Global Gridded Emission Inventory of Organophosphate Flame Retardants from 2010 to 2020.

As a substitute for brominated flame retardants, organophosphate flame retardants (OPFRs) have become a global concern due to their high toxicity and bioaccumulation. To paint an overall picture of OPFRs in the global environment, the present study develops a gridded global emission inventory of OPFRs on a spatial resolution of 1 × 1° from 2010 to 2020. Revealing a 3.31% average annual increase in emissions, totaling 21,324.42 tons. The production process is the primary source, accounting for 55.43% of emissions, with consumption processes making up the rest. Major sources are in Asia, North America, and Europe. The inventory is verified by implementing emission data into a global atmospheric transport model to predict OPFR concentrations in the global environment and comparing modeled concentrations with field sampled data. The results indicate that the inventory is reliable except for the pristine polar region, where the emission inventory and modeled concentrations underestimate OPFR levels in the atmosphere, likely resulting from ignorance of chemical reactions and the secondary derivative of parent OPFRs during their global long-distance atmospheric transport in the model. This comprehensive data set aids in formulating OPFR emission control policies and assessing health risks.

Province-Level Decarbonization Potentials for China's Road Transportation Sector.

Decarbonizing road transportation is an important task in achieving China's climate goals. Illustrating the mitigation potentials of announced policies and identifying additional strategies for various vehicle fleets are fundamental in optimizing future control pathways. Herein, we developed a comprehensive analysis of carbon dioxide (CO2) emissions from on-road vehicles as well as their mitigation potentials based on real-world databases and up-to-date policy scenarios. Total CO2 emissions of China's road transportation are estimated to be 1102 million tons (Mt) in 2022 and will continue to increase if future strategies are implemented as usual. Under current development trend and announced policy controls (i.e., integrated scenario), annual CO2 emissions are estimated to peak at 1235 Mt in 2025 and then decline to approximately 200 Mt around 2050. The scenario analysis indicates that electrification of passenger vehicles emerges as the most imperative decarbonization strategy for achieving carbon peak before 2030. Additionally, fuel economy improvement of conventional vehicles is identified to be effective for CO2 emission reduction for trucks until 2035 while new energy vehicle promotion shows great mitigation potentials in the long term. This study provides insight into heterogeneous low-carbon transportation transition strategies and valuable support for achieving China's dual-carbon goals.

Multidirectional Fate Path Model to Connect Phosphorus Emissions with Freshwater Eutrophication Potential.

Excessive anthropogenic phosphorus (P) emissions put constant pressure on aquatic ecosystems. This pressure can be quantified as the freshwater eutrophication potential (FEP) by linking P emissions, P fate in environmental compartments, and the potentially disappeared fraction of species due to increase of P concentrations in freshwater. However, previous fate modeling on global and regional scales is mainly based on the eight-direction algorithm without distinguishing pollution sources. The algorithm fails to characterize the fate paths of point-source emissions via subsurface pipelines and wastewater treatment infrastructure, and exhibits suboptimal performance in accounting for multidirectional paths caused by river bifurcations, especially in flat terrains. Here we aim to improve the fate modeling by incorporating various fate paths and addressing multidirectional scenarios. We also update the P estimates by complementing potential untreated point-source emissions (PSu). The improved method is examined in a rapidly urbanizing area in Taihu Lake Basin, China in 2017 at a spatial resolution of 100 m × 100 m. Results show that the contribution of PSu on FEP (62.6%) is greater than that on P emissions (58.5%). The FEP is more spatially widely distributed with the improved fate modeling, facilitating targeted regulatory strategies tailored to local conditions.

Emission of Intermediate Volatile Organic Compounds from Animal Dung and Coal Combustion and Its Contribution to Secondary Organic Aerosol Formation in Qinghai-Tibet Plateau, China.

