Scientific Data, 2022, 9 (1), 502. https://doi.org/10.1038/s41597-022-01611-z

Abstract

Material utilisation has been playing a fundamental role in economic development, but meanwhile, it may have environmental and social consequences. Given China’s rapid economic growth, understanding China’s material utilisation patterns would inform decisions for researchers and policymakers. However, fragmented data from multiple statistical sources hinder us from comprehensively portraying China's material utilisation dynamics. This study harmonised China-specific official statistics and constructed a China economy-wide material flow accounts database. This database covers hundreds of materials and more than 30 years (1990-2020) from thousands of data sources, which is comprehensive, long-term, up-to-date, and publicly accessed. This database would provide insights into the historical metabolic dynamics of China’s economy with elaboration on the production, consumption, and end-of-life disposal of materials. This database also allows for international analyses since it is developed based on an internationally standardised analytical framework. Furthermore, this study would benefit studies on policy impact evaluation, environmental pressure assessment, and sustainable development strategies.

The dataset can be assessed via: https://doi.org/10.6084/m9.figshare.c.5994589.v1

For full text, please visit: https://www.nature.com/articles/s41597-022-01611-z

International trade has been considered a critical driving force of materials’ physical flows and their environmental pressures, which has been a global research hotspot. Various databases have been developed and applied to support the physical trade analysis, in which the United Nations Commodity Trade Statistics Database (UN Comtrade) is the original and probably the most widely-used data source. However, data quality issues in UN Comtrade were identified reportedly, which may lead to diametrically conflicted conclusions if not properly addressed. To advance analyses on physical trade flow based on UN Comtrade data, we established an improved methodology to greatly increase UN Comtrade data quality. We applied improved methodology to all available trade records from 1988-2019 (retrieved in 2020/10/4) in 6-digit HS0 codes of all reporters. Our work is designed in two parts, which are (1) detecting and handling outliers, and (2) estimating the missing values, because our previous attempts reveal that the bilateral asymmetry issue caused by misreporting has been highly resolved based on trade data with outliers eliminated and missing values estimated. Details and contributions of our work can be found in our publications.

Downloading the full dataset

MaC (Material Cycle and Manufacturing Capital) is a collaborative research platform to measure and manage material base for sustainable development. As the core function, MaC platform is designed to monitor the anthropogenic material cycle and its spatio-temporal distribution by collecting and synthesizing dispersed data of production, manufacturing, consumption, trade, and recycling of various materials. Under such a basis, MaC aims to expand the applicability and serviceability of material cycle to address the pressing technical, economic, and environmental challenges.

MaC welcomes and acknowledges all stakeholders contributing to the accounting of material flows, and all datasets are free to download for research purposes upon request. At present, under the support of UNEP-NSFC, CAS, and other industrial projects, MaC starts with the global accounting of 55 metals which are empowered by the following six key components:

• MeT-CYCLE to provide detailed datasets of national and global metal flows and stocks along its life cycle;
• MeT-MEG to provide the life cycle inventory of regional-specific metal mining and metallurgy processes;
• MeT-ECON to provide high-resolution datasets of metal flows and stocks within economic sectors;
• MeT-GEO to provide the geographic distribution datasets of metal stocks and production facilities;
• MeT-TRADE to provide all metal-contained trade flows linking all nations in the world;
• MeT-Nexus to provide the metal-specific integrated assessment model to link metal cycle with energy, economic, and climate modelling.

Song, Lulu; Wang, Peng*; Hao, Min; Dai, Min; Xiang, Keying; Li, Nan; Chen, Wei-Qiang*

Journal of Cleaner Production 2020 262, 121393. DOI: 10.1016/j.jclepro.2020.121393

