Matching end-of-life household vehicle generation and recycling capacity in Chinese cities: A spatio-temporal analysis for 2022-2050

End-of-life vehicles (ELVs) present both opportunities and challenges for the environment and the economy, where effective recycling management plays a decisive role. Recently, the primary focus of recycling management has shifted from simply meeting demand to refining and optimizing processes at the city-scale. However, the mismatch in recycling capacity has become a significant obstacle to maximizing environmental and economic benefits. To reveal this issue and propose improvements in the context of China, this study simulates end-of-life internal combustion engine vehicles (ICEVs) and new energy vehicles (NEVs) at the city-scale from 2021 to 2050, and analyzes their spatio-temporal pattern and recycling capacity matching. The results indicate that the number of ELVs in China will continue to increase, peaking between 3.5 and 3.7 million. This growth will be mainly driven by third- to fifth-tier cities, as well as central and southwestern cities. Regarding recycling capacity matching, most cities possess excess dismantling capacity, while first-tier cities face coordination problems in battery collection. Spatial coordination across cities or provinces is a viable approach for dismantling enterprises and should be prioritized over indiscriminate deregistration or establishing new facilities. The absence of initiative within the recycling system results in uncoordinated battery collection. Implementing a recycling-sharing mechanism and establishing a reuse market can effectively tackle this problem by leveraging market incentives. These analyses provide practical suggestions to maximize the environmental and economic benefits of resource recycling, thereby contributing to the UN's 2030 Sustainable Development Goals (SDGs).

Health burden evaluation of industrial parks caused by PM2.5 pollution at city scale

Industrial park is an important emission sector of PM2.5 pollution. Previous studies have provided valuable information on the impact of PM2.5 from industrial parks on human health, but relevant studies at city scale are limited. In this study, the health burden of industrial parks was evaluated based on PM2.5-related premature deaths and economic contributions. The premature deaths were calculated in terms of a novel research model by integrating the Bayesian maximum entropy (BME) model, weighted concentration-weighted trajectory (WCWT), and integrated exposure-response function (IER). Take Tianjin City for example, it was found that since the main diffusion direction of PM2.5 in Tianjin is from south to north, the industrial parks in the south of Tianjin and close to the central city with high population density have high health burden. These industrial parks need to be focused on or even relocated in the future. The research model can provide scientific basis for the health burden evaluation of industrial parks at city scale, so as to help local governments optimize the layout of industrial parks and formulate environmental responsibility management policies for industrial parks.

Anthropogenic CO2 emission reduction during the COVID-19 pandemic in Nanchang City, China

China is the largest CO₂ emitting country on Earth. During the COVID-19 pandemic, China implemented strict government control measures on both outdoor activity and industrial production. These control measures, therefore, were expected to significantly reduce anthropogenic CO₂ emissions. However, large discrepancies still exist in the estimated anthropogenic CO₂ emission reduction rate caused by COVID-19 restrictions, with values ranging from 10% to 40% among different approaches. Here, we selected Nanchang city, located in eastern China, to examine the impact of COVID-19 on CO₂ emissions. Continuous atmospheric CO₂ and ground-level CO observations from January 1st to April 30th, 2019 to 2021 were used with the WRF-STILT atmospheric transport model and a priori emissions. And a multiplicative scaling factor and Bayesian inversion method were applied to constrain anthropogenic CO₂ emissions before, during, and after the COVID-19 pandemic. We found a 37.1-40.2% emission reduction when compared to the COVID-19 pandemic in 2020 with the same period in 2019. Carbon dioxide emissions from the power industry and manufacturing industry decreased by 54.5% and 18.9% during the pandemic period. The power industry accounted for 73.9% of total CO₂ reductions during COVID-19. Further, emissions in 2021 were 14.3-14.9% larger than in 2019, indicating that economic activity quickly recovered to pre-pandemic conditions.

