Tracing fossil-based plastics, chemicals and fertilizers production in China.

Phasing down fossil fuels is crucial for climate mitigation. Even though 80-90% of fossil fuels are used to provide energy, their use as feedstock to produce plastics, fertilizers, and chemicals, is associated with substantial CO2 emissions. However, our understanding of hard-to-abate chemical production remains limited. Here we developed a chemical process-based material flow model to investigate the non-energy use of fossil fuels and CO2 emissions in China. Results show in 2017, the chemical industry used 0.18 Gt of coal, 88.8 Mt of crude oil, and 12.9 Mt of natural gas as feedstock, constituting 5%, 15%, and 7% of China's respective total use. Coal-fed production of methanol, ammonia, and PVCs contributes to 0.27 Gt CO2 emissions ( ~ 3% of China's emissions). As China seeks to balance high CO2 emissions of coal-fed production with import dependence on oil and gas, improving energy efficiency and coupling green hydrogen emerges as attractive alternatives for decarbonization.

Integrated optimization modelling framework for low-carbon and green regional transitions through resource-based industrial symbiosis.

The development and utilization of bulk resources provide the basic material needs for industrial systems. However, most current resource utilization patterns are unsustainable, with low efficiencies and high carbon emissions. Here, we report a quantitative tool for resource-based industries to facilitate sustainable and low-carbon transitions within the regional economy. To evaluate the effectiveness of this tool, the saline Qinghai Lake region was chosen as a case study. After optimizing the industrial structure, the benefits of economic output, resource efficiency, energy consumption, solid waste reduction, and carbon emission reduction can be obtained. The scenario analyses exhibit disparities in different transition paths, where the carbon mitigation, economic output, and resource efficiency that benefit from optimal development paths are significantly better than those of the traditional path, indicating the urgency of adopting cleaner technology and industrial symbiosis for regional industries.

Decreasing resilience of China's coupled nitrogen-phosphorus cycling network requires urgent action.

The coupled nature of the nitrogen (N) and phosphorus (P) cycling networks is of critical importance for sustainable food systems. Here we use material flow and ecological network analysis methods to map the N-P-coupled cycling network in China and evaluate its resilience. Results show a drop in resilience between 1980 and 2020, with further decreases expected by 2060 across different socio-economic pathways. Under a clean energy scenario with additional N and P demand, the resilience of the N-P-coupled cycling network would suffer considerably, especially in the N layer. China's socio-economic system may also see greater N emissions to the environment, thus disturbing the N cycle and amplifying the conflict between energy and food systems given the scarcity of P. Our findings on scenario-specific synergies and trade-offs can aid the management of N- and P-cycling networks in China by reducing chemical fertilizer use and food waste, for example.

Achieving artificial carbon cycle via integrated system of high-emitting industries and CCU technology: Case of China.

Process-related carbon emissions, which cannot be completely eliminated by the improvement of processes and energy structure, are recognized as an enormous challenge for in-depth decarbonization. To accelerate the achievement of carbon neutrality, the concept of 'artificial carbon cycle' is proposed based on the integrated system of process-related carbon emissions from high-emitting industries and CCU technology as a potential pathway towards a sustainable future. This paper conducts a systematic review on the integrated system with the case of China, which is the largest carbon-emitting and manufacturing country, to provide a clearer and more meaningful analysis. Multi-index assessment was used to organize the literature and draw the useful conclusion. Based on literature review, the high-quality carbon sources, reasonable carbon capture approaches and promising chemical products were identified and analyzed. Then the potential and practicability of the integrated system was further summarized and analyzed. Finally, key factors of future development including technology improvement, green hydrogen, clean energy and industrial cooperation were stressed to provide a theoretical reference for future researchers and policy makers.

Rapid Increase in China's Industrial Ammonia Emissions: Evidence from Unit-Based Mapping.

