The legacy environmental footprints of manufactured capital.

The foundations of today's societies are provided by manufactured capital accumulation driven by investment decisions through time. Reconceiving how the manufactured assets are harnessed in the production-consumption system is at the heart of the paradigm shifts necessary for long-term sustainability. Our research integrates 50 years of economic and environmental data to provide the global legacy environmental footprint (LEF) and unveil the historical material extractions, greenhouse gas emissions, and health impacts accrued in today's manufactured capital. We show that between 1995 and 2019, global LEF growth outpaced GDP and population growth, and the current high level of national capital stocks has been heavily relying on global supply chains in metals. The LEF shows a larger or growing gap between developed economies (DEs) and less-developed economies (LDEs) while economic returns from global asset supply chains disproportionately flow to DEs, resulting in a double burden for LDEs. Our results show that ensuring best practice in asset production while prioritizing well-being outcomes is essential in addressing global inequalities and protecting the environment. Achieving this requires a paradigm shift in sustainability science and policy, as well as in green finance decision-making, to move beyond the focus on the resource use and emissions of daily operations of the assets and instead take into account the long-term environmental footprints of capital accumulation.

Direct, Embedded, and Embodied Trade of Arsenic: 1990-2019.

International arsenic trade, physical and virtual, has resulted in considerable transfer of arsenic pollution across regions. However, no study has systematically captured, estimated, and compared physical and virtual arsenic trade and its relevant impacts. This study combines material flow analysis and embodied emission factors to estimate embedded (including direct and indirect trade) and embodied arsenic trade during 1990-2019, encompassing 18 arsenic-containing products among 244 countries. Global embedded arsenic trade increased considerably from 47 ± 7.3 to 450 ± 68 kilotonnes (kt) during this time and was dominated by indirect arsenic trade, contributing 94 and 90% to global arsenic trade in 1990 and 2019, respectively. Since the 1990s, global arsenic trade centers and the main flows have shifted from European and American markets to developing countries. The mass of arsenic involved in embodied trade increased from 87.5 ± 26 kt in 1990 to 800 ± 236 kt in 2019. Direct trade and indirect trade aggravate arsenic environmental emissions in major importing countries, like China, while embodied trade aggravates arsenic environmental emissions in major exporting countries, like Peru and Chile. The trade-related arsenic pollution transfer calls for a rational arsenic emission responsibility-sharing mechanism and corresponding policy recommendations for different trading countries.

Material resource decoupling dilemma: Convergence and traps of in-use stock productivity in national economy development.

Various studies have suggested decoupling material stock from economic output as an important measure for promoting sustainable development. Here, we develop three theoretical hypotheses to describe the evolution features and economic effects of material stock intensity, and predict in theory that (1) Countries with higher material stock intensity are more likely to decouple economic growth from material stock. (2) Material stock intensity follows convergence trends. (3) Higher material stock intensity leads to higher long-run economic growth rates. To examine the adaptability of these hypotheses, we choose steel in-use stock as the proxy for the material capital stock and use panel data in 85 countries from 1950 to 2018 to conduct empirical analysis. Our empirical results in most countries support the theoretical predictions of the hypotheses. In particular, a 0.1t/k$ increase in steel stock intensity leads to a 2.12% increase in the probability of decoupling between steel stock and economic output next year and a 0.34% increase in the long-run GDP per capita growth rate annually. Moreover, steel stock intensity converges to approximately 0.25t/k$ to 0.35t/k$ at mature development stages. We predict that, except China, which is expected to follow decoupling trends, other large developing economies will couple economic output with steel stock. However, the shape of intensity curves is still uncertain for highly developed countries in the future.

s

Recently, the bilayer perovskite nickelate La_{3}Ni_{2}O_{7} has been reported to show evidence of high-temperature superconductivity (SC) under a moderate pressure of about 14 GPa. To investigate the superconducting mechanism, pairing symmetry, and the role of apical-oxygen deficiencies in this material, we perform a random-phase approximation based study on a bilayer model consisting of the d_{x^{2}-y^{2}} and d_{3z^{2}-r^{2}} orbitals of Ni atoms in both the pristine crystal and the crystal with apical-oxygen deficiencies. Our analysis reveals an s^{±}-wave pairing symmetry driven by spin fluctuations. The crucial role of pressure lies in that it induces the emergence of the γ pocket, which is involved in the strongest Fermi-surface nesting. We further found the emergence of local moments in the vicinity of apical-oxygen deficiencies, which significantly suppresses the T_{c}. Therefore, it is possible to significantly enhance the T_{c} by eliminating oxygen deficiencies during the synthesis of the samples.

