Mapping and measuring urban-rural inequalities in accessibility to social infrastructures

Equal access to social infrastructures is a fundamental prerequisite for sustainable development,but has long been a great challenge worldwide.Previous studies have primarily focused on the accessibility to social infras-tructures in urban areas across various scales,with less attention to rural areas,where inequality can be more severe.Particularly,few have investigated the disparities of accessibility to social infrastructures between urban and rural areas.Here,using the Changsha-Zhuzhou-Xiangtan urban agglomeration,China,as an example,we investigated the inequality of accessibility in both urban and rural areas,and further compared the urban-rural difference.Accessibility was measured by travel time of residents to infrastructures.We selected four types of social infrastructures including supermarkets,bus stops,primary schools,and health care,which were funda-mentally important to both urban and rural residents.We found large disparities in accessibility between urban and rural areas,ranging from 20 min to 2 h.Rural residents had to spend one to two more hours to bus stops than urban residents,and 20 min more to the other three types of infrastructures.Furthermore,accessibility to multiple infrastructures showed greater urban-rural differences.Rural residents in more than half of the towns had no access to any infrastructure within 15 min,while more than 60%of the urban residents could access to all infrastructures within 15 min.Our results revealed quantitative accessibility gap between urban and rural areas and underscored the necessity of social infrastructures planning to address such disparities.

Urbanity mapping reveals the complexity,diffuseness,diversity,and connectivity of urbanized areas

There are urgent calls for new approaches to map the global urban conditions of complexity,diffuseness,diversity,and connectivity.However,existing methods mostly focus on mapping urbanized areas as bio physical entities.Here,based on the continuum of urbanity framework,we developed an approach for cross-scale urbanity map-ping from town to city and urban megaregion with different spatial resolutions using the Google Earth Engine.This approach was developed based on multi-source remote sensing data,Points of Interest-Open Street Map(POIs-OSM)big data,and the random forest regression model.This approach is scale-independent and revealed significant spatial variations in urbanity,underscoring differences in urbanization patterns across megaregions and between urban and rural areas.Urbanity was observed transcending traditional urban boundaries,diffusing into rural settlements within non-urban locales.The finding of urbanity in rural communities far from urban areas challenges the gradient theory of urban-rural development and distribution.By mapping livelihoods,lifestyles,and connectivity simultaneously,urbanity maps present a more comprehensive characterization of the complex-ity,diffuseness,diversity,and connectivity of urbanized areas than that by land cover or population density alone.It helps enhance the understanding of urbanization beyond biophysical form.This approach can provide a multifaceted understanding of urbanization,and thereby insights on urban and regional sustainability.

Mechanism of micro-wetting of highly hydrophobic coal dust in underground mining and new wetting agent development

The internal mechanism of the high hydrophobicity of the coal samples from the Pingdingshan mining area was studied through industrial,element,and surface functional group analysis.Laboratory testing and molecular dynamics simulations were employed to study the impact of three types of surfactants on the surface adsorption properties and wettability of highly hydrophobic bituminous coal.The results show that the surface of highly hydrophobic bituminous coal is compact,rich in inorganic minerals,and poorly wettable and that coal molecules are dominated by hydrophobic functional groups of aromatic rings and aliphatic structures.The wetting performance of surfactants as the intermediate carrier to connect coal and water molecules is largely determined by the interaction force between surfactants and coal(Fs-c)and the interaction force between surfactants and water(Fs-w),which effectively improve the wettability of modified coal dust via modifying its surface electrical properties and surface energy.A new type of wetting agent with a dust removal rate of 89%has been developed through discovery of a compound wetting agent solution with optimal wetting and settling performance.This paper provides theoretical and technical support for removing highly hydrophobic bituminous coal dust in underground mining.

