Organic aerosols (OA) are a significant component of fine particulate matter in the ambient air and are formed through primary and secondary processes. Primary organic aerosols (POA) are directly ...released from sources, while secondary organic aerosols (SOA) are formed through the oligomerization and/or oxidation of volatile organic compounds (VOCs) in the atmosphere. Recently, there has an increasing attention on the SOA budgets, their formation pathways, and photochemical evolution due to their impacts on climate and human health. Biomass burning (BB) is a significant source of OA, contributing around 5-30 % to the SOA burden globally. Agricultural residue burning (ARB) is a type of BB that contributes ~10 % of total atmospheric OA mass worldwide, whereas it contributes higher in Asian regions like China and India. ARB emits a significant amount of air pollutants, including VOCs, into the atmosphere. However, there is inadequate information on the transformation of ARB emissions to SOA due to limited laboratory studies. The present review focuses on the formation mechanism of SOA from ARB emissions, summarizing the current state of the art about ARB precursors and their oxidation products from chamber-based studies, including measurement methods and analytical instrumentation. The review also discusses the role of different types of oxidants in OA mass enhancement, factors affecting the overall SOA yield, and the uncertainties involved in the process.
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•Chamber-based studies on SOA formation from ARB are summarized.•The role of different types of oxidants in OA mass enhancement is discussed.•Factors affecting the overall SOA yield are deliberated.•It is suggested to integrate efforts combining laboratory and field studies.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Smoke emissions from biomass burning considerably influence regional and local air quality. Many natural wildfires and agricultural burns occur annually in Central Mexico during the hot, dry season ...(March to May), potentially leading to air quality problems. Nevertheless, the impact of these biomass burning emissions on Mexico City's air quality has not been investigated in depth. This study examines a severely deteriorated air quality case from 11 to 16 May 2019, during which fine particle concentrations (PM2.5) exceeded the 99th percentile of the available official dataset (2005–2019). Specifically, this work aims to highlight the role of fires and regional pollution in the severe episode observed in Mexico City, identifying the fires that were the sources of regional pollution, the type of fuel burned in those fires, and the dominant atmospheric transport pattern. Biomass burning emissions were calculated for different land cover types using satellