Present Knowledge and Future Perspectives of Atmospheric Emission Inventories of Toxic Trace Elements: A Critical Review.

Toxic trace elements (TEs) can pose serious risks to ecosystems and human health. However, a comprehensive understanding of atmospheric emission inventories for several concerning TEs has not yet been developed. In this study, we systematically reviewed the status and progress of existing research in developing atmospheric emission inventories of TEs focusing on global, regional, and sectoral scales. Multiple studies have strengthened our understanding of the global emission of TEs, despite attention being mainly focused on Hg and source classification in different studies showing large discrepancies. In contrast to those of developed countries and regions, the officially published emission inventory is still lacking in developing countries, despite the fact that studies on evaluating the emissions of TEs on a national scale or one specific source category have been numerous in recent years. Additionally, emissions of TEs emitted from waste incineration and traffic-related sources have produced growing concern with worldwide rapid urbanization. Although several studies attempt to estimate the emissions of TEs based on PM emissions and its source-specific chemical profiles, the emission factor approach is still the universal method. We call for more extensive and in-depth studies to establish a precise localization national emission inventory of TEs based on adequate field measurements and comprehensive investigation to reduce uncertainty.

Analysis of VOC emissions and O3 control strategies in the Fenhe Plain cities, China.

Long-term continuous hourly measurements of ambient volatile organic compounds (VOCs) are scarce at the regional scale. In this study, a one-year hourly measurement campaign of VOCs was performed in Lvliang, Linfen, and Yuncheng in the heavily polluted Fenhe Plain region in China. The VOC average (±standard deviation, std) concentrations in Lvliang, Linfen, and Yuncheng were 44.4 ± 24.9, 45.7 ± 24.9, and 37.5 ± 25.0 ppbv, respectively. Compared to published data from the past two decades in China, the observed VOCs were at high concentration levels. VOCs in the Fenhe Plain cities were significantly impacted by industrial sources according to calculated emission ratios but were less affected by liquefied petroleum gas and natural gas (LPG/NG) and traffic emissions than those in megacities abroad. The emission inventories and observation data were combined for verification and identification of the key VOC species and sources controlling ozone (O3). Industrial emissions were the largest source of VOCs, accounting for 65%-79% of the total VOC emissions, while the coking industry accounted for 45.2%-66.0%. The emission inventories significantly underestimated oxygenated VOC (OVOC) emissions through the verification of VOC emission ratios. O3 control scenarios were analyzed by changing VOC/NOX reduction ratios through a photochemical box model. O3 control strategies were formulated considering local pollution control plans, emission inventories, and O3 formation regimes. The O3 reduction of reactivity-control measures was comparable with emission-control measures, ranging from 16% to 41%, which was contrary to the general perception that ozone formation potential (OFP)-based measures were more efficient for O3 reduction. Sources with high VOC emissions are accompanied by high OFP on the Fenhe Plain, indicating that the control of high-emission sources can effectively mitigate O3 pollution on this region.

Seasonal Variations in the Characteristics of Microbial Community Structure and Diversity in Atmospheric Particulate Matter from Clean Days and Smoggy Days in Beijing.

Microorganisms are an important part of atmospheric particulate matter and are closely related to human health. In this paper, the variations in the characteristics of the chemical components and bacterial communities in PM10 and PM2.5 grouped according to season, pollution degree, particle size, and winter heating stage were studied. The influence of environmental factors on community structure was also analyzed. The results showed that seasonal variations were significant. NO3- contributed the most to the formation of particulate matter in spring and winter, while SO42- contributed the most in summer and autumn. The community structures in summer and autumn were similar, while the community structure in spring was significantly different. The dominant phyla were similar among seasons, but their proportions were different. The dominant genera were no-rank_c_Cyanobacteria, Acidovorax, Escherichia-Shigella and Sphingomonas in spring; Massilia, Bacillus, Acinetobacter, Rhodococcus, and Brevibacillus in summer and autumn; and Rhodococcus in winter. The atmospheric microorganisms in Beijing mainly came from soil, water, and plants. The few pathogens detected were mainly affected by the microbial source on the sampling day, regardless of pollution level. RDA (redundancy analysis) showed that the bacterial community was positively correlated with the concentration of particulate matter and that the wind speed in spring was positively correlated with NO3- levels, NH4+ levels, temperature, and relative humidity in summer and autumn, but there was no clear consistency among winter samples. This study comprehensively analyzed the variations in the characteristics of the airborne bacterial community in Beijing over one year and provided a reference for understanding the source, mechanism, and assessment of the health effects of different air qualities.