Intermediate volatility organic compounds (IVOCs) are important precursors to secondary organic aerosols (SOAs), but they are often neglected in studies concerning SOA formation. This study addresses the significant issue of IVOCs emissions in the Qinghai-Tibetan plateau (QTP), where solid fuels are extensively used under incomplete combustion conditions for residential heating and cooking. Our field measurement data revealed an emission factor of the total IVOCs (EFIVOCs) ranging from 1.56 ± 0.03 to 9.97 ± 3.22 g/kg from various combustion scenarios in QTP. The markedly higher EFIVOCs in QTP than in plain regions can be attributed to oxygen-deficient conditions. IVOCs were dominated by gaseous phase emissions, and the primary contributors of gaseous and particulate phase IVOCs are the unresolved complex mixture and alkanes, respectively. Total IVOCs emissions during the heating and nonheating seasons in QTP were estimated to be 31.7 ± 13.8 and 6.87 ± 0.45 Gg, respectively. The estimated SOA production resulting from combined emissions of IVOCs and VOCs is nearly five times higher than that derived from VOCs alone. Results from this study emphasized the pivotal role of IVOCs emissions in air pollution and provided a foundation for compiling emission inventories related to solid fuel combustion and developing pollution prevention strategies.

Significant Increase in Ammonia Emissions in China: Considering Nonagricultural Sectors Based on Isotopic Source Apportionment.

Isotopic source apportionment results revealed that nonagricultural sectors are significant sources of ammonia (NH3) emissions, particularly in urban areas. Unfortunately, nonagricultural sources have been substantially underrepresented in the current anthropogenic NH3 emission inventories (EIs). Here, we propose a novel approach to develop a gridded EI of nonagricultural NH3 in China for 2016 using a combination of isotopic source apportionment results and the emission ratios of carbon monoxide (CO) and NH3. We estimated that isotope-corrected nonagricultural NH3 emissions were 4370 Gg in China in 2016, accounting for an increase in the total NH3 emissions from 7 to 31%. As a result, compared to the original NH3 EI, the annual emissions of total NH3 increased by 35%. Thus, in comparison to the simulation driven by the original NH3 EI, the WRF-Chem model driven by the isotope-corrected NH3 EI has reduced the model biases in the surface concentrations and dry deposition flux of reduced nitrogen (NHx = gaseous NH3 + particulate NH4+) by 23 and 31%, respectively. This study may have wide-ranging implications for formulating targeted strategies for nonagricultural NH3 emissions controls, making it facilitate the achievement of simultaneously alleviating nitrogen deposition and atmospheric pollution in the future.

Regional sources of NH3, SO2 and CO in the Third Pole.

The Third Pole (TP) is a high mountain region in the world, and is well-known for its pristine environment, but recent development activities in the region have degraded its air quality. Here, we investigate the spatial and temporal changes of the air pollutants ammonia (NH3), sulphur dioxide (SO2) and carbon monoxide (CO) in TP, and reveal their sources using satellite measurements and emission inventory. We observe a clear seasonal cycle of NH3 in TP, with high values in summer and low values in winter. The intense agriculture activities in the southern TP are the cause of high NH3 (6-8 × 1016 molec./cm2) there. Similarly, CO shows a distinct seasonal cycle with high values in spring in the southeast TP due to biomass burning. In addition, the eastern boundary of TP in the Sichuan and Qinghai provinces also show high values of CO (about 1.5 × 1018 mol/cm2), primarily owing to the industrial activities. There is no seasonal cycle found for SO2 distribution in TP, but relatively high values (8-10 mg/m2) are observed in its eastern boundary. The high-altitude pristine regions of inner TP are also getting polluted because of increased human activities in and around TP, as we estimate positive trends in CO (0.5-1.5 × 1016 mol/cm2/yr) there. In addition, positive trends are also found in NH3 (0.025 × 1016 molec./cm2/yr) during 2008-2020 in most regions of TP and SO2 (about 0.25-0.75 mg/m2/yr) in the Sichuan and Qinghai region during 2000-2020. As revealed by the emission inventory, there are high anthropogenic emissions of NH3, SO2 and CO within TP. There are emissions of pollutants from energy sectors, oil and refinery, agriculture waste burning and manure management within TP. These anthropogenic activities accelerate the ongoing development in TP, but severely erode its environment.

