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Organic aerosols (OAs) in the atmosphere affect Earth's energy budget by not only scattering but also absorbing solar radiation due to the presence of the so-called "brown carbon" (BrC) component. However, the absorptivities of OAs are not represented or are poorly represented in current climate and chemical transport models. In this study, we provide a method to constrain the BrC absorptivity at the emission inventory level using recent laboratory and field observations. We review available measurements of the light-absorbing primary OA (POA), and quantify the wavelength-dependent imaginary refractive indices (kOA, the fundamental optical parameter determining the particle's absorptivity) and their uncertainties for the bulk POA emitted from biomass/biofuel, lignite, propane, and oil combustion sources. In particular, we parametrize the kOA of biomass/biofuel combustion sources as a function of the black carbon (BC)-to-OA ratio, indicating that the absorptive properties of POA depend strongly on burning conditions. The derived fuel-type-based kOA profiles are incorporated into a global carbonaceous aerosol emission inventory, and the integrated kOA values of sectoral and total POA emissions are presented. Results of a simple radiative transfer model show that the POA absorptivity warms the atmosphere significantly and leads to ∼27% reduction in the amount of the net global average POA cooling compared to results from the nonabsorbing assumption. [ABSTRACT FROM AUTHOR]

China is the world's largest emitter of anthropogenic air pollutants, and measurable amounts of Chinese pollution are transported via the atmosphere to other countries, including the United States. However, a large fraction of Chinese emissions is due to manufacture of goods for foreign consumption. Here, we analyze the impacts of trade-related Chinese air pollutant emissions on the global atmospheric environment, linking an economic-emission analysis and atmospheric chemical transport modeling. We find that in 2006, 36% of anthropogenic sulfur dioxide, 27% of nitrogen oxides, 22% of carbon monoxide, and 17% of black carbon emitted in China were associated with production of goods for export. For each of these pollutants, about 21% of export-related Chinese emissions were attributed to China-to-US export. Atmospheric modeling shows that transport of the export-related Chinese pollution contributed 3-10% of annual mean surface sulfate concentrations and 0.5-1.5% of ozone over the western United States in 2006. This Chinese pollution also resulted in one extra day or more of noncompliance with the US ozone standard in 2006 over the Los Angeles area and many regions in the eastern United States. On a daily basis, the export-related Chinese pollution contributed, at a maximum, 12-24% of sulfate concentrations over the western United States. As the United States outsourced manufacturing to China, sulfate pollution in 2006 increased in the western United States but decreased in the eastern United States, reflecting the competing effect between enhanced transport of Chinese pollution and reduced US emissions. Our findings are relevant to international efforts to reduce transboundary air pollution. [ABSTRACT FROM AUTHOR]

We propose a method to simulate vehicle emissions in Chinese cities of different sizes and development stages. Twenty two cities are examined in this study. The target year is 2007. Among the cities, the vehicle emission factors were remarkably different (the highest is 50–90% higher than the lowest) owing to their distinct local features and vehicle technology levels, and the major contributors to total vehicle emissions were also different. A substantial increase in vehicle emissions is foreseeable unless stronger measures are implemented because the benefit of current policies can be quickly offset by the vehicle growth. Major efforts should be focused on all cities, especially developing cities where the requirements are lenient. This work aims a better understanding of vehicle emissions in all types of Chinese cities. The proposed method could benefit national emission inventory studies in improving accuracy and help in designing national and local policies for vehicle emission control. [Copyright &y& Elsevier]

This paper examines Beijing air quality in the winter and summer of 2001 using an integrated air quality modeling system (Fifth Generation Mesoscale Meteorological Model [MM5]/Community Multiscale Air Quality [CMAQ]) in nested mode. The National Aeronautics and Space Administration (NASA) Transport and Chemical Evolution over the Pacific (TRACE-P) emission inventory is used in the 36- (East Asia), 12- (East China), and 4-km (greater Beijing area) domains. Furthermore, we develop a local Beijing emission inventory that is used in the 4-km domain. We also construct a corroborated mapping of chemical species between the TRACE-P inventory and the Carbon Bond IV (CB-IV) chemical mechanism before the integrated modeling system is applied to study ozone (O3) and particulate matter (PM) in Beijing. Meteorological data for the integrated modeling runs are extracted from MM5. Model results show O3 hourly concentrations in the range of 80-159 parts per billion (ppb) during summer in the urban areas and up to 189 ppb downwind of the city. High fine PM (PM2.5) concentrations (monthly average of 75 μg · m-3 in summer and 150 μg · m-3 in winter) are simulated over the metropolitan and downwind areas with significant secondary constituents. A comparison against available O3 and PM measurement data in Beijing is described. We recommend refinements to the developed local Beijing emission inventory to improve the simulation of Beijing's air quality. The 4-km modeling configuration is also recommended for the development of air pollution control strategies. [ABSTRACT FROM AUTHOR]

