Carey Jang

On the future of carbonaceous aerosol emissions

[1] This paper presents the first model-based forecasts of future emissions of the primary carbonaceous aerosols, black carbon (BC) and organic carbon (OC). The forecasts build on a recent 1996 inventory of emissions that contains detailed fuel, technology, sector, and world-region specifications. The forecasts are driven by four IPCC scenarios, A1B, A2, B1, and B2, out to 2030 and 2050, incorporating not only changing patterns of fuel use but also technology development. Emissions from both energy generation and open biomass burning are included. We project that global BC emissions will decline from 8.0 Tg in 1996 to 5.3–7.3 Tg by 2030 and to 4.3–6.1 Tg by 2050, across the range of scenarios. We project that OC emissions will decline from 34 Tg in 1996 to 24–30 Tg by 2030 and to 21–28 Tg by 2050. The introduction of advanced technology with lower emission rates, as well as a shift away from the use of traditional solid fuels in the residential sector, more than offsets the increased combustion of fossil fuels worldwide. Environmental pressures and a diminishing demand for new agricultural land lead to a slow decline in the amount of open biomass burning. Although emissions of BC and OC are generally expected to decline around the world, some regions, particularly South America, northern Africa, the Middle East, South Asia, Southeast Asia, and Oceania, show increasing emissions in several scenarios. Particularly difficult to control are BC emissions from the transport sector, which increase under most scenarios. We expect that the BC/OC emission ratio for energy sources will rise from 0.5 to as much as 0.8, signifying a shift toward net warming of the climate system due to carbonaceous aerosols. When biomass burning is included, however, the BC/OC emission ratios are for the most part invariant across scenarios at about 0.2. INDEX TERMS: 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801); 0322 Atmospheric Composition and Structure: Constituent sources and sinks; 0365 Atmospheric Composition and Structure: Troposphere—composition and chemistry; 0325 Atmospheric Composition and Structure: Evolution of the atmosphere; KEYWORDS: aerosols, emissions, projections, global, black carbon, organic carbon

Impact assessment of ammonia emissions on inorganic aerosols in East China using response surface modeling technique.

Ammonia (NH(3)) is one important precursor of inorganic fine particles; however, knowledge of the impacts of NH(3) emissions on aerosol formation in China is very limited. In this study, we have developed Chinas NH(3) emission inventory for 2005 and applied the Response Surface Modeling (RSM) technique upon a widely used regional air quality model, the Community Multi-Scale Air Quality Model (CMAQ). The purpose was to analyze the impacts of NH(3) emissions on fine particles for January, April, July, and October over east China, especially those most developed regions including the North China Plain (NCP), Yangtze River delta (YRD), and the Pearl River delta (PRD). The results indicate that NH(3) emissions contribute to 8-11% of PM(2.5) concentrations in these three regions, comparable with the contributions of SO(2) (9-11%) and NO(x) (5-11%) emissions. However, NH(3), SO(2), and NO(x) emissions present significant nonlinear impacts; the PM(2.5) responses to their emissions increase when more control efforts are taken mainly because of the transition between NH(3)-rich and NH(3)-poor conditions. Nitrate aerosol (NO(3)(-)) concentration is more sensitive to NO(x) emissions in NCP and YRD because of the abundant NH(3) emissions in the two regions, but it is equally or even more sensitive to NH(3) emissions in the PRD. In high NO(3)(-) pollution areas such as NCP and YRD, NH(3) is sufficiently abundant to neutralize extra nitric acid produced by an additional 25% of NO(x) emissions. The 90% increase of NH(3) emissions during 1990-2005 resulted in about 50-60% increases of NO(3)(-) and SO(4)(2-) aerosol concentrations. If no control measures are taken for NH(3) emissions, NO(3)(-) will be further enhanced in the future. Control of NH(3) emissions in winter, spring, and fall will benefit PM(2.5) reduction for most regions. However, to improve regional air quality and avoid exacerbating the acidity of aerosols, a more effective pathway is to adopt a multipollutant strategy to control NH(3) emissions in parallel with current SO(2) and NO(x) controls in China.

Effectiveness of national air pollution control policies on the air quality in metropolitan areas of China

Understanding the effectiveness of national air pollution controls is important for control policy design to improve the future air quality in China. This study evaluated the effectiveness of major national control policies implemented recently in China through a modeling analysis. The sulfur dioxide (SO2) control policy during the 11th Five Year Plan period (2006-2010) had succeeded in reducing the national SO2 emission in 2010 by 14% from its 2005 level, which correspondingly reduced ambient SO2 and sulfate (SO4(2-)) concentrations by 13%-15% and 8%-10% respectively over east China. The nitrogen oxides (NO(x)) control policy during the 12th Five Year Plan period (2011-2015) targets the reduction of the national NO(x) emission in 2015 by 10% on the basis of 2010. The simulation results suggest that such a reduction in NO(x) emission will reduce the ambient nitrogen dioxide (NO2), nitrate (NO3(-)), 1-hr maxima ozone (O3) concentrations and total nitrogen deposition by 8%, 3%-14%, 2% and 2%-4%, respectively over east China. The application of new emission standards for power plants will further reduce the NO2, NO3(-), 1-hr maxima O(3 concentrations and total nitrogen deposition by 2%-4%, 1%-6%, 0-2% and 1%-2%, respectively. Sensitivity analysis was conducted to evaluate the inter-provincial impacts of emission reduction in Beijing-Tianjin-Hebei and the Yangtze River Delta, which indicated the need to implement joint regional air pollution control.

