Identifying the driving factors of water consumption from water-energy-food nexus in the Yangtze River Delta region, China.

As one of the most economically developed regions in China, the Yangtze River Delta (YRD) region has always been in the leading position in the country in terms of economic development. However, with the changes in the global economic situation and the promotion of scientific and technological innovation, the Yangtze River Delta region is also facing new development challenges and opportunities. Digital empowerment, as an important driving force of the new round of technological revolution, is of great significance to the development of new quality productivity in the Yangtze River Delta region. As new quality productivity has become the buzzword of China's economic development, how can the Yangtze River Delta recognize the timing and take the pulse of development? Therefore, this study aims to deeply explore the path of digitally-enabled new quality productivity in the Yangtze River Delta region, and provide theoretical and practical support for the sustainable development of the regional economy. By analyzing the impact of digital empowerment on new-quality productivity in the Yangtze River Delta region, this study intends to explore the mechanism of the role of digital empowerment in enhancing new-quality productivity and propose corresponding paths and strategies. Specific research questions include: what is the current status of digital empowerment in the Yangtze River Delta region? What is the impact mechanism of digital empowerment on new quality productivity? How should the path of digital empowerment of new quality productivity in the Yangtze River Delta region be constructed?

Distinct responses of PM2.5 and O3 extremes to persistence of weather conditions in eastern China

Air pollution characteristics and their relationship with emissions and meteorology in the Yangtze River Delta region during 2014–2016

Co-occurrence of ozone and PM2.5 pollution in urban/non-urban areas in eastern China from 2013 to 2020: Roles of meteorology and anthropogenic emissions

The concept of major function-oriented zones is highly compatible with the idea of spatially synergistic carbon reduction. In this study, 2005–2020 is taken as the research period, and 305 counties in the Yangtze River Delta (YRD) region are taken as the research unit. The S0M-K-means clustering model and GeoDetector are adopted on the basis of carbon emission/absorption accounting to analyse the spatial and temporal variations in the carbon balance in the YRD region. Furthermore, carbon balance zoning and influencing factors are analysed. Then, a regional spatially synergistic carbon reduction pathway is proposed. The results show that carbon absorption in the YRD region struggles to offset carbon emissions; the regional carbon imbalance is gradually becoming worse; and each county’s carbon emission/absorption shows a significant spatial imbalance. Optimised development zones and key development zones are high-value agglomerations of carbon emissions, while the main sources of carbon sinks in the YRD region are the key ecological functional zones. The YRD region has 87 high carbon control zones, 167 carbon emission optimisation zones, and 51 carbon sink functional zones, which are further subdivided into 9 types of carbon balance zones in accordance with the major function-oriented zones (MFOZs). Based on the driving factors of carbon balance changes in the YRD region, this study proposes differentiated spatially synergistic carbon reduction paths for each zone in accordance with the carbon balance zones. As the Yangtze River Delta is an essential engine for China’s economic development, the study of its carbon balance is highly relevant in formulating differentiated low-carbon development pathways for each functional zone and promoting regional spatially synergistic carbon reduction to realise the target of “dual-carbon” development.