High-resolution emission inventory of biogenic volatile organic compounds for rapidly urbanizing areas: A case of Shenzhen megacity, China.

The effects of volatile organic compounds on urban air quality and the ozone have been widely acknowledged, and the contributions of relevant biogenic sources are currently receiving rising attentions. However, inventories of biogenic volatile organic compounds (BVOCs) are in fact limited for the environmental management of megacities. In this study, we provided an estimation of BVOC emissions and their spatial characteristics in a typical urbanized area, Shenzhen megacity, China, based on an in-depth vegetation investigation and using remote sensing data. The total BVOC emission in Shenzhen in 2019 was estimated to be 3.84 × 109 g C, of which isoprene contributed to about 24.4%, monoterpenes about 44.4%, sesquiterpenes about 1.9%, and other VOCs (OVOCs) about 29.3%. Metropolitan BVOC emissions exhibited a seasonal pattern with a peak in July and a decline in January. They were mainly derived from the less built-up areas (88.9% of BVOC emissions). Estimated BVOCs comprised around 5.2% of the total municipal VOC emissions in 2019. This percentage may increase as more green spaces emerge and anthropogenic emissions decrease in built-up areas. Furthermore, synergistic effects existed between BVOC emissions and relevant vegetation-based ecosystem services (e.g., air purification, carbon fixation). Greening during urban sprawl should be based on a trade-off between BVOC emissions and ecosystem benefits of urban green spaces. The results suggested that urban greening in Shenzhen, and like other cities as well, need to account for BVOC contributions to ozone. Meanwhile, greening cites should adopt proactive environmental management by using plant species with low BVOC emissions to maintain urban ecosystem services while avoid further degradation to ozone pollution.

Managing synthetic N-fertilizer emissions in India: Insights from field surveys across 102 districts.

The use of fixed emission factors (EFs), combined with insufficient temporal distribution, leads to substantial uncertainties in current emission inventories for India, the world's second-largest producer and consumer of synthetic N-fertilizers. Our study aimed to improve the NH3 and N2O emission estimates by utilizing crop-specific district-level activity data and refined EFs tailored to Indian conditions. In this study, a comprehensive NH3 and N2O emission inventory (EI) is methodically developed at 0.1° * 0.1° spatial and monthly temporal resolution for the year 2018-19 considering 52 crops. The data for developing this inventory is aggregated through detailed field surveys, conducted across 102 districts of 14 states, and relevant government databases. EFs have been adjusted for the Indian context by refining them to reflect local conditions through consideration of ambient temperature, application rate, and other factors. Further, upon preparing an EI for FA, a spectrum of mitigation strategies are evaluated to assess their effectiveness in reducing emissions. Yearly total NH3 and N2O emissions amount to 3.15 Tg and 138.53 Gg, with urea fertilizer as the dominant contributor accounting for 93.85% and 96.44% of emissions, respectively. Key crops such as rice, wheat, maize, sugarcane, and cotton collectively represent approximately 82% of the total N consumption. The state of Uttar Pradesh emerges as the largest emitter, contributing 706.5 Gg and 25.31 Gg of NH3 and N2O emissions, respectively. Conversely, PB and HR exhibit the highest NH3 emissions per capita. Temporally, NH3 emissions peak in August, while N2O emissions peak in July, with both pollutants reaching their nadir in February. Among the array of mitigation strategies assessed in this study, 'adhering to recommended fertilizer doses' and 'incorporating urease inhibitors' demonstrated substantial potential for reducing emissions. The current study aids policymaking to mitigate the environmental and health impacts of atmospheric emissions from synthetic N-fertilizers. Future researchers can adopt this study as a benchmark to improve Indian FA emission estimates, which helps in promoting sustainable agricultural practices and contributes to climate change mitigation efforts.

