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In China, with the rapid development of economy and the advancement of urbanization, the deterioration of urban ecological environment is obvious. In order to obtain the quantitative state of urban ecological security, this paper contributes an integrated and coupled emergy ecological footprint framework and Beijing city was selected to verify methodology effect in this paper. The results demonstrate that: (1) from 2010 to 2019, the change range of EEFB is from 6.37 to 9.29%; meanwhile, EEFI is from 7.95 to 17.72%; EEFE is from 36.36 to 63.71%; EEFP is from 18.45% to 41.65%. Comparing the proportions of four subparts, the energy resource products (EEFE) and emissions (EEFP) are the main factors, far more significant than biological resources (EEFB) and industrial products (EEFI). (2) Compared to all ECCS data, there is a definite growing trend in Beijing city, from 2.68E + 4 hm2/cap in 2010 to 4.72E+4 hm2/cap in 2019, approximately 42.22% growth range. (3) Four sustainable indicators analysis: The changes of EEFT, EBI, and EEF are from 3.1, 2.46, and 1.02 in 2010 to 0.688, 9.29 and 1.14 in 2019, respectively. For EDI, total proportions of fossil land and built-up land are 85.25% to 90.43% of the entire EEF in Beijing city. These results reflect that Beijing city is suffering from a substantial ecological challenge due to remarkable ecological deficit, awfully high emergy ecological footprint intensity, and low cooperation level between ecological system and economic system. To identify key improvement factors, Pearson correlation analysis was conducted in this paper and revealed the most positive and negative elements, which are the unbalanced industrial structure and a large proportion heavy and polluting industries in Beijing city. Finally, based on the pivotal influencing factors, corresponding strategies and measures are proposed to improve and optimize the ecological security in Beijing city.

We use emergy-based urban metabolism analysis in this study to investigate the local coupling and telecoupling between urbanization and the eco-environment in the Beijing-Tianjin-Hebei urban agglomeration. Our analysis encompasses the last 35 years spanning the period between 1980 and 2014. In addition, we analyze urban metabolic efficiency and environmental pressure in these couplings. There are three main conclusions of this study. First, we show that the total metabolic emergy value of the Beijing-Tianjin-Hebei urban agglomeration has increased over the last 35 years, and that external elements have replaced internal ones as the leading contributors to urban metabolism in this region. The proportion of metabolic emergy derived from external elements increased from 30.87% in 1980 to 67.43% in 2014. The emergy extroversion ratio has continued to increase over our study period, while the development of this urban agglomeration had become progressively and more heavily reliant on external elements. Second, over the study period, the metabolic emergy intensity of elements of local coupling and telecoupling in the Beijing-Tianjin-Hebei urban agglomeration has declined at an accelerating rate, from 1.15×10^21 Sej/100 million RMB in1980 to 9.69×10^19 Sej/100 million RMB in 2014. This reflects a continuous increase in the economic efficiency of this area.Correspondingly, emergy use per capita increased from 7.8×10^15 Sej/person in 1980 to 5.83×10^16 Sej/person in 2014, suggesting a gradual rise in the level of social welfare in this urban agglomeration. However, we also observed a consistently elevated environmental loading ratio（ELR） in our analysis in terms of metabolism of local coupling and telecoupling elements. This result indicates that environmental pressure has also increased constantly within the Beijing-Tianjin-Hebei urban agglomeration. Third,our analysis shows that the ELR of metabolic emergy from internal elements increased from 8.30 in 1980 to 43.46 in 2014, while the ratio from external elements increased from 4.15 to 92.03. Thus, we quantitatively investigated the dependency of development within this urban agglomeration on external elements as well as the resultant environmental load. The conclusions of this study provide the basis for quantitative policy-making in the Beijing-Tianjin-Hebei region, optimizing economic structures, improving economic efficiency, controlling environmental pollution, and promoting the coordinated development of this region.

The Yellow River is an important ecological shelter zone and economic belt in China. However, rapid urbanization and industrialization has produced a fragile ecological environment conditions and unbalanced economic development in the Yellow River Basin (YRB). Ecological protection and high-quality development of the YRB has been China’s national strategy since 2019. As the only coastal province with the largest economy and population in the YRB, the sustainable development of Shandong Province is of great importance in the region. This study evaluated the dynamic trend of sustainability levels of the nine cities in Shandong Province in the YRB through emergy analysis. Emergy-based indicators were established and analyzed from 2010 to 2019, taking account of the ecological service emergy (ESE) needed to dilute pollutants and emergy equivalent loss (EEL) on ecosystem quality and human health damage. Results showed that emergy sustainable indicators (ESI) in Tai’an, Heze, Dezhou, and Liaocheng ranged from 1 to 10, which had the potential for sustainable development. The ESI value of Jinan, Jining, Zibo, Dongying, and Binzhou was less than 1, which indicated that these cities were under great ecological pressure. The value of emergy indicators for sustainable development (EISD) of the nine cities all declined from 2010 to 2016, but remained stable from 2017 to 2019. Based on findings from the emergy analysis regarding policy implications and local conditions, the study concludes by providing proposals to improve regional sustainability.