Material Flow Analysis of Dysprosium in the United States.

Dysprosium (Dy) is increasingly being adopted in various clean energy products around the world, intriguing many nations' interests in its availability. However, since data are inaccessible, crucial information about Dy supplies and demands across products and countries remains incomplete. To fill these knowledge gaps, we performed a dynamic bottom-up material flow analysis of Dy, taking the United States (1987-2018) as a case. The results show that the United States (US) domestic demands experienced a growing trend (by 45-fold) with fluctuation and several shifts among applications, primarily owing to technological advancement. A large imbalance (80 times) exists between domestic mineral supplies and market demands, resulting in significant import dependency, with the net import reliance of alloys, chemicals, finished products, and concentrates being 97, 44, 40, and 31%, respectively. Dy is mainly imported as finished products (55.7%) and alloys (43.2%), with concentrates (0.4%) and chemicals (0.7%) accounting for less than 2%. This import dependency may result from fragmentation of the US supply chains because of the stricter environmental regulations on upstream industries and reshoring of the downstream industries. These findings suggest that rare-earth mineral production in the US is about to restart, and it is important for industries to seek international collaboration to boost product competition.

Unlocking Dysprosium Constraints for China's 1.5 °C Climate Target.

Some key low-carbon technologies, ranging from wind turbines to electric vehicles, are underpinned by the strong rare-earth-based permanent magnets of the Nd, Pr (Dy)-Fe-Nb type (NdFeB). These NdFeB magnets, which are sensitive to demagnetization with temperature elevation (the Curie point), require the addition of variable amounts of dysprosium (Dy), where an elevation of the Curie point is needed to meet operational conditions. Given that China is the world's largest REE supplier with abundant REE reserves, the impact of an ambitious 1.5 °C climate target on China's Dy supply chain has sparked widespread concern. Here, we explore future trends and innovation strategies associated with the linkage between Dy and NdFeBs under various climate scenarios in China. We find China alone is expected to exhaust the global present Dy reserve within the next 2-3 decades to facilitate the 1.5 °C climate target. By implementing global available innovation strategies, such as material substitution, reduction, and recycling, it is possible to avoid 48%-68% of China's cumulative demand for Dy. Nevertheless, ongoing efforts in REE exploration and production are still required to meet China's growing Dy demand, which will face competition from the United States, European Union, and other countries with ambitious climate targets. Thus, our analysis urges China and those nations to form wider cooperation in REE supply chains as well as in NdFeB innovation for the realization of a global climate-safe future.

Environmental impacts and improvement potentials for copper mining and mineral processing operations in China.

There has been growing concern among the public over the environmental impacts of the copper (Cu) mining and mineral processing industries. As an effective tool enabling interactions of all energy and material flows with the environment, Life Cycle Assessment (LCA) is used in many countries to identify environmental hotspots associated with operations, based on which improvements can be made. However, robust LCA research in this sector is lacking in China. This study aimed to fill this critical gap by investigating two typical Cu mining and mineral processing operations using different mining technologies, based on globally harmonized LCA methodologies. The results of the overall environmental impacts were obtained using a sensitivity analysis. Electricity (38%-74%), diesel (8%-24%) and explosives (4%-22%) were identified as the three main controlling factors. At the same time, the mineral processing stage was found to be the major production stage (60%-79%), followed by the mining stage (17%-39%) and the wastewater treatment (1%-13%). Global Warming Potential (GWP) was prioritized as the most important environmental issue (59%) across the selected impact categories. In addition, it was initially found that underground mining technology has better environmental performance than open-pit technology. Finally, the potential for improvement was estimated and discussed for the three identified controlling factors. Using GWP as an example, using green electricity can effectively reduce CO2 emissions by 47%-67%, whereas replacing diesel and explosives with cleaner fuels and explosives may contribute to lower CO2 emissions by 6% and 9%, respectively.