Ammonia (NH3) is an important precursor of secondary inorganic aerosols and greatly impacts nitrogen deposition and acid rain. Previous studies have mainly focused on the agricultural NH3 emissions, while recent research has noted that industrial sources could be significant in China. However, detailed estimates of NH3 emitted from industrial sectors in China are lacking. Here, we established an unprecedented high-spatial-resolution data set of China's industrial NH3 emissions using up-to-date measurements of NH3 and point source-level information covering eight major industries and 27 subdivided process categories. We found that China emitted 798 (90% confidence interval: 668-933) gigagrams of industrial NH3 into the atmosphere in 2019, equivalent to 44 ± 20% of the industrial emissions worldwide; this flux is 3-fold larger than that in 1998 and has fluctuated since 2014. Furthermore, although fertilizer production is responsible for approximately half of the emissions in China, the emissions from cement production and coal-fired power plants increased dramatically from near zero to 164 and 41 gigagrams, respectively, in the past two decades, primarily due to the NH3 escape caused by the large-scale application of the denitration process. Our results reveal that, unlike other major air pollutants, China's industrial NH3 emission control is still in a critical period, and stricter NH3 emission standards and innovation in pollution control technologies are highly desirable.

Improved interactive inference approach for constructing a complex multi-industrial symbiosis network.

The development of industrial parks is an important avenue to promote economic growth in the context of modernization. Industrial symbiosis (IS), mainly characterized by the physical exchange of product, by-product, and waste, has been established worldwide in industrial parks for better economic, environmental, and resource-consuming performances. The suitable design of input-output matching builds the base of IS practice. This paper aims to table an improved constructing approach based on interactive inference processes for a complex multi-industrial symbiosis network (MISN). Interactive reasoning rules are simplified, material group reduction is introduced, and the multi-industrial stepwise constructing process is established. The proposed approach has been applied to an assumed district in Qaidam Circular Economy Experiment Area (QCEEA). Three new node information databases are collected. A MISN which is across four industries and includes 79 nodes is built through four steps of constructing and 22 rounds of interaction. Results and comparisons confirm its superiority on designing complex network with numerous resource- and non-resource-based nodes over previous methods. Specifically, this new approach reduces the amount of inference calculation, improves the construction efficiency, and can be utilized in non-resource industries. Preliminary discussions are made to the sequences of target industries when constructing a MISN and implicate which would lower manual workload of extra adjustment and supplement.

Hotspots of reactive nitrogen loss in China: Production, consumption, spatiotemporal trend and reduction responsibility.

Effective and fair mitigation measures hinge on the identification of hotspots and tracking provenance on reactive nitrogen (Nr) loss at a high spatial resolution. We assessed the Nr loss intensity in China at 1 km spatial resolution from 1980 to 2015. The total Nr loss increased from 20.2 to 54.5 Tg N yr-1, with hotspots (>100 kg N ha-1 yr-1) concentrated in the North China Plain, the Middle and Lower Yangtze River and the Sichuan Basin. The Nr loss hotspots covered less than 20% of the Chinese territory but contributed more than 90% of total Nr loss since 1990. Geographical disparity in Nr loss has increased and calls for a fair regional policy synergy. Compared to managing Nr loss based only on production, we demonstrate that the estimation of Nr loss responsibility driven by consumption has greater potential to allocate a fair share of responsibility for reducing Nr loss.

Regression analysis and driving force model building of CO2 emissions in China.

In recent years, global warming has become increasingly devastating, leading to severe consequences, such as extreme weather events and sea-level rise. To reduce carbon dioxide emissions, it is essential to recognize different emission sources and key driving factors. Three main carbon emission sources from the period between 1990 and 2017 were identified in China: the energy industry, fuel combustion in other industries, and industrial process. For each source, a driving force model was developed via multiple linear regression. Based on these models, forecasts of the carbon intensity and total CO2 emissions were obtained from 2018 to 2030. The results demonstrate that the CO2 emission intensity and total emissions will continue to decrease but more effort will be required to achieve the goal of Paris Agreement.

Effect of balanced nutrient fertilizer: A case study in Pinggu District, Beijing, China.