Future global emissions of aerosols will play an important role in governing the nature and magnitude of future anthropogenic climate change. We present in this paper a number of future scenarios of emissions of black carbon (BC) and organic carbon (OC) by world region, which we combine with sulfate (SO4) assessed in terms of the emissions of its precursor, SO2. We find that aerosol emissions from the household and industrial sectors are likely to decline along almost all future pathways. Transportation emissions, however, are subject to complex interacting forces that can lead to either increases or decreases. Biomass burning declines in many scenarios, but the Amazon rainforests remain vulnerable if unsustainable economic growth persists. East Asia is the key region for primary aerosols, and trends in China will have a major bearing on the direction and magnitude of releases of BC (expected reductions in the range of 640--1290 Gg), OC (reductions of 520--1900 Gg), and SO2 (ranging from an increase of 21 Tg to a reduction of 30 Tg). Analysis of joint BC, OC, and SO2 emission changes identifies a number of key world regions and economic sectors that could be effectively targeted for aerosol reductions. [ABSTRACT FROM AUTHOR]

The emission of fine carbonaceous particles in China is a serious threat to human health, ecological systems, and regional and global climate regimes. China is thought to release about 20 percent of the global black carbon through the combustion of coal and biofuels without adequate particle controls. The household and industrial sectors are mainly responsible, but the country's grow mg transportation sector is a concern for the future. The economic cost of damage from black carbon likely exceeds the cost of controlling emissions by several fold, but as yet such costs have not been quantified. [ABSTRACT FROM AUTHOR]

Acid deposition is a serious problem throughout much of Asia. Emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) have been increasing steadily, as nations strive to increase their levels of economic development. Coal and fuel oil have been the main choices for powering industrial development; and, until recently, only a few countries had taken steps to avert the atmospheric emissions that accompany fuel combustion. This paper discusses trends in emissions of SO2 and NOx that have occurred in Asian countries in the period 1985–1997, using results from the RAINS-Asia computer model and energy-use trends from the IEA Energy Statistics and Balances database. Emissions of SO2 in Asia grew from 26.6 Tg in 1985 to 33.7 Tg in 1990 and 39.2 Tg in 1997. Though SO2 emissions used to grow as fast as fossil-fuel use, recent limitations on the sulfur content of coal and oil have slowed the growth. The annual-average emissions growth between 1990 and 1997 was only 2.2%, considerably less than the economic growth rate. Emissions of NOx, on the other hand, continue to grow rapidly, from 14.1 Tg in 1985 to 18.7 Tg in 1990 and 28.5 Tg in 1997 (6.2% per year between 1990 and 1997), with no signs of abating. Thus, though SO2 remains the major contributor to acidifying emissions in Asia, the role of NOx will become more and more important in the future. [ABSTRACT FROM AUTHOR]

This work evaluates the effectiveness of on-road primary particulate matter emission reductions that can be achieved by long-term vehicle scrappage and retrofit measures on regional and global levels. Scenario analysis shows that scrappage can provide significant emission reductions as soon as the measures begin, whereas retrofit provides greater emission reductions in later years, when more advanced technologies become available in most regions. Reductions are compared with a baseline that already accounts for implementation of clean vehicle standards. The greatest global emission reductions from a scrappage program occur 5 to 10 years after its introduction and can reach as much as 70%. The greatest reductions with retrofit occur around 2030 and range from 16-31%. Monte Carlo simulations are used to evaluate how uncertainties in the composition of the vehicle fleet affect predicted reductions. Scrappage and retrofit reduce global emissions by 22-60% and 15-31%, respectively, within 95% confidence intervals, under a midrange scenario in the year 2030. The simulations provide guidance about which strategies are most effective for specific regions. Retrofit is preferable for high-income regions. For regions where early emission standards are in place, scrappage is suggested, followed by retrofit after more advanced emission standards are introduced. The early implementation of advanced emission standards is recommended for Western and Eastern Africa. [ABSTRACT FROM AUTHOR]