Effectiveness of mobile health interventions for pregnant women with gestational diabetes mellitus: a systematic review and meta-analysis.

Gestational diabetes mellitus is a growing global health problem. Inadequate management during pregnancy can lead to maternal and foetal complications. Currently, mobile health (mHealth) delivers healthcare services, playing an increasingly important role in the management of blood glucose in GDM. This study aimed to systematically evaluate the effectiveness of mHealth intervention in pregnant women with GDM. Based on randomised controlled trials of mHealth application in GDM patients searched from the database, literature screening, data extraction, and quality evaluation were conducted independently by two researchers. Statistical analysis was performed using Review Manager 5.4 software. The review included 27 studies with a total of 3483 patients. The results showed a significant improvement in glycemic control. In addition, mHealth interventions could reduce the occurrence of adverse pregnancy outcomes and improve self-management ability. In a subgroup analysis, recording of delivery mode and WeChat combined phone call indicated significant differences with mHealth interventions. It was suggested that mHealth interventions imposed a positive effect on glycemic control and reduction of adverse pregnancy outcomes in GDM patients. Our results demonstrated that the application of mHealth interventions can act as an effective and feasible approach to self-management to promote the self-management level and awareness of GDM patients.

Cascading impacts of global metal mining on climate change and human health caused by COVID-19 pandemic.

The coronavirus disease 2019 (COVID-19) pandemic has significantly disrupted global metal mining and associated supply chains. Here we analyse the cascading effects of the metal mining disruption associated with the COVID-19 pandemic on the economy, climate change, and human health. We find that the pandemic reduced global metal mining by 10-20% in 2020. This reduction subsequently led to losses in global economic output of approximately 117 billion US dollars, reduced CO2 emissions by approximately 33 million tonnes (exceeding Hungary's emissions in 2015), and reduced human health damage by 78,192 disability-adjusted life years. In particular, copper and iron mining made the most significant contribution to these effects. China and rest-of-the-world America were the most affected. The cascading effects of the metal mining disruption associated with the pandemic on the economy, climate change, and human health should be simultaneously considered in designing green economic stimulus policies.

Embedded Health Risk from Arsenic in Globally Traded Rice.

International food trade is fundamental to global food security but with often negative consequences in the producing country. We propose a method of quantifying flows of inorganic arsenic (iAs) and embedded increased lifetime cancer risks (EHR) at a global scale, where negative impacts are felt on the importing country. Computations were made for 153 countries. Vietnam exports the most iAs embedded in rice (796 kg/year) followed by India (788 kg/year), Thailand (485 kg/year), and the United States (323 kg/year). We show that continental China, Indonesia, and Malaysia have the highest imports of iAs (292, 174, and 123 kg/year, respectively). Bangladesh ranks highest in EHR followed by Vietnam and Cambodia (150, 141, and 111 per 100,000, respectively). Countries that depend exclusively on imported rice are importing a substantial amount of risk, as, e.g., Kiribati and Solomon Islands (57 and 53 per 100,000, respectively). We discuss the potential policy options for reducing population dietary health risks by well-balanced apportioning of rice sources. This study targets policy design solutions based on health gains, rather than on safe levels of the risk factor alone.

China's roadmap to plastic waste management and associated economic costs.