Abstract

China’s unprecedented industrialization and urbanization has boosted tremendous steel use nationwide, making it the global largest steel producer and consumer. However, there is a limited knowledge on the historical evolution and future transitions of China’s provincial steel use, which prohibits more specific resource management policies. We applied dynamic material flow analysis to estimate and predict the provincial steel stocks and flows during 1978-2050 in 31 provinces of mainland China, with a bottom-up data collection on over 100 categories of steel-containing products. We find steel stocks have reached 5.9 ± 1.5 tons per capita (t/cap) in 2018, and identify a significant gradient decline of steel stocks from eastern coastal regions to western inland regions. By 2050, steel stocks will be around 12.3 Gt, ranging from 9.3 Gt to 15.3 Gt. It is expected that the regional disparity of steel stocks will be narrowed in the near future. Our spatial analysis reveals the coming steel demand peak occurring during 2016-2022 and scrap boom after 2030. However, such patterns differ among provinces. The scrap in some eastern provinces will exceed demand around 2030, while central and western provinces will become larger suppliers of scrapped steel after 2040. China should tailor its circular economy policies to local and inter-regional levels to boost inter-regional scrap circulation for more sustainable and balanced development.

Spatial distribution of provincial steel stocks during 1978-2050.

Spatial distribution of provincial steel scrap for the baseline scenario in 2030 (a), 2040 (b), 2050 (c), and stocks, demand (inflows), and scrap (outflows) during 1978e2050 of Shanghai pattern (d) and Anhui pattern (e).

For full text, please visit

https://www.sciencedirect.com/science/article/pii/S0959652620314402

Nuss, Philip*; Chen, Wei-Qiang*; Ohno, Hajime; Graedel, T. E.

Environmental Science & Technology 2016 50 (7), 4091–4101. DOI: 10.1021/acs.est.5b05094

Abstract

Metals are used in numerous products and are sourced via increasingly global and complex supply chains. Monetary input–output tables (MIOT) and network analysis can be applied to intersectoral supply chains and used to analyze structural aspects. We first provide a concise review of the literature related to network analysis applied to MIOTs. On the basis of a physical input–output table (PIOT) table of aluminum in the United States economy in 2007, we identify key sectors and discuss the overall topology of the aluminum network using tools of network analysis. Sectors highly dependent on metal product inputs or sales are identified using weighted degree centrality and their hierarchical organization is explored via clustering. Betweenness centrality and random walk centrality (page rank) are explored as means to identify network bottlenecks and relative sector importance. Aluminum, even though dominated by uses in the automobile, beverage and containers, and construction industries, finds application in a wide range of sectors. Motor vehicle parts manufacturing relies on a large number of upstream and downstream suppliers to function. We conclude by analyzing structural aspects of a subnetwork for automobile manufacturing and discuss how the use of network analysis relates to current criticality analyses of metal and mineral resources.

Industry clusters of the aluminum network determined using the clustering method of Kagawa and colleagues.

For full text, please visit

https://doi.org/10.1021/acs.est.5b05094

Wang, Peng; Ryberg, Morten*; Yang, Yi; Feng, Kuishuang; Kara, Sami*; Hauschild, Michael; Chen, Wei-Qiang*

Nature Communications 2021 12: 2066. DOI: 10.1038/s41467-021-22245-6

Abstract

Steel production is a difficult-to-mitigate sector that challenges climate mitigation commitments. Efforts for future decarbonization can benefit from understanding its progress to date. Here we report greenhouse gas emissions from global steel production over the past century (1900-2015) by combining material flow analysis and life cycle assessment. We find that ~45 Gt steel was produced in this period leading to emissions of ~147 Gt CO2-eq. The historical improvement in process efficiency (~67%) was offset by a 44-fold increase in annual steel production, resulting in a 17-fold net increase in annual emissions. Despite regional technical improvements, the industry’s decarbonization progress stagnated after 1995 mainly due to expansion of emerging production flows with high carbon intensity. This raise concerns on the expected demand expansion in emerging economies, which may jeopardize steel industry’s prospects for following 1.5°C emission reduction pathways. This warrants urgent implementations of regionally specific joint supply- and demand-side mitigation measures.

Steel production technologies and their total GHG emissions from 1900 to 2015.

Feasibility of material and technical efficiency improvement scenarios to avoid the exhaustion of steel-related 1.5DS carbon budgets.

