Ecological network analysis for an industrial solid waste metabolism system

Nursing and waste management in health services: unveiling meanings in the hospital context

OBJECTIVE

To unveil the meanings that nursing professionals attribute to practices related to waste management in health services, within the hospital context.

METHOD

Qualitative research, whose theoretical and methodological references were, respectively, Complexity Theory and Grounded Theory. A total of 30 nursing professionals from a public hospital in Rio de Janeiro participated in the study, between January and August 2022. A semi-structured interview was used for data collection.

RESULTS

The professionals indicate the need for better knowledge about waste management in healthcare services, while revealing their understanding on the importance of this process and of themselves as important elements in impacting the environment and health.

CONCLUSION

The complexity of the meanings attributed to healthcare waste management practices indicates the dialogue between the fragility of nursing professionals' knowledge and their expanded perceptions about the impacts they can have on this reality.

How does the digital economy affect the provincial "zero-waste city" construction? Evidence from China

The digital economy is playing a crucial effect in the field of environmental governance. Digital and intelligent management is an essential means to fully realize the "zero-waste city" construction. The present paper investigates the impact of digital economy on China's provincial "zero-waste city" construction. The results indicate that digital economy can contribute to "zero-waste city" construction. The digital economy has a positive nonlinear effect on the construction of "zero-waste city," but the marginal effect is diminishing. The digital economy can facilitate "zero-waste city" construction by improving industrial structure upgrading and green technology innovation. Heterogeneity analysis reveals that digital economy contributes to the construction of "zero-waste city" in the eastern and western regions and high-level environmental regulation regions, while this impact is insignificant in the central region and low-level environmental regulation regions. The digital economy exerts the most significant positive influence on waste resource recycling followed by waste final disposal and then waste reduction at the source. These findings underscore the effect of digital economy in fostering "zero-waste city" construction and promoting sustainable waste management. The present study provides new ideas for the "zero-waste city" construction in emerging developing countries such as China.

Development of an industrial solid waste ecological analysis model in Shanghai, China

Amid China's rapid economic expansion, the country's industrial solid waste (ISW) problem is escalating. As each sector generates distinct types of ISW, a multi-indicator assessment of each sector is essential to address China's New Solid Waste Policy. To investigate the ISW situation of each sector and perform a comprehensive assessment, we formulate an industrial solid waste ecological analysis framework based on ISW generation and ISW flow in the sector. Various indicators (i.e., solid waste utilization coefficient, solid waste threat coefficient, and solid waste threat intensity) are employed to assess the utilization of solid waste generated for each sector, as well as the threat of solid waste originating in each sector to society. Ecological network analysis probes the interrelationships between diverse sectors. Taking Shanghai in 2017 as an example, the study indicates that some sectors (e.g., production and supply of electric power and heat power (EH) and metal smelting and rolling processing sector (MS)) exhibit higher direct ISW generation and the direct industrial solid waste value-added coefficient (SVAC) for common industrial solid waste (CISW). Specifically, the direct CISW generation of EH and MS is 539.21Mt and 277.00Mt respectively. The direct SVAC of EH and MS is 157.06kg/103RMB and 126.27kg/103RMB respectively. These sectors should prioritize reducing emissions at the source. Additionally, the threats to society from various sectors are relatively insignificant for the CISW, while for the hazardous waste (HW), all sectors pose a considerable threat to Shanghai's society. Moreover, some sectors (e.g., mining industry) exhibit the highest mutualism relationships in the CISW and the HW. Enhancing mining sector technologies is a vital strategy for mitigating ISW sources. Specifically, MI has 9 pairs of mutualism relationships in the CISW and 8 pairs in the HW. These insights will provide empirical evidence for tackling the ISW problem in Shanghai.

Hierarchy performance assessment of industrial solid waste utilization - tracking resource recycling and utilization centers in China

The massive production and accumulation of industrial solid waste (ISW) have led to environmental pollution and natural resource underutilization. China's efforts to build trial industrial waste resource utilization centers provide strong support for sustainable development. However, these centers and the factors driving ISW utilization have yet to be evaluated. This paper utilizes context-dependent data envelopment analysis models without explicit inputs (DEA-WEI) to evaluate the overall utilization performance of 48 industrial waste resource utilization centers in China from 2018 to 2020. It also builds a Tobit model to assess which indicators and waste types affect overall ISW utilization. The results show overall ISW utilization performance of centers in the sample has improved, with the average value falling from 1.7193 in 2018 to 1.5624 in 2020. However, there are clear regional performance gaps, with East China having the highest utilization performance (1.3113) while the Southwest had the lowest (2.2958). Finally, this paper proposes measures to improve the overall utilization of industrial waste resources based on an analysis of the factors driving solid waste utilization.