Plastic is one commonly used polymer material to support our daily lives. However, once the plastic waste enters the environment, it slowly degrades, which causes long-term and deep ecological environmental problems. As the world's largest plastic producer and consumer, China generated around 26.74 million tons of plastic waste in 2019, and has made ambitious policies to cope with the plastic waste issues. This study predicts the generation trends and management costs of plastic waste in China from 2020 to 2035 under three different scenarios (Business as usual-BAU, Current policy scenario -CPS, and Target policy scenario-TPS), in which China is divided into three regions for specific policy implications. In addition, the scenario analysis and Monte Carlo simulations are used to obtain confidence interval of assessments. The results show that the plastic waste emission will be 34.82 million tons under BAU, 13.49 million tons under CPS and 2.63 million tons under TPS in 2035, respectively, and there will be significant changes in regional contributions in plastic waste emission (e.g., Eastern region: 45.7% to 9.7%; Central region:25.2% to 30.9%; Western region: 29.1% to 59.4% from 2019 to 2035 under TPS). In addition, the environmental and economic benefits increase with the rigor of plastic waste management policy as there will generate a net income of US$3.01 billion under TPS compared to the cost of US$ 2.61 billion under BAU and US$120 million under CPS. In view of this, it is vital that China develop appropriate plastic management policies based on the status of various regions, attempt to achieve economic development while reducing plastic waste emissions, and finally achieving a "win-win" situation of economy and environment.

An overview of flood-induced transport disruptions on urban streets and roads in Chinese megacities: Lessons and future agendas.

Urban road transport disruptions caused by urban floods have become severe in the Chinese megacities due to climate change and urbanisation. Urban road planning, design, and land drainage systems are insufficiently coping with intense rainstorms, especially in the wet season. This is reflected in more research findings on urban flood impacts and road transport disruption over the past decade. Here we provide a critical overview of current research on urban road inundation, road traffic delays, and accessibility losses under flood conditions, and illustrate up-to-date practices with the relevant governmental institutions. Our review implies that urban flood management in road design is still at an embryonic stage in the Chinese megacities. Hence, we review the lessons and experiences of urban flood impacts on roads in the global context. We argue that it is essential to enhance better co-production practices on emergency responses and recovery measures between authorities, which is vital to improving flood resilience in uncertain climates.

Material Flow Patterns of the Global Waste Paper Trade and Potential Impacts of China's Import Ban.

Waste paper, an essential substitute for wood and other plant-based fibers in paper making, is an indispensable part of the circular economy; yet, the impacts of China's ban on global waste paper cycles have not been well understood. We modeled the evolution of the global waste paper trade network during 1995-2019. We found that the cumulative trade volume of global waste paper reached 1010 million tons in the last 25 years and showed a downward trend since 2015. The global import center of waste paper experienced a transfer from Europe to East Asia and then to Southeast Asia. The ban has stimulated some developed countries to reduce the exports of unsorted waste paper since 2017, but for many major importers their changes in waste paper trade patterns were related to waste paperboard, which was not banned by China, suggesting that this import change trend may be inevitable and irrespective of China's ban. Besides, India has replaced China to become a new import hub of unsorted waste paper. Our results lay a foundation for exploring the evolution of the future global solid waste cycle under the background of zero import of solid waste increasingly implemented by China and many other developing countries.

Multidimensional Analyses Reveal Unequal Resource, Economic, and Environmental Gains and Losses among the Global Aluminum Trade Leaders.

Disputes around trade inequality have been growing over the last 2 decades, with different countries claiming inequality in different terms including monetary deficits, resource appropriation and degradation, and environmental emission transfer. Despite prior input-output-based studies analyzing multidimensional trade consequences at the sector level, there is a lack of bottom-up studies that uncover the complexity of trade imbalances at the product level. This paper quantifies four types of flows, monetary, resource, embodied energy use, and embodied greenhouse gas (GHG) emissions, resulting from aluminum trade for the four economies with the highest aluminum trade, that is, the United States, China, Japan, and Australia. Results show that the United States has a negative balance in monetary flows but a positive balance in resource flows, embodied energy use, and GHG emissions. China has a positive balance in monetary and resource flows but a negative balance in embodied energy use and GHG emissions. Japan has a positive balance in all flows, while Australia has a negative balance in all flows. These heterogeneous gains and losses along the global leaders of aluminum trade arise largely from their different trade structures and the heterogeneities of price, energy use, and GHG emission intensities of aluminum products; for example, Japan mainly imports unwrought aluminum, and its quantity is 3 times that of the exported semis and finished aluminum-containing products that have similar energy and GHG emission intensities but 20 times higher prices, while Australia mainly exports bauxite and alumina that have the lowest prices, the quantity of which is 25 times that of imported semis and finished products. This study suggests that resource-related trade inequalities are not uniform across economic and environmental impacts and that trade policies must be carefully considered from various dimensions.