For full text, please visit

https://www.nature.com/articles/s41467-021-22245-6

Shi, Jiujie; Zhang, Chao*; Chen, Wei-Qiang*

Sustainable Production and Consumption 2021 25, 187-197. DOI: 10.1016/j.spc.2020.08.005

Abstract

Soaring consumption of plastic products globally generates vast amount of plastic wastes, which has been a grand challenge for today's solid waste management system. China has been the world largest importer of plastic wastes for the last three decades. However, due to growing environmental awareness, China decided to stop importing plastic wastes in 2017. This study analyzes the historical evolution of the international plastic wastes trade by using complex network analysis method and shows that China's management policies are the main driving forces to the expansion and shrinkage of the global plastic wastes trade network. We find that the trade network grew most tremendously during mid-1990s to early 2010s. The global total trade volume increased from 0.9 million tons in 1992 to 16.4 million tons in 2012, and the number of trade connections increased from 452 to 2248 during the same period. 2–6% of the trade relations contributed more than 80% of the global total trade volumes. Trade flows among continents or sub-continental regions increased from 38% to 64% during 1997–2012, indicating longer transport distances and spatially more separated trade partners in the network. Results also show that the growth trend stagnated and the network became multipolar again after 2012, when China launched a series of campaigns to strengthen regulations on solid wastes import. China's import ban on plastic wastes issued in 2017 led to a dramatic decline of trade volumes. More and more stringent environmental protection measures in China and other developing countries are transforming the geographic pattern of global waste trade network and may drive developed countries to reconstruct their recycling systems.

(a) Global total trade volumes of plastic wastes, (b) Total number of countries and trade connections, (c) Trend of network density and average clustering coefficient, (d) Proportion of trade connections accounting for 80% of the total trade volume and Gini coefficient of trade connections, (e) The modularity of international trade network of plastic wastes, (f) The proportion of countries in different communities.

Trade flows crossing continents or sub-continental regions (MMT) in 1992(a), 1997(b), 2012(c) and 2017(d). WEu: Western Europe, LA: Latin America, EA: East Asia, Af: Africa, SA: Southeast Asia, Oc: Oceania, NA: Northern America, Oa: Other regions (including Eastern Europe, the Middle East and Central Asia).

For full text, please visit

https://www.sciencedirect.com/science/article/pii/S2352550920302992#fig0003

Yang, Yi*; Hobbie, Sarah E.; Hernandez, Rebecca R.; Fargione, Joseph; Grodsky, Steven M.; Tilman, David; Zhu, Yong-Guan; Luo, Yu; Smith, Timothy M.; Jungers, Jacob M.; Yang, Ming; Chen, Wei-Qiang*

One Earth 2020 3 (2), 176-186. DOI: 10.1016/j.oneear.2020.07.019

Abstract

Degraded farmlands have been abandoned worldwide, especially in high- and middle-income countries. These lands help combat climate change as they undergo natural recovery of vegetation and soil carbon and remove carbon dioxide from the atmosphere. However, recovery can be slow, requiring decades to centuries to approach pre-cultivation or natural states, and in some cases, soils remain degraded without active restoration. In this perspective, we present an overview of how carbon capture and storage on abandoned farmland can be accelerated and maximized via managing plant diversity as both a means and an end of restoration, creating and applying biochar to soil, and co-developing with renewable energy as techno-ecological synergies. These strategies can jointly tackle climate change and land degradation while contributing to and reinforcing multiple other Sustainable Development Goals. Although challenges exist, adoption of these strategies could be facilitated by increasing governmental and corporate initiatives at global and regional levels, especially developing carbon-offset markets for agriculture.

An Illustration of How Different Strategies Contribute to the UN SDGs.