Agriculture has played an indispensable role in the economic and social development of China. However, the inappropriate application of fertilizers in agriculture has brought about environmental pollution. Therefore, under the requirements of green development, the inevitable choice has been reducing the application amount while increasing the utilization rate of fertilizers. To solve the problems resulting from fertilizers, this research designed and made Balanced Nutrient Fertilizer based on the nutrient balance method. To test Balanced Nutrient Fertilizer, continuous planting experiments on three crops (peas, corns, and peaches) were carried out in Pinggu District, Beijing. Furthermore, a substance flow analysis (SFA) was conducted to obtain a deeper understanding of the Balanced Nutrient Fertilizer. Through a series of tests, the application of Balanced Nutrient Fertilizer was shown to increase the crop yield by 3%. The product quality was also improved. In addition, the amount of nutrients applied was significantly reduced in the experimental group (specifically, 35%-88% for nitrogen, 69%-93% for phosphorus, and 8%-82% for potassium). The results of the SFA revealed that applying the Balanced Nutrient Fertilizer could meet the required amount of nutrients for the best crop growth, greatly decrease the negative influence of chemical fertilizers on the soil and reduce agricultural non-point source pollution.

Estimation and analysis of municipal food waste and resource utilization potential in China.

With rapid urbanization, municipal food waste (MFW), which is an important part of municipal solid waste, has attracted considerable attention owing to its environmental impact and polluting nature. There has been little research on the quantity and distribution of food waste (FW) produced in China. This study focused on a systematic estimation and analysis of MFW produced in administrative divisions at the prefecture-level and above in China for the first time. From the national level to the prefectural level, with the shrinking of the research units, more intuitive support was obtained for relevant decisions. On the basis of the estimated results, suggestions are provided for proper FW treatment technologies and operational scale of the facilities, and the resource utilization potential has also been estimated. The distribution results indicated that FW characteristics have great variability in the different economic regions of China. Furthermore, it was found that the available FW has a resource utilization potential that is equivalent to 4669.1 million m3 of biogas, 3.6 million tons of biodiesel, and 1.5 million tons of organic fertilizer (dry weight). It is worth mentioning that this amount of biogas can replace 7.5 million tons of standard coal. However, only a small part of the generated MFW can be treated in the existing treatment plants in China. Finally, current key bottlenecks of FW treatment in China have been discussed, and detailed suggestions are presented for further improvement of MFW management.

A temporal-spatial analysis and future trends of ammonia emissions in China.

Excessive anthropogenic activities have led to high-level ammonia loss and volatilization, which is regarded as a key factor in Chinese haze formation. In this study, a comprehensive analysis of ammonia emission estimations is accomplished at both temporal (1980-2016) and spatial (provincial) scales using a mass-balanced model, and emission projections through 2030 are also studied in different development scenarios. The results show that the ammonia emissions increased from 4.7 Tg N yr-1 in 1980 to 11 Tg N yr-1 in 2016, which is an approximately 2.4-fold increase. The cropland and livestock emissions are the largest contributors, as most reports show approximately 80% contributions; however, nonagriculture sources of fuel combustion, waste treatment and ammonia escape have grown rapidly in recent years, accounting for 14% in 2016. The spatial differences also reveal the complex heterogeneity in Chinese provinces. In addition, the emission intensities of major agriculture and non-agriculture sources are 0-80 kg N ha-1 yr-1 and over 100 kg N ha-1 yr-1, respectively, indicating a higher degree of ammonia concentration from non-agriculture emissions, which should attract wide concern. In terms of scenario analysis, emissions would reach 12.8 Tg N yr-1 in 2030 under the currently developed model and 7.3 Tg N yr-1 under a series of reduction policies; the spatial analysis also shows that the North China Plain has a 2.1 Tg N yr-1 reduction potential. The results of this study provide new insights into ammonia emission estimations and a better understanding of the environmental impacts of ammonia emitted from different sources.

Evaluation of a new extended producer responsibility mode for WEEE based on a supply chain scheme.