Superconductivity in Single-Quintuple-Layer Bi2Te3 Grown on Epitaxial FeTe.

How an interfacial superconductivity emerges during the nucleation and epitaxy is of great importance not only for unveiling the physical insights but also for finding a feasible way to tune the superconductivity via interfacial engineering. In this work, we report the nanoscale creation of a robust and relatively homogeneous interfacial superconductivity (TC ≈ 13 K) on the epitaxial FeTe surface, by van der Waals epitaxy of single-quintuple-layer topological insulator Bi2Te3. Our study suggests that the superconductivity in the Bi2Te3/FeTe heterostructure is generated at the interface and that the superconductivity at the interface does not enhance or weaken with the increase of the Bi2Te3 thickness beyond 1 quintuple layer (QL). The observation of the topological surface states crossing Fermi energy in the Bi2Te3/FeTe heterostructure with the average Bi2Te3 thickness of about 20 QL provides further evidence that this heterostructure may potentially host Majorana zero modes.

Kohn-Luttinger Mechanism Driven Exotic Topological Superconductivity on the Penrose Lattice.

The Kohn-Luttinger mechanism for unconventional superconductivity (SC) driven by weak repulsive electron-electron interactions on a periodic lattice is generalized to the quasicrystal (QC) via a real-space perturbative approach. The repulsive Hubbard model on the Penrose lattice is studied as an example, on which a classification of the pairing symmetries is performed and a pairing phase diagram is obtained. Two remarkable properties of these pairing states are revealed, due to the combination of the presence of the point-group symmetry and the lack of translation symmetry on this lattice. First, the spin and spacial angular momenta of a Cooper pair is decorrelated: for each pairing symmetry, both spin-singlet and spin-triplet pairings are possible even in the weak-pairing limit. Second, the pairing states belonging to the 2D irreducible representations of the D_{5} point group can be time-reversal-symmetry-breaking topological SCs carrying spontaneous bulk super current and spontaneous vortices. These two remarkable properties are general for the SCs on all QCs, and are rare on periodic lattices. Our work starts the new area of unconventional SCs driven by repulsive interactions on the QC.

Byproduct Surplus: Lighting the Depreciative Europium in China's Rare Earth Boom.

Europium (Eu) is often regarded as a critical mineral due to its byproduct nature, importance to lighting technologies, and global supply concentration. However, the existing indicator-based criticality assessments have limitations to capture Eu's supply chain information and thus fall short of reflecting its true criticality. This study quantified the flows and stocks of Eu in mainland China from 1990 to 2018. Results show that: (1) China's Eu demand decreased by 75% from 2011 to 2018, as a result of the lighting technology transition from fluorescent lamps to light-emitting diodes, which significantly reduced Eu's importance; (2) the supply of Eu mined as a byproduct kept increasing together with the growing rare earth production, which caused a substantial supply surplus being ≈1900 t by 2018; (3) despite the leading role of China in global Eu production, Eu mined in China was exported mainly in the form of intermediate and final products, and ≈90% Eu embedded in domestically produced final products was used for export recently. This study indicates that Eu's criticality is not as severe as previously assessed and highlights the necessity of material flow analysis for a holistic and dynamic view on the entire supply chain of critical minerals.

Flows, Stock, and Emissions of Poly- and Perfluoroalkyl Substances in California Carpet in 2000-2030 under Different Scenarios.

