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Accurately capturing the urbanization process is essential for planning sustainable cities and realizing the United Nations Sustainable Development Goal 11. However, until recently, most of the studies on urban expansion in the world have focused on area growth but have little knowledge of height dynamics. This study mapped the spatial distribution of urban built-up areas (UBA) in the Yangtze River Delta (YRD), one of the most urbanized regions in China, to investigate the spatio-temporal evolution in both the horizontal and vertical directions from 1990 to 2020. We coupled and analyzed the horizontal and vertical urban expansion from the 3-D perspective and identified the dominant types. The results showed that 30 cities (73.17 % of the total number of cities) were increasing in the 3-D combined expansion intensity. The decreasing cities were mainly located in Anhui Province. Despite the increasing number of skyscrapers, horizontal growth has dominated urban expansion over the past three decades. The UBA area of the YRD has grown from 4,855.30 km2 to 44,447.15 km2, while the average building height has slowly decreased by 1.26 m. Significant unevenness and differences existed in horizontal and vertical expansions of varying provinces and cities. Our study can accurately grasp the 3-D urban expansion process in the YRD and could promote the efficient development and sustainable utilization of urban land resources in China and beyond.
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There has been much discussion in the conservation and policy realms of COVID-19 as a zoonotic disease, or a disease transmitted from wildlife to humans. However, wildlife consumption in China is not only a potential source of disease but also a practice embedded in complex beliefs about health. This paper used survey data (N = 974) collected in China in June 2021 to examine attitudes and behaviors related to (a) wildlife consumption, (b) Traditional Chinese Medicine (TCM) and (c) zoonotic risk after the emergence of the COVID-19 pandemic. 40.1% of respondents self-reported that they are less likely to consume wild animals since the outbreak of COVID-19. Respondents who used wildlife supplements for TCM, who believed in the benefits of wild animal consumption and fresh slaughter of wildlife, and who had higher levels of agreement with the zoonotic origin of COVID-19 were more likely to report that they had decreased their wildlife consumption after the outbreak of COVID-19. Use of wildlife in TCM significantly increased the odds that a respondent believed that COVID-19 was very likely zoonotic. We discuss how situating wildlife consumption within complex beliefs about health and disease can assist with protecting wildlife and public health in the wake of COVID-19.
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Animales Salvajes , COVID-19 , Animales , Humanos , Pandemias , COVID-19/epidemiología , Zoonosis/epidemiología , China/epidemiologíaRESUMEN
Given the link between perceptions of zoonotic risk and support for regulations such as wildlife consumption bans, debates regarding the origins of COVID-19 are likely to have conservation implications. Specifically, alternative hypotheses that cast doubt on COVID-19's zoonotic origins could potentially lessen momentum for China's wildlife policy reforms and their associated conservation impacts. To better understand the impact of COVID-19 origin debates on China's wildlife policies, we conducted a 974-respondent survey across mainland China, supplemented by policy and media reviews. We examined perceptions of three facets of COVID-19 origins: geographic location, source (e.g., wildlife farm, wet market, etc.), and specific wildlife species as transmitters. Our findings reveal that 64.6 % of respondents believed COVID-19 originated in the United States or Europe, not in China. Further, compared to the baseline group of respondents who selected China as the origin country, respondents who selected the United States or Europe as the origin had a greater likelihood of selecting laboratories/research and imported frozen foods as likely sources, while these respondents had a lower likelihood of selecting wild animals in a wet market or natural causes as likely sources. Despite such varied beliefs regarding COVID-19 origins, support for wildlife policy reforms was strong: 89.5 % of respondents who previously consumed wildlife self-indicated reduced consumption after the pandemic and 70.5 % of respondents supported banning the trade of all wildlife species. Moreover, those respondents who selected wild animals in a wet market as a likely source of COVID-19 had a greater likelihood of supporting a trade ban on all wild-caught wildlife and all farmed wildlife. Our results indicate that, although investigation of COVID-19's origins is on-going and politicized, there is clear support for wildlife reforms in China that can promote conservation outcomes.