Large Virtual Transboundary Hazardous Waste Flows: The Case of China

The Basel Convention and prior studies mainly focused on the physical transboundary movements of hazardous waste (transporting waste from one region to another for cheaper disposal). Here, we take China, the world's largest waste producer, as an example and reveal the virtual hazardous waste flows in trade (outsourcing waste by importing waste-intensive products) by developing a multiregional input-output model. Our model characterizes the impact of international trade between China and 140 economies and China's interprovincial trade on hazardous waste generated by 161,599 Chinese enterprises. We find that, in 2015, virtual hazardous waste flows in China's trade reached 26.6 million tons (67% of the national total), of which 31% were generated during the production of goods that were ultimately consumed abroad. Trade-related production is much dirtier than locally consumed production, generating 26% more hazardous waste per unit of GDP. Under the impact of virtual flows, 40% of the waste-intensive production and relevant disposal duty is unequally concentrated in three Chinese provinces (including two least-developed ones, Qinghai and Xinjiang). Our findings imply the importance of expanding the scope of transboundary waste regulations and provide a quantitative basis for introducing consumer responsibilities. This may help relieve waste management burdens in less-developed "waste havens".

Ecological network analysis of the carbon metabolism system in mountainous cities based on the land-carbon nexus: a case study of the main urban area of Chongqing, China

The analysis of urban carbon metabolism will help to mitigate global warming and achieve China's "Dual Carbon" targets. Taking the main urban area of Chongqing (MUAC) as an example, this study accounted for the carbon release and carbon absorption in MUAC, constructed an urban carbon flow model based on the land-carbon nexus, and evaluated the urban carbon metabolic system from 2000 to 2020 by using the ecological network analysis method. The results show that MUAC is dominated by a "carbon source" effect, and the net carbon flow is always negative. The negative carbon flow mainly comes from the conversion of cultivated land to construction land, and the positive carbon flow mainly comes from the conversion of construction land to cultivated land and woodland. The ecological relationship of carbon metabolism in MUAC is dominated by exploitation and control relationships, which mainly exist in the ecological relationship between construction land and cultivated land, and the spatial distribution is concentrated in the central and western areas of MUAC. Our research results can provide a reference for Chongqing's green and low-carbon sustainable development as a means toward the realization of the "Dual Carbon" targets and provide a reference for other similar mountainous cities in western China.

Changes of bacterial and fungal communities and relationship between keystone taxon and physicochemical factors during dairy manure ectopic fermentation

BACKGROUND

Due to interactions with variety of environmental and physicochemical factors, the composition and diversity of bacteria and fungi in manure ectopic fermentation are constantly changing. The purpose of this study was to investigated bacterial and fungal changes in dairy manure ectopic fermentation, as well as the relationships between keystone species and physicochemical characteristics.

METHODS

Ectopic fermentation was carried out for 93 days using mattress materials, which was combined with rice husk and rice chaff (6:4, v/v), and dairy waste mixed with manure and sewage. Physicochemical characteristics (moisture content, pH, NH4+-N (NN), total organic carbon (TO), total nitrogen (TN) and the C/N ratio) of ectopic fermentation samples were measured, as well as enzymatic activity (cellulose, urease, dehydrogenase and alkaline phosphatase). Furthermore, the bacterial and fungal communities were studied using 16S rRNA and 18S rRNA gene sequencing, as well as network properties and keystone species were analyzed.

RESULTS

During the ectopic fermentation, the main pathogenic bacteria reduced while fecal coliform increased. The C/N ratio gradually decreased, whereas cellulase and dehydrogenase remained at lower levels beyond day 65, indicating fermentation maturity and stability. During fermentation, the dominant phyla were Chloroflexi, Firmicutes, Proteobacteria, Bacteroidetes, and Actinobacteria of bacteria, and Ascomycota of fungi, while bacterial and fungal community diversity changed dramatically and inversely. The association between physicochemical characteristics and community keystone taxon was examined, and C/N ratio was negative associated to keystone genus.

