Country-specific net-zero strategies of the pulp and paper industry.

The pulp and paper industry is an important contributor to global greenhouse gas emissions1,2. Country-specific strategies are essential for the industry to achieve net-zero emissions by 2050, given its vast heterogeneities across countries3,4. Here we develop a comprehensive bottom-up assessment of net greenhouse gas emissions of the domestic paper-related sectors for 30 major countries from 1961 to 2019-about 3.2% of global anthropogenic greenhouse gas emissions from the same period5-and explore mitigation strategies through 2,160 scenarios covering key factors. Our results show substantial differences across countries in terms of historical emissions evolution trends and structure. All countries can achieve net-zero emissions for their pulp and paper industry by 2050, with a single measure for most developed countries and several measures for most developing countries. Except for energy-efficiency improvement and energy-system decarbonization, tropical developing countries with abundant forest resources should give priority to sustainable forest management, whereas other developing countries should pay more attention to enhancing methane capture rate and reducing recycling. These insights are crucial for developing net-zero strategies tailored to each country and achieving net-zero emissions by 2050 for the pulp and paper industry.

Potential of technological innovation to reduce the carbon footprint of urban facility agriculture: A food-energy-water-waste nexus perspective.

As an emerging form of agriculture, urban facility agriculture is an important supplement to traditional agriculture and one of the ways to alleviate the urban food crisis, but it may generate a high carbon footprint. A comprehensive assessment of urban facility agriculture is a necessity for promoting its low-carbon development. In this study, the carbon footprint of urban facility agriculture under four different technological innovation models was simulated by life cycle assessment and a system dynamics model for a carbon footprint accounting without considering economic risk. Case 1, as the basic case, is Household farm facility agriculture. Case 2 is the introduction of vertical hydroponic technology based on Case 1, Case 3 is the introduction of distributed hybrid renewable energy micro-grid technology based on Case 2, and Case 4 is the introduction of automatic composting technology based on Case 3. These four cases demonstrate the gradual optimization of the food-energy-water-waste nexus in urban facility agriculture. This study further uses the system dynamics model for carbon reduction potential considering economic risk to simulate the diffusion (promotion) scale and carbon reduction potential of different technological innovations. Research results show that with the superposition of technologies, the carbon footprint per unit land area is gradually reduced, and the carbon footprint of Case 4 is the lowest at 4.78e+06 kg CO2eq. However, the gradual superposition of technologies will further limit the diffusion scale of technological innovation, thereby reducing the carbon reduction potential of technological innovation. In Chongming District, Shanghai, under theoretical circumstances, the carbon reduction potential of Case 4 is the highest at 1.6e+09 kg CO2eq, but the actual carbon reduction potential is only 1.8e+07 kg CO2eq due to excessive economic risks. By contrast, the actual carbon reduction potential of Case 2 is the highest with 9.6e+08 kg CO2eq. To fully achieve the carbon reduction potential of technology innovation, it is necessary to promote the scale diffusion of Urban facility agricultural technology innovation by raising the sales price of agricultural products and the grid connection price of renewable electricity.

Coupled impacts of climate and land use changes on regional ecosystem services.

Ecosystem services (ES) are key to maintaining sustainable regional development. Climate change and land cover and land use change (LULC) are one of the main factors leading to changes in regional ecosystem services. Existing studies have simulated regional ES changes under different future scenarios, providing valuable guidance for regional sustainable management. However, most studies focus on the effects of individual factors (LULC or climate change) on ES, paying insufficient attention to the coupled effects of the two elements. Yunnan Province is a biodiversity hotspot facing challenges in ES in the context of future climate change and rapid socio-economic development. In order to achieve sustainable management, policies must be developed in advance to address possible future ecological risks. In this study, we simulated the coupled effects of climate change and LULC on six types of ES using the SD, FLUS, and InVEST models. The scenario framework of shared socioeconomic pathways SSP245 and SSP585 was combined with LULC scenario dynamics to assess the changes of ES in 2030 and 2050, identifying sensitive areas and providing a scientific basis for local ecosystem management. In 2020, the eastern part of Yunnan Province was the coldspot area for all ES. Under the future scenarios, Yunnan Province's ES show different loss rates and distinct spatial heterogeneity. Future climate change and LULC changes have a more significant negative impact on water conservation and water quality purification. About 66% of its counties will become sensitive areas for water production services, and 37% of counties will endure reduced water purification functions by more than 50%. According to the analytical results, we then proposed several suggestions to improve regional ES management.

