtained from FICA Seeds Limited (Uganda). The pot experiments and analysis of samples were done at Mbarara University of Science and Technology (Mbarara) and Directorate of Government Analytical Laboratory, Kampala (Uganda), respectively. &#x0D; Methodology: The fresh CCA contaminated soils and sewage sludge biosolid were analyzed for physicochemical parameters and heavy metals (chromium, copper and arsenic). Sewage sludge biosolid was added to 1 kg of the contaminated soils at 5-25% (w/w) in 2 L plastic containers, watered and maintained at 25 ℃ for 14 days to stabilize. Controls were set up with unamended soils. Thereafter, maize was planted in the potted soils for 40 days. The concentrations of the trace metals in the soils were determined after 20 and 40 days of maize growth by atomic absorption spectroscopy.&#x0D; Results: The concentrations of chromium, copper and arsenic in fresh CCA contaminated soils were 365.8 ± 6.18 mg/kg, 109.72 ± 14.04 mg/kg and 28.22 ± 3.8 mg/kg, respectively. Basing on mobility factor, bioavailability of the trace metals followed the chemical sequence copper (8.9%) &lt; chromium (17.1%) &lt; arsenic (30.2%).&#x0D; Conclusion: The maize variety experimented could be used to phytoextract or phytostabilize the trace metals in the CCA contaminated soils without or with 5-25% amendment. Amendment with sewage sludge biosolid improved the phytoremediation potential of maize. Arsenic was the most mobile and bioavailable metal in CCA contaminated soils. Further studies should use other local maize varieties such as Longe series.

Dual electrospinning of a nanocomposites biofilm: Potential use as an antimicrobial barrier

The accumulation of plastic waste and infectious diseases has led the scientific community to search for new materials to make nanocomposites biofilms. With the help of nanotechnology, the materials that make up the new nanocomposites biofilm can be manipulated, achieving an improvement in its mechanical properties and granting antimicrobial powers. Biofilms based on electrospun fibers as a barrier material can protect against infectious microorganisms. For these applications, the electrospinning method allows the encapsulation of active agents in the polymeric fibers. This article presents the development of a nanocomposites biofilm with potential use as an antimicrobial barrier, which incorporates polylactic acid microfibers with active agents. Among them, copper ions supported on Chilean natural zeolite nanoparticles and reinforced with acetylated cellulose nanofibers. The study begins with obtaining cellulose nanofibers through mechanical methods. Nanofibers were acetylated to ensure adequate dispersion in the polymer matrix and to improve the mechanical properties of biofilms. Polymers and nanoparticles were incorporated into biofilms through a dual configuration (simultaneous injection) electrospinning stage.Results indicated that acetylated cellulose nanofibers with an average diameter of 83 nm were obtained. The FT-IR characterization confirmed the appearance of bands of adhered acetyl groups in primary hydroxyl groups of the nanocellulose. Morphological analysis of biofilms indicated the presence of continuous, randomly oriented microfibrillar structures and average fiber diameter from 1.7 μm to 2.4 μm. According to copper distribution maps, it was confirmed that the electrospinning technique was able to encapsulate nanoparticles of Chilean natural zeolite with copper ions. For all biofilms to which acetylated nanofibers were added, there was an increase in mechanical properties. The thermal degradation profile revealed that the addition of nanoparticles favored the thermal degradation resistance of films. The water vapor permeability test showed that the increased contraction of nanoparticles in the biofilms does not cause an increase in this parameter. The microbiological tests confirmed the biofilms antibacterial activity towards the Gram (-) Salmonella Typhimurium bacteria (responsible for foodborne diseases in poultry products) and Gram (+) Staphylococcus aureus (whose presence accounts for of sanitary and hygienic quality in food processing).

Using Ligand-Accelerated Catalysis to Repurpose Fluorogenic Reactions for Platinum or Copper.

The development of a fluorescent probe for a specific metal has required exquisite design, synthesis, and optimization of fluorogenic molecules endowed with chelating moieties with heteroatoms. These probes are generally chelation- or reactivity-based. Catalysis-based fluorescent probes have the potential to be more sensitive; however, catalytic methods with a biocompatible fluorescence turn-on switch are rare. Here, we have exploited ligand-accelerated metal catalysis to repurpose known fluorescent probes for different metals, a new approach in probe development. We used the cleavage of allylic and propargylic ethers as platforms that were previously designed for palladium. After a single experiment that combinatorially examined >800 reactions with two variables (metal and ligand) for each ether, we discovered a platinum- or copper-selective method with the ligand effect of specific phosphines. Both metal–ligand systems were previously unknown and afforded strong signals owing to catalytic turnover. The fluorometric technologies were applied to geological, pharmaceutical, serum, and live cell samples and were used to discover that platinum accumulates in lysosomes in cisplatin-resistant cells in a manner that appears to be independent of copper distribution. The use of ligand-accelerated catalysis may present a new blueprint for engineering metal selectivity in probe development.