Heterogeneous Variations on Historical and Future Trends of CO2 and Multiple Air Pollutants from the Cement Production Process in China: Emission Inventory, Spatial-Temporal Characteristics, and Scenario Projections.

Cement production is a major contributor to carbon dioxide (CO2) and multiple hazardous air pollutant (HAP) emissions, threatening climate mitigation and urban/regional air quality improvement. In this study, we established a comprehensive emission inventory by coupling the unit-based bottom-up and mass balance methods, revealing that emissions of most HAPs have been remarkably controlled. However, an increasing 6.0% of atmospheric mercury emissions, as well as 14.1 and 23.7% of fuel-related and process-related CO2 emission growth were witnessed unexpectedly. Industrial adjustment policies have imposed a great impact on the spatiotemporal changes in emission characteristics. Monthly emissions of CO2 and multiple HAPs decreased from December to February due to the "staggered peak production," especially in northern China after implementing the intensified action plan for air pollution control in winter. Upgrading environmental technologies and adjusting capacity structures are identified as dominant driving forces for reducing HAP emissions. Besides, energy intensity improvement can help offset some of the impact caused by the increase in clinker/cement production. Furthermore, scenario analysis results show that ultra-low emission and low-carbon technology transformation constitute the keys to achieve the synergic reduction of CO2 and multiple HAP emissions in the future.

Effects of long-term exposure to PM2.5 and chemical constituents on blood lipids in an essential hypertensive population: A multi-city study in China.

Previous studies on the effects of fine particulate matter (PM2.5) and chemical constituents on lipid disorder among hypertension populations, particularly in China, are very limited. We aimed to examine the effects of long-term exposure to PM2.5 and chemical constituents on dyslipidemias in China. Finally, we included 34,841 participants with essential hypertension from 19 regions in China during 2010-2011. Data were modeled using the generalized additive mixed model. We found that PM2.5 and chemical constituents exposure were positively associated with the increased risk of dyslipidemias and increased levels of total cholesterol (TC) and triglyceride (TG). The odds ratio for hypercholesterolemia was 1.356 [95% confidence interval (CI): 1.246, 1.477] for PM2.5, and the strongest association with PM2.5 constituents was found for nitrate. Each 10 µg/m3 increase in PM2.5 showed a significant increase of TC by 2.60% (95% CI: 2.03, 3.17) and TG by 2.91% (95% CI: 1.60, 4.24), respectively. Meanwhile, an interquartile range increase in nitrate, ammonium and organic matter had stronger associations with TC and TG parameters than black carbon, sulfate, and mineral dust. Our findings may contribute to a better understanding of the chronic effects of PM2.5 and chemical constituents on lipid disorder in an essential hypertensive population.

Fine particulate matter (PM2.5/PM1.0) in Beijing, China: Variations and chemical compositions as well as sources.

