Search

Owing to rapid urbanization and industrialization over decades, nitrogen dioxide (NO2) has become a serious air pollutant in China. The Chinese government has proposed a series of strict strategies for the reduction of nitrogen oxides (NOx) emissions. This research studies the spatio-temporal characteristics of NO2 pollution over China from October 2004 to June 2020 based on satellite observations. The findings are as follows. Overall, NO2 vertical column densities (VCDs) first increased from 2005 to 2012, and then displayed a decreasing trend after 2013. In addition, the centroid of NO2 values over China during the period of 2006–2010 was located in north Henan and shifted towards the west, suggesting that the NO2 pollution in the eastern region decreased more rapidly than that in the western region. On the other hand, another important aim of this research is to forecast the trajectory of dynamic spatial differences of NO2 pollution. Technically, we investigated σ and β convergence of the NO2 pollution across Chinese cities. The results of the σ convergence test based on standard deviations of annual mean NO2 VCDs showed that, from 2005 to 2011, the differences in NO2 VCDs widened year by year. However, since 2013, we have witnessed a narrowing gap of NO2 pollution among different cities. We found that the σ convergence results based on the kernel density estimates revealed that the convergence of NO2 pollution across cities are heavily dependent on the improvements of the cities with high levels of NO2 concentrations. Besides, the results of the β convergence models confirmed the absolute and conditional β convergence. In addition, we found that the convergence speed in winter was faster than in summer.

Poverty is a common problem faced by various social and economic forms. Eliminating poverty is a major issue of common concern and research all over the world. Land policies for poverty alleviation are an effective means of affecting land agriculture development, increasing the productivity of cultivated land, and promoting growth in farmers’ income and production. In recent years, it has played an important role in promoting poverty alleviation in poverty-stricken areas. However, the poverty alleviation needs of township units have not been precisely identified, and one-size-fits-all land policies are unable to effectively allocate poverty alleviation resources. Consequently, the actual efficiency of policies has been severely restricted, leading to regional differences in poverty alleviation. In response to this bottleneck, this study takes Siyang County in Jiangsu Province as a case study and adopts the geographical detector model to diagnose and identify the spatial differentiation characteristics and dominant factors of poverty and in various townships. The results can be summarised as ‘four dominant factors of poverty—four regional types of poverty townships—four targeted land poverty alleviation patterns’. Detailed results are as follows: the dominant factors affecting differentiation of rural poverty in Siyang County are labour, technology, land resources, and financial support. The various townships of the county were thus classified into four types according to the main factor affecting poverty: labour-constrained, land-constrained, capital-constrained, and technique-constrained, and proposed four targeted land poverty alleviation patterns for the different constraint types and then to improve the effectiveness of land development policies to successfully achieve precise poverty alleviation and reinforce strategies revitalising rural communities.

This study focused on characteristics of dissolved organic matter (DOM) in a vertical flow constructed wetland (VF CW) with a free water surface constructed wetland (FWS CW) in front using three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectroscopy. 3D-EEM fluorescence spectroscopy was employed to characterize the DOM samples along with the CW systems. Five main peaks could be identified from the 3D-EEM fluorescence spectra of the DOM samples in both CW systems. The fluorescence regional was divided into five parts and including five peaks using fluorescence regional integration method. The results indicated soluble microbial by-products (SMB) predominated in all the process and the DOM was mainly composed of SMB because of higher microbial activity and more microbial diversity in VF CW compared with FWS CW. We could conclude that VF CW had hardly removal ability of the humic acid-like. The hybrid CW systems had ability to remove the nonbiodegradable compounds and mostly owed to FWS CW.