CONCLUSION

These data indicated that microbial composition and diversity interacted with fermentation environment and parameters, while regulation of keystone species management of physicochemical factors might lead to improved maturation rate and quality during dairy manure ectopic fermentation. These findings provide a reference to enhance the quality and efficiency of waste management on dairy farm.

Exploring the embodied carbon flow interactive relationships in China from an ecological network perspective: a model framework and application at provincial level

Energy-related carbon emissions take a large proportion in China, and the interregional trade caused by provincial disparities has led to significant differences in carbon footprint (CF) and embodied carbon flows among provinces that make great bottlenecks for the balance of economic development and carbon mitigation. In this study, we developed an embodied carbon flow-based ecological network (ECFEN) model with economic trade and emission data through combining the multi-regional input-output model and ecological network analysis approach. The developed ECFEN model was applied to 30 provinces in China to quantify the interprovincial flow of carbon embodied in final goods and services and identify the ecological utility (competitive, exploitative, and exploited) and control/dependence relationships between different regions. The main findings can be summarized as follows: Firstly, Jiangsu had the highest total CF with amount of 906 Mt, which was approximately 24.5 times than that of Hainan (37 Mt). Especially, the local CF in Shandong was the largest among all of the provinces with an amount of 683 Mt. Secondly, 13 pairs of embodied carbon flow paths exceeded 20 Mt, and the remarkable embodied carbon flowed from resource-oriented regions (e.g., Inner Mongolia, Shanxi, Hebei) to economically developed eastern coastal provinces and municipalities (e.g., Jiangsu, Guangdong, Beijing, Chongqing). Metallurgy and electricity, water, and gas contributed 30-80% of the total embodied carbon import and export for each province. Thirdly, the exploitative and exploited relationship dominated the ecological relationship between provinces. Meanwhile, the resource-oriented regions played the role of controllers while economically developed provinces were dependents. On the one hand, the central government could take vertical compensation measures such as financial subsidies for major exporter and controllers. On the other hand, it is necessary to take horizontal technical transfer especially from economically developed southeast coastal provinces to western underdeveloped inland area. The obtained results and policy implications are expected to provide reasonable insights for decision-makers to formulate carbon mitigation strategies under the domestic circulation strategy.

Ecological network analysis of industrial wastes metabolism based on input-output model for Jiangsu, China

The enormous discharge of industrial waste seriously hinders the sustainable development of cities. However, most studies only involve a single or limited category of industrial pollutants, ignoring the environmental pressure caused by multiple resources and environmental factors. This paper combines input-output analysis and ecological network analysis to construct an industrial waste metabolic input-output (IWMIO) model, which explores the industrial waste discharge and discharge relationships among different sectors in Jiangsu Province from the three aspects of industrial wastewater, industrial waste gas, and industrial solid waste. The results show that the indirect discharge of industrial waste is greater than the direct discharge in the industrial waste metabolism system. TI (Tertiary industry), CI (Chemical industry), SPM (Smelting and pressing of metals), and PSEH (Production and supply of electricity and heat) dominate the industrial waste metabolism system. In addition, MWC (Mining and washing of coal), MNMP (Manufacture of non-metallic mineral products), SPM (Smelting and pressing of metals) have more mutualism and competition relationships with other sectors, so the control of industrial waste discharge in these sectors contributes to achieving emission reduction targets. Based on the research results, this paper proposes corresponding policy recommendations such as considering both direct and indirect emissions of sectors when formulating waste reduction policies and developing pertinent industrial waste reduction programs based on the characteristics of the identified sectors. The results of this paper are helpful to identify the dependence and influence relationships of various sectors in the industrial waste metabolism system, promote industrial waste discharge control, and provide theoretical support for the adjustment of industrial structure and the formulation of related policies in Jiangsu Province.