Superselective Hg(II) Removal from Water Using a Thiol-Laced MOF-Based Sponge Monolith: Performance and Mechanism.

Point-of-use (POU) devices with satisfying mercury (Hg) removal performance are urgently needed for public health and yet are scarcely reported. In this study, a thiol-laced metal-organic framework (MOF)-based sponge monolith (TLMSM) has been investigated for Hg(II) removal as the POU device for its benchmark application. The resulting TLMSM was characterized by remarkable chemical resistance, mechanical stability, and hydroscopicity (>2100 wt %). Importantly, the TLMSM has exhibited high adsorption capacity (∼954.7 mg g-1), fast kinetics (kf ∼ 1.76 × 10-5 ms-1), broad working pH range (1-10), high selectivity (Kd > 5.0 × 107 mL g-1), and excellent regeneration capability (removal efficiency >90% after 25 cycles). The high applicability of TLMSM in real-world scenarios was verified by its excellent Hg(II) removal performance in various real water matrices (e.g., surface waters and industrial effluents). Moreover, a fixed-bed column test demonstrated that ∼1485 bed volumes of the feeding streams (∼500 µg L-1) can be effectively treated with an enrichment factor of 12.6, suggesting the great potential of TLMSM as POU devices. Furthermore, the principal adsorption complexes (e.g., single-layer -S-Hg-Cl and double-layer -S-Hg-O-Hg-Cl and -S-Hg-O-Hg-OH) formed during the adsorption process under a wide range of pH were synergistically and systematically unveiled using advanced tools. Overall, this work presents an applicable approach by tailoring MOF into a sponge substrate to achieve its real application in heavy metal removal from water, especially for Hg(II).

Reducing Carbon Footprint Inequality of Household Consumption in Rural Areas: Analysis from Five Representative Provinces in China.

Household consumption carbon footprint and inequality reductions are vital for a sustainable society, especially for rural areas. This study, focusing on rural China, one of the fastest growing economies with a massive population, explored the carbon footprint and inequality of household consumption using the latest micro household survey data of 2018 linked to environmental extended input--output analysis. The results show that in 2018 in rural China, the average household carbon footprint is 2.46 tons CO2-eq per capita, which is around one-third of China's average footprint, indicating the large potential for further growth. Housing (45.32%), transportation (20.45%), and food (19.62%) are the dominant contributors to the carbon footprint. Meanwhile, great inequality, with a Gini coefficient of 0.488, among rural households is observed, which is largely due to differences in type of house built or purchased (explaining 24.44% of the variation), heating (18.10%), car purchase (12.44%), and petrol consumption (12.44%). Provinces, average education, and nonfarm income are among the important factors influencing the inequality. In the process of urbanization and rural revitalization, there is a high possibility that the household carbon footprint continues to increase, maintaining high levels of inequality. The current energy transition toward less carbon-intensive fuels in rural China is likely to dampen the growth rates of carbon footprints and potentially decrease inequality. Carbon intensity decrease could significantly reduce carbon footprints, but increase inequality. More comprehensive measures to reduce carbon footprint and inequality are needed, including transitioning to clean energy, poverty alleviation, reduction of income inequality, and better health care coverage.

Exploring the formulation of ecological management policies by quantifying interregional primary ecosystem service flows in Yangtze River Delta region, China.