Atmospheric VOCs in an industrial coking facility and the surrounding area: Characteristics, spatial distribution and source apportionment.

Industrial coking facilities are an important emission source for volatile organic compounds (VOCs). This study analyzed the atmospheric VOC characteristics within an industrial coking facility and its surrounding environment. Average concentrations of total VOCs (TVOCs) in the surrounding residential activity areas (R1 and R2), the coking facility (CF) and the control area (CA) were determined to be 138.5, 47.8, 550.0, and 15.0 µg/m3, respectively. The cold drum process and coking and quenching areas within the coking facility were identified as the main polluting processes. The spatial variation in VOCs composition was analyzed, showing that VOCs in the coking facility and surrounding areas were mainly dominated by aromatic compounds such as BTX (benzene, toluene, and xylenes) and naphthalene, with concentrations being negatively correlated with the distance from the coking facility (p < 0.01). The sources of VOCs in different functional areas across the monitoring area were analyzed, finding that coking emissions accounted for 73.5%, 33.3% and 27.7% of TVOCs in CF, R1 and R2, respectively. These results demonstrated that coking emissions had a significant impact on VOC concentrations in the areas surrounding coking facility. This study evaluates the spatial variation in exposure to VOCs, providing important information for the influence of VOCs concentration posed by coking facility to surrounding residents and the development of strategies for VOC abatement.

Improved Spatial Resolution in Modeling of Nitrogen Oxide Concentrations in the Los Angeles Basin.

The extent to which emission control technologies and policies have reduced anthropogenic NOx emissions from motor vehicles is large but uncertain. We evaluate a fuel-based emission inventory for southern California during the June 2021 period, coinciding with the Re-Evaluating the Chemistry of Air Pollutants in CAlifornia (RECAP-CA) field campaign. A modified version of the Fuel-based Inventory of Vehicle Emissions (FIVE) is presented, incorporating 1.3 km resolution gridding and a new light-/medium-duty diesel vehicle category. NOx concentrations and weekday-weekend differences were predicted using the WRF-Chem model and evaluated using satellite and aircraft observations. Model performance was similar on weekdays and weekends, indicating appropriate day-of-week scaling of NOx emissions and a reasonable distribution of emissions by sector. Large observed weekend decreases in NOx are mainly due to changes in on-road vehicle emissions. The inventory presented in this study suggests that on-road vehicles were responsible for 55-72% of the NOx emissions in the South Coast Air Basin, compared to the corresponding fraction (43%) in the planning inventory from the South Coast Air Quality Management District. This fuel-based inventory suggests on-road NOx emissions that are 1.5 ± 0.4, 2.8 ± 0.6, and 1.3 ± 0.7 times the reference EMFAC model estimates for on-road gasoline, light- and medium-duty diesel, and heavy-duty diesel, respectively.

Investigation of Plant-Level Volatile Organic Compound Emissions from Chemical Industry Highlights the Importance of Differentiated Control in China.

The chemical industry is a significant source of nonmethane volatile organic compounds (NMVOCs), pivotal precursors to ambient ozone (O3), and secondary organic aerosol (SOA). Despite their importance, precise estimation of these emissions remains challenging, impeding the implementation of NMVOC controls. Here, we present the first comprehensive plant-level assessment of NMVOC emissions from the chemical industry in China, encompassing 3461 plants, 127 products, and 50 NMVOC compounds from 2010 to 2019. Our findings revealed that the chemical industry in China emitted a total of 3105 (interquartile range: 1179-8113) Gg of NMVOCs in 2019, with a few specific products accounting for the majority of the emissions. Generally, plants engaged in chemical fibers production or situated in eastern China pose a greater risk to public health due to their higher formation potentials of O3 and SOA or their proximity to residential areas or both. We demonstrated that targeting these high-risk plants for emission reduction could enhance health benefits by 7-37% per unit of emission reduction on average compared to the current situation. Consequently, this study provides essential insights for developing effective plant-specific NMVOC control strategies within China's chemical industry.