A stepwise emission clustering analysis method for analyzing the effects of heavy metal emissions from multiple income groups

Emissions of various heavy metals (i.e. Hg, As, Cd, Cr and Pb) have emerged as one of the most tremendous pressures on the socio-economic and environmental systems. The pressures caused by such heavy metals would be getting intensified if no adequate and timely solution is implemented, especially because their emissions are associated with economic activities (i.e. regional trade and household consumption). In this study, emissions of various heavy metals derived from regional trade as well as rural and urban household consumption are quantified to identify the critical regions and significant household consumption. In order to detail the impacts of household consumption on such emissions, rural and urban household are divided respectively into five and seven groups with hierarchic income from poorest to richest. The Hg, As, Cd, Cr and Pb emissions caused by intermediate commodity consumption are 1172.86, 2607.57, 23.28, 57.49 and 85.16 tons, respectively. Among them, such emissions induced by self-consumption are 662.95, 1539.34, 12.28, 33.10 and 43.49 tons. Shandong, Guangdong and Jiangsu are identified for high self-emissions due to their advanced economy and rare resources. On the contrast, Hebei and Shanxi with abundant resources are the critical regions for the high transfer-out emissions. Moreover, emissions of multiple heavy metals are inequal due to the variations of rural and urban income groups. Emissions caused by R5 are identified through stepwise cluster analysis for its significant difference in compare with other income groups. It is verified that the main difference of emissions in economically developed regions are caused by rural income groups, while urban income groups are the critical reason for the disaggregation of emissions in less developed regions. Policies should be further implemented based on the regional similarity and income-group inequality.

Microstructure Evolution and Improved Permeability of Ceramic Waste-Based Bricks

The resource and large-scale utilization of waste ceramic materials, magnesium slag, and coal gangue are one of the important ways for the sustainable development in metallurgy, coal, and other related enterprises. In this paper, waste ceramic materials were used as aggregates; coal gangue and magnesium slag were used as mixed binder; and the all solid-waste-based permeable bricks with excellent performance were prepared by forming pressure at 5 MPa. The mechanical properties and water permeability of the all-solid-waste-based permeable bricks were evaluated. The results proved that the porous channel of permeable brick is mainly composed of waste ceramic materials with a particle size of 2–3 mm. Pore structures below 200 μm were mainly composed of fine aggregate and mixed binder. Using 60% coarse aggregate, 20% fine aggregate, 10% coal gangue, and 10% magnesium slag as raw materials, the all-solid-waste-based permeable bricks were obtained by pressing at 6 MPa and sintering at 1200 °C, which exhibited the best performance, and its water permeability, compressive strength, and apparent porosity were 1.56 × 10⁻² cm/s, 35.45 MPa, and 13.15%, respectively. Excellent water permeability, compressive strength, and apparent porosity of the all solid-waste-based permeable bricks were ascribed to the high content of connecting open pores, and closely adhesive force were ascribed to the porous microstructure constructed by the grading of waste ceramic materials and the tight conjoined points of the liquid phases in coal gangue and magnesium slag at a high sintering temperature.

The Influencing Effects of Industrial Eco-Efficiency on Carbon Emissions in the Yangtze River Delta

A low-carbon economy is the most important requirement to realize high-quality integrated development of the Yangtze River Delta. Utilizing the following models: a super-efficiency slacks-based measure model, a spatio-temporal correlation model, a bivariate LISA model, a spatial econometric model, and a geographically weighted random forest model, this study measured urban industrial eco-efficiency (IEE) and then analyzed its influencing effects on carbon emission in the Yangtze River Delta from 2000 to 2017. The influencing factors included spatio-temporal correlation intensity, spatio-temporal association type, direct and indirect impacts, and local importance impacts. Findings showed that: (1) The temporal correlation intensity between IEE and scale efficiency (SE) and carbon emissions exhibited an inverted V-shaped variation trend, while the temporal correlation intensity between pure technical efficiency (PTE) and carbon emissions exhibited a W-shaped fluctuation trend. The negative spatial correlation between IEE and carbon emissions was mainly distributed in the developed cities of the delta, while the positive correlation was mainly distributed in central Anhui Province and Yancheng and Taizhou cities. The spatial correlation between PTE and carbon emissions exhibited a spatial pattern of being higher in the central part of the delta and lower in the northern and southern parts. The negative spatial correlation between SE and carbon emissions was mainly clustered in Zhejiang Province and scattered in Jiangsu and Anhui provinces, with the cities with positive correlations being concentrated around two locations: the junction of Anhui and Jiangsu provinces, and within central Jiangsu Province. (2) The direct and indirect effects of IEE on carbon emissions were significantly negative, indicating that IEE contributed to reducing carbon emissions. The direct impact of PTE on carbon emissions was also significantly negative, while its indirect effect was insignificant. Both the direct and indirect effects of SE on carbon emissions were significantly negative. (3) It was found that the positive effect of IEE was more likely to alleviate the increase in carbon emissions in northern Anhui City. Further, PTE was more conducive to reducing the increase in carbon emissions in northwestern Anhui City, southern Zhejiang City, and in other cities including Changzhou and Wuxi. Finally, it was found that SE played a relatively important role in reducing the increase in carbon emissions only in four cities: Changzhou, Suqian, Lu’an, and Wenzhou.