Clay brick is a commonly used building material in China. Due to the enormous land destruction and excessive consumption of resources, such as materials and energy in the manufacture of clay brick, it is important to study its overall sustainability, i.e., in terms of impact on the environment, services, and economy. In this study, emergy analysis is employed, which offers a holistic perspective, unlike typical environmental studies. A series of emergy indices such as renewability rate (R%), nonrenewability rate (N%), unit emergy values (UEVs), emergy yield ratio (EYR), environmental loading ratio (ELR), and emergy sustainability index (ESI) were used to study manufacturing of clay brick. In addition to calculating UEVs of clay brick manufacturing in China (7.18 × 1012 sej/kg), our detailed analysis shows that the nonrenewable resources and imported energy have a dominant impact on the emergy contribution (50.6%) and within the nonrenewable resources, clay is the foremost item, accounting for 33.5% of local emergy inputs. Given different electricity UEVs, the change ranges of clay brick system UEVs are 14.9% (scenario 1), 7.24% (scenario 2), 8.91% (scenario 3), and 6.94% (scenario 4). Furthermore, several policy suggestions are discussed for improving the sustainability of the evaluated system, involving the energy structure adjustment, recycling material replacement, and promotion of energy-saving systems.

The supply of energy through fossil fuels and the increase in harmful environmental effects caused by it has caused the supply of energy through renewable energies to be given more attention. Since residential buildings account for a significant part of the world's energy consumption, supplying their needed energy through renewable energies can be a way to reduce non-renewable energy consumption and its harmful effects on the environment. This study suggests using a combination of solar and wind energy to provide electricity, heating, cooling and freshwater for a residential building in Russia. This system, which includes FPC solar collector, a wind turbine, an absorption chiller, a hydrogen storage system and a reverse osmosis desalination unit, is subjected to a comprehensive economic–environmental evaluation through emergy analysis. Performance evaluation of the proposed system to meet the hourly demand of a building for one year and in different weather conditions of four cities of Khabarovsk, Yakutsk, Yekaterinburg and St. Petersburg is investigated. The emergy analysis results illustrated that although the system has an unstable economic–environmental performance in the climatic conditions of Yakutsk city, it is stable with an environmental sustainability index (ESI) of more than 1 in the other three cities. The emergy sustainability index of the system in Khabarovsk city with a value of 2.37E + 00 showed that the system in this city has the best performance from view of economic–environmental point.

Integrated rice–crayfish systems are expanding rapidly and are the most widely applied planting–breeding modes in Jianghan Plain in China. We conducted nutrient use efficiency, economic, and emergy analysis of three rice production modes, namely, rice monoculture (RM), rice–crayfish rotation (RCR), and rice–crayfish coculture (RCC), in Jingzhou City, which is located in the Jianghan Plain. Compared with RM mode, rice–crayfish systems using the RCR and RCC modes increased rice yield by 5–7%, showed more than 8% higher chemical nutrient use efficiency, and increased the value-to-cost ratio from 1.5-fold to 2.7-fold and the benefit–cost ratio from 2.5-fold to 3.8-fold, while decreasing irrigation water consumption and land occupation by 31% and 82–86%, respectively. RCC resulted in 10% higher crayfish yield, 12% higher phosphorus use efficiency, and 38% higher feed use efficiency than RCR. However, compared with RM, rice–crayfish systems decreased renewable fraction by 10–14%, emergy yield ratio by 9%, and emergy sustainability index by 23–26%, and they increased environmental loading ratio to 18–23%. Labor and service, fertilizer utilization, and machine and tools play important roles in these negative environmental effects. Scenario analysis showed that the rice–crayfish systems increased sustainability index by 38–45%. The technical training of new planting–breeding technology should be adopted by farmers for the efficient use of fertilizers and improvement of food yield. This study suggests that rice‑crayfish systems are not a panacea to sustain cleaner food production.