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Solar energy is considered one of the key solutions to the growing demand for energy and to reducing greenhouse gas emissions. Thanks to the relatively low cost of land use for solar energy and high power generation potential, a large number of photovoltaic (PV) power stations have been established in desert areas around the world. Despite the contribution to easing the energy crisis and combating climate change, large-scale construction and operation of PV power stations can change the land cover and affect the environment. However, few studies have focused on these special land cover changes, especially vegetation cover changes, which hinders understanding the effects of the extensive development of solar energy. Here, we used Continuous Change Detection and Classification - Spectral Mixture Analysis (CCDC-SMA) based on Landsat images to monitor changes in vegetation abundance before and after the PV power stations deployment. To reduce the interference of PV shading on vegetation abundance estimation, we improved the vegetation (VG) fraction from SMA and developed the Photovoltaics-Adjusted Vegetation (PAVG) fraction for vegetation abundance measurements in PV power stations. Results show that PV power stations in China's 12 biggest deserts expanded from 0 to 102.56 km2 from 2011 to 2018, mainly distributed in the central part of north China. The desert vegetation in the deployment area of PV power stations presented a significant greening trend. Compared to 2010, the greening area reached 30.80 km2, accounting for 30% of the total area of PV power stations. Overall, the large-scale deployment of PV power stations has promoted desert greening, primarily due to government-led Photovoltaic Desert Control Projects and favorable climatic change. This study shows the great benefits of PV power stations in combating desertification and improving people's welfare, which bring sustainable economic, ecological and social prosperity in sandy ecosystems.
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Gases de Efecto Invernadero , Energía Solar , Humanos , Ecosistema , Luz Solar , Cambio Climático , ChinaAsunto(s)
Antibacterianos , Agua Potable , Lagos , Ríos , Contaminantes Químicos del Agua , Antibacterianos/análisis , Antibacterianos/normas , Agua Potable/química , Agua Potable/normas , Monitoreo del Ambiente , Lagos/química , Ríos/química , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/normasRESUMEN
The rapid economic development has highlighted the global climate change problem and carbon dioxide emissions have brought challenges to global climate change. The combined carbon emissions of the United States and China are nearly half of global carbon emissions. These two countries have made great contributions to environmental protection and responded actively to global warming, and set the goal of carbon neutrality. This study takes the United States and China as examples to compare their national paths and policies to achieve carbon neutrality while also analyzing the stage effects of carbon emission reduction in these two countries. This study found that the policy systems in the United States and China are opposites of each other. The United States is a "Bottom to Top" system while China is a "Top to Bottom". The CO2 emission in the United States is currently in the absolute carbon emission reduction period, that is, the reduction of total carbon emissions; while China is in the relative carbon emission reduction period, that is, the reduction of carbon emission intensity. China's transition time from carbon peaking to carbon neutrality is shorter than that of the United States, which is a huge challenge for China because its population is much larger than that of the United States. The results of this research can be used by other countries and regions for supporting carbon reduction policy decision-making and achieving UN sustainable development goals (SDGs).
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Dióxido de Carbono , Desarrollo Económico , Dióxido de Carbono/análisis , China , Cambio Climático , Políticas , Estados UnidosRESUMEN
The identification of vulnerable people and places to flood is crucial for effective disaster risk management. Here, we combine flood hazard and social vulnerability index to capture the potential risk of flood. In this paper, Nanjing was taken as the case study to explore the spatial pattern of social vulnerability towards flood at the community scale by developing an index system. Based on the flood risk results of ArcSWAT, the risk of flood disaster in Nanjing was evaluated. The results show the following. (1) Social vulnerability exhibits a central-peripheral pattern in general, which means that the social vulnerability degree is high in the central city and decreases gradually to the suburbs. (2) The susceptibility to flood disaster has a similar circle-layer pattern that is the highest in the urban centre, lower in the exurban areas, and the lowest in the suburb areas. (3) By using the GIS-based zoning approach, communities are classified into four types by comprehensively considering their flood susceptibility and social vulnerability. The spatial pattern is explained, and policy recommendation for reducing flood risk is provided for each type of community. The research has important reference significance for identifying the spatial pattern of social vulnerability to flood and then formulating targeted adaptation countermeasures.