Particulate matter (i.e., PM1.0 and PM2.5), considered as the key atmospheric pollutants, exerts negative effects on visibility, global climate, and human health by associated chemical compositions. However, our understanding of PM and its chemical compositions in Beijing under the current atmospheric environment is still not complete after witnessing marked alleviation during 2013-2017. Continuous measurements can be crucial for further air quality improvement by better characterizing PM pollution and chemical compositions in Beijing. Here, we conducted simultaneous measurements on PM in Beijing during 2018-2019. Results indicate that annual mean PM1.0 and PM2.5 concentrations were 35.49 ± 18.61 µg/m3 and 66.58 ± 60.17 µg/m3, showing a positive response to emission controls. The contribution of sulfate, nitrate, and ammonium (SNA) played an enhanced role with elevated PM loading and acted as the main contributors to pollution episodes. Discrepancies observed among chemical species between PM1.0 and PM2.5 in spring suggest that sand particles trend to accumulate in the range of 1-2.5 µm. Pollution episodes occurred accompanied with southerly clusters and high formation of SNA by heterogeneous reactions in summer and winter, respectively. Results from positive matrix factorization (PMF) combined with potential source contribution function (PSCF) models showed that potential areas were seasonal dependent, secondary and vehicular sources became much more important compared with previous studies in Beijing. Our study presented a continuous investigation on PM and sources origins in Beijing, which provides a better understanding for further emission control as well as a reference for other cities in developing countries.

Atmospheric Vanadium Emission Inventory from Both Anthropogenic and Natural Sources in China.

Vanadium is a strategically important metal in the world, although sustained exposure under high vanadium levels may lead to notable adverse impact on health. Here, we leverage a bottom-up approach to quantitatively evaluate vanadium emissions from both anthropogenic and natural sources during 1949-2017 in China for the first time. The results show that vanadium emissions increased by 86% from 1949 to 2005 to a historical peak value and then gradually decreased to 12.9 kt in 2017. With the effective implementation of air pollution control measures, vanadium emissions from anthropogenic sources decreased sharply after 2011. During 2011-2017, about half of vanadium emissions came from coal and oil combustion. In addition, industrial processes and natural sources also cannot be ignored, with the total contributions of more than 24%. The high levels of vanadium emissions were mainly distributed throughout the North China Plain and the eastern and coastal regions, especially in several urban agglomerations. Furthermore, the comprehensive evaluation by incorporating contrastive analysis, Monte Carlo approach, and GEOS-Chem simulation shows that vanadium emissions estimated in this study were reasonable and acceptable. The findings of our study provide not only a scientific foundation for investigating the health effects of vanadium but also useful information for formulating mitigation strategies.

Highly Resolved Inventory of Mercury Release to Water from Anthropogenic Sources in China.

This study developed an up-to-date and point-source-based inventory of mercury (Hg) releases to water in China by applying probabilistic release factors that combined industry removal efficiencies, reuse of reclaimed water, and receiving water types. In 2017, the national mercury release to water was estimated to be 50 (35-66) tons, in which 47%, 8%, 7%, and 25% were from nonferrous metal smelting, vinyl chloride monomer (VCM) production, coal-fired boilers, and domestic sewage, respectively. Approximately 95% of mercury was released to inland rivers, and the rest was discharged to lakes or coastal water. The significant sources were identified based on their mercury releases to water. The control of mercury release to water in China shall focus on zinc smelting plants, municipal sewage treatment plants, and the VCM production process. For zinc smelting plants, China can tighten the limit of mercury concentration in discharged wastewater and combine Hg-catcher device in traditional integrated treatment. For municipal sewage treatment plants and the VCM production process, promoting processes of Hg-free production can reduce mercury inputs at the source. Our study provides insights for other parties to identify the relevant sources of mercury release to water and to conduct control measures, so as to promote the global convention implementation.

Significant but Spatiotemporal-Heterogeneous Health Risks Caused by Airborne Exposure to Multiple Toxic Trace Elements in China.