For full text, please visit

https://www.sciencedirect.com/science/article/pii/S2590332220303638

Chen, Wei-Qiang*; Shi, Ya-Lan; Wu, Shi-Liang; Zhu, Yong-Guan

Journal of Cleaner Production 2016 139, 328-336. DOI: 10.1016/j.jclepro.2016.08.050

Abstract

Arsenic is a trace element and a global contaminant. There are currently large uncertainties associated with our understanding and quantification of the arsenic cycles in the global environment. This study proposes a research framework where the major anthropogenic processes affecting anthropogenic arsenic cycles (AACs) are identified. A characteristic of this framework is that it divides AACs into two parts: one related to intentional uses, and the other driven by unintentional uses. Several significant features of AACs are summarized as follows: (1) existing studies reveal that AACs at Earth's surface is at the same order of magnitudes as its natural cycles; (2) arsenic mostly enters modern anthroposphere as a companion element of nonferrous metal ores or fossil fuels, and currently there is abundant arsenic reserves relative to the limited intentional use of arsenic; (3) China owns the majority of arsenic reserves and is the biggest producer of arsenic for the present day, while U.S. was the biggest user of arsenic in the whole 20th century; (4) there were several waves of rise and fall of intentional arsenic use in the 20th century of U.S., with the rises driven by various applications of arsenic in agriculture and industry (such as glass making in the 1900s, agricultural applications in the 1920s, and wood preservatives in the 1970s), and the falls mainly resulting from the regulations in response to its toxicity; (5) the majority of intentional arsenic uses are in the form of chemical compounds rather than single substance, and almost all intentional uses of arsenic not only are unrecyclable but also result in emissions that may last years or decades after being used.

A research framework for characterizing anthropogenic arsenic cycles related to intentional uses and resulting from unintentional uses in national or global anthropogenic systems.

For full text, please visit

https://www.sciencedirect.com/science/article/pii/S0959652616311945

Ren, Yanan; Liu, Guangxin; Pu, Guangying; Chen, Yimeng; Chen, Wei-Qiang*; Shi, Lei

Journal of Cleaner Production 2020 276, 124221. DOI: 10.1016/j.jclepro.2020.124221

Abstract

Plastics are the paradigmatic material of the current era. Plastics’ trade articulates interest in trading partnerships and concerns about trade security. We focus on the International Plastic Resin Trade Network (IPRTN) and analyze its spatiotemporal evolution in 1988–2017 from global, regional, and national scales. As a profile of globalization, the network became increasingly interconnected under the combined effect of the involvement of more participating countries, the increase in the closeness of trade links, and the increase in trade volume, which grew by 0.4-fold, 7.7-fold, and 14.9-fold, respectively. Despite the growth, IPRTN maintained fairly stable topological characteristics including small-world property (average path length, 1.95 ± 0.10; clustering coefficient, 0.63 ± 0.06), high reciprocity (reciprocity value, 0.54 ± 0.03), disassortative mixing (assortativity value, −0.46 ± 0.23), and exponential degree distribution. Generally, the plastic resin trade was spatially heterogeneous with high intra-regional trade proportions (1988–1997, 78.4%; 1998–2007, 79.9%; 2008–2017, 75.1%), and Europe, Asia, and North America were the dominating regions. These facts brought IPRTN with a regionally dependent community structure. Five communities were finally formed: the Middle East-Africa community, the Eastern Europe community, the Western Europe community, the Americas community, and the East Asia-Southeast Asia-Oceania community. We found that the US-China plastic resin trade was mainly complementary. Thus, mutual tariffs in the US-China trade war, which covers plastic resins, will cause adverse effects and need to be resolved through active consultations. To ensure trade security, we remind countries with poor trade robustness to pay attention to changes in trade policies of these critical trade players and to enrich trade channels.

IPRTN in 1988 (a) and 2017 (b).

Evolution of IPRTN’s community structure. The same color marks countries in the same community.

For full text, please visit

https://www.sciencedirect.com/science/article/abs/pii/S0959652620342669

Huang, Qiao; Chen, Guangwu; Wang, Yafei*; Xu, Lixiao; Chen, Wei-Qiang*

Science of The Total Environment 2020 725, 138137. DOI: 10.1016/j.scitotenv.2020.138137