China is promoting extended producer responsibility (EPR) for waste electrical and electronic equipment (WEEE). However, the present EPR policy in China, in fund mode, has been facing the challenge of fund deficit severely since 2016. A new sustainable EPR mode is needed to solve this problem. In this paper, a mandatory recycling EPR mode is designed and studied as a potential solution. A quantitative evaluation system is innovatively established to evaluate the effectiveness of the mode and to compare the new mode to the present mode. The evaluation system first summarizes a supply chain scheme of electrical and electronic equipment (EEE) in each mode, which describes the life cycle of China's EEE from products to wastes to renewed resources. The supply chain schemes are complex since they contain five to six different stakeholders. Then classical game theory models are applied to the supply chain scheme based on the interaction among different stakeholders to calculate the indicators used for evaluation. At last, the two modes are compared in terms of economic, environmental and social effects in the case of the air-conditioner market. Results show the mandatory recycling mode is similar to the fund mode in economic and social effects. It is more financially sustainable, capable of enabling a higher recycling rate and more beneficial to certified recycling companies. Therefore, applying the recycling obligation mode in the future to maintain the EPR system is recommended.

Exploring regional air quality evolution by developing a driving force model: Case study of Beijing.

While the economy and society of China are developing rapidly, various ecological and environmental problems continue to emerge. The problem of air pollution is becoming an issue of increasing concern. Since 2013, Beijing, Tianjin, and Hebei Provinces have collaborated to control air pollution and have achieved certain success. However, the air pollution problem in the capital, Beijing, remains severe. In this study, a quantitative evaluation and analysis method is established for assessing urban air quality and its influencing factors by developing a driving force model. The model combines multiple regression and principal component analysis to account for social, economic, meteorological, and regional factors. The influencing factors with the highest contributions are regional transmission, energy consumption, and industrial structure. This model is used to project the future trend of the air quality in Beijing based on the evolution of the influencing factors, aimed to provide a theoretical basis for policies improving Beijing's air quality.

Evaluation and analysis on the green development of China's industrial parks using the long-tail effect model.

Industrial parks (IPs) have always been an important driving force for China's economic development. China has a great number of IPs, and this number is continuing to increase. The rapid development of IPs has brought great pressure on national resources utilization and environmental protection. The Chinese government has committed to the green development of IPs. In recent years, a series of policies on the green development of IPs have been introduced and implemented. Different from the limitation on the number of IPs in previous studies, this study used a larger data set containing 911 IPs. These IPs were divided into eight types according to their leading industries. The long-tail effect model was attempted to be used to provide quantitative description and analysis of the numerical distribution patterns of the indicators of economic output, environmental pollution, and resource consumption in IPs. Based on the long-tail effect model, for this paper, the performance of green development (PGD) in different types of IPs and IPs in different regions was further analyzed. The results show that China's IPs exhibit the distribution pattern of a long-tail effect in all three aspects mentioned above. In terms of environmental pollution, for some types of IPs, the individual performance of IPs in the head part of the model is more prominent. For other types of IPs, the cumulative results caused by IPs in the tail part of the model should be of concern. The PGD of IPs is closely related to their types. There are also obvious differences in the PGD of IPs in eastern and western China. Based on detailed discussion of the research results, at the end, policy implications are provided for the government to make decisions on the green development of IPs.

Promoting information technology for the sustainable development of the phosphate fertilizer industry: a case study of Guizhou Province, China.

The information technology revolution has brought unprecedented opportunities to the sustainable development of the traditional phosphate fertilizer industry. In this paper, the changes in characteristic indexes during this technological progress and business innovation are investigated at the industrial level and for different stakeholders using scenario simulation analysis based on system dynamics. The results show that information technology will have a significant impact on the traditional fertilizer industry. The popularity of information technology represents a win-win situation for industries, farmers, enterprises and governments. The sustainable development of the phosphate fertilizer industry promoted by information technology means that agrochemical services are a new growth point for the industry, and farmers will be the largest beneficiaries. Enterprises will adjust their product structures to achieve the relevant phosphate reduction goals before 2020. At the government level, the indirect benefits from energy savings, water conservation and reductions in non-point source pollution control treatment also increase significantly. In the new production and sales model, the development of the phosphate fertilizer industry is completely decoupled from resource consumption. In the future, this technological progress will eventually form a sustainable network of industrial innovation patterns. Our finding suggests that the application of information technology in the phosphate fertilizer industry can stimulate the vitality of each entity in the industry and achieve a win-win situation.