Alternative wood preservation method: double treatment and its effectiveness against wood decay fungi

In this study, two single wood treatments—copper impregnation (I) with thermo-hydro treatment (T) and vice versa—were combined to determine the effectiveness against wood decay fungi. Pine (Pinus sylvestris L.) sapwood and birch (Betula spp.) boards were treated accordingly, then cut into small-size specimens and exposed to brown rot (Coniophora puteana) and white rot (Trametes versicolor) fungi to determine mass loss (ML). The specimens were collected from the board ends and middle part to detect copper distribution and, consequently, decay resistance. Wood leaching according to EN 84 was performed to evaluate the double treatment efficiency in outdoor conditions (use class 3, EN 335). The durability of the board ends and middle part differed in single-impregnated wood. The higher amount of copper at the board ends tended to cause lower ML. Double-treated I/T boards showed a similar tendency. In double-treated T/I wood, a higher copper amount at the board ends provided a higher ML in this part. Obviously, the interaction between thermal and chemical treatment has affected the wood structure, copper distribution and fixation. In leached pine and birch wood, the double treatments T/I and I/T were more efficient against brown rot than single thermo-hydro treatment and impregnation procedures, ensuring the durability class (DC) 2 (CEN/TS 15083–1). Regarding white rot, there was no pronounced difference between both double treatments and single treatments as they ensured DC1.

Simulation of Heavy Metal Pollution of Watercourses in the Basin of the Nizhnekamskoe Reservoir

The physically based ECOMAG-HM model, developed to simulate heavy metal cycles in large river basins, was used to study the spatial and temporal regularities in the formation of copper and zinc distributions in water bodies in the basin of the Nizhnekamskoe Reservoir. Maps of the mean annual concentrations of the metals in river network and the mean annual modules of diffuse runoff with its genetic components have been compiled. The contributions of point and diffuse sources to river water pollution by copper and zinc have been evaluated. To specify the estimates of the effect of economic activity on river water pollution, numerical experiments have been carried out to simulate the scenarios of an increase in the amount of metals discharged as wastewater components, wastewater emergency volleys, and complete elimination of anthropogenic impact on a drainage basin.

Understanding the process of smelting copper-rich high-silicon concentrates in combination with copper-rich high-sulphur concentrates

This paper describes an experimental study that looked at pyrometallurgical processing of high-silicon concentrates produced by the Jezkazgan Concentrator Plant in combination with high-sulphur copper sulphide concentrates from the Aktogay deposit. Additional components included converter slag and concentrate produced after flotation of cool converter slag from the Balkhash Smelter. A blend of the Aktogay and Jezkazgan concentrates mixed to the ratio of 1:2.6 was smelted in a laboratory environment at the temperature of 1,400 oC together with the additions of converter slag and converter slag concentrate. The study demonstrated the effect of the gas phase on the distribution of copper, iron and sulphur between the products. In an oxidation environment, mattes containing 51.9&ndash;56.6% of copper were obtained due to a high desulphurization degree of sulphide burden and partial conversion of iron into molten slag. In a reduction environment, typical of the smelting process adopted by the Jezkazgan Copper Smelter, the concentration of copper in mattes was 48.7&ndash;50.3%. The melting and conductivity temperatures of the produced slags were determined that would meet the smelting specification. The authors also demonstrate the possibility to produce mattes containing 49&ndash;50% of copper (which is in line with the bessemerizing specification adopted by the Jezkazgan Copper Smelter), as well as slags with low metal concentrations. The process of combined smelting of copper-rich low- and high-sulphur concentrates described in this paper can now be tested in the production environment of the Jezkazgan Copper Smelter.This research study was funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan under the Grant no. АР05130400.

Using X-ray microtomography to characterize the burrowing behaviour of earthworms in heterogeneously polluted soils