As an economic pillar, major resource consumer, and polluter of cities, the chemical industry determines many cities’ transformation, prosperity, and decay. It is thus a major concern for achieving the UN Sustainable Development Goals. In China, which is at the stage of accelerated industrialization that is varied across regions, the chemical industry has gradually retreated from developed cities, such as Beijing and Shanghai, in the eastern region, and has become the inevitable choice for industrialization of less-developed cities, such as Xi’an, Chengdu, and Chongqing, in the western region. This study took the perspectives of chemical industrial sectors and their spatial differences to understand the changing patterns of the chemical industry and its dominant cities. It identified chemical industrial cities (CICs), examined their spatial-temporal patterns with respect to their industry scale and structure, and accounted for factors influencing the spatial evolution from coastal areas to inland regions. The results show that large CICs were mainly located in coastal port regions with balanced industrial sectors, while small CICs were mainly distributed in inland areas with abundant oil and coal resources and a single dominant industrial sector. The location factors of ports, markets, and technology play important roles in the eastern region, while resource conditions and foreign direct investment promote the chemical industry’s development in the central, western, and northeastern cities. These findings improve the understanding of CICs’ spatial transformation and shed light on the policy-making of chemical industrial development in China and other developing countries.

The paper presents the data that is related in the research paper entitled “High-speed rail network development and winner and loser cities in megaregions: The case study of Yangtze River Delta, China” (Wang and Duan, in press) [1] . This data article describes the modelling results of spatially continuous accessibility surfaces through transport modes of the highway, conventional rail and high-speed rail networks in the Yangtze River Delta mega-region, China. By using a door-to-door approach to integrate intra- and inter-city travel, the data is stimulated in the geographic information system environment. It is calculated by the datasets of transport networks, land-use types and transport speeds which are mainly collected from the OpenStreetMap and GlobeLand30 and relevant design specifications on transport infrastructures, respectively. The data is stored in raster format and provides high spatial resolution at 100 m. The data can be used as a baseline in the studies of transport economics and planning.

Heavy metal pollution is frequent in China and has received increasing attention globally. This study investigated the influence of Chinese industrialization and urbanization on soil environmental quality. Soil samples from Jiangsu Province were collected, the Cd, Pb, Cr, Cu, Zn, Hg, and As contents were measured, and their spatial variability structure, spatial distribution pattern, and pollution degree were analyzed. The mean values of Hg, Cd, Pb, Cr, Cu, and As were all higher than the background values in Jiangsu Province. Cr and As levels represented moderate pollution, Cu, Zn, Cd, and Pb represented mild pollution, Cr and As represented slight pollution, and Hg was not a pollutant. Spatial distribution patterns were both zonal and concentrated in nature. High concentrations of heavy metals were distributed in developed cities and industrial parks along the Yangtze River. Soil heavy metal pollution showed a decreasing trend from south to north, consistent with the economic gradient. Industrialization had the greatest influence on the spatial heterogeneity of heavy metal pollution. Cr, Cu, Zn, and As were affected by both natural and anthropogenic sources, while Cd and Pb were mainly affected by the latter. Hg was mainly derived from industrial activities such as petrochemical production. There was spatial consistency between industrial enterprise distribution and soil heavy metal pollution with a tendency toward composite pollution accumulated by multiple elements in the soil surrounding industries.

The degradation efficiencies of p-chloronitrobenzene (pCNB) in aqueous solution by processes employing ozone alone and ozone/iron silicates based on iron silicates dried at 60, 250, 600, or 800°C were investigated. The results demonstrated that iron silicate dried at 60°C possessed better catalytic capacity for the ozonation of pCNB than that dried at higher temperatures owing to increased concentrations of hydrogen peroxide (H2O2) and the formation of hydroxyl radicals (). Adsorption of pCNB on the surface of iron silicate exhibited no remarkable influence on the degradation efficiency of pCNB. An increase in the drying temperature was found to slightly increase the adsorption ability and significantly reduce the catalytic activity of the iron silicate. Because of the formation of a new crystalline phase, the catalytic activity of iron silicate dried at 800°C was the lowest. The results of the mechanism analysis suggest that Fe2O3, FeOOH, and silicato-iron(III) surface complexes are the dominant ...

