With most eastern Chinese cities facing major air quality challenges, there is a strong need for city-scale emission inventories for use in both chemical transport modeling and the development of pollution control policies. In this paper, a high-resolution emission inventory of air pollutants and CO2 for Nanjing, a typical large city in the Yangtze River Delta, is developed incorporating the best available information on local sources. Emission factors and activity data at the unit or facility level are collected and compiled using a thorough onsite survey of major sources. Over 900 individual plants, which account for 97% of the city's total coal consumption, are identified as point sources, and all of the emission-related parameters including combustion technology, fuel quality, and removal efficiency of air pollution control devices (APCD) are analyzed. New data-collection approaches including continuous emission monitoring systems and real-time monitoring of traffic flows are employed to improve spatiotemporal distribution of emissions. Despite fast growth of energy consumption between 2010 and 2012, relatively small inter-annual changes in emissions are found for most air pollutants during this period, attributed mainly to benefits of growing APCD deployment and the comparatively strong and improving regulatory oversight of the large point sources that dominate the levels and spatial distributions of Nanjing emissions overall. The improvement of this city-level emission inventory is indicated by comparisons with observations and other inventories at larger spatial scale. Relatively good spatial correlations are found for SO2, NOX, and CO between the city-scale emission estimates and concentrations at 9 state-opertated monitoring sites (R = 0.58, 0.46, and 0.61, respectively). The emission ratios of specific pollutants including BC to CO, OC to EC, and CO2 to CO compare well to top-down constraints from ground observations. The inter-annual variability and spatial distribution of NOX emissions are consistent with NO2 vertical column density measured by the Ozone Monitoring Instrument (OMI). In particular, the Nanjing city-scale emission inventory correlates better with satellite observations than the downscaled Multi-resolution Emission Inventory for China (MEIC) does when emissions from power plants are excluded. This indicates improvement in emission estimation for sectors other than power generation, notably industry and transportation. High-resolution emission inventory may also provide a basis to consider the quality of instrumental observations. To further improve emission estimation and evaluation, more measurements of both emission factors and ambient levels of given pollutants are suggested; the uncertainties of emission inventories at city scale should also be fully quantified and compared with those at national scale.
Urban systems, with the overall fluxes of energy, water, material, and wastes, can be modeled with a range of metabolic processes. To quantify the urban metabolism, we use the “emergy” assessment method (all materials and energy are transformed to solar energy equivalents) and then present a group of urban metabolic indicators, which quantify urban metabolic balance, capacity, and outputs to assess a city’s metabolic efficiencies. In this paper, we use 31 Chinese cities as a sample to illustrate how the model can be operated to evaluate the urban metabolism by emergy analysis. Our results indicate that metropolises and coastal cities were more metabolically efficient with higher metabolic balance, capacities, and outputs; but with more external dependency on imported resources. Central and western cities had lower metabolic efficiencies, with a high ratio of non-renewable emergy reliance. Policy implications highlight the need for renewable energy sources and improved management of imported services, goods, and fuels to achieve higher urban resilience and sustainability.
As China develops its booming, fossil fuel-powered economy, is it taking lessons from the history of Western industrialization and the unforeseen environmental harms that accompanied it? Given the risks of climate change, is there an imperative, shared responsibility to help China respond to the environmental effects of its coal dependence? By linking global hazards to local air pollution concerns—from indoor stove smoke to burgeoning ground-level ozone—this volume of eighteen studies seeks integrated strategies to address simultaneously a range of harmful emissions. Counterbalancing the scientific inquiry are key chapters on China’s unique legal, institutional, political, and cultural factors in effective pollution control.
Energizing China, the stage-setting publication of an ongoing program of Harvard–China research collaboration, is distinguished by its conceptual breadth and spirit of exchange. Its contributors include twenty-two Western and seventeen Chinese scholars with a disciplinary reach that includes science, public health, engineering, economics, public policy, law, business, and China studies.
The relationship between dense urban development, often represented by high-rise buildings, and its location vis-à-vis metro stations reflects the connection between transportation infrastructure and land use intensity. Existing literature on high-rise buildings has focused either on developed countries or on cities where urban and public transit developments have occurred in an uncoordinated manner. This paper examines the following questions: What is the spatial proximity and spatial correlation between high-rise buildings and metro stations in different stages of development in various parts of the city? What were some of the factors that resulted in the observed patterns? The results suggest that buildings constructed after 2000 and buildings within the urban core/Shanghai Proper districts had a greater spatial proximity to the metro stations. However, the spatial correlation, measured by the number of high-rise buildings within a 500-meter buffer from the nearest metro stations and the time-distance to these stations, is stronger in the outer districts than in the urban core. These differences can be accounted for by Shanghai’s stages of urban development, the existence of metro infrastructure when high-rise development was undertaken, and the city’s land use policies. This case study sheds light on the relationship between high-density developments and metro systems in other large cities in China and other developing countries where rapid urban development coincides with the establishment of a comprehensive public transit system.