Surface ozone concentrations in the Yangtze River Delta (YRD) region in China have shown a significant increase with the dramatic reduction of anthropogenic nitrogen oxide (NOx) emissions since 2013. As the nonlinearity between ozone and its precursors (i.e., NOx and volatile organic compounds (VOCs)) varies greatly in time and space, we quantify the monthly changes of surface ozone with the co-control of NOx and VOCs anthropogenic emissions in the YRD region from May to October 2017 by using the GEOS-Chem model. Model evaluations show that the GEOS-Chem model exhibits good performance to simulate ozone concentrations in the region. For May–September 2017, most areas in the YRD region are under a transitional regime, but the regions with high anthropogenic emissions including Shanghai and southern Jiangsu are under a VOCs-limited regime. In October, basically, the entire YRD region is under a VOCs-limited regime. Generally, reducing VOCs emissions only is the most effective method for ozone control in the YRD. Nanjing is under a VOCs-limited regime in May, June, September, and October, and under a transition regime from July to August. The VOCs/NOx emission reduction ratio of 1:1 is effective for ozone mitigation in Nanjing (Shanghai) in May, June, and September (for May–September); the corresponding ratio is 2:1 in October. Hangzhou belongs to a transitional regime from May to September and is under a VOCs-limited regime in October. Reducing NOx emissions only would control ozone in Hangzhou from May to September, while the VOCs/NOx emission reduction ratio of 1:1 is favorable to reduce ozone concentrations in October. During high pollution days on July 22–27, 2017, the three cities belong to a transitional regime and reducing NOx emissions only is generally the most effective way to control high ozone pollution. GEOS-Chem tagged ozone simulation shows that ozone problem in the region is caused by the joint effect of local generation and regional and long-distance transport. Local generation (19.0–50.7%) is generally the largest contributor to monthly mean ozone concentrations in Jiangsu and Shanghai, Zhejiang, and central eastern China; the contribution of ozone from regions outside the YRD is larger in spring and autumn (42–76.0%) than in summer (23.3–51.8%). Since the annual VOCs (NOx) anthropogenic emissions in the region have shown a decline by 8% (11%) from 2017 to 2020 and would continue to reduce by 10% (10%) by 2025 according to the Chinese government requirement, the growth of ozone would be stopped in the YRD for May–September but likely to continue in October. Our study thus would provide a scientific base for guiding the effective emission reduction strategies to control ozone pollution in the YRD region.

Human activities challenge carbon storage in the Yangtze River Delta, China.

The expansion of the industrial economy has resulted in high carbon emissions (CE) from the Yangtze River Delta (YRD) region. Industrial CE reduction is a non-negligible way to achieve green and low-carbon development. In this paper, we aim to study the decoupling effect of industrial CE and its socio-economic influencing factors in the YRD region from 2005 to 2020. First, the decoupling relationship between industrial CE and industrial output in the YRD region is measured. Then, using the LMDI method, the variation of industrial CE is decomposed into six factors: energy structure ( Δ c s ), energy intensity ( Δ c i ), economic scale ( Δ c e ), labor structure ( Δ c l ), urbanization rate ( Δ c u ) and population size ( Δ c p ) effect. Subsequently, by combining with the decoupling and LMDI models, the contribution of each factor to the decoupling of industrial CE is studied, and the elasticity of each factor is expressed by η s , η i , η e , η l , η u , and η p . The main findings show that: (1) There are two states of weak and strong decoupling between industrial CE and the industrial economy in the YRD. (2) Δ c e is the most powerful factor in promoting industrial CE, while Δ c i and Δ c l are the factors that inhibit industrial CE in the YRD. (3) η i and η l have promoted the decoupling of industrial CE from economic advancement in the YRD and its three provinces and one city, while η e has consistently been the largest obstacle to the decoupling process. Finally, the policy recommendations proposed in this paper aim to help policy-makers and practitioners in the YRD region achieve a win-win balance between industrial CE and industrial output, and inspire further research on the decoupling and decomposition of industrial CE from an academic perspective.