Estimates of population exposure to atmospheric pollution and health-related externalities in a real city: The impact of spatial resolution on the accuracy of results

Health impacts of atmospheric pollution is an important issue in urban environments. Its magnitude depends on population exposure which have been frequently estimated by considering different approaches relating pollutant concentration and population exposed to it. However, the uncertainties due to the spatial resolution of the model used to estimate the pollutant concentration or due to the lack of representativeness of urban air quality monitoring station (AQMS) have not been evaluated in detail. In this context, NO₂ annual average concentration at pedestrian level in the whole city of Pamplona (Spain) modelled at high spatial resolution (~1 m) by Computational Fluid Dynamic (CFD) simulations is used to estimate the total population exposure and health-related externalities by using different approaches. Air pollutant concentration and population are aggregated at different spatial resolutions ranging from a horizontal grid cell size of 100 m × 100 m to a coarser resolution where the whole city is covered by only one cell (6 km × 5 km). In addition, concentrations at AQMS locations are also extracted to assess the representativeness of those AQMS. The case with a spatial resolution of 100 m × 100 m for both pollutant-concentration distribution and population data is used as a reference (Base case) and compared with those obtained with the other approaches. This study indicates that the spatial resolution of concentration and population distribution in the city should be 1 km × 1 km or finer to obtain appropriate estimates of total population exposure (underestimations <13%) and health-related externalities (underestimations <37%). For the cases with coarser resolutions, a strong underestimation of total population exposure (>31%) and health-related externalities (>76%) was found. On the other hand, the use of AQMS concentrations can induce important errors due to the limited spatial representativeness, in particular in terms of population exposure.

Assessing the environmental performance for more local and more circular biowaste management options at city-region level

Biomass, biobased materials and food waste are considered priority areas for Europe's transition towards a circular economy (CE). Waste management is a central activity for this transition and offers multiple CE implementation options which should be evaluated from environmental perspective. The purpose of this work was to analyze the environmental consequences when redirecting biowaste flows from conventional to more circular management systems and to identify the CE option with the best environmental performance. We were particularly interested in studying the combined management of green and food waste, analyzing the challenges when introducing separate collection and different treatment processes, and evaluating the substitution potential for by-products. To determine environmental impacts, we performed a life cycle assessment (LCA) based on local data. Following the purpose analyzing a change in the system, we applied a consequential LCA and compared impacts from processes that are replaced with impacts from alternative management options such as co-composting, anaerobic digestion (AD) and decentralized composting. The LCA results show clear advantages for impacts on ecosystems and resource use for the local AD system with separate combined collection. The decentralized system shows reductions in resource use, whereas the industrial co-composting system has higher or similar impacts than the baseline scenario. We conclude that local systems with combined food and green waste management can show benefits if process emissions are properly managed and if by-products are used in applications with high substitution potentials. However, a change towards a CE does not necessarily result in environmental benefits. Our research highlights the complexity of biowaste systems and proposes a novel combination of local data, databases and models to handle this issue. With this research we are further contributing to the understanding of the combined management of food and green waste, which is a relevant, but so far under-researched, management option for cities.

CFD modelling of air quality in Pamplona City (Spain): Assessment, stations spatial representativeness and health impacts valuation

A methodology based on CFD-RANS simulations (WA CFD-RANS, Weighted Averaged Computational Fluid Dynamic-Reynolds-Averaged Navier-Stokes simulations) which includes appropriate modifications, has been applied to compute the annual, seasonal, and hourly average concentration of NO₂ and NO_X throughout the city of Pamplona (Spain) at pedestrian level during 2016. The results have been evaluated using measurements provided both by the city's network of air quality monitoring stations and by a network of mobile microsensors carried around by cyclists during their daily commutes, obtaining a maximum relative error lower than 30% when computing NO₂ annual average concentrations. The model has taken into account the actual city layout in three dimensions, as well as the traffic emissions. The resulting air pollution maps provided information critical for studying the traffic-related health effects of NO₂ and their associated external costs in the city of Pamplona and the spatial representativeness of the current network of air quality monitoring stations (it has not been carried out for an entire city to date). The developed methodology can be applied to similar cities, providing useful information for the decision-makers.