This paper presents a spatial analysis of likely/potential hotspots of sustainability issues in Mainland China through an empirical investigation of patterns of ecological vulnerability in and of China’s megaregions. To be specific, this paper assesses the level of patterns of the ecological vulnerability of 16 megaregions through an indicator system, which includes soil erosion, desertification, ecosystem vulnerability, key ecological areas, and water and land resources. Empirical results reveal that while most megaregions are located in the less vulnerable areas, there are a couple of megaregions with a vulnerable basis of ecological environment. These megaregions consist of Chengdu-Chongqing, Guanzhong Tianshui Economic Zone, Shandong Peninsula, Wuhan City Circle, Beijing-Tianjin-Hebei, and Liaoning Coastal Belt. Furthermore, a typology of these megaregions is identified based on their development level and ecological vulnerability.

In this work, pyrolysis characteristics and kinetics of microalgae Diplosphaera sp. MM1 cultivated in different mediums were investigated by TG-FTIR and Py-GC/MS. Harvested MM1s biomass varied with the changing in proximate and ultimate analyses presented different weight loss behaviors. The weight loss of MM1s cultivated in dairy and winery wastewater in main pyrolysis region was ~48.4 wt% and ~52.9 wt%, respectively, and both showed secondary weight loss after 570 °C. However, MM1 harvested from BG-11 medium exhibited maximum weight loss of ~63.5 wt% and no secondary weight loss. Further, the activation energies of MM1s harvested from dairy and winery wastewater (176.3 kJ/mol and 130.4 kJ/mol, respectively) were lower than that of BG-11medium (189.4 kJ/mol). The best mechanism function for MM1s pyrolysis was third-order f(α) = (1-α)3. Py-GC/MS results of MM1 cultivated in winery wastewater showed highest contents of C4–C10 and C11–C21 that characterized the carbon level of gasoline and diesel, respectively, which are the major components of bio-oils.

Human activities do not only change the land use/land cover (LULC), but also release a large amount of anthropogenic heat through intensive activities above ground, which drives the formation of urban heat island (UHI). This study used the Nanjing metropolitan area as the research area and taken 2017 as the observation time and chosen land surface characteristic parameters, point of interest (POI) density and urban functional area data to quantify the driving mechanism of human activities at a grid scale. The results indicated as follows: i) The response relationships between the LST and its driving factors have a clear scale effect at the grid scale. The driving factors had the highest explanatory power at the 300 m grid; ii) LULC had a significant effect on LST, impervious layers and bare soil increased the LST, vegetation and water relieved it; iii) In different urban functional areas, the relationship between LST and POI density was piecewise. In addition to density, the types of human activities also have a significant impact on the UHI, in which industrial heat release has the most significant effect on the local temperature of the city, followed by daily heat production and transportation heat release.

PM2.5 is a main source of China&rsquo, s frequent air pollution. Using real-time monitoring of PM2.5 data in 338 Chinese cities during 2014&ndash, 2017, this study employed multi-temporal and multi-spatial scale statistical analysis to reveal the temporal and spatial characteristics of PM2.5 patterns and a spatial econometric model to quantify the socio-economic driving factors of PM2.5 concentration changes. The results are as follows: (1) The annual average value of PM2.5 concentration decreased year by year and the monthly average showed a U-shaped curve from January to December. The daily mean value of PM2.5 concentration had the characteristics of pulse-type fluctuation and the hourly variation presented a bimodal curve. (2) During 2014&ndash, 2017, the overall PM2.5 pollution reduced significantly, but that of more than two-thirds of cities still exceeded the standard value (35 &mu, g/m3) regulated by Chinese government. PM2.5 pollution patterns showed high values in central and eastern Chinese cities and low values in peripheral areas, with the distinction evident along the same line that delineates China&rsquo, s uneven population distribution. (3) Population agglomeration, industrial development, foreign investment, transportation, and pollution emissions contributed to the increase of PM2.5 concentration. Urban population density contributed most significantly while economic development and technological progress reduced PM2.5 concentration. The results also suggest that China in general remains a &ldquo, pollution shelter&rdquo, for foreign-funded enterprises.