Abstract. Rapid sulfate formation is recognized as a key characteristic of severe winter haze in China. However, air quality models tend to underestimate sulfate formation during heavy haze periods, and heterogeneous formation pathways have been proposed as promising mechanisms to reduce gaps between observation and model simulation. In this study, we implemented a reactive SO2 uptake mechanism through the SO2+NO2 heterogeneous reactions in the Comprehensive Air Quality Model with Extensions (CAMx) to improve simulation of sulfate formation in the Yangtze River Delta (YRD) region. Parameterization of the SO2+NO2 heterogeneous reactions is based on observations in Beijing and considered both the impact of relative humidity and aerosol pH on sulfate formation. Ammonia is reported to be critical for the formation of secondary inorganic aerosols. Estimation of ammonia emissions is usually associated with large uncertainties and models tend to underestimate ammonia concentrations substantially. Sensitivity tests were conducted to evaluate the influence of the SO2+NO2 heterogeneous reactions as well as ammonia emissions on modeled sulfate concentrations during a period with several heavy haze episodes in the YRD region. Base case model results show large underestimation of sulfate concentrations by 36 % under polluted conditions in the YRD region. Adding the SO2+NO2 heterogeneous reactions or doubling ammonia emissions alone leads to slight model improvement (∼6 %) on simulated sulfate concentrations in the YRD region. However, model performance significantly improved when both the SO2+NO2 heterogeneous reactions and doubled ammonia emissions were included in the simulation: predicted sulfate concentrations during polluted periods increased from 23.1 µg m−3 in the base scenario to 29.1 µg m−3 (representing an increase of 26 %). Aerosol pH is crucial for the SO2+NO2 heterogeneous reactions, and our calculated aerosol pH is always acidic and increased by 0.7 with doubled ammonia emissions. Modeling results also show that this reactive SO2 uptake mechanism enhanced sulfate simulations by 1 to 5 µg m−3 for the majority of the eastern and central parts of China, with more than 20 µg m−3 increase in sulfate concentrations over the northeastern plain. These findings suggest that the SO2+NO2 heterogeneous reactions could be potentially important for sulfate formation in the YRD region as well as other parts of China. Further studies are needed to constrain the uncertainties associated with the parameterization of the SO2+NO2 heterogeneous reactions based on local data as well as to evaluate this mechanism in other regions. In addition, ammonia emissions were found to be a key driving variable of the spatial patterns of sulfate enhancement due to the new pathway. Substantial efforts are needed to improve the accuracy of the ammonia emission inventory.

Measuring regional differences in agricultural green total factor productivity (AGTFP) provides a basis for policy guidance on agricultural green development in the Yangtze River Delta (YRD) region. By constructing a two-period Malmquist-Luenberger index under the carbon emission constraint, we measure the AGTFP of cities in the YRD region from 2001 to 2019. Furthermore, adopting the Moran index method and the hot spot analysis method, this paper analyzes the global spatial correlation and local spatial correlation of AGTFP in this region. Moreover, we investigate its spatial convergence. The results show that the AGTFP of 41 cities in the YRD region is on an increasing trend; the growth of AGTFP in the eastern cities is mainly driven by green technical efficiency, while this growth in the southern cities is mainly stimulated by green technical efficiency and green technological progress. We also find a significant spatial correlation between cities' AGTFP in the YRD region from 2001 to 2019, but with certain fluctuations, showing a U-shaped trend of "strong-weak-strong". In addition, absolute β convergence of the AGTFP exists in the YRD region, and this convergence speed is accelerated with the addition of spatial factors. This evidence provides support for implementing the regional integration development strategy and optimizing the regional agricultural spatial layout. Our findings offer implications for promoting the transfer of green agricultural technology to the southwest of the YRD region, strengthening the construction of agricultural economic belts and agricultural economic circles, and improving the efficiency of agricultural resource use.

Estimation of biogenic VOC emissions and its impact on ozone formation over the Yangtze River Delta region, China

For the Yangtze River Delta (YRD) region of China, exploring the spatio-temporal characteristics of carbon emissions from energy consumption (CEECs) and their influencing factors is crucial to achieving carbon peaking and carbon neutrality as soon as possible. In this study, an improved LMDI decomposition model based on the Tapio model and Kaya’s equation was proposed. Combined with the improved LMDI and k-means cluster analysis methods, the energy structure, energy intensity, unit industrial output value and population size were selected as the driving factors, and the contribution of each driving factor to the CEECs of prefecture-level cities was quantitatively analyzed. Our study found that: (1) By 2020, the total amount of CEECs in the 26 prefecture-level cities in the YRD will stabilize, while their intensity has shown a downward trend in recent years. (2) The decoupling relationship between CEECs and economic development generally showed a trend from negative decoupling to decoupling. The dominant factor in decoupling was generally the shift of DEL values towards urbanization rate and energy intensity and the open utilization of energy technologies. (3) From 2000 to 2010, the dominant factors affecting CEECs in 26 cities were energy intensity and energy structure, followed by industrial output value and urbanization rate. In general, the promotion effect of economic development on carbon emissions in the YRD region was greater than the inhibitory effect. After 2010, the restrictive effect of various factors on CEECs increased significantly, among which the role of gross industrial output was crucial. The research results can provide a scientific policy basis for the subsequent spatial management and control of carbon emission reduction and carbon neutrality in the YRD region at a finer scale.

