Ecosystem services are the benefits people obtain from ecosystems, and ecosystem services trade-offs have been widely applied to the development of land-use policy. Although previous studies have ...focused on trade-offs of ecosystem services, a scenario approach has been seldom used. The scenario approach can reveal the changes of ecosystem services for different land-use patterns in the future, and is of great significance for land-use decisions and ecosystem management. Based on the actual situation of deteriorating water quality and dwindling water supply in the Erhai Lake Basin of southwest China, this study put forward to convert paddy land to dry land (PLDL) in the basin, and simulated its potential impact on ecosystem services. Taking environmental pollution, social impact, economic benefit and residential participation into consideration, four scenarios of PLDL were designed. Then, four ecosystem services (water purification, water yield, soil conservation and rice production) were calculated for each scenario. The optimal scenario of PLDL in the Erhai Lake Basin was identified by trade-offs of the four ecosystem services. The results showed that the total nitrogen export could be reduced by 42.07% and water yield can be increased by 5.61% after converting 100% of paddy lands to dry land, thereby greatly improving the water quality and increasing the water yield of Erhai Lake. However, PLDL involving 100% of paddy lands also increased the sediment export by 17.22%, and eliminated rice production in the region. By comparing the four PLDL scenarios for converting just 50% of paddy lands, the residential participation scenario was identified to be the best choice for PLDL implementation because it achieved the best level of water purification and had the smallest negative effect on other ecosystem services. The optimal scenario for each township showed spatial differentiation, and there were conflicts between the optimal scenarios at basin scale and township scale, suggesting that the object and the spatial-temporal scale should be taken into consideration in land-use decisions using ecosystem services trade-offs.
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•Scenarios approach is applied in land use decision and ecosystem management.•The optimal land-use pattern is identified using ecosystem services trade-offs.•The resident participation scenario is chosen to convert paddy land to dry land.•The object and spatial scale is essential in land use decision-making.
Ecosystem service is the key comprehensive indicator for measuring the ecological effects of urbanization. Although various studies have found a causal relationship between urbanization and ecosystem ...services degradation, the linear or non-linear characteristics are still unclear, especially identifying the impact thresholds in this relationship. This study quantified four ecosystem services (i.e. soil conservation, carbon sequestration and oxygen production, water yield, and food production) and total ecosystem services (TES), and then identified multiple advantageous area of ecosystem services in the peri-urban area of Beijing City. Using piecewise linear regression, the response of TES to urbanization (i.e., population density, GDP density, and construction land proportion) and its thresholds were detected. The results showed that, the TES was high in the north and west and low in the southeast, and there were seven multiple advantageous areas (distributed in the new urban development zone and ecological conservation zone), one single advantageous area (distributed in the ecological conservation zone), and six disadvantageous areas (mainly distributed in the urban function extended zone). TES response to population and economic urbanization each had a threshold (229personkm−2 and 107.15millionyuankm−2, respectively), above which TES decreased rapidly with intensifying urbanization. However, there was a negative linear relationship between land urbanization and TES, which indicated that the impact of land urbanization on ecosystem services was more direct and effective than that of population and economic urbanization. It was also found that the negative impact of urbanization on TES was highest in the urban function extended zone, followed in descending order by that in the new urban development zone and ecological conservation zone. According to the detected relationships between urbanization and TES, the economic and population urbanization should be strengthened accompanied by slowing or even reducing land urbanization, so as to achieve urban ecological sustainability with less ecosystem services degradation.
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•Multiple advantageous area of ecosystem services (ESs) was identified.•There were thresholds of ESs response to population and economic urbanization.•ESs response to land urbanization was proved to be linear decreasing.
Climate change and human activities have caused a wide range of ecological risks in the Qinghai–Tibet Plateau (QTP) over the past two decades, such as land degradation and biodiversity loss. ...Therefore, it is imperative to assess the ecological security and drivers for its sustainable development. However, there still lacks a spatial understanding of ecological security in the QTP, as well as the geographic driving forces. In this study, a pressure–state–response (PSR) framework and the coupled fuzzy and obstacle degree models were used to evaluate the spatial pattern and factors that modulate ecological security of the QTP. The southeast of the plateau exhibited high pressure and state levels, indicating that population and economic development activities were concentrated in these regions owing to the good natural conditions. The ecological security evaluation value of the QTP is moderately low, with a median value of 47.4 (the full mark is 100). Seven regions with low ecological security were identified where targeted planning and governance measures should be implemented based on the local natural and economic conditions. Population density, net primary productivity index (NPP) of vegetation, and GDP per unit area were the main factors that modulated ecological security in the QTP, with obstacles accounting for 17.52%, 13.20%, and 12.97%, respectively. These results improve our understanding of the major vulnerable areas and main driving forces of ecological security, providing key information for optimization of ecological security pattern in the QTP.