Analysis of driving factors on China's industrial solid waste generation: Insights from critical supply chains

Industrial solid waste (ISW) poses a huge potential threat to human health and the environment. To prevent pollution at its source, it is necessary to analyze the socioeconomic drivers and identify the key supply chains that cause changes in ISW generation. In this study, based on monetary input-output tables (MIOTs) in China from 2011 to 2015, structural decomposition analysis (SDA) was used to study the influence of socioeconomic drivers on common industrial solid waste (CISW) and hazardous waste (HW) generation. Structural path decomposition (SPD) was used to further trace the effects of drivers at the supply chain level and obtain more meaningful results for policy formulation. Economic expansion was found to play the most crucial role in the increase in total ISW generation while the reduction of generation intensity effectively slowed the growth trend. From the final demand perspective, fixed capital formation contributed the most to ISW generation growth, accounting for 65.05% of the total final demand effect. Construction was the primary trigger. For CISW, the supply chain with the greatest overall influence was "metal ore mining industry → fixed capital formation" (including intermediate consumption of metal smelting, general and special machinery, and construction), reflecting how fixed capital formation indirectly affected the metal ore mining industry. The supply chain with the greatest influence on HW generation was "paper industry → exports." Based on the findings, corresponding policy adjustments are proposed.

Regional waste footprint and waste treatments analysis

This paper provides a detailed analysis of the waste footprint and waste treatments at subnational level, for Brussels, Flanders, and Wallonia. The paper details the waste footprint components into direct waste from households (disposed in bins), indirect waste generated upstream in the supply chains and induced by household consumption and waste materials from the degradation of in-use stocks. For each component, we analysed the contribution of waste types, products consumed and location where the waste was generated, as well as the associated treatments. The results show that Flanders had the highest total waste footprint in absolute terms; Brussels the highest direct waste in capita terms and Wallonia the highest indirect waste and stock depletion in capita terms. In each region, almost 78 ± 2% of the regional waste footprints were attributed to the consumption of food products, manufactured products and restaurants and accommodation services. For each region, around 45 ± 4% of the indirect waste was generated within its boundaries, 16 ± 9% in other regions and 39 ± 5% out of Belgium. Incineration was the predominant waste treatment type of the regional waste footprint, followed by recycling. Landfill was the second widely applied treatment for indirect waste. Results constitute key information relevant to enhance the waste data monitoring practices at regional level with effects at national level. We unveiled the waste footprint and associated treatments inherent to the interregional and international linkages. Results are also useful resources to substantiate waste management and circular economy policies, enacting on waste prevention and reduction, ecodesign and product lifetime extension.

Environmentally-extended input-output and ecological network analysis for Energy-Water-CO2 metabolic system in China

Resource and environmental elements as controlling factors for ecologic and socio-economic are crucial to seek new ideas and paths for development and prosperity. In this study, environmentally-extended input-output analysis and ecological network analysis were combined to develop three ecological networks including energy ecological network, water ecological network, and carbon ecological network for searching the complex relationships among different departments for water utilization, energy consumption, and carbon emissions under considering China as a superorganism with various complex metabolic processes and the most fundamental metabolic materials. The embodied ecological elements intensity, the indirect consumption and emissions, the embodied material flows, the ecological relationships, and the dependence intensities among sectors was obtained through transforming the monetary input-output data to physical data from 2007, 2012, and 2017. The results show that the Energy Ecological Network and Water Ecological Network were in a relatively stable state with a mutualism index greater than 1, and the relationship among different sectors in the CO₂ Ecological Network needs to be further adjusted. AM (Advanced Manufacture) and Agr (Agriculture) played the top exporter and importer roles with AM as the largest embodied energy consumer and CO₂ emitter, and Agr as the largest embodied water user. More measures about resource conservation and emission reduction for AM and Agr are desired. Con (construction) had a strong dependence intensity on other sectors with amounts of over 90%. Resources and environmental effects on Con can be improved by increasing the utilization efficiency of intermediate products. The results could provide scientific policy implications and guidelines to promote the stable and healthy operations by revealing the dynamic change of sectors within the Energy-Water-CO₂ metabolic system in China.

Exploring the industrial solid wastes management system: Empirical analysis of forecasting and safeguard mechanisms

Industrial solid wastes (ISWs) not only destroys the ecological environment, but also seriously affects human health, which is one of the main obstacles to sustainable development. Consequently, Effective management of ISWs is essential to support efforts to achieve cleaner production and ecological upgrading of industrial structure. In this study, metabolic grey model (MGM (1,1)) is adopted to forecasting the ISWs generation and treatment in China. Meanwhile, we develop an ISWs management system involving its safeguard mechanisms. Forecasting results show that China's ISWs generated have been a slowly increasing trend from 2018 to 2025, which will be controlled between 389819 million tons and 488002 million tons, and the utilization, disposal and storage of ISWs have a significant upward trend. However, the ratio of ISWs utilized will eventually remain at around 50% in the future. According to the prediction results, the application of this ISWs management system can increase the efficiency of waste recycling and reuse, and make ISWs become renewable resources. Research results also illustrate that the safeguard mechanisms, including government policy tools, collaborative agents of the industry-university, green technology innovation, and circulation of green products, have ensured a highly efficient recycling and beneficial waste management to create more added values for the ISWs materials.

Two-pathway perspective for heavy metal emission mitigation: A case study of Guangdong Province, China

Heavy metal emissions have attracted much worldwide attention for its recalcitrance and persistence. In this study, a two-pathway environmental simulation model is developed to uncover heavy metal emissions as induced by intra-provincial production and extra-provincial investments, filling the gap of mitigating heavy metal emissions from separate pathway. This developed model is applied to Guangdong Province, China targeting on the mitigation of Hg, As, Cd, Cr, and Pb emissions. Additionally, emission reduction simulations are implemented on the basis of key sector identification. The effects of intra-provincial production reduction are more notable than those of extra-provincial investment reduction. In addition, mitigation of Hg and As emissions can be achieved through the reduction in both intra-provincial production and extra-provincial investment. In the contrast, it is not expected that the reduction of extra-provincial investment be duo to the emission mitigation of Cd, Cr and Pb. Moreover, an examination of five optimized scenarios reveals that the most remarkable emission mitigation pathway is the reduction of intra- and extra-provincial activities. This study is an indispensable reference for multi-pathway emission mitigation for heavy metals.

Efficiency assessment of industrial solid waste generation and treatment processes with carry-over in China

Industrial solid waste (ISW) harms the eco-environment as well as human health; thus, both the generation and treatment processes of ISW are important aspects of a reduction of discharged ISW. Currently, only part of the generated ISW is treated, while the remainder is stored for later treatment, which is referred to as carry-over between two adjacent periods. According to such a two-stage process (with carry-over), a network slacks-based measure model is proposed to measure the overall and divisional efficiencies of 30 Chinese regions during 2011-2015. The main findings are summarized in the following: firstly, failing to consider carry-over underestimates both overall and divisional efficiencies. Secondly, the average annual generation efficiency exceeded the average annual treatment efficiency during the study period; however, this gap increasingly narrowed. Thirdly, the overall efficiency is more closely related to the treatment efficiency than to the generation efficiency. Moreover, synergies were identified between generation efficiency and treatment efficiency for each region. Fourthly, significant regional differences affect both overall and divisional efficiencies, and significant stage efficiency differences also affect both coastal and inland areas. To increase the overall efficiencies of different regions of China, different policies are suggested.