Ecosystem services (ESs) play an important supporting role in the development of human society and the economy. Despite the increasing number of ESs quantitative evaluation studies that have been conducted at different scales, the assessment of ESs flows between different administrative regions, which provides valuable implications for ecological protection and compensation, has drawn little attention. The aim of this study is to fill in this gap by providing a comprehensive ES interregional flow analysis method that evaluates ecosystem service values (ESVs) and quantifies the interregional flows in the Yangtze River Delta (YRD), which is home to one of the largest urban agglomerations in China. The results showed that the total ESV of the YRD increased from 2.02E+12 Chinese Yuan (CNY) in 2000 to 2.33E+12 CNY in 2019, a 15.23% increase rate. All types of ESVs displayed an increasing trend during the 20 years. According to the analysis of interregional ES flows in the YRD, Zhejiang province played a crucial role as a service providing area (SPA) for the spatial value transfer at the provincial level in both 2000 and 2019. Anhui province was the largest service benefitting area (SBA) of water conservation and CSOP, while Jiangsu province was the largest SBA of soil retention. The recognition of interregional ESV flows can provide valuable information for environmental planning and management to help improve China's ecological compensation policies for different administrative divisions.

Climate change vulnerability assessment for smallholder farmers in China: An extended framework.

Climate change brings uncertainty and challenges to achieving sustainable development goals. The dually vulnerable regions in terms of the environment and economy are facing substantial threats from climate change; particularly, smallholder farmers who heavily rely on natural ecosystems in these regions are being the most affected. Paying attention to the vulnerability assessment of these regions is conducive to precisely improving the ability of their people to cope with climate change. This study aimed to construct an extended framework of climate change vulnerability assessment at the household level by combining the Intergovernmental Panel on Climate Change vulnerability assessment framework with the sustainable livelihood framework. Four typical regions with different climatic and geographical conditions in China, including the Inner Mongolia Autonomous Region (marked as AOHAN, representing the type of grassland, similarly hereinafter), Qinghai Province (HYMH, plateau), Yunnan Province (YLNL, mountain), and the Guangxi Zhuang Autonomous Region (NNQZ, coastal zone), were selected to apply the framework. In total, 29 villages from these four regions were selected at random, and 360 face-to-face interviews were conducted in selected villages based on a pretested questionnaire. The results show that AOHAN had the greatest vulnerability, as well as the highest exposure level among the four regions, which was also the major source of differences in vulnerability. Further analysis shows that although the sensitivity and adaptive capacity showed relatively small differences, the sources of sensitivity and adaptation strategies were quite different among the four regions. In terms of sensitivity, YLNL had the highest level of sensitivity in housing, water, and livestock, and AOHAN assumed the highest sensitivity in land. The advantages and disadvantages in terms of adaptive capacity also varied widely among the four regions. More specifically, AOHAN had a balanced adaptive capacity; YLNL largely relied on the advantages in social and human capitals to compensate for the disadvantage in physical capital; and the strengths in physical and financial capitals are the main sources of adaptive capacities for NNQZ and HYMH, respectively. In general, the vulnerability assessment framework proposed in this study provides guidelines for vulnerability assessments at the household level in the face of climate change. In addition, heterogeneous measures to cope with the threats of climate change should be put forward precisely, based on the climatic, geographical and socioeconomic characteristics of each region.

Sustainability evaluation based on the Three-dimensional Ecological Footprint and Human Development Index: A case study on the four island regions in China.

Sustainable development emphasizes the sustainability of natural resources and the environment as well as the development of social welfare. Under the background of resource scarcity and environmental constraints, maximizing social welfare is an inevitable choice to achieve sustainable development. Ecological Wellbeing Performance (EWP) can comprehensively reflect the efficiency of natural capital conversion into social welfare, and improving EWP is a feasible measure to achieve sustainable development. Moreover, island areas are the extremely complicated ecological-social-economic systems due to the traits that are geographical isolation, scarce resources, and frequent natural disasters, so that emphasizing the sustainability of island systems is a key step for achieving sustainable development goals. This study developed the EWP model based on the improved Three-dimensional Ecological Footprint (EF) and urban-scale Human Development Index (HDI), to synthetically evaluate and analyze the sustainable development of four major island regions in China with the data in 2017. Results found that: (1) The four regions are all in ecological deficits, being in exchange for overdraft natural capital for economic development. The EFdepth is greater than the original length 1 indicating the excessive consumption of the natural capital stock. The EFsize reflects the abundance and liquidity of regional natural capital, all the four regions are with the generally low level of flow capital utilization. Hainan with highest EFsize 0.428 is due to its comparatively sparse population density, abundant resources, and strong ecological capacity, while the relatively large population density and more restricted natural capital flows make Taiwan in the lowest value. (2) Judging from the evaluation results of the HDI, Chongming (0.796) and Hainan (0.773) high development level are relatively behind Taiwan (0.912) and Zhoushan (0.827) very high development level, for the impact of income is greater, that is, economic development in Hainan and Chongming is slightly weak. (3) Taiwan, with the highest EWP 3.646, shows the excellent natural resource utilization efficiency and sustainability, followed by Zhoushan, Chongming, and Hainan. In general, increasing HDI while reducing EF can be an ideal way to improve the efficiency of ecological resources and achieve sustainable urban development.