Improved Anthropogenic Mercury Emission Inventories for China from 1980 to 2020: Toward More Accurate Effectiveness Evaluation for the Minamata Convention.

Anthropogenic mercury (Hg) emission inventories are crucial for the effectiveness evaluation of the Minamata Convention on Mercury. In this study, we developed an integrated Dynamic Inventory for Mercury Emission (DIME) model and improved the accuracy of emission estimates for primary sources in China. Long-term historical speciated Hg emission inventories for China were established. The total Hg emissions increased from 217.0 t in 1980 to 357.8 t in 2020 with a peak value of 506.6 t in 2010. Three stages with distinct leading drivers were identified. At Stage 1 (1980-1997), Hg emissions doubled with the rapid growth of economy; the driver was offset by the increase of dust and SO2 control measures at Stage 2 (1997-2010) except for cement production; and co-benefits from strict control measures induced the decoupling of Hg emissions from the economy at Stage 3 (2010-2020). The ultralow emission (ULE) retrofits in key industries had pronounced Hg removal efficiencies. Large emission reduction potential still exists in the cement industry. The improved emission estimation methods for key sectors, the consistency in methodology for historical Hg emission inventories, and the more accurate spatial distribution of speciated Hg emissions in this study provide a practical toolkit for the effectiveness evaluation of the Minamata Convention.

Projections of National-Gridded Emissions of Hydrofluoroolefins (HFOs) in China.

Hydrofluoroolefins (HFOs) are being used as substitutes for potent greenhouse gas hydrofluorocarbons (HFCs). However, the use and environmental impacts of HFOs are of great concern due to the rapid degradation of HFOs to produce persistent and phytotoxic trifluoroacetic acid (TFA). Here, we provide a comprehensive projection of HFO emissions in China during 2024-2060 for the first time. Under the Kigali Amendment to the Montreal Protocol, China's HFO emissions are estimated to increase from 1.7 (1.3-2.3) to 148.8 (111.4-185.4) kt in 2024-2060 with cumulative emissions of 2.8 (2.0-3.5) Gt, and cumulative reduced HFCs emissions are evaluated to be 5.4 Gt CO2-equivalent. High HFO emissions would be distributed mainly in the North China Plain and the eastern and coastal areas. HFO-1234yf (2,3,3,3-tetrafluoropropene) contributes most of HFO emissions with a cumulative emission of 1.7 Gt in 2024-2060, while the cumulative increment of TFA deposition from HFO-1234yf emissions would reach 0.4-1.0 Gt. The long-term national-gridded HFO emission inventories can provide scientific support for evaluating the environmental risks of HFOs and developing HFC phase-out pathways for addressing climate change.

Updating On-Road Vehicle Emissions for China: Spatial Patterns, Temporal Trends, and Mitigation Drivers.

Vehicle emissions in China have been decoupled from rapid motorization owing to comprehensive control strategies. China's increasingly ambitious goals for better air quality are calling for deep emission mitigation, posing a need to develop an up-to-date emission inventory that can reflect the fast-developing policies on vehicle emission control. Herein, large-sample vehicle emission measurements were collected to update the vehicle emission inventory. For instance, ambient temperature correction modules were developed to depict the remarkable regional and seasonal emission variations, showing that the monthly emission disparities for total hydrocarbon (THC) and nitrogen oxide (NOX) in January and July could be up to 1.7 times in northern China. Thus, the emission ratios of THC and NOX can vary dramatically among various seasons and provinces, which have not been considered well by previous simulations regarding the nonlinear atmospheric chemistry of ozone (O3) and fine particulate matter (PM2.5) formation. The new emission results indicate that vehicular carbon monoxide (CO), THC, and PM2.5 emissions decreased by 69, 51, and 61%, respectively, during 2010-2019. However, the controls of NOX and ammonia (NH3) emissions were not as efficient as other pollutants. Under the most likely future scenario (PC [1]), CO, THC, NOX, PM2.5, and NH3 emissions were anticipated to reduce by 35, 36, 35, 45, and 4%, respectively, from 2019 to 2025. These reductions will be expedited with expected decreases of 56, 58, 74, 53, and 51% from 2025 to 2035, which are substantially promoted by the massive deployment of new energy vehicles and more stringent emission standards. The updated vehicle emission inventory can serve as an important tool to develop season- and location-specific mitigation strategies of vehicular emission precursors to alleviate haze and O3 problems.