A modeling study of coarse particulate matter pollution in Beijing: regional source contributions and control implications for the 2008 Summer Olympics.

Abstract In the last 10 yr, Beijing has made a great effort to improve its air quality. However, it is still suffering from regional coarse particulate matter (PM10) pollution that could be a challenge to the promise of clean air during the 2008 Olympics. To provide scientific guidance on regional air pollution control, the Mesoscale Modeling System Generation 5 (MM5) and the Models-3/Community Multiscale Air Quality Model (CMAQ) air quality modeling system was used to investigate the contributions of emission sources outside the Beijing area to pollution levels in Beijing. The contributions to the PM10 concentrations in Beijing were assessed for the following sources: power plants, industry, domestic sources, transportation, agriculture, and biomass open burning. In January, it is estimated that on average 22% of the PM10 concentrations can be attributed to outside sources, of which domestic and industrial sources contributed 37 and 31%, respectively. In August, as much as 40% of the PM10 concentrations came from regional sources, of which approximately 41% came from industry and 31% from power plants. However, the synchronous analysis of the hourly concentrations, regional contributions, and wind vectors indicates that in the heaviest pollution periods the local emission sources play a more important role. The implications are that long-term control strategies should be based on regional-scale collaborations, and that emission abatement of local sources may be more effective in lowering the PM10 concentration levels on the heavy pollution days. Better air quality can be attained during the Olympics by placing effective emission controls on the local sources in Beijing and by controlling emissions from industry and power plants in the surrounding regions.

Modeling intercontinental air pollution transport over the trans‐Pacific region in 2001 using the Community Multiscale Air Quality modeling system

[1] The Community Multiscale Air Quality modeling system is used to study the intercontinental transport of air pollution across the Pacific region. Baseline simulations are conducted for January, April, July, and October 2001 at a 108 km horizontal grid resolution. A sensitivity simulation is conducted for April 2001 to study the impact of Asian anthropogenic emissions on the United States’s air quality. Process analysis is conducted to study pollutant formation and transport and to quantify the relative contributions of atmospheric processes to ozone (O3) and fine particulate matter (PM2.5). Model simulations are evaluated with available surface, aircraft, and satellite observations. Simulated meteorology basically captures the synoptic pattern, but precipitation amounts are significantly underpredicted. Most of the PM2.5 components are overestimated over the United States and most gases are underestimated over east Asia. Simulated NO2 and CO columns agree well with satellite observations. Aerosol optical depths and tropospheric O3 residuals are underpredicted, especially in July. The simulated horizontal fluxes and process analyses show that the transport in the lower free troposphere followed by a large-scale subsidence over the United States provides a major Asian pollution export pathway for most pollutants, while the transport in the planetary boundary layer also plays an important role, especially for CO, O3 ,P M2.5, and SO4� . The background concentrations of O3 and SO4� in the western United States can increase by � 1 ppb (� 2.5%) and 0.4 m gm � 3 (� 20%) in monthly average, up to 2.5 ppb and 1.0 m gm � 3 in daily average, respectively, due to the Asian emissions in April.

Modeling Regional/Urban Ozone and Particulate Matter in Beijing, China

Abstract 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 down-wind 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

Simulation of long-range transport aerosols from the Asian Continent to Taiwan by a Southward Asian high-pressure system

Aerosol is frequently transported by a southward high-pressure system from the Asian Continent to Taiwan and had been recorded a 100% increase in mass level compared to non-event days from 2002 to 2005. During this time period, PM2.5 sulfate was found to increase as high as 155% on event days as compared to non-event days. In this study, Asian emission estimations, Taiwan Emission Database System (TEDS), and meteorological simulation results from the fifth-generation Mesoscale Model (MM5) were used as inputs for the Community Multiscale Air Quality (CMAQ) model to simulate a long-range transport of PM2.5 event in a southward high-pressure system from the Asian Continent to Taiwan. The simulation on aerosol mass level and the associated aerosol components were found within a reasonable accuracy. During the transport process, the percentage of semi-volatile PM2.5 organic carbon in PM2.5 plume only slightly decreased from 22-24% in Shanghai to 21% near Taiwan. However, the percentage of PM2.5 nitrate in PM2.5 decreased from 16-25% to 1%. In contrast, the percentage of PM2.5 sulfate in PM2.5 increased from 16-19% to 35%. It is interesting to note that the percentage of PM2.5 ammonium and PM2.5 elemental carbon in PM2.5 remained nearly constant. Simulation results revealed that transported pollutants dominate the air quality in Taipei when the southward high-pressure system moved to Taiwan. Such condition demonstrates the dynamic chemical transformation of pollutants during the transport process from continental origin over the sea area and to the downwind land.