Optimization of ultrasonic-assisted extraction for determination of polycyclic aromatic hydrocarbons in biochar-based fertilizer by gas chromatography-mass spectrometry.

Application of biochar-based fertilizers is increasingly being considered for its potential agronomic and environmental benefits. However, biochar may contain residues of polycyclic aromatic hydrocarbons (PAHs) as a result of its production by pyrolysis. The strong adsorption of PAHs to biochar makes extraction and analysis of biochar-based fertilizers difficult. This study optimizes the extraction of PAHs in biochar-based fertilizer samples by using an ultrasonic bath for quantification by gas chromatography-mass spectrometry. Among 12 solvents, acetone-cyclohexane (1:1) mixture was selected as the optimum solvent for extraction. Three variables affecting the extraction were studied by Box-Behnken design. The optimum conditions were 57 °C extraction temperature, 81 min extraction time, and two extraction cycles, which were validated by assessing the linearity of analysis, LOD, LOQ, recovery, and levels of PAHs in real biochar-based fertilizer samples. Results revealed that the 16 U.S. EPA PAHs had good linearity, with squared correlation coefficients greater than 0.99. LODs were low, ranging from 2.2 ng g(-1) (acenaphthene) to 23.55 ng g(-1) (indeno[1,2,3-cd]perylene), and LOQs varied from 7.51 ng g(-1) to 78.49 ng g(-1). The recoveries of 16 individual PAHs from the three biochar-based fertilizer samples were 81.8-109.4 %. Graphical Abstract Use of RSM to optimize UAE for extraction of the PAHs in biochar-based fertilizer.

Optimization and determination of polycyclic aromatic hydrocarbons in biochar-based fertilizers.

The agronomic benefit of biochar has attracted widespread attention to biochar-based fertilizers. However, the inevitable presence of polycyclic aromatic hydrocarbons in biochar is a matter of concern because of the health and ecological risks of these compounds. The strong adsorption of polycyclic aromatic hydrocarbons to biochar complicates their analysis and extraction from biochar-based fertilizers. In this study, we optimized and validated a method for determining the 16 priority polycyclic aromatic hydrocarbons in biochar-based fertilizers. Results showed that accelerated solvent extraction exhibited high extraction efficiency. Based on a Box-Behnken design with a triplicate central point, accelerated solvent extraction was used under the following optimal operational conditions: extraction temperature of 78°C, extraction time of 17 min, and two static cycles. The optimized method was validated by assessing the linearity of analysis, limit of detection, limit of quantification, recovery, and application to real samples. The results showed that the 16 polycyclic aromatic hydrocarbons exhibited good linearity, with a correlation coefficient of 0.996. The limits of detection varied between 0.001 (phenanthrene) and 0.021 mg/g (benzo[ghi]perylene), and the limits of quantification varied between 0.004 (phenanthrene) and 0.069 mg/g (benzo[ghi]perylene). The relative recoveries of the 16 polycyclic aromatic hydrocarbons were 70.26-102.99%.

Effect of biochar on nitrous oxide emission and its potential mechanisms.