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.

Atmospheric Observation and Emission of HFC-134a in China and Its Four Cities.

1,1,1,2-Tetrafluoroethane (HFC-134a) is widely used as a refrigerant to replace dichlorodifluoromethane (CFC-12), and a small amount of it is used in the foam and medical aerosol sectors, with a high global warming potential and fast-increasing atmospheric concentration. The emission of HFC-134a in China has been growing at an average annual growth rate of 14.4% since 2009, reaching 53.0 (47.5-58.7) kt yr-1 in 2020. Among the five emission sources, emissions from the mobile air conditioning (MAC) sector accounted for the highest proportion of 65% on average of the total, followed by the commercial air conditioning (CAC) sector (25%), the medical aerosols sector (8%), the foam sector (2%), and leakage emission from the production (less than 0.1%). The emissions of HFC-134a in four cities in China (Beijing, Guangzhou, Hangzhou, and Lanzhou) were also estimated and discussed. Beijing had the highest HFC-134a emission of 2.2 kt yr-1 in 2020, and Lanzhou had the lowest emission of only 0.2 kt yr-1. In Beijing and Guangzhou, emissions from the CAC sector surpassed those from the MAC sector, becoming the most important source of HFC-134a. The average annual growth rate of HFC-134a's emissions during 2009-2019 was close to its concentration enhancement growth rate of 12.7%, and the emissions also showed significant correlations with the concentration enhancements in both China and four cities. This indicates the importance of the muti-city and long-term observations for the verification of HFC-134a's emission estimates at a regional scale.

Iron and Steel Industry Emissions: A Global Analysis of Trends and Drivers.

The iron and steel industry (ISI) is important for socio-economic progress but emits greenhouse gases and air pollutants detrimental to climate and human health. Understanding its historical emission trends and drivers is crucial for future warming and pollution interventions. Here, we offer an exhaustive analysis of global ISI emissions over the past 60 years, forecasting up to 2050. We evaluate emissions of carbon dioxide and conventional and unconventional air pollutants, including heavy metals and polychlorinated dibenzodioxins and dibenzofurans. Based on this newly established inventory, we dissect the determinants of past emission trends and future trajectories. Results show varied trends for different pollutants. Specifically, PM2.5 emissions decreased consistently during the period 1970 to 2000, attributed to adoption of advanced production technologies. Conversely, NOx and SO2 began declining recently due to stringent controls in major contributors such as China, a trend expected to persist. Currently, end-of-pipe abatement technologies are key to PM2.5 reduction, whereas process modifications are central to CO2 mitigation. Projections suggest that by 2050, developing nations (excluding China) will contribute 52-54% of global ISI PM2.5 emissions, a rise from 29% in 2019. Long-term emission curtailment will necessitate the innovation and widespread adoption of new production and abatement technologies in emerging economies worldwide.

Global Anthropogenic Emissions of Full-Volatility Organic Compounds.