Large amounts of chemicals are released into soil environments due to human activities, thereby harming organisms and their habitats. Earthworms are important bioindicators for chemical risk assessments of soil ecosystems, but the question remains of how they respond to different patterns of pollution. Laboratory experiments in soil mesocosms were carried out to observe changes in the burrowing behaviour of two earthworm species (Aporrectodea caliginosa and Lumbricus terrestris) with regard to different spatial distributions of benzo(a)pyrene, cadmium and copper, using X-ray computed microtomography (μCT). This is, to our knowledge, the first contribution of μCT to study earthworm behaviour in heterogeneously multi-polluted soils. Columns (14 × 30 cm) were filled with a silt loam soil and packed to represent two scenarios of heterogeneous pollution: a) ‘binary’, containing polluted soil in the low half part and unpolluted soil on top; and b) ‘patches’, containing small portions of polluted soil randomly placed into an unpolluted matrix. Earthworms were introduced individually in the columns and left in climatic chambers for 7 weeks. μCT images revealed that earthworms avoided the polluted zones differently (e.g. A. caliginosa>L. terrestris, ‘binary’ configuration). Individuals of L. terrestris that entered polluted areas showed a lower burrowing activity (volume and length of the burrow system) than those that did not enter. The presence of ‘patches’ of polluted soil did not cause a reduction of the burrowing activity such as that found in the ‘binary’ columns, although earthworms showed avoidance. Our results indicate that pollutants had a greater effect on earthworms’ burrowing behaviour in the presence of larger portions of contaminated soil compared with small random ones. The more evident avoidance behaviour of A. caliginosa pinpoints its usefulness in toxicity bioassays based on avoidance patterns, but questions its use in assays based on bioaccumulation of pollutants in tissues, for which L. terrestris may perform better.

Optimization of the grain boundary character distribution of pure copper by low-strain thermomechanical processing

Abstract Although thermomechanical processing has been widely used in grain boundary engineering, the relationship between thermomechanical parameters and grain boundary character distribution is still not well understood. In the present study, electron backscatter diffraction was used to study the grain boundary character distribution in pure copper after lowstrain thermomechanical treatments. It was found that the low-R coincidence site lattice frequency and grain size decreases in the following sequence, 10% compression &gt; 15% compression &gt; 5% compression, except for 700 0C. During thermomechanical treatments of copper, strain-induced grain boundary migration and grain growth may occur during annealing of 5% compressed copper, and recrystallization dominates during annealing of 15% compressed copper, while the annealing mechanism of 10% compressed copper changes from strain-induced grain boundary migration and grain growth to recrystallization when the annealing temperature exceeds 600 0C. The results indicated that during single-step low-strain thermomechanical treatments, straininduced grain boundary migration and grain growth would gradually change to recrystallization with the increase of pre-deformation level and annealing temperature. Among the three mechanisms, strain-induced grain boundary migration seems to be more effective than recrystallization and grain growth in the optimization of grain boundary character distribution, and it is suggested that this is due to the high boundary migration rate of strain-induced grain boundary migration.

Arabidopsis COPPER TRANSPORTER 1 undergoes degradation in a proteasome-dependent manner.

The essential nutrient copper is toxic in excess. Therefore, plants must tightly control copper uptake and distribution. Arabidopsis thaliana high-affinity copper transporters (COPTs) mediate copper uptake, partitioning, and redistribution. Here we show that COPT1 localizes to the plasma membrane and endoplasmic reticulum in stably transgenic plants expressing a COPT1-green fluorescent protein (GFP) fusion protein, and the fusion protein is rapidly degraded upon plant exposure to excess copper. MG132 treatment largely abolished copper-induced degradation of COPT1, implying a link between the proteasome and COPT1 activity in modulating copper uptake. Co-immunoprecipitation analyses revealed that COPT1 cannot be ubiquitinated in the presence of excess copper and MG132. Through site-directed mutagenesis, we identified Lys159 in the C-terminal cytoplasmic tail of COPT1 as critical for copper acquisition, but not for copper-mediated down-regulation of COPT1, in plants. Furthermore, pharmacological analysis showed that treatment with a vesicle trafficking inhibitor or a V-ATPase inhibitor does not alter the subcellular dynamics of COPT1-GFP, consistent with the absence of a connection between the endosomal recycling/vacuolar system and COPT1 degradation. Together, our data suggest that proteasomal degradation rather than vacuolar proteolysis is important for the regulation of copper transport to maintain copper homeostasis in plants.

Mapping the structural evolution in the global scrap copper trade network

The rise in industrialization and urbanization has elevated consumer lifestyles and has dramatically increased copper consumption in the past three decades. Due to the growing scarcity of copper ore and lower manufacturing costs associated with using recycled copper, copper recycling has gained increasing attention. Because of the uneven geographical distribution of scrap copper, the international scrap copper trade has formed and is experiencing rapid growth. This study applies complex network theory to map the structural evolution of the global scrap copper trade from 1988 to 2017 according to the UN-Comtrade database. The results show that the global scrap copper trade has been reshaped from the pre-existing geopolitical realities through the interaction of geopolitical relations and geo-economics. The America-Asia community is the largest trading community and is driven by the USA and China. China is the largest recipient of scrap copper due to a lack of self-sufficiency with respect to copper and scrap copper resources. India is considered another long-term potential market for exporters, which can result in reducing dependence on a single market such as China. These findings, together with policy-related discussions, help authorities understand the complex international scrap copper trade relationships and propose effective import-export policies to reduce the risk of trade disruption.