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Desastres , Inundaciones , China , Planificación de Ciudades , Sistemas de Información Geográfica , HumanosRESUMEN
Water shortage and pollution have become prominent in the arid regions of northwest China, seriously affecting human survival and sustainable development. The Bosten Lake basin has been considered as an example of an arid region in northwest China, and the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model has been used to quantitatively evaluate the future water yield and water purification services for four representative concentration pathways (RCP) scenarios. The results show that for the four RCP scenarios, the annual average precipitation in 2020-2050 decreases compared to that in 1985-2015; the area of cultivated land and unused land decreases, and the area of other land-use types increases from 2015 to 2050. The water yield service reduces, while the water purification service increases from 2015 to 2050 in the Bosten Lake basin. In 2050, the water yield and water purification services are the best for the RCP6.0 scenario, and are the worse for the RCP4.5 scenario and RCP8.5 scenario, respectively. The distribution of the water yield and water purification services show a gradual decline from northwest to southeast.
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Ecosistema , Purificación del Agua , China , Conservación de los Recursos Naturales , Clima Desértico , Humanos , Lagos , AguaRESUMEN
With the global increase in population and urban expansion, the simultaneous rise of social demand and degradation of ecosystems is omnipresent, especially in the urban agglomerations of China. In order to manage environmental problems and match ecosystem supply and social demand, these urban agglomerations promoted regional socio-ecological integration but ignored differential city management during the process of integration. Therefore, it is necessary to design a general framework linking ecosystem supply and social demand to differential city management. In addition, in previous studies, ecosystem services supply-demand amount (mis)match assessment was emphasized, but ecosystem services supply-demand type (mis)match assessment was ignored, which may lead to biased decisions. To deal with these problems, this study presented a general ecosystem services framework with six core steps for differential city management and developed a double-indices (amount and type) method to identify ecosystem services supply-demand (mis)matches in an urban agglomeration. This framework and the double-indices method were applied in the case study of the Yangtze River Delta Urban Agglomeration. Ecosystem supply-demand amount and type (mis)match levels and spatial pattern of twenty-six cities were identified. Twenty-six cities in the YRDUA were classified into five kinds of cities with different levels of ES supply-demand (mis)matches for RS, three kinds of cities for PS, and four kinds of cities for CS. Differential city management strategies were designed. Despite its limitations, this study can be a reference to giving insights into ES supply-demand (mis)match assessment and management.
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Ecosistema , Ríos , China , Ciudades , Conservación de los Recursos Naturales , UrbanizaciónRESUMEN
The complete lockdown due to COVID-19 pandemic has contributed to the improvement of air quality across the countries particularly in developing countries including India. This study aims to assess the air quality by monitoring major atmospheric pollutants such as AOD, CO, PM2.5, NO2, O3 and SO2 in 15 major cities of India using Air Quality Zonal Modeling. The study is based on two different data sources; (a) grid data (MODIS- Terra, MERRA-2, OMI and AIRS, Global Modeling and Assimilation Office, NASA) and (b) ground monitoring station data provided by Central Pollution Control Board (CPCB) / State Pollution Control Board (SPCB). The remotely sensed data demonstrated that the concentration of PM2.5 has declined by 14%, about 30% of NO2 in million-plus cities, 2.06% CO, SO2 within the range of 5 to 60%, whereas the concentration of O3 has increased by 1 to 3% in majority of cities compared with pre lockdown. On the other hand, CPCB/SPCB data showed more than 40% decrease in PM2.5 and 47% decrease in PM10 in north Indian cities, more than 35% decrease in NO2 in metropolitan cities, more than 85% decrease in SO2 in Chennai and Nagpur and more than 17% increase in O3 in five cities amid 43 days pandemic lockdown. The restrictions of anthropogenic activities have substantial effect on the emission of primary atmospheric pollutants.