Dynamic wastewater-induced research based on input-output analysis for Guangdong Province, China

Large amounts of wastewater discharge have emerged as a burden in the process of industrialization and urbanization. In this study, a dynamic wastewater-induced input-output model is developed to systematically analyze the related situation. The developed model is applied to Guangdong Province, China to analyze its prominent characteristics from 2002 to 2015. Combining input-output analysis, ecological network analysis and structural decomposition analysis, the developed model reveals issues of direct and indirect discharges, relationships among various discharges, and driving forces of wastewater discharges. It is uncovered that Primary Manufacturing and Advanced Manufacturing dominate the system because of significant temporal and spatial variations in wastewater discharge. In addition, Manufacturing of paper, computer and machinery and Services are the key industries responsible for large amounts of wastewater discharge and unhealthy source-discharge relationships. The largest wastewater discharge occurred in 2005 and indirect wastewater discharge is the main form. Furthermore, final demand is found to be the biggest driving force of wastewater discharge. Finally, a three-phase policy implementation system implemented in stages proposes solutions to wastewater problems.

Unfolding interregional energy flow structure of China's construction sector based on province-level data

The construction sector is a critical part in achieving energy conservation targets in China, as it accounts for approximately 30% of the annual national energy supply for building construction. Therefore, this study integrates multi-regional input-output analysis and ecological network analysis to track energy fluxes and pathways from the construction sector, aiming to facilitate the configuration of the energy-flow structure and improve understanding of the region's responsibilities. Results of a spatial distribution analysis show that the eastern area of China leads in fossil energy consumption (e.g., coal and crude oil), whereas western China is the largest consumer of natural gas. Spatial relationship analyss indicate that eastern areas are located at the top of the trophic structure, implying that these regions are prioritized in energy consumption over the surrounding regions. By contrast, most regions located in the northern parts of China are characterized by resource-abundant areas and are at the bottom of the trophic structure, thereby indicating their comparatively weak role in an exploitation relationship. An investigation of major metropolitan areas demonstrates that mandatory targets set by national instruments are stratified in accordance with their diverse role and status in energy consumption at the beginning of the 12th Five-Year Plan period. However, these targets remain insignificant in the context of the inner area.

Measurement of air-pollution inequality through a three-perspective accounting model

China is suffering from serious air pollution. Regional air quality varies significantly due to intensive inter-provincial trades, diversified resource endowments and complicated economic structures. This study breaks the limitations of measuring environmental inequality only from a single perspective and establishes a three-perspective atmospheric pollutant equivalents accounting model (or APE accounting model) for air-pollution inequality assessment under environmentally-extend multi-regional input-output framework. From three perspectives of local production (i.e. production-based), final demand (i.e. consumption-based) and primary supply (i.e. income-based), APE emissions, APE transfers and environmental Gini coefficient are investigated to exam emission responsibilities of various impact factors, evaluate the impacts of inter-provincial trades on pollutants transfers, and characterize regional emission inequalities at both provincial and sectoral levels. The results indicate that local emitters are merely parts of contributors to air pollution. Direct emitters like Hebei Province, primary suppliers like Inner Mongolia and final consumers like Shandong Province induce large amounts of air pollutants as embedded within various economic activities. Because of unequal supply-demand levels and complex exchange mechanisms, three-perspective APE emissions are significantly heterogeneous, especially in mining, construction, energy and material-transformation sectors. Particularly, inequality of the mining sector in embodied emissions has the highest environmental Gini coefficient (0.881). This model provides a framework to assess regional environmental inequality and its findings provide scientific bases for the formulation of desired regional air pollution control policies.

The Potential of Industrial Symbiosis: Case Analysis and Main Drivers and Barriers to Its Implementation

Industrial symbiosis, which is characterised mainly by the reuse of waste from one company as raw material by another, has been applied worldwide with recognised environmental, economic, and social benefits. However, the potential for industrial symbiosis is not exhausted in existing cases, and there is still a wide range of opportunities for its application. Through a comprehensive literature review, this article aims to compile and analyse studies that focus on potential industrial symbiosis in real contexts, to highlight the margin of optimisation that is not being used. The cases reported in the publications identified here were characterised and analysed according to geographic location, type of economic activity, waste/by-products, main benefits, and the methods employed in the studies. From this analysis, we conclude that there is great potential for applications involving industrial symbiosis throughout the world, and especially in Europe, corresponding to 53% of the total cases analysed. Manufacturing stood out as the sector with the highest potential for establishing symbiosis relationships, and the most common types of waste streams in potential networks were organic, plastic and rubber, wood, and metallic materials. This article also discusses the main drivers and barriers to realising the potential of industrial symbiosis. The diversity of industries, geographical proximity, facilitating entities and legislation, plans, and policies are shown to be the main drivers.