The trends of aquacultural nitrogen budget and its environmental implications in China.

The rapid development of aquaculture has sustained aquatic food production but has also led to a host of environmental problems, ranging from eutrophication of aquatic ecosystems to global acidification. China has become the world's largest producer and consumer of aquaculture products. Nitrogen is an essential nutrient in aquaculture ecosystems, and the quantitative environmental fate and impact of nitrogen during aquaculture processes have notable environmental consequences but have received little attention. Here, we established a nitrogen cycling model for China's aquaculture ecosystem to investigate the creation and fate of reactive nitrogen over a decadal time scale. A nitrogen balance analysis showed that reactive nitrogen input in the aquaculture ecosystem increased from 9.43 Tg N yr-1 in 1978 to 18.54 Tg N yr-1 in 2015, while aquaculture production increased from 0.034 to 1.33 Tg N yr-1 during the same period. The environmental fate analysis showed that nitrogen emissions, accumulation, sediment deposition, and export into the oceans increased by 9.05-fold, 0.24-fold, 9.04-fold, and 2.56-fold, respectively. Finally, we investigated four scenarios representing different consumption levels of aquatic products and provided policy recommendations (larger aquaculture size, standardized aquaculture production model, nutritional element management and balanced dietary structure, etc.) on improved management practices in aquaculture ecosystems.

From Production to Consumption: A Coupled Human-Environmental Nitrogen Flow Analysis in China.

Anthropogenic inputs of reactive nitrogen (Nr) provide sufficient food, energy, and industrial products to meet human demands; however, only a fraction of Nr is consumed as food and nonfood goods, and the rest is lost to the environment and negatively affects ecosystems. High-resolution studies of nitrogen flows are invaluable to increase nitrogen use efficiencies and reduce environmental emissions. In this study, a comprehensive substance flow analysis of nitrogen for China in 2014 is presented. Based on the conceptual framework, which highlights the key roles of human drivers, the analysis of the synthetic ammonia supply and demand balance shows that 75% of ammonia is used for agricultural purposes. Moreover, the life cycle analysis of food nitrogen shows that human food consumption accounts for approximately 7% of the total Nr inputs. A quantitative analysis of pollutant emissions shows that industrial and crop production are the main sources of atmospheric emissions, while livestock farming and crop production are the main sources of water emissions. Finally, we investigate four scenarios (efficiency improvement, high recycling rate, nitrogen oxide emission reduction, and a combined scenario) and provide relevant policy recommendations (large farm size, standardized agricultural production model, flue gas denitration, etc.) for improving nitrogen management practices.

[Change traits of phosphorous consumption structure in China and their effects on environmental phosphorous loads].

Substance flow analysis was used to construct a model to analyze change traits of China's phosphorous (P) consumption structure from 1980 to 2008 and their influences on environmental phosphorous loads, then the correlation between several socioeconomic factors and phosphorous consumption pollution was investigated. It is found that phosphorous nutrient inputs of urban life and rural life on a per capita level climbed to 1.20 kg x a(-1) and 0.99 kg x a(-1) from 0.83 kg x a(-1) and 0.75 kg x a(-1) respectively, but phosphorous recycling ratios of urban life fell to 15.6% from 62.6%. P inputs of animal husbandry and planting also kept increasing, but the recycling ratio of the former decreased from 67.5% to 40.5%, meanwhile much P input of the latter was left in agricultural soil. Correlation coefficients were all above 0.90, indicating that population, urbanization level, development levels of planting and animal husbandry were important incentives for P consumption pollution in China. Environmental Kuznets curve showed that China still stayed in the early development stage, promoting economic growth at an expense of environmental quality. This study demonstrates that China's P consumption system is being transformed into a linear and open structure, and that P nutrient loss and environmental P loads increase continually.