Abstract: Understanding of the relative impacts of emission reductions and meteorological variations on air quality during the 2008 Beijing Olympics has an important policy implication. In this work, detailed process analyses and sensitivity simulations under different emission and meteorology scenarios were conducted using CMAQ and the Process Analysis tool to quantify the air quality benefits from emission reductions and meteorological variations in August 2008. The results indicate that emission-driven changes dominate surface concentration reductions of SO2, NO2, VOCs, daily maxima O3 and PM2.5 by −11% to −83%. The effect of meteorology-driven changes on species concentrations can be either ways (by −46% to 105%) at different locations. The dominant processes contributing to O3, PM2.5, SO4 2−, NO3 −, and secondary organic aerosol (SOA) are identified. Gas-phase chemistry is a major process for O3 production, and PM processes are dominant sources for PM2.5 in the planetary boundary layer (PBL). The reduced emissions weaken the source contributions of gas-phase chemistry to O3 and those of PM processes to PM2.5, with weaker vertical mixing processes and horizontal transport in the PBL. Compared with 2007, 2008 has a higher humidity, lower temperature and more precipitation that benefit O3 reduction within the PBL, and a weaker vertical mixing that disbenefits reductions of all pollutants concentrations. Stronger process contributions of cloud processes (e.g., below- and in-cloud scavenging, and wet deposition) in 2008 help reduce concentrations of PM2.5, NO3 −, and SOA, but they (e.g., aqueous-phase chemistry) enhance surface SO4 2− concentrations. Smaller process contributions of aerosol processes help reduce the concentrations of SOA and SO4 2− but enhance NO3 − and PM2.5 in lower layers (1–6) due to the evaporation of NO3 −. The ratios of increase under the controlled simulation, indicating that the emission control actions enforced during the 2008 Olympics weakened the sensitivity of O3 chemistry to VOC emissions in urban areas. [Copyright &y& Elsevier]

• The spatial patterns of industrial SO 2 emissions of 288 cities were analyzed. • Nighttime Light data were processed and adopted as a proxy of urbanization level. • Urbanization and population size were major contributing factors. • Tradeoffs between urbanization and industrial SO 2 emission control were discussed. • The impact of urbanization was the highest in the Northeast and Southwest regions. The spatial distribution and the identification of the influential factors of industrial sulfur dioxide (SO 2) emissions have received extensive attention. However, evidence is still lacking on the spatial impacts of urbanization on industrial SO 2 emissions at the city scale in China. This work builds a Geography Weighted Regression (GWR) model on a Stochastic Impacts by Regression on Population, Affluence and Technology (STIRPAT) framework to investigate the spatially heterogeneous impacts of potential influencing factors on city-level industrial SO 2 emissions from 288 prefecture-level cities in China. The results show that the GWR model significantly improved the goodness-of-fit of the model. The influence of night-time light intensity of the cities, as a proxy of the urbanization level, was calculated to be median (min, max): −0.505(-0.918, −0.413). The highest impacts of urbanization were observed in the Northeast and Southwest regions. Industrial influencing factors had generally promoted the growth of SO 2 emissions, with higher positive impacts in western cities. We concluded that urbanization had a significant and negative effect on industrial SO 2 emissions in most Chinese cities. It is necessary to formulate emission reduction and city development policies simultaneously based on the trade-offs between urbanization and air pollution control targets. [ABSTRACT FROM AUTHOR]

We developed an air pollutant emission inventory for marine vessels in the Shanghai Port in 2003. We estimated emissions under cruising and maneuvering conditions based on two categories of vessels: (1) vessels in the Outer Port, which enter the area following notification of the Shanghai Maritime Safety Administration, a division of the Ministry of Communications of P.R. China; and (2) vessels in internal waterways, which enter those waters following notification of the local Port Administration Centers. Vessels in the Outer Port consist of three subcategories: (1) international vessels that are engaged in foreign commerce; (2) domestic vessels traveling along the downstream portion of the Huangpu River; and (3) domestic vessels traveling along the coast. We also estimate emissions from vessels over 1000 DWT operating under hotelling conditions in the Outer Port. In 2003, the total number of calls was approximately 1.3 million, of which 57% is attributed to vessels in internal waterways and 43% to vessels in the Outer Port. Total marine emissions for NOx, SO2, PM, HC, and CO2 in 2003 are estimated to be 58 160, 51 180, 6960, 4560, and 3 012 800 tons, respectively. Emissions are allocated to 1 km × 1 km grid cells for the 129 km × 102 km Shanghai Port study domain. [ABSTRACT FROM AUTHOR]