Impact of inert organic nitrate formation on ground-level ozone in a regional air quality model using the Carbon Bond Mechanism 4

A regional air quality model is used to assess the impact of inert organic nitrate formation on ground-level ozone in the eastern United States during summer. The chemical mechanism used is the Carbon Bond Mechanism 4 (CBM4), which is widely used by regulatory agencies in the United States in air quality modeling applications. Recently, modifications were made to the reaction mechanism involving the organic peroxy radicals which form inert organic nitrates without a critical scientific review of the effects of these changes. In this study, we demonstrate for the first time that the simulated large-scale distribution of ground-level ozone is extremely sensitive to these mechanism changes. Inclusion of radical-radical reactions involving the organic peroxy radicals suppresses inert organic nitrate formation, and leads to significant increases in nitrogen oxide levels over large parts of the model domain. As a consequence of increased rates of ozone photochemical production, ozone mixing ratios are enhanced by as much 10–25 ppbv when these additional radical termination pathways are considered in the model.

Source attribution for mercury deposition in the contiguous United States: regional difference and seasonal variation.

Quantifying the contribution of emission sources responsible for mercury deposition in specific receptor regions helps develop emission control strategies that alleviate the impact on ecosystem and human health. In light of the maximum available control technology (MACT) rules proposed by U.S. Environmental Protection Agency (EPA) and the ongoing intergovernmental negotiation coordinated by United Nations Environmental Programme (UNEP) for mercury, the Community Multiscale Air Quality Modeling System (CMAQ-Hg) was applied to estimate the source contribution in six subregions of the contiguous United States (CONUS). The considered source categories include electric generating units (EGU), iron and steel industry (IRST), other industrial point sources excluding EGU and IRST (OIPM), the remaining anthropogenic sources (RA), natural processes (NAT), and out-of-boundary transport (BC). It is found that, on an annual basis, dry deposition accounts for two-thirds of total annual deposition in CONUS (474 Mg yr−1), mainly contributed by reactive gaseous mercury (about 60% of total deposition). The contribution from large point sources can be as high as 75% near the emission sources (<100 km), indicating that emission reduction may result in direct deposition decrease near the source locations. Out-of-boundary transport contributes from 68% (Northeast) to 91% (West Central) of total deposition. Excluding the contribution from out-of boundary transport, EGU contributes to about 50% of deposition in the Northeast, Southeast, and East Central regions, whereas emissions from natural processes are more important in the Pacific and West Central regions (contributing up to 40% of deposition). This suggests that the implementation of the new EPA MACT standards will significantly benefit only these three regions. Emission speciation is a key factor for local deposition. The source contribution exhibits strong seasonal variation. Deposition is greater in warm seasons due to stronger Hg0 oxidation. However, the contribution from anthropogenic sources is smaller in warm seasons because of larger emissions from natural processes and stronger vertical mixing that facilitates transport. Implications: In the United States, electric generation, industrial combustion, and waste incineration are the most important anthropogenic emission sources of mercury. These sources can contribute up to 75% of total annual mercury deposition near the source locations. Controlling emissions from these sources will benefit more significantly to the eastern United States. Speciation of mercury emissions plays an important role in local deposition. Total annual mercury deposition caused by foreign anthropogenic emissions is significant compared to that from domestic sources on a national basis, suggesting that a coordinated global emission reduction effort is important for effectively reducing mercury deposition in the United States.

Evaluation of health benefit using BenMAP-CE with an integrated scheme of model and monitor data during Guangzhou Asian Games

Guangzhou is the capital and largest city (land area: 7287 km(2)) of Guangdong province in South China. The air quality in Guangzhou typically worsens in November due to unfavorable meteorological conditions for pollutant dispersion. During the Guangzhou Asian Games in November 2010, the Guangzhou government carried out a number of emission control measures that significantly improved the air quality. In this paper, we estimated the acute health outcome changes related to the air quality improvement during the 2010 Guangzhou Asian Games using a next-generation, fully-integrated assessment system for air quality and health benefits. This advanced system generates air quality data by fusing model and monitoring data instead of using monitoring data alone, which provides more reliable results. The air quality estimates retain the spatial distribution of model results while calibrating the value with observations. The results show that the mean PM2.5 concentration in November 2010 decreased by 3.5 μg/m(3) compared to that in 2009 due to the emission control measures. From the analysis, we estimate that the air quality improvement avoided 106 premature deaths, 1869 cases of hospital admission, and 20,026 cases of outpatient visits. The overall cost benefit of the improved air quality is estimated to be 165 million CNY, with the avoided premature death contributing 90% of this figure. The research demonstrates that BenMAP-CE is capable of assessing the health and cost benefits of air pollution control for sound policy making.