Extensive use of biochar to mitigate nitrous oxide (N2O) emission is limited by the lack of understanding on the exact mechanisms altering N2O emission from biochar-amended soil. Biochars produced from rice straw and dairy manure at 350 and 500 degrees C by oxygen-limited pyrolysis were used to investigate their influence on N2O emission. A quadratic effect of biochar levels was observed on the N2O emissions. The potential mechanisms were explored by terminal restriction fragment length polymorphism (T-RFLP) and real-time polymerase chain reaction (qPCR). A lower relative abundance of bacteria, which included ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), was observed at 4% biochar application rate. Reduced copy numbers of the ammonia monooxygenase gene amoA and the nitrite reductase gene nirS coincided with decreased N2O emissions. Therefore, biochar may potentially alter N2O emission by affecting ammonia-oxidizing and denitrification bacteria, which is determined by the application rate of biochar in soil. Implications: Biochar research has received increased interest in recent years because of the potential beneficial effects of biochar on soil properties. Recent research shows that biochar can alter the rates of nitrogen cycling in soil systems by influencing nitrification and denitrification, which are key sources of the greenhouse gas nitrous oxide (N2O). However, there are still some controversial data. The purpose of this research was to (1) examine how applications of different dose of biochar to soil affect emission of N2O and (2) improve the understanding of the underlying mechanisms.

Environmental impact of adult incontinence products in China in the context of population aging.

With the rise of the aging population, the demand for adult incontinence products keeps increasing in developing countries. The increasing market demand for adult incontinence products will inevitably drive up upstream production, leading to more resources and energy consumption, carbon emissions, and heavier environmental pollution. It is imperative to explore the environmental impact of those products and seek opportunities to reduce the environmental impact, which is insufficient. This study aims to fill the gap in research on comparative analysis of energy consumption, carbon emissions, and the environmental impact of adult incontinence products from a life cycle perspective under different energy saving and emission reduction scenarios in the context of aging in China. Based on empirical data from a top papermaking manufacturer in China, this study applies Life Cycle Assessment (LCA) method to analyze the impact of adult incontinence products from cradle to grave. Then different scenarios in the future are set to explore the potential of and the possible pathways for energy-saving and emission-reduction of adult incontinence products from the perspective of the whole life cycle. The results indicate that the energy and materials inputs are the environmental hotspots of adult incontinence products. Under the future trend of the aging population, the predictable optimization of energy structure, optimization of material composition, and final disposal methods are far from being able to cope with the enormous environmental burden brought by the increase in the consumption of adult incontinence products, especially in 2060 which shows 3.33 to 18.40 times the annual environmental burden under the optimal energy saving and emission reduction scenario, compared to the base year 2020. Research on new environmentally friendly materials and recycling technology should be the focus of the technological development of adult incontinence products.

Environmental assessment of fabric wet processing from gate-to-gate perspective: Comparative study of weaving and materials.

Textile industry has yet to be developed beyond low efficiency, high resources consumption, and toxic emissions, with wet processing process a dominant contributor to resources consumption and pollution emissions. Recognition of the environmental impact of the representative wet processing is essential to achieve eco-friendly development of textile industry. Using Life Cycle Assessment (LCA), this study addressed the environmental impacts of wet processing of woven/knitted cotton and polyester fabrics from 4 textile enterprises in China by deploying gate to gate system boundary. One ton of grey cloth was chosen as the functional unit. Eighteen midpoint impact categories and three endpoint impact categories were assessed via ReCiPe 2016 v1.1 (H) method. The results indicated "dyeing unit" as the dominant unit for all the impact categories at the midpoint, which was mainly derived from electricity consumed by cotton wet processing and detergents used in polyester wet processing. Among 4 different fabric wet processing, woven polyester wet processing exhibited the highest impact, while the least impact was assigned to knitted cotton. In the midpoint categories of water use, dyeing unit was also the major contributor in wet processing of knitted cotton (41.20 m3) and knitted polyester (44.70 m3). Pretreatment accounted for an overwhelming percentage of water use in woven cotton (48.00 %) and woven polyester (56.00 %). Woven polyester wet processing was also the most energy-intensive and resource-consuming industry among all scenarios, with a 3.37-fold higher fossil resource scarcity per ton of fabric compared with woven cotton. The results recommend measures for cleaner production in the wet processing.

A novel peroxymonosulfate activation process by single-atom iron catalyst from waste biomass for efficient singlet oxygen-mediated degradation of organic pollutants.