Traditional global emission inventories classify primary organic emissions into nonvolatile organic carbon and volatile organic compounds (VOCs), excluding intermediate-volatility and semivolatile organic compounds (IVOCs and SVOCs, respectively), which are important precursors of secondary organic aerosols. This study establishes the first global anthropogenic full-volatility organic emission inventory with chemically speciated or volatility-binned emission factors. The emissions of extremely low/low-volatility organic compounds (xLVOCs), SVOCs, IVOCs, and VOCs in 2015 were 13.2, 10.1, 23.3, and 120.5 Mt, respectively. The full-volatility framework fills a gap of 18.5 Mt I/S/xLVOCs compared with the traditional framework. Volatile chemical products (VCPs), domestic combustion, and on-road transportation sources were dominant contributors to full-volatility emissions, accounting for 30, 30, and 12%, respectively. The VCP and on-road transportation sectors were the main contributors to IVOCs and VOCs. The key emitting regions included Africa, India, Southeast Asia, China, Europe, and the United States, among which China, Europe, and the United States emitted higher proportions of IVOCs and VOCs owing to the use of cleaner fuel in domestic combustion and more intense emissions from VCPs and on-road transportation activities. The findings contribute to a better understanding of the impact of organic emissions on global air pollution and climate change.

Real-World Emission Characteristics of Full-Volatility Organics Originating from Nonroad Agricultural Machinery during Agricultural Activities.

Nonroad agricultural machinery (NRAM) emissions constitute a significant source of air pollution in China. Full-volatility organics originating from 19 machines under 6 agricultural activities were measured synchronously. The diesel-based emission factors (EFs) for full-volatility organics were 4.71 ± 2.78 g/kg fuel (average ± standard deviation), including 91.58 ± 8.42% volatile organic compounds (VOCs), 7.94 ± 8.16% intermediate-volatility organic compounds (IVOCs), 0.28 ± 0.20% semivolatile organic compounds (SVOCs), and 0.20 ± 0.16% low-volatility organic compounds (LVOCs). Full-volatility organic EFs were significantly reduced by stricter emission standards and were the highest under pesticide spraying activity. Our results also demonstrated that combustion efficiency was a potential factor influencing full-volatility organic emissions. Gas-particle partitioning in full-volatility organics could be affected by multiple factors. Furthermore, the estimated secondary organic aerosol formation potential based on measured full-volatility organics was 143.79 ± 216.80 mg/kg fuel and could be primarily attributed to higher-volatility-interval IVOCs (bin12-bin16 contributed 52.81 ± 11.58%). Finally, the estimated emissions of full-volatility organics from NRAM in China (2021) were 94.23 Gg. This study provides first-hand data on full-volatility organic EFs originating from NRAM to facilitate the improvement of emission inventories and atmospheric chemistry models.

Emissions database development and dispersion model predictions of airborne particulate elements in the Canadian Athabasca oil sands region.

This study developed an emission inventory for 29 elements in PM2.5 and PM2.5-10 covering an area of approximately 300 by 420 km2 in the Athabasca Oil Sands Region in northern Alberta, Canada. Emission sources were aggregated into nine categories, of which the Oil Sands (OS) Sources emitted the most, followed by the Non-OS Dust sources for both fine and coarse elements over the study area. The top six fine particulate elements include Si, Ca, Al, Fe, S, and K (933, 442, 323, 269, 116, and 103 tonnes/year, respectively), the sum of which accounted for 20.5% of the total PM2.5 emissions. The top five coarse elements include Si, Ca, Al, Fe, and K (3713, 1815, 1198, 1073, and 404 tonnes/year), and their sum accounted for 29% of the total PM2.5-10 emissions. Using this emission inventory as input, the CALPUFF dispersion model simulated reasonable element concentrations in both PM2.5 and PM2.5-10 when compared to measurements collected at three sites during 2016-2017. Modeled PM10 concentrations of all elements were very close to the measurements at an industrial site with the highest ambient concentration, overestimated by 65% at another industrial site with moderate ambient concentration, and underestimated by 27% at a remote site with very low ambient concentration. Model-measurement differences of annual average concentrations were within 20% for Si, Ca, Al, Fe, Ti, Mn, and Cu in PM2.5, and were 20-50% for K, S, and Zn in PM2.5 at two sites located within the OS surface mineable area. Model-measurement differences were larger, but still within a factor of two for elements in PM2.5-10 at these two sites and for elements in both PM2.5 and PM2.5-10 at a background site.