Effects of spatial resolution of remotely sensed data on estimating urban impervious surfaces

Impervious surfaces are the result of urbanization that can be explicitly quantified, managed and controlled at each stage of land development. It is a very useful environmental indicator that can be used to measure the impacts of urbanization on surface runoff, water quality, air quality, biodiversity and rnicroclimate. Therefore, accurate estimation of impervious surfaces is critical for urban environmental monitoring, land management, decision-making and urban planning. Many approaches have been developed to estimate surface imperviousness, using remotely sensed data with various spatial resolutions. However, few studies, have investigated the effects of spatial resolution on estimating surface imperviousness. We compare medium-resolution Landsat data with high-resolution SPOT images to quantify the imperviousness in Beijing, China. The results indicated that the overall 91% accuracy of estimates of imperviousness based on TM data was considerably higher than the 81% accuracy of the SPOT data. The higher resolution SPOT data did not always predict the imperviousness of the land better than the TM data. At the whole city level, the TM data better predicts the percentage cover of impervious surfaces. At the sub-city level, however, the ring belts from the central core to the urban-rural peripheral, the SPOT data may better predict the imperviousness. These results highlighted the need to combine multiple resolution data to quantify the percentage of imperviousness, as higher resolution data do not necessarily lead to more accurate estimates. The methodology and results in this study can be utilized to identify the most suitable remote sensing data to quickly and efficiently extract the pattern of the impervious land, which could provide the base for further study on many related urban environmental problems.

Evolution and future of urban ecological science:ecology in,of,and for the city

The contrast between ecology in cities and ecology of cities has emphasized the increasing scope of urban ecosystem research.Ecology in focuses on terrestrial and aquatic patches within cities,suburbs,and exurbs as analogs of non-urban habitats.Urban fabric outside analog patches is considered to be inhospi-table matrix.Ecology of the city differs from ecology in by treating entire urban mosaics as social-ecolog-ical systems.Ecology of urban ecosystems incorporates biological,social,and built components.Originally posed as a metaphor to visualize disciplinary evolution,this paper suggests that the contrast has conceptual,empirical,and methodological contents.That is,the contrast constitutes a disciplinary or“local”paradigm shift.The paradigm change between ecology in and ecology of represents increased complexity,moving from focus on biotic communities to holistic social-ecological systems.A third paradigm,ecology for the city,has emerged due to concern for urban sustainability.While ecology for includes the knowledge generated by both ecology in and ecology of,it considers researchers as a part of the system,and acknowledges that they may help envision and advance the social goals of urban sustainability.Using urban heterogeneity as a key urban feature,the three paradigms are shown to contrast in five important ways:disciplinary focus,the relevant theory of spatial heterogeneity,the technology for representing spatial structure,the resulting classification of urban mosaics,and the nature of application to sustainability.Ecology for the city encourages ecologists to engage with other specialists and urban dwellers to shape a more sustainable urban future.

Global urbanization as a shifting context for applying ecological science toward the sustainable city

There is an abundance of conceptual frameworks relevant to sustainability in urban systems.However,to advance urban ecological science and its application to sustainable urban transformations,key existing frameworks must be synthesized.This paper is a conceptual synthesis cast in essay form in order to encompass a broad range of relevant ideas.It starts from the premise that the familiar models of metropolitan and megalopolitan urban structure,of industrially driven urban development,and of the contrasts between urban and non-urban lands are manifestly inadequate representations of evolving global reality.Such inadequacy is illustrated with examples from the United States and from China.Both the form and the interactions involved in contemporary urbanization and urban change suggest the need for a new integrated framework synthesizing two existing yet still evolving concepts:(1)The urban megaregion framework accommodates the spatial extent,interdigitation of contrasting land uses,and the linked spatial relations between nominally urban and nominally rural areas.(2)The new concept of the continuum of urbanity emphasizes the shifts in livelihood and lifestyle driven by regional and global teleconnections and their joint effects on local environments and landscapes.Together these frameworks suggest a common conceptual structure for addressing urban areas of different ages,sizes,forms,and dynamics in both urbanizing and urbanized areas in developing and developed countries and regions.The synthesis of frameworks points to empirical research needs,and has the potential to better match sustainability plans and actions with the diverse urban forms and dynamics now appearing around the world.

Insights into multisource sludge distributed in the Yangtze River basin, China: Characteristics,correlation, treatment and disposal