Single-atom dispersed catalysts (SACs) have gained considerable attention in organic contaminants remediation due to their superior reactivity and stability. However, the complex and costly synthesis processes limit their practical applications in environmental protection. Herein, a facile and cost-effective single-atom iron catalyst (Fe-SA/NC) anchored on nitrogen-doped porous carbon was first fabricated by using waste biomass as a carbon source. The Fe-SA/NC catalyst exhibited outstanding performance with a high turnover frequency of 1.72 min-1 toward antibiotics degradation via peroxymonosulfate activation. ECOSAR program and algae growth experiments demonstrated that the byproducts produced during the sulfamethoxazole degradation process were not detrimental to the aquatic environment. Radical quenching and electron paramagnetic resonance experiments revealed that Fe-SA/NC remarkably promoted 1O2 production in PMS-assisted reaction, and thus 1O2 contributed as much as 78.77% to sulfamethoxazole degradation. As indicated by experiment and density functional theory (DFT) calculations, FeN2O2 configuration serves as the active site. DFT calculations further presented the most rational generation route of 1O2 as PMS→OH* â†’O* â†’1O2. We also designed Fe-SA/NC embedded spherical pellets for contaminants elimination at the device level. This study offers new insights into the synthesis of SACs from waste biomass and their practical application in environmental remediation.

Coupling of crop and livestock production can reduce the agricultural GHG emission from smallholder farms.

Ensuring global food security and environmental sustainability is dependent upon the contribution of the world's hundred million smallholder farms, but the contributions of smallholder farms to global agricultural greenhouse gas (GHG) emissions have been understudied. We developed a localized agricultural life cycle assessment (LCA) database to calculate GHG emissions and made the first extensive assessment of the smallholder farms' GHG emission reduction potentials by coupling crop and livestock production (CCLP), a redesign of current practices toward sustainable agriculture in China. CCLP can reduce the GHG emission intensity by 17.67%, with its own feed and manure returning to the field as an essential path. Scenario analysis verified that greater GHG emission reduction (28.09%-41.32%) will be achieved by restructuring CCLP. Therefore, this mixed farming is a mode with broader benefits to provide sustainable agricultural practices for reducing GHG emissions fairly.

Is mulch film itself the primary source of meso- and microplastics in the mulching cultivated soil? A preliminary field study with econometric methods.

There has been an increasing interest in the pollution caused by meso- and microplastics (MMPs) in terrestrial ecosystems. Mulch film was once considered to be the most important source of MMPs in the mulching cultivated soil. However, the academic community has not given sufficient scientific evidence. In this study, stratified random sampling method was used to selectively interview households in Hebei province, China (400 households, 20 villages, 5 counties). Finally, household characteristics and mulch film use behavior of 41 households were collected, and corresponding soil samples were sampled. The results showed that 1) the abundance of MMPs was 29.3 ± 33.1 items·kg-1 (DW) and the particle size of MMPs was 2.95 × 103±1.75 × 103 µm, and the proportion of MMPs derived from Polyethylene (PE) was only 18.8%; 2) the mass of MMPs was 2.90 ± 3.72 mg kg-1 (DW) and the proportion of PE MMPs was 43.75%, which has the highest mass percentage; 3) After controlling the endogenous and dummy variables, the use history of mulch film (HistMF) was found to be positively correlated to the abundance of MMPs and inversely correlated to the particle size, but nor with the mass of MMPs; 4) Regarding the heterogeneous characteristics of MMPs, including particle size, color, shape, and type, the findings found the absence of a significant correlation between HistMF and the abundance and mass of PE. In summary, mulch-derived MMPs are not the primary source of MMPs in the mulching cultivated soil in terms of abundance but probably be in terms of mass.

Heterogeneous Effects of Skill Training on Rural Livelihoods around Four Biosphere Reserves in China.

The growing contradiction between protection and livelihood is a common challenge for most protected areas in developing countries. Skill training is an important way to increase household income and alleviate the dilemma between conservation and development. However, its effects on household income around protected areas have rarely been explored. This paper aims to evaluate the effect of skill training on the income of households around four Biosphere Reserves in China and explore its mechanism. Based on the information collected from 381 households through face-to-face interviews, this study adopted descriptive analysis and multiple regression to yield consistent results. The results showed that agricultural and off-farm skill training had no impact on the total household income. The results from the mechanism analysis found that participation in off-farm skill training had a significant and positive effect on the total income of the households outside protected areas and participation in agricultural training had a positive effect on agricultural income. The findings indicate that the local government and protected area administration should increase the publicity for skill training, enrich the types training, appropriately supply livelihood support projects that reconcile conservation and development, and strengthen the infrastructure development around protected areas to promote off-farm employment and the circulation and sale of agricultural products. However, the impacts of any associated intensification should be carefully monitored.