Abstract

Solid waste recycling is crucial for easing China's resource constraints and for promoting the country's sustainable economic development. Previous studies regarding solid waste recycling have mainly assessed its economic value, the status quo, problems and challenges, however, little is known at this stage about its driving factors. The purpose of the current study is to identify the socioeconomic drivers of solid waste recycling, investigating it's evolution in China from 2005 to 2017. The study employs a systematic technique of input-output (IO) analysis and IO-based structural decomposition analysis (IO-SDA). Results reveal that China experienced an increase in the recycling of five types of solid waste, these include waste steel, waste nonferrous metals, waste plastics, waste paper and waste rubber for the period 2005–2017. The increase in solid waste recycling was driven mainly by fixed capital formation and exports, while urban household consumption was found to be a dominant driver due to China's increasing urban population. In order to better track and identify the recycling of solid waste, there is an urgent need to promote the classification of household solid waste at the national level. An increase of solid waste recycling was driven mainly by the growth of recycling intensity, population increase and changes in the structure of GDP, which was partly offset by per capita GDP changes. It is recommended that policy-makers increase the amount of investment in solid waste recycling capacity in rural areas so as to enhance recycling intensity contributing to the overall recycling effort.

Graphic Abstract.

Breakdown of the five solid-waste recycling drivers by sectoral main final demands for 2005–2017.

For full text, please visit

https://www.sciencedirect.com/science/article/pii/S0048969720316508

Wang, Lu; Wang, Peng*; Chen, Wei-Qiang*; Wang, Qian-Qian; Lu, Hu-Sheng

Journal of Cleaner Production 2020 270, 122464. DOI: 10.1016/j.jclepro.2020.122464

Abstract

Scandium (Sc) is the most expensive rare earth element and is widely considered as one of the most critical materials for various emerging applications such as the third-generation Solid Oxide Fuel Cell (SOFC) battery. The global Sc demand is expected to increase rapidly, while its supply is mainly constrained by limited mineral reserve and environmental burdens associated with its production. There are few Sc deposits distributed in the world, with small reserves and complicated extraction processes. A large amount of Sc is mainly concentrated in tailings and has not been extracted in large quantities. Besides, detailed assessments on the potential environmental impacts of rare earths production, and Sc in particular, are very rare. This study aims to fill this gap to assess the environmental impacts of the production of Sc2O3, where the technical processes are modelled based on a recent project of Sc recovery from rare earths tailings in Bayan Obo mine. The environmental impacts of 5 major processes and 22 sub-processes involved in the beneficiation stage and the smelting stage have been evaluated with the synergies of various inventory data. It is found that the beneficiation stage accounts for 88% of the overall impact, around 56% of which is contributed by the secondary separation process. Among the ten assessed categories, Human toxicity non-cancer (HTNC) and Global Warming Air (GWA) are the top two significant impacts caused by Sc2O3 production. Through comparative analysis with published results, it’s found that the environmental impact of Sc2O3 production from the tailings of Bayan Obo mine are much lower than those of direct production from the mixed rare earths ores. Our hotspot analysis identifies that the consumption of steam in Fe separation (II) and oxalic acid in oxalic acid precipitation are the major contributors to the total environmental impacts of Sc2O3 production. Thus, strategies to reduce their use and improve environmental performance in their production are highly encouraged. This study can provide a basis for sustainable raw material sourcing for the clean development of the third-generation SOFC battery.

Graphic Abstract.

Potential environmental impact of each process.

For full text, please visit

https://www.sciencedirect.com/science/article/pii/S0959652620325117

Chen, Wei-Qiang*; Graedel, T. E.; Nuss, Philip; Ohno, Hajime

Environmental Science & Technology 2016 50 (7), 3905–3912. DOI: 10.1021/acs.est.5b05095

Abstract

Based on the combination of the U.S. economic input-output table and the stocks and flows framework for characterizing anthropogenic metal cycles, this study presents a methodology for building material flow networks of bulk metals in the U.S. economy and applies it to aluminum. The results, which we term the Input–Output Material Flow Networks (IO-MFNs), achieve a complete picture of aluminum flow in the entire U.S. economy and for any chosen industrial sector (illustrated for the Automobile Manufacturing sector). The results are compared with information from our former study on U.S. aluminum stocks and flows to demonstrate the robustness and value of this new methodology. We find that the IO-MFN approach has the following advantages: (1) it helps to uncover the network of material flows in the manufacturing stage in the life cycle of metals; (2) it provides a method that may be less time-consuming but more complete and accurate in estimating new scrap generation, process loss, domestic final demand, and trade of final products of metals, than existing material flow analysis approaches; and, most importantly, (3) it enables the analysis of the material flows of metals in the U.S. economy from a network perspective, rather than merely that of a life cycle chain.