Recent studies show that international trade affects global distributions of air pollution and public health. Domestic interprovincial trade has similar effects within countries, but has not been ...comprehensively investigated previously. Here we link four models to evaluate the effects of both international exports and interprovincial trade on PM
pollution and public health across China. We show that 50-60% of China's air pollutant emissions in 2007 were associated with goods and services consumed outside of the provinces where they were produced. Of an estimated 1.10 million premature deaths caused by PM
pollution throughout China, nearly 19% (208,500 deaths) are attributable to international exports. In contrast, interprovincial trade leads to improved air quality in developed coastal provinces with a net effect of 78,500 avoided deaths nationwide. However, both international export and interprovincial trade exacerbate the health burdens of air pollution in China's less developed interior provinces. Our results reveal trade to be a critical but largely overlooked consideration in effective regional air quality planning for China.International and domestic interprovincial trade of China are entangled, but their health impacts have been treated separately in earlier studies. Here Wang. quantify the complex impacts of trade on public health across China within an integrative framework.
Air pollution in the form of fine particulate matter, or PM2.5, can decrease human life expectancy and increase the overall mortality rate. Based on a time series of remotely sensed PM2.5 ...concentrations, this study analyzed the spatiotemporal patterns of this crucial pollutant in China from 1999 to 2011 using trend analysis and standard deviation ellipse analysis, and carried out a health risk assessment of human exposure to PM2.5. The results showed that PM2.5 concentrations increased significantly from 1999 to 2011 in China, especially in the central and eastern parts of the country. The proportion of areas with PM2.5 concentrations higher than 35μg/m3 increased year by year, and the areas with PM2.5 concentrations lower than the annual primary standard of 15μg/m3 decreased continuously. The areas most polluted by PM2.5 were south of Hebei, north of Henan and west of Shandong provinces, with changes in the overall spatial distribution of the pollutant occurring faster along a south–north axis than along an east–west axis, and also faster along an east–south axis than along a west–north axis. Based on the PM2.5 concentrations in China from 1999 to 2011, a two-tier standard (level-I and level-II) was proposed for delineated areas to assist in nationwide air pollution control. It was also found that the proportion of the population exposed to PM2.5 concentrations greater than 35μg/m3 increased year by year, and increased faster than the proportion of population exposed to PM2.5 concentrations in the range 15–35μg/m3. The health risk in the central and eastern areas of the country was the highest. Based on these results, PM2.5 pollution poses an increasingly serious risk to human health across China and there is an immediate need to implement its regional control. In addition, more attention should be paid at the national scale in terms of pollution risk, rather than focusing narrowly on a city scale.
•PM2.5 increased significantly in central and eastern China during 1999–2011.•National center of average PM2.5 shifted to the southeast in China.•A spatial zoning with two standard contours was proposed for PM2.5 control.•Health risk was the highest in central and eastern China, with fast growth rate.•Spatial patterns of PM2.5 are quantified using standard deviation ellipse analysis.
The urban-rural fringe, known as the region located between the urban and rural areas, is the frontier of urban expansion against rural reservations. Identifying this particular region precisely, ...which was usually simplified by researchers, is the most important prerequisite in studies related to urban-rural patterns. In this study, we proposed a new model, combining wavelet transform and kernel density estimation, to identify the urban-rural fringe based on land use data. After testing the model using Beijing City as a case study, it is proved that the model is able to delineate the boundaries of urban-rural fringe precisely with respect to different landscape patterns at different regions (central urban area, urban-rural fringe area, and outer rural area). Furthermore, due to the advantage of the self-adaptive-bandwidth kernel density estimation, the model can also distinguish some of the satellite towns from the central urban area and outer rural area with the boundaries of urban-rural fringe.
•A quantitative model is proposed to identify urban-rural fringe.•Mutation points can be detected automatically using spatial wavelet transform.•The density surface of the mutational points is constructed by modified KDE.•Noise mutation points are eliminated by slicing the density surface.•Urban-rural fringe in Beijing City are precisely identified based on land use map.