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Many coastal cities are short of land for development and, coupled with the need to mitigate the impact of extreme events against a background of ongoing sea-level rise, coastal land reclamation (CLR) has emerged as a frequently applied solution, most especially in Asia. However, the sustainability of these newly reclaimed lands under the combined onslaught of increasing population pressure, SRL, greater frequency of extreme events, and land subsidence is largely unknown. In order to assess the spatial extent and temporal trends in recent CLR projects, we mapped and tabulated the annual magnitude of change in coastal land gain from 1988 to 2018 for eight major Asian coastal cities. Across these cities, both the spatial extent and rate of CLR is remarkable; some 700 km2 has been reclaimed in just three decades. >35% of this new coastal land has been constructed in Shanghai alone (562 km2), while Singapore and Incheon have also experienced substantial land gains. These three cities alone account for almost 10% of all the land gained globally over the last three decades. An analysis of the spatio-temporal patterns reveals that, since recently reclaimed areas are predominantly characterized by construction, including ports, airports, commercial and residential uses, economic development is the most prominent driver. Shanghai, however, represents a significant departure from this trend, whereby >50% of the new coastal land gained during the recent past has not been devoted to construction projects and is vegetated, suggesting a different policy context. Commercial or otherwise, subsidence is widely reported as a major characteristic of recently reclaimed coastal land and is a major environmental challenge. Mapping recent rates of land subsidence over these newly reclaimed lands reveal that most are subject to significant levels of deformation, in the case of the international airport at Incheon, Republic of Korea, exceeding 25 cm annually.
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In this paper, a new polarization-maintaining fiber (PMF) composed of an elliptical ring core and two circular air holes is exploited. The PMF could support 10 guided modes with refractive index differences $\Delta {n_{{\rm eff}}}$Δneff of all the adjacent modes larger than ${{10}^{ - 4}}$10-4. Moreover, the optimum parameters of the PMF covering the entire $C + L$C+L band are obtained. Last, the chromatic dispersion $D$D of the designed elliptical ring core fiber, the confinement loss $\alpha $α, and the power fraction $\chi $χ of the two-air core are calculated. The calculation results show that $D$D, $\alpha $α, and $\chi $χ are compatible with traditional step-index fiber, and the designed elliptical ring core fiber is suitable for mode-division multiplexing and optical fiber sensors.
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Bosten Lake is an important region of Northwest China that has transformed from a freshwater lake to a saltwater lake since the 1970s. The water quality in the Bosten Lake basin is important for social and economic development, and nitrogen (N) and phosphorus (P) are the key indicators of water quality. The land use data, precipitation data and Digital Elevation Model (DEM) data with the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model were used to simulate the N and P exports of the Bosten Lake basin. The spatial and temporal dynamics of nitrogen and phosphorus exports, and the response of nitrogen and phosphorus exports to land use change and precipitation change were analyzed between 2000 and 2015. The results show that the amount of N and P exports increased during 2000-2015, and the N and P exports are mainly distributed around Bosten Lake. The N and P exports are greatly affected by cultivated land, built-up areas and grassland, while they are less affected by other land use types. The high precipitation areas with small exports of N and P are mainly distributed in mountain areas, while small precipitation areas with large exports of N and P are distributed in plains where the cultivated land and built-up areas are concentrated. The InVEST model can be used in Northwest China, and the statistical downscaling of reanalysis precipitation data can be used in the InVEST model to improve the simulation accuracy in the data scarce regions of Northwest China.
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Lagos/química , Nitrógeno/análisis , Fósforo/análisis , Calidad del Agua , China , Ecosistema , Monitoreo del Ambiente/métodos , Agua Dulce/química , Modelos Biológicos , Agua de Mar/química , Contaminantes Químicos del Agua/análisisRESUMEN
In this paper, the property of panda polarization maintaining fiber Bragg gratings (PPM-FBGs) embedded in a composite laminate system (CLS) under a transversal force from 1 × 105 Pa to 5 × 105 Pa is explored. Both the wavelengths shift and the rotation angle of the principal axes of the PPM-FBGs are surveyed theoretically. We investigate the corresponding relation between the direction of external force and the rotation angle of principal axes of the PPM-FBGs and prove that the magnitude and direction of the strain distribution in the CLS can be monitored simultaneously, which can realize the detection of interlaminar damage of the CLS. We find that the strain, which corresponds to the shift of wavelengths of the PPM-FBGs, has a different angular dependence, and therefore the potential failure forms of the CLS can be differentiated.