Vegetation Net Primary Productivity (NPP) plays a crucial role in terrestrial carbon sinks and the global carbon cycle. Investigating the spatiotemporal dynamics and influencing factors in the Yangtze River Delta (YRD) region can furnish a solid scientific foundation for green, low-carbon, and sustainable development in China, as well as a reference for other rapidly urbanizing regions. This study focuses on the YRD region as an illustration and utilizes the Carnegie–Ames–Stanford Approach (CASA model) to quantify NPP in this region from 2000 to 2018. Investigation into the spatiotemporal dynamics and influencing factors was conducted using Theil–Sen median trend analysis and scenario analysis. The results indicate that the NPP in the YRD region from 2000 to 2018 exhibited pronounced spatial differentiation characteristics, typically exhibiting a spatial distribution pattern of being high in the south and low in the north, high in the west and low in the east. Additionally, the expansion of built-up areas and the reduction in cultivated land have the potential to reduce NPP in the YRD region. Moreover, the influence of land-use and land-cover change (LULCC) is anticipated to be relatively limited compared to that of climate change. Furthermore, changes in precipitation were found to be positively correlated with changes in NPP, with the effect being relatively more pronounced. The correlation between temperature and NPP demonstrated spatial differentiation, with a mainly positive correlation in the central and southern parts of the YRD and a mainly negative correlation in the northern part. Changes in solar radiation had a negative correlation with changes in NPP. Based on these results, it is recommended that local governments strictly enforce urban development boundaries and manage the disorderly expansion of built-up areas, enhance the regional irrigation infrastructure, and address air pollution, so as to ensure the necessary conditions for the growth of vegetation, reduce greenhouse gas emissions, and control regional temperature rises. This study can provide stronger evidence for revealing the influencing mechanisms of NPP through the control of impact conditions and the exclusion of confounding factors via scenario analysis. The policy implications can offer insights into NPP enhancement and environmental management for the YRD and other rapidly urbanizing regions.

Stable and transport indices applied to winter air pollution over the Yangtze River Delta, China.

ABSTRACTTo investigate the characteristics and sources of PM2.5 in the Yangtze River Delta (YRD) region, a total of 10 sampling sites were selected in the three major cities of Shanghai, Nanjing, and Ningbo and the regional background city of Lin’an, and 380 samples were collected in spring and winter. The spatiotemporal characteristics of the PM2.5 mass concentration and the chemical components were analyzed. Meanwhile, air mass clusters and the positive matrix factorization (PMF) source apportion model were comprehensively used to identify the sources of PM2.5. The mass concentration of PM2.5 in winter (83.51–107.64 µg m–3) was higher than that in spring (54.11–85.72 µg m–3). Sulfate, nitrate, and ammonium (SNA) dominated the PM2.5, accounting for 39.0% in spring and 46.1% in winter in the YRD region. Higher ratio of secondary organic carbon (SOC) to organic carbon (OC) generally occurred in winter due to increased emissions of organic precursors. The mean equivalent ratio of AE/CE was 0.81 ± 0.25 in winter and 0.96 ± 0.33 in spring, which indicated a slight alkalinity of the atmospheric particles in the YRD region. Secondary aerosols (29.44%) and traffic (25.66%) were identified as the main sources of PM2.5 in the YRD during spring, and they contributed 22.71% and 29.71% in winter. In addition, air mass flow from Northern China imported substantial fugitive soils to the YRD region in spring and enhanced the contribution of combustion in winter through long-range transport, while air masses originating from Southwestern China were strongly associated with biomass burning. Our results showed that the PM2.5 concentration and chemical characterization in the YRD region was significantly influenced by air mass transport.