Agent-based model for simulation of the sustainability revolution in eco-industrial parks.

Eco-industrial parks (EIPs) are of increasing importance for implementing industrial ecology strategies and are facing increasing challenges in terms of environmental pollution and resource scarcity. As a complex adaptive system, an EIP involves multiple sectors and faces various disturbances that influence its evolutionary trajectories. This study adopts an agent-based model to simulate the material flows and industrial symbiosis process in the EIP, considering the initiative of each company and the ever-changing environment. The proposed EIP model emphasises the heterogeneity of companies and attempts to reflect multiple and dynamic factors that have received less attention in previous studies. This model contains two types of agents, companies and the external environment. A company agent makes decisions and interacts with other agents following its own behaviour rules, while the external environment agent functions to coordinate the material flows and exert influence on the companies. The model has been verified and validated by simulating a 20-year-period development of an empirical EIP in China. The simulation results are assessed by three indicators: eco-connectance, eco-efficiency, and industrial symbiosis indicator. Results showed that during the growing phase, the eco-connectance increased from 0.02 to 0.1 for the non-disturbance situation. The eco-efficiency and industrial symbiosis indicator also realised 78.5% and 74.8% of their total increments. The outcome of this research provides insights for the design of the strategies to improve the industrial symbiosis performance and is of high potential to facilitate EIPs in promoting eco-transformation and sustainable development.

Phosphorus flow analysis of different crops in Dongying District, Shandong Province, China, 1995-2016.

Investigating the phosphorus (P) sources, pathways, and final sinks are important to reduce P pollution and improve P management. In this study, substance flow analysis (SFA) was performed for P flow analysis from 1995 to 2016 in different crops of Dongying District, a core region of the alluvial delta at the estuary of the Yellow River. The results showed that P input steadily increased from 1.48 × 104 t in 1995 to 2.16 × 104 t in 2007, and then decreased from 1.90 × 104 t in 2010 to 1.78 × 104 t in 2016. Chemical fertilizers made the highest contribution to P input. The cotton with the highest P load was on the top of P load risk ranks. More importantly, this study applied the Partial Least Squares Path Modeling (PLS-PM) model for P flow analysis and established the numerical relationship between the variables (including fertilizers, straws return-to-field, harvested grains, discarded straw, and P erosion and runoff), P use efficiency (PUE) and P load. The analysis revealed that fertilizer and crop production are the key factors affecting the PUE. Therefore, optimizing the use of P-fertilizer whilst maintaining yields can be an effective strategy to improve the local region PUE.

Determinants of smallholder farmers' choice on mulch film thickness in rural China.

Agricultural mulch film pollution has become a prevailing concern. Studies have shown that the thickness of mulch film is a key factor affecting mulch film recycling, but research about farmers' choice on mulch film thickness is lacking. Based on survey data from 2025 households in five Chinese provinces in 2018, the Heckman two-stage model was used to analyze the influencing factors of farmers' choice on mulch film thicknesses. Mulch film had been used by 21.98% of the sample households, and 41.47% of the used mulch film did not meet the national thickness standard. The econometric results showed that farmers' product cognition and market factors were the two most important factors, and there was a significant negative correlation with the choice of film thickness. In addition, the choice of mulch film with different thicknesses was affected by household characteristics, subjective norms, and farmland property rights. Strengthening and stabilizing farmland property rights is a long-term mechanism to promote farmers to choose thicker mulch film. In addition to strengthening the production and sale of substandard film supervision, farmers' choice of film thickness should be included in village regulations and other rural grass-roots governance systems, especially in the mechanism design between agricultural farmland protective subsidies and the prevention of mulch film pollution, rather than just considering the recycling itself.