Airborne trace elements (TEs) pose a notable threat to human health due to their toxicity and carcinogenicity, whereas their exposures and associated health risks in China remain unclear. Here, we present the first nationwide assessment of spatiotemporal exposure to 11 TEs in China by coupling a bottom-up emission inventory with a modified CMAQ model capable of TE simulation. Associated health risks of 11 TEs are then evaluated using a set of risk assessment models. Our results show that the CMAQ model could reasonably reproduce the spatiotemporal variations of 11 TEs in China compared to observations. We find significant but spatiotemporal-heterogeneous cancer risks associated with high-level exposure of TEs in China. Gridded cell concentrations of hexavalent chromium, arsenic, and nickel in eastern and central China usually exceed China's air quality standard limits, resulting in significant cancer risks that affected over 85% of the entire population in China in 2015. National annual mean population-weighted concentrations of 11 TEs decrease by 9.8-35.6% from 2012 to 2015, largely attributed to emission reduction from coal combustion. Our study provides critical insights for policymakers to implement stricter measures to alleviate health burdens and benefit relevant epidemiological research on airborne TEs.

Non-Negligible Stack Emissions of Noncriteria Air Pollutants from Coal-Fired Power Plants in China: Condensable Particulate Matter and Sulfur Trioxide.

In this study, we investigated the emission characteristics of condensable particulate matter (CPM) and sulfur trioxide (SO3) simultaneously through ammonia-based/limestone-based wet flue gas desulfurization (WFGD) from four typical coal-fired power plants (CFPPs) by conducting field measurements. Stack emissions of filterable particulate matter (FPM) all meet the Chinese ultralow emission (ULE) standards, whereas CPM concentrations are prominent (even exceed 10 mg/Nm3 from two CFPPs). We find that NH4+ and Cl- increase markedly through the ammonia-based WFGD, and SO42- is generally the main ionic component, both in CPM and FPM. Notably, the occurrence of elemental Se in FPM and CPM is significantly affected by WFGD. Furthermore, the established chemical profiles in FPM and CPM show a distinct discrepancy. In CPM, the elemental S mainly exists as a sulfate, and the metallic elements of Na, K, Mg, and Ca mainly exist as ionic species. Our results may indicate that not all SO3 are included in CPM and they co-exist in stack plume. With the substantial reduction of sulfur dioxide (SO2), S distributed in SO3, CPM, and FPM becomes non-negligible. Finally, the emission factors of CPM and SO3 under typical ULE technical routes fall in the ranges of 74.33-167.83 and 48.76-86.30 g/(t of coal) accordingly.

Migration and Emission Characteristics of Ammonia/Ammonium through Flue Gas Cleaning Devices in Coal-Fired Power Plants of China.

To investigate the up-to-date migration and emission characteristics of NH3/NH4+ in coal-fired power plants (CFPPs) after implementing ultralow emission retrofitting, typical air pollution control devices (APCDs) in CFPPs, including flue gas denitrification, dust collectors, combined wet flue gas desulfurization (WFGD), and wet precipitators are involved in field measurements. The results show that most of the excessive injected and/or unreacted ammonia from the flue gas denitrification system, whether selective catalytic reduction (SCR) or selective noncatalytic reduction (SNCR), is converted into particle-bound NH4+ (>91%), and the rest (less than 9%) is carried by flue gas in the form of gaseous NH3, with a concentration value of 0.15-0.54 mg/(N m3) at the denitrification outlet. When passing through dust collectors, particle-bound NH4+ concentration decreases substantially along with the removal of particle matter. In WFGD, the dissolution and volatilization effects affect the gaseous ammonia concentration, which decreases when using limestone slurry and a 20% solution of ammonia as a desulfurization agent, while liquid ammonia solution with a high concentration (99.8%) may cause the flue gas NH3 concentration to increase considerably by 13 times. Particle-bound NH4+ concentration is mainly influenced by the relative strength of desulfurization slurry scouring and flue gas carrying effects and increases 2.84-116 times through ammonia-based WFGD. Furthermore, emission factors of NH3 for combinations of APCDs are discussed.

Fine particulate matter pollution in North China: Seasonal-spatial variations, source apportionment, sector and regional transport contributions.