Ecological network analysis of an urban water metabolic system based on input-output model: A case study of Guangdong, China

When considering a region as a superorganism, there are various processes of metabolism that reflect the growth and maintenances of the system, as well as the interactions with the surroundings. Ecological Network Analysis combined with the input-output model is utilized to analyze the water consumption structure and the interaction control relationships among different sectors within the urban ecosystem. The integrated approach is applied to the case study of Guangdong Province, China. The Water Ecological Network model is developed by the monetary I-O table of Guangdong province in 2012. The network control analysis is employed to describe the pathway of indirect water. In addition, the competitive and mutual relationship among different sectors is concluded by the approach of network utility analysis. This study also newly compares "virtual water (which is the indirect water) imports of per unit Gross Domestic Product (GDP)" and "water consumption of per unit GDP" to reveal which of them contributes more to the urban metabolism. The results indicate that the top three controllers are machinery, equipment and other services, followed closely by food and tobacco processing. The model results also show that the negative effects among different sectors accounting for the majority in all relationships, which indicates that the system under investigation is not in a mutualism state. This is due to that the competition of water uses between the economic sectors weaken the virtual water circulation within the system. The results are valuable to provide scientific suggestions for improving water use efficiency and make reasonable virtual water policy.

Energy-induced mercury emissions in global supply chain networks: Structural characteristics and policy implications

Mercury emission flows in the global supply chains have evolved into an ever-increasing complex network. However, the underlying structural features remain unknown. Therefore, the global embodied mercury flow network was constructed to reveal the characteristics of energy-induced mercury emissions embodied in international trade at both national and sectoral scales. The small-world nature of the global mercury flows network was identified at both scales. Results showed that the global mercury flow network can be divided into 4 national communities, within which the spillover effects of the interventions in one region spread more easily. Detecting the mercury-intensive supply-chain clusters highlights the importance of monitoring these clusters that dominate mercury emissions in global supply chains, which could offer insights on where policy can be implemented effectively. Moreover, vital regions (e.g., mainland China, the USA, and Germany) and sectors (e.g., Petroleum, Chemical and Non-Metallic Mineral Products, Metal Products and Electrical and Machinery in mainland China) for global mercury control have been unveiled by using an integrated centrality measurement system. Our results highlight that, for the overall mercury reduction, regional and even global collaboration should be enhanced along with efforts in individual regions, and enterprises in these important sectors should invest more to green their cluster-wise supply chains.

Transfer of virtual water embodied in food: A new perspective

Food and water are inextricably linked. With the increase of water consumption in irrigation and food growth, water shortage has become an urgent issue. Irrational cross-regional transfer of water embodied in food exacerbates water scarcity and restrict China's sustainable development. Given that, a Virtual Water-Food Nexus Model is developed to quantify the inter-provincial transfer of water embodied in food and to identify the complicated interactions between different provinces. In detail, Environmental Input-Output Analysis is applied to quantitatively estimate the inter-provincial water transfer embodied in food trades. Based on the network constructed by interrelated nature of nexus, the mutual interactions, control situation, and the dominant and weak pathways are examined through the combination of Ecological Network Analysis and Principal Component Analysis. Two new indictors water consumption intensity and water supply capacity are first performed to measure the role of each province from the supply and consume side respectively. It is revealed that interregional food transactions failed to realize water resources dispatching management. Many water-deficient regions suffered from massive virtual water losses through food exports, but water-rich areas still import large quantities of food containing virtual water. Results show that exploitation and competition dominate the ecological relationships between provinces. Agricultural GDP ratio is the indicator which most affect water consumption intensity and water supply capacity. Network-based research contributes more insights into the recognition of water management responsibilities across provinces and municipalities. These findings will provide a scientific support to adjust unreasonable allocation of water resources in China in an attempt to addressing the contradiction between food demand and water shortages.