Under extreme drought conditions, water shortage loss assessment is essential for regional water use system management decisions and the development of drought mitigation measures. This study addresses current research on economic losses in water use systems, which often overlooks the social and ecological losses caused by drought mitigation measures. The impact of measures such as water use compression, industrial structure adjustment, and hierarchical, zoned and time-divided water allocation on various water use subsystems is analysed. A comprehensive framework for quantifying regional water shortage losses was established using emergy analysis, enabling unified evaluation of multidimensional impacts. The framework was applied to quantify water use system losses in Chuxiong Prefecture, Yunnan Province, during the severe drought event in 2009 ~ 2012. The results show that the overall trend of water shortage losses in the water use system initially increased before gradually declining, with subsystem losses ranked as follows: domestic water > agricultural water > industrial water > ecological water. This study offers a new perspective for evaluating water shortage losses under extreme drought conditions.

The agricultural sector contributes 18% of global greenhouse gas (GHG) emissions. For the agricultural sector, most countries have pledged to reduce emissions by around 50% relative to emissions in 1990. One of the paths of achieving this goal is practicing a circular agriculture system that integrates livestock and farming. The present study evaluates and compares the sustainability of an agricultural system progressively transitioning from linearity to circularity. The study's objective is to verify the hypothesis that a circular agricultural system has a good self-organizing capacity, minimizes non-renewable purchased inputs, causes minimum stress to the environment, and maximizes economic and social benefits compared to the agricultural system in standalone. To analyze the environmental effect of the agricultural system, the present study uses emergy analysis and evaluation of avoided impact due to recycling of waste from livestock and farming. A case study of three farming systems is used for the assessment in the present work. The linear agricultural system (AS-P), the agricultural system with livestock (AS-L), and the circular agricultural system that integrate livestock and feedback (AS-IFL). The circular agricultural system was shown to have significant recycling advantages, with 3.29 E + 17 solar emergy joules (sej)/ year saved emergy and 2.51E + 06 kg avoided carbon dioxide emissions per hectare per year. The resources saved as a result of the system's great recycling potential make it even more cost-effective. Fodder accounted for a significant portion of the purchased input, which might be decreased by in-house cultivation or the utilization of farm-generated agro wastes. The current study supports the concept that crop and animal farming are complementary and lead to a sustainable agricultural system in which one system's waste is used as a resource for the other. Out of the three human basic needs (food, clothing, and shelter), two are related to agriculture. Therefore, sustainable agriculture is in the interest of humanity’s wellbeing as it is a major subsystem of plant earth.

In the context of rapid population growth and limited arable land resources, the agricultural system has to provide enough food in a sustainable way. Regional agricultural systems have good consistency in agricultural practices, management decisions, social economy, and climate, which is of great significance in ensuring food security. In this study, emergy analysis and the logarithmic mean divisia index method were integrated to construct an evaluation framework from the dimensions of socio-economic environment, resource environment, climate environment, and ecological environment. Then we evaluated and analyzed the changes in agricultural system sustainability from 1990 to 2019 in the mainstream of Liaohe River Basin, a typical agricultural basin in China. The results showed that the Emergy sustainability index (ESI) decreased from 0.17 to 0.14, and factors Δ Pt/Gt (social and economic development level), Δ G/I (agricultural economic benefits), and Δ Gt/G (economic structure) from the socio-economic environment dimension had the greatest impact on changes in ESI. Moreover, society and economy affected the factors in the resource environmental dimensions through the allocation of policies and resources, which in turn directly affected ESI. The influence of factors from the climatic environment and ecological environment weakens as the ability to manage agricultural systems increases. The research provided a reference for the planning and management of sustaining agricultural systems at a regional scale.

Bibliometric and visualization tools ar e effective for uncovering information contained in vast amounts of literature data. We retrieved publications from the Web of Science (2008–2020) and used the Statistical Analysis Toolkit for Informetrics (SATI) and CiteSpace to conduct a bibliometric analysis of emergy studies, review the focus of the studies, summarize current research, and identify academic trends. The SATI-based charts provided an overall description of yearly published articles, literature sources, high-frequency keywords, authors, institutions, and highly cited papers. CiteSpace was applied to determine the frontiers and hotspots of emergy theory. A dual-map analysis was used to reveal the connection between multiple disciplines. Keyword clustering analysis was performed to evaluate research hotspots. Moreover, burst analysis and timeline maps presented a holistic picture of cutting-edge issues and the evolutionary trajectory of emergy studies in recent years. An alluvial flow map analysis of the landmark literature depicted the transmission of knowledge in the emergy field. In addition, this article also evaluated the current status of collaborative research in emergy-related fields. The results can provide a reference for researchers to explore hot issues or target a specific field of study.