A series of novel composite anion exchange membranes for alkaline fuel cell were prepared by incorporating quaternized graphenes (QGs) into the chloromethylated polysulfone (CMPSU), and followed by ...quaternization and alkalization. The highly exfoliated quaternized graphenes (QGs) were obtained by epoxide ring opening reaction of APTES-functionalized graphenes (A-FGs) with glycidyltrimethylammonium chloride (GDTMAC). The influence of the content of QGs on the properties of the obtained composite membranes was studied. The results indicated that the QPSU−0.5%-QGs showed a 4-fold improvement in the bicarbonate conductivity than that of pristine QPSU membrane at 80°C, and the QPSU−0.25%-QGs showed a 3-fold increase in Young׳s modules and tensile strength. The performance improvement of the membranes could be attributed to the formation of the interconnected transfer channels provided by the QGs and the excellent compatibility between QPSU and QGs. In addition, the good morphologies without phase separation, acceptable thermal properties, alkaline resistances and oxide stabilities, low water uptakes and swelling ratios were also presented in the composite membranes. Our study demonstrated that the incorporation of proper content of QGs into the polymer matrix to fabricate the composite membranes is a facile way to improve the properties of the anion fuel cell membranes, especially in the anion conductivity and mechanical property.
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•Highly dispersed quaternized graphenes (QGs) were prepared.•Quaternized graphenes (QGs) reinforced polysulfone composite anion exchange membranes were fabricated.•QPSU−0.5%-QGs showed a 4-fold improvement in the bicarbonate conductivity than that of QPSU at 80°C.•Our strategy opens up a new perspective in the preparation of novel composite anion exchange membranes for AMFC.
Land use mutilfunctionality (LUMF) has recently received increasing attention in scientific and policy contexts because its capacity to bridge the connections between mutilfunctionality and land ...uses, as well as to integrate production, living and ecology approaches in policy development. This study established a conceptual framework for identifying and evaluating LUMF in spatial grid context from the perspective of structure, function, and well-being. Embedded in the spatial reference framework, a set of spatialization models were applied to quantify and visualize land use functions (LUFs), e.g. production, living, and ecology functions, by using multi-source and multi-scale data (land use data, remote sensing data, meteorological data, and statistical data, etc.) in Zhangjiakou City. The interactions of LUFs were measured, and on this basis, land use zoning was proposed. The results showed that the functionality indexes of production, living, and ecology ranged from 0 to 0.500, 0 to 0.994, and 0 to 0.998, respectively. The high production and living functions, and the low ecology function mainly occurred in well-developed regions, especially in the city center, where existed the strong synergies between production and living functions, as well as the strong trade-offs between the above two functions and ecology function. The low production and living functions, and the high ecology function were mainly distributed in mountain and hilly areas, located in the eastern and southern parts, where existed the weak synergies between production and living functions, and the strong trade-offs among production, living, and ecology functions. Four categories of land use zones were divided at town-level, namely, ecological preservation zones, urbanization development zones, agricultural production zones, and countryside improvement zones, mainly based on the spatial distribution of the synergies and trade-offs among LUFs. This study provides a pathway for quantitatively evaluating LUMF, and making land use zoning division, which provides quantitative information for policy-makers to implement land use optimization, economic development, and ecological protection in the light of the interactions of LUFs.
•A conceptual framework was established to identify and assess land use multifunctionality.•Production, living, and ecology functions were mapped in Zhangjiakou City at grid-scale.•The spatial heterogeneity did exist in different land use functions.•There was trade-offs or synergies relationships among land use functions in space.•The concept of land use multifunctionality was applied in land use zoning.
In this paper, we study the cooperation problem over a group of discrete-time nonlinear dynamically decoupled multi-agent systems (MAS). A distributed model predictive control (DMPC) scheme is ...proposed in the event-triggered context. Agents cooperate through a coupled cost function subject to input constraints. From the practical perspective, the additive disturbances are taken into account in the controller design. Using the contraction theory in the framework of Riemannian manifolds, a novel constraint is constructed in the DMPC optimization problem to provide the capability of disturbance rejection. Moreover, the event-triggered mechanism is introduced for saving computational and communicational resources. The event-triggering condition is developed by checking the Riemannian distance between the actual and optimal state trajectories. The stability of the closed-loop system and recursive feasibility of the DMPC scheme, thereafter, are rigorously analyzed. In particular, the stability analysis is built upon the contraction theory, which distinguishes this work from the existing results using the conventional Lyapunov theory. It is shown that the recursive feasibility is guaranteed if the additive disturbances are bounded and the event-triggering condition is properly designed. The numerical simulation results demonstrate the effectiveness of the proposed algorithm.
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