Material flow network of aluminum in the entire 2007 U.S. economy.

Material flow network of aluminum for producing automobiles in the United States in 2007.

For full text, please visit

https://doi.org/10.1021/acs.est.5b05095

Ohno, Hajime*; Nuss, Philip; Chen, Wei-Qiang*; Graedel, Thomas E.

Environmental Science & Technology 2016 50 (7), 4082–4090. DOI: 10.1021/acs.est.5b05093

Abstract

Metals have strongly contributed to the development of the human society. Today, large amounts of and various metals are utilized in a wide variety of products. Metals are rarely used individually but mostly together with other metals in the form of alloys and/or other combinational uses. This study reveals the intersectoral flows of metals by means of input-output (IO) based material flow analysis (MFA). Using the 2007 United States IO table, we calculate the flows of eight metals (i.e., manganese, chromium, nickel, molybdenum, niobium, vanadium, tungsten, and cobalt) and simultaneously visualize them as a network. We quantify the interrelationship of metals by means of flow path sharing. Furthermore, by looking at the flows of alloys into metal networks, the networks of the major metals iron, aluminum, and copper together with those of the eight alloying metals can be categorized into alloyed-, nonalloyed-(i.e., individual), and both mixed. The result shows that most metals are used primarily in alloy form and that functional recycling thereby requires identification, separation, and alloy-specific reprocessing if the physical properties of the alloys are to be retained for subsequent use. The quantified interrelation of metals helps us consider better metal uses and develop a sustainable cycle of metals.

Cobalt input-output network for the United States, 2007.

(a) Networks of eight metals commonly used in alloys in the U.S. economy, 2007. Colors represent the individual metals; arrow widths represent edge weights; (b) Expanded view of (a) to show detail in the Motor Vehicle and Construction sectors.

For full text, please visit

https://doi.org/10.1021/acs.est.5b05093

Xu, Wen; Chen, Wei-Qiang*; Jiang, Daqian; Zhang, Chao; Ma, Zijie; Ren, Yan; Shi, Lei

Ecosystem Health and Sustainability 2020 6, 1756925. DOI: 10.1080/20964129.2020.1756925

Abstract

Introduction:China’s import bans on solid wastes starting from 2017 have challenged theglobal trade system of plastic wastes, which remains poorly characterized. This study choosespolyethylene (PE) as a case and aims to map out the global trade networks of PE waste (GPETN)from 1976 to 2017.Outcomes:Wefind that the size and complexity of the GPETN had been growing until 2016. Afterthe mid-1990s, PE waste basicallyflowed from developed economies, mainly the EU and the US, todeveloping economies such as China. Since 2001 when admitted into the WTO, China’sPEwasteimport surged until 2014 when it absorbed over 60% of global export. Regulations on solid wasteimport following the Green Fence campaign in 2013 resulted in substantial reductions in China’simport as well as the global export of PE waste after 2014. Several other developing economies, suchas Malaysia, Turkey, and Vietnam, had transitioned to net importers, but their imports were insuffi-cient to replace China as new recycling bases for PE waste.Conclusion: The results highlight the urgent need of a joint effort for developed and devel-oping countries to build a stronger global circular economy system with sufficient capacity totreat PE waste locally.

The evolution of PE waste trade communities with more than three members in 1976, 1986, 1996, 2006, 2016, and 2017. One color represents one community. The colors of boxes in the flow chart correspond with the color nodes in the network graph, the same color representing the same community. The size of nodes represents the trade mass of the country relative to global trade mass.

For full text, please visit

https://www.tandfonline.com/doi/full/10.1080/20964129.2020.1756925?scroll=top&needAccess=true