In this study, we present a holistic analysis of the stock and emissions of poly- and perfluoroalkyl substances (PFAS) in California carpet in 2000-2030. Our high estimate is that, in 2017, the total PFAS accumulated in in-use carpet stock and landfilled carpet are ∼60 and ∼120 tonnes, respectively, and the resultant PFAS emissions are ∼800 and ∼100 kg, respectively. Among the three subclasses (side-chain polymers, PFAA, and nonpolymeric precursors), side-chain polymers dominate the in-use stock and landfill accumulation, while nonpolymeric precursors dominate the resultant emissions. Our low estimate is typically 8-15% of the high estimate and follows similar trends and subclass breakdowns as the high estimate. California's new Carpet Stewardship Regulations (24% recycling of end-of-life carpet) will reduce the landfilled PFAS by 6% (7 tonnes) at the cost of increasing the in-use stock by 2% (2 tonnes) in 2030. Aggressive PFAS phase-out by carpet manufacturers (i.e., reduce PFAS use by 15% annually starting 2020) could reduce the in-use PFAS stock by 50% by 2030, but its impact on the total landfilled PFAS is limited. The shift toward short-chain PFAS will also significantly reduce the in-use stock of long-chain PFAS in carpet by 2030 (only 25% of the total PFAS will be long-chain). Among the data gaps identified, a key one is the current area-based PFAS emission reporting (i.e., g PFAS emitted/area carpet/time), which leads to the counterintuitive result that reducing the PFAS use in carpet production has no impact on the PFAS emissions from in-use stock and landfills. Future technical studies should either confirm this or consider a mass-based unit (e.g., g PFAS emitted/g PFAS used/time) for better integration into regional substance flow analysis. Other noticeable data gaps include the lack of time-series data on emissions from the in-use stock and on leaching of side-chain polymers from landfills.

Material-energy-water nexus: Modelling the long term implications of aluminium demand and supply on global climate change up to 2050.

Aluminium is a widely used metal and one of the most energy intensive industries, and therefore it has been included in most energy models and scenarios. Material demand and supply are broadly linked to energy, water, and climate change. In this study, we develop four global and regional process based scenarios for the material-energy-water nexus combined with CO2 emissions and applied to aluminium. The scenarios used in this study are; Market World (MW), Toward Resilience (TR), Security Foremost (SF), and Equitability World (EW). The results indicate that global CO2 emissions are expected to increase as a result of increasing aluminium demand, although aluminium secondary supply, energy efficiency, and cleaner energy supply technologies are expected to increase in the next 30 years. Policy and sustainability (TR and EW) scenarios are ultimately the best in terms of global climate change since the two scenarios have the lowest CO2 emissions, although they also have the highest aluminium demand and energy. It is therefore necessary to implement cleaner energy supply and energy efficiency technologies at high rates in aluminium industry to mitigate possible increase in CO2 emissions.

Regional disparities in decoupling economic growth and steel stocks: Forty years of provincial evidence in China.

Human-made material stocks promote the economic prosperity, while the consumption, maintenance, and operation of them have led to adverse environmental impacts. Decoupling materials stocks from economic growth is a key strategy for relieving environmental pressures and achieving sustainable development. China's unprecedented development offers a unique opportunity for uncovering the relationship between in-use stocks and economic growth. In this study, we analyzed the regional disparity of in-use steel stocks estimated by bottom-up accounting method during 1978-2018 in 31 provinces in mainland China, explored the stocks productivity on provincial and regional scale, and conducted a decoupling analysis of in-use steel stocks with economic growth. The results showed that there was a huge disparity among the provincial total steel stocks, per-capita steel stocks, and stocks density. Some provinces, e.g. Beijing, Tianjin, and Shanghai, that had the highest stocks density had comparatively lower per-capita steel stocks and total steel stocks, indicating higher share of in-use steel stocks and lower material intensive economic structure. In-use steel stocks in China showed no clear signs of saturation or flatten off pattern although their growth rate declined recently. An increase in steel stocks productivity was found during 1978-2018, which means relative decoupling of in-use steel stocks from economic growth, but still far away from absolute decoupling. The dematerialization pattern revealed in this study deepens our understanding of material-economy interactions. Policy implications for dematerialization transition should focus on developing compact cities, prolonging the lifespan of products, and advancing technological development.