Sludge is the by-product of wastewater treatment process. Multisource sludge can be defined as sludge from different sources. Based on the sludge properties of five typical cities in the Yangtze River basin, including Jiujiang, Wuhu, Lu’an, Zhenjiang and Wuhan, this study investigated and summarized the characteristic variations and distribution differences of multiple indicators and substances from municipal sludge, dredged sludge, and river and lake sediments. The results demonstrated pH of multisource sludge was relatively stable in the neutral range. Organic matter and water content among municipal sludge were high and varied considerably between different wastewater treatment plants. Dredged sludge had an obviously higher sand content and wider particle distribution, which could be considered for graded utilization depending on its size. The nutrients composition of river and lake sediments was usually stable and special, with lower nitrogen and phosphorus content but higher potassium levels. The sources of heavy metals and persistent organic pollutants in multisource sludge were correlated, generally much higher among municipal sludge than dredged sludge and river and lake sediments, which were the most important limitation for final land utilization. Despite various properties of multisource sludge, the final fate and destination have some overall similarities, which need to be supplemented and improved by standards and laws. The study provided a preliminary analysis of suitable technical routes for municipal sludge, dredged sludge, river and lake sediments based on their different characteristics respectively, which was of great significance for multisource sludge co-treatment and disposal in the future of China.

Integrating structure and function:mapping the hierarchical spatial heterogeneity of urban landscapes

Background:Cities are social-ecological systems characterized by remarkably high spatial and temporal heterogeneity,which are closely related to myriad urban problems.However,the tools to map and quantify this heterogeneity are lacking.We here developed a new three-level classification scheme,by considering ecosystem types(level 1),urban function zones(level 2),and land cover elements(level 3),to map and quantify the hierarchical spatial heterogeneity of urban landscapes.Methods:We applied the scheme using an object-based approach for classification using very high spatial resolution imagery and a vector layer of building location and characteristics.We used a top-down classification procedure by conducting the classification in the order of ecosystem types,function zones,and land cover elements.The classification of the lower level was based on the results of the higher level.We used an objectbased methodology to carry out the three-level classification.Results:We found that the urban ecosystem type accounted for 45.3%of the land within the Shenzhen city administrative boundary.Within the urban ecosystem type,residential and industrial zones were the main zones,accounting for 38.4%and 33.8%,respectively.Tree canopy was the dominant element in Shenzhen city,accounting for 55.6%over all ecosystem types,which includes agricultural and forest.However,in the urban ecosystem type,the proportion of tree canopy was only 22.6%because most trees were distributed in the forest ecosystem type.The proportion of trees was 23.2% in industrial zones,2.2%higher than that in residential zones.That information“hidden”in the usual statistical summaries scaled to the entire administrative unit of Shenzhen has great potential for improving urban management.Conclusions:This paper has taken the theoretical understanding of urban spatial heterogeneity and used it to generate a classification scheme that exploits remotely sensed imagery,infrastructural data available at a municipal level,and object-based spatial analysis.For effective planning and management,the hierarchical levels of landscape classification(level 1),the analysis of use and cover by urban zones(level 2),and the fundamental elements of land cover(level 3),each exposes different respects relevant to city plans and management.

Quantifying the characteristics of particulate matters captured by urban plants using an automatic approach

It is widely accepted that urban plant leaves can capture airborne particles. Previous studies on the particle capture capacity of plant leaves have mostly focused on particle mass and/or size distribution. Fewer studies, however, have examined the particle density, and the size and shape characteristics of particles, which may have important implications for evaluating the particle capture efficiency of plants, and identifying the particle sources. In addition, the role of different vegetation types is as yet unclear. Here, we chose three species of different vegetation types, and firstly applied an object-based classification approach to automatically identify the particles from scanning electron microscope（SEM）micrographs. We then quantified the particle capture efficiency, and the major sources of particles were identified. We found（1） Rosa xanthina Lindl（shrub species） had greater retention efficiency than Broussonetia papyrifera（broadleaf species） and Pinus bungeana Zucc.（coniferous species）, in terms of particle number and particle area cover.（2） 97.9% of the identified particles had diameter ≤10 μm, and 67.1% of them had diameter ≤2.5 μm. 89.8% of the particles had smooth boundaries, with 23.4% of them being nearly spherical.（3） 32.4%–74.1% of the particles were generated from bare soil and construction activities, and 15.5%–23.0% were mainly from vehicle exhaust and cooking fumes.

Sustainable urban systems:from landscape to ecological processes

Our world is experiencing unprecedented land cover and land use changes(LCLUC)due to population growth,economic development,and global climate change.Urbanization,one major form of LCLUC,has received growing attention for its significant role in changing ecological processes and functions of urban landscapes.There is a growing need,from both the academic and the policy-making communities,for science-based information and evidence to enhance our understanding of the urban ecological processes and societal needs because of the rapid urbanization over the past few decades across the world.Such information is key to informing the development of best practices for improved landscape and urban planning.