Large areas of mainland China have been suffering frequently from heavy haze pollution during the past years, which feature high concentrations of fine particulate matter (PM2.5, particulate matters with aerodynamic diameters less than 2.5 µm) and low visibility. Moreover, these areas manifested strong regional complex pollution characteristics, particularly in North China including Beijing and the five surrounding provinces (BSFP). In this study, by using the localized comprehensive emission inventory of BSFP region in 2012 as an input, the Comprehensive Air Quality Model with Extensions-Particulate Matter Source Apportionment Technology (CAMx/PSAT) was used to assess the seasonal variations and source apportionment of PM2.5 in the highly polluted BSFP region, with a specific focus on the sectoral and sub-regional contributions to PM2.5 in Beijing during winter and summer. Results showed that the PM2.5 concentrations of BSFP region was higher in winter than that in summer. And the heavily polluted area in BSFP region shrinked noticeably in summer, compared with winter. As for source apportionment of PM2.5, residential and remaining industrial sectors constituted the top two sources of PM2.5 mass concentrations in Beijing. In addition, agricultural source represented a major contributor to ammonium, whereas transportation and power sectors constituted major sources to nitrates. In terms of contributions from sub-regions, the local sources ranked as the dominant contributors to PM2.5 in Beijing, while the main external contributions originated from the surrounding areas, such as Hebei and Shandong. Results of daily source apportionment to PM2.5 in Beijing showed that sub-regional long-distance transport became stronger when haze pollution was severe, in which contribution from remaining industrial sector would be higher than that of other periods. The results will allow for an improved understanding of the causes and origins of heavy regional PM2.5 pollution, and thus will benefit the development of effective joint control policies and identification of key polluting emission categories in North China and ultimately serve as references for other highly polluted megacities in the world.

Measure-Specific Effectiveness of Air Pollution Control on China's Atmospheric Mercury Concentration and Deposition during 2013-2017.

China took aggressive air pollution control measures from 2013 to 2017, leading to the mitigation of atmospheric mercury pollution as a cobenefit. This study is the first to systematically evaluate the effect of five major air pollution control measures in reducing mercury emissions, the total gaseous mercury (TGM) concentration and mercury deposition flux (FLX) for unit emissions reduction. From 2013 to 2017, China's mercury emissions decreased from 571 to 444 tons, resulting in a 0.29 ng m-3 decrease in the TGM concentration, on average, and in a 17 µg m-2 yr-1 decrease in FLX. Ultralow emission renovations of coal-fired power plants are identified as the most effective emission abatement measure. As a result of this successful measure, coal-fired power plants are no longer the main mercury emitters. In 2017, the cement clinker sector became the largest emitter due to the use of less effective mercury removal measures. However, in terms of the mitigated TGM concentration and FLX levels per unit emission abatement, newly built wet flue gas desulfurization (WFGD) systems in coal-fired industrial boilers have become particularly effective in decreasing FLX levels. Therefore, to effectively reduce atmospheric mercury pollution in China, prioritizing mercury emissions control of cement clinkers and coal-fired industrial boilers is recommended.

A Highly Resolved Mercury Emission Inventory of Chinese Coal-Fired Power Plants.

As the largest coal consumer in China, the coal-fired power plants have come under increasing public concern in regard to atmospheric mercury pollution. This study developed an up-to-date and high-resolution mercury emission inventory of Chinese coal-fired power plants using a unit-based method that combined data from individual power plants, provincial coal characteristics, and industry removal efficiencies. National mercury emissions in 2015 were estimated at 73 tons, including 54 tons of elemental mercury, 18 tons of gaseous oxidized mercury and 1 ton of particle-bound mercury. Pulverized coal boilers emitted 65 tons, mainly in the coastal provinces and coal-electricity bases. Circulating fluidized bed boilers emitted 8 tons, mainly in Inner Mongolia and Shanxi Province. The average mercury emission intensity over the Chinese mainland was 18.3 g/GWh, which was similar to the limit for low-rank coal-fired units in the United States. The overall uncertainty of national mercury emission was estimated to be -19% to 20%, with the mercury content in coal being the major contributor. In most provinces, monthly mercury emissions generally peaked in December and August. However, monthly partition coefficients of southwest China were obviously lower than other regions from June to October due to the high proportion of hydropower generation.

Effects of Wet Flue Gas Desulfurization and Wet Electrostatic Precipitators on Emission Characteristics of Particulate Matter and Its Ionic Compositions from Four 300 MW Level Ultralow Coal-Fired Power Plants.

To achieve ultralow-emission (ULE) standards, wet electrostatic precipitators (WESP) installed downstream from wet flue gas desulfurization (WFGD) have been widely used in Chinese coal-fired power plants (CFPPs). We conducted a comprehensive field test study at four 300 MW level ULE CFPPs, to explore the impact of wet clean processing (WFGD and WESP) on emission characteristics of three size fractions of particulate matter (PM: PM2.5, PM10-2.5, and PM>10) and their ionic compositions. All these CFPPs are installed with limestone-based/magnesium-based WFGD and followed by WESP as the end control device. Our results indicate that particle size distribution, mass concentration of PM, and ionic compositions in flue gas change significantly after passing WFGD and WESP. PM mass concentrations through WFGD are significantly affected by the relative strength between desulfur slurry scouring and flue gas carrying effects. Concentrations of ions in PM increase greatly after passing WFGD; especially, SO42- in PM2.5, PM10-2.5, and PM>10 increase on average by about 1.4, 3.9, and 8.3 times, respectively. However, WESP before the stack can effectively reduce final PM emissions and their major ionic compositions. Furthermore, emission factors (kg/(t of coal)) of PM for different combinations of air pollution control devices are presented and discussed.

Multi-dimension apportionment of clean air "parade blue" phenomenon in Beijing.

The mass concentration and major chemical components of fine particulate matter were measured before, during and after Beijing's massive parade commemorating 70th anniversary of the Chinese Victory in World War II on September 3, 2015. Regional emission inventory, positive matrix factorization (PMF), observations from space and backward air mass trajectories were jointly applied to identify the major pollution sources and their temporal and spatial variations. The contributions of emissions variations and the meteorological conditions related to the "parade blue" phenomenon in Beijing and its surrounding areas were investigated in detail. The main cause of the decreased PM2.5 mass concentration was attributed to the absolute reduction in emissions of primary air pollutants. The chemical composition of PM2.5 varied significantly before, during and after the parade. Fugitive dust particles were well controlled, the secondary formation of PM2.5 was reduced along with the controlled gaseous precursors' emissions from vehicles and industrial sources during the temporary intensified control period. During the parade period, the SO2 and NO2 column concentrations in Beijing and the surrounding areas decreased sharply, indicating that the coordinated reduction in primary emissions from the surrounding areas of Beijing played an important role in lowering the ambient concentration of SO2 and NO2 and accordingly lowered PM2.5 and improved the regional air quality. A comparison of the temperature, humidity, and wind speed and direction during the same periods in 2014 and 2015 showed that the meteorological conditions positively influenced the achievement of "parade blue".

Atmospheric emission characteristics and control policies of five precedent-controlled toxic heavy metals from anthropogenic sources in China.

A bottom-up inventory of atmospheric emissions of five precedent-controlled toxic heavy metals (HMs), including mercury (Hg), arsenic (As), lead (Pb), cadmium (Cd), and chromium (Cr), from primary anthropogenic sources in China is established for the period 2000­2010. Total emissions of HMs demonstrate a gradually ascending trend along with the increase of coal consumption and industrial production, which are estimated at approximately 842.22 t for Hg, 4196.31 t for As, 29272.14 t for Pb, 795.29 t for Cd, and 13715.33 t for Cr for 2010. Coal combustion is found to be the primary source of HMs emissions. Owing to the dramatic differences of coal use by industrial and power sectors among provinces, spatial allocation performs remarkably uneven characteristics, and spatial distribution features are demonstrated by allocating the emissions into 0.5° × 0.5° grid cells with GDP and population as surrogate indexes. Further, HMs emissions from specified anthropogenic sources under three different control scenarios for the target year 2015 are projected, and collaborative and specialized control strategies are proposed to meet the demand of emission reduction goals of different regions. In the future, a whole processes control management system will be the most effective way for control of HMs.

Atmospheric emission inventory of hazardous trace elements from China's coal-fired power plants--temporal trends and spatial variation characteristics.

Coal-fired power plants are the important sources of anthropogenic atmospheric releases of various hazardous trace elements (HTE) because a large quantity of emissions can cause wide dispersion and possible long-distance transportation. To obtain the temporal trends and spatial variation characteristics of various HTE discharged from coal-fired power plants of China, a multiple-year comprehensive emission inventory of HTE including Hg, As, Se, Pb, Cd, Cr, Ni, and Sb has been established for the period 2000-2010. Thanks to the cobenefit removal effects of conventional particulate matter/sulfur dioxide/nitrogen oxides (PM/SO2/NOx) control devices, emissions of these 8 toxic elements have shown a gradual decline since the peak in 2006. The total emissions of Hg, As, Se, Pb, Cd, Cr, Ni, and Sb are substantial and are estimated at about 118.54, 335.45, 459.4, 705.45, 13.34, 505.03, 446.42, and 82.33 tons (t), respectively, in 2010. Shandong, Jiangsu, Shanxi, and Hebei always rank among the top ten provinces with the highest emissions. Further, future emissions for 2015 and 2020 are projected with scenario analysis. Advanced technologies and integrated management strategies to control HTE are in great need.

A comprehensive global inventory of atmospheric Antimony emissions from anthropogenic activities, 1995-2010.

Antimony (Sb) and its compounds are considered as global pollutants due to their health risks and long-range transport characteristics. A comprehensive global inventory of atmospheric antimony emissions from anthropogenic activities during the period of 1995-2010 has been developed with specific estimation methods based on the relevant data available for different continents and countries. Our results indicate that the global antimony emissions have increased to a peak at about 2232 t (t) in 2005 and then declined gradually. Global antimony emissions in 2010 are estimated at about 1904 t (uncertainty of a 95% confidence interval (CI): -30% ∼ 67%), with fuel combustion as the major source category. Asia and Europe account for about 57% and 24%, respectively, of the global total emissions, and China, the United States, and Japan rank as the top three emitting countries. Furthermore, global antimony emissions are distributed into gridded cells with a resolution of 1° × 1°. Regions with high Sb emissions are generally concentrated in the Southeastern Asia and Western Europe, while South Africa, economically developed regions in the eastern U.S., and Mexico are also responsible for the high antimony emission intensity.

Emissions of volatile organic compounds from Chinese coal-fired power plants: Characteristics, source profile, inventories, and impacts.

Volatile organic compounds (VOCs) are key precursors for secondary organic aerosols (SOA) and ozone, imposing severe impacts on human health and environment. Considering the massive coal consumption, coal fired power plants (CFPPs) in China are non-negligible VOCs contributors, whose emission characteristics remain inadequately understood. Here, we investigated emission characteristics of 117 VOCs by field tests in four typical CFPPs, and a latest localized CFPPs source profile was compiled by integrating literature reviews. Then speciated-VOCs emission inventories for 2018-2022 were established based on dynamic emission factors and unit-level activity data. The results suggested that oxygenated VOCs (OVOCs) constituted the dominant group (76.5 %), with propionaldehyde (32.0 %) and formaldehyde (24.5 %) being the predominant species. OVOCs (93.2 %) and aromatics (77.4 %) were identified as the primary contributors to ozone and SOA, respectively. Driven by both the rise in coal consumption and technological advancements, nationwide VOCs emissions decreased from 83,393 t in 2018 to 53,251 t in 2022. Regional disparities and varying rates of decline in provincial emissions were evident, with VOCs emissions predominantly concentrated in northern and eastern provinces. Neimenggu, Shandong, Shanxi, Jiangsu, and Guangdong were identified as the top five provinces with the highest emissions. We believe this study would be conducive to a more comprehensive understanding and effective control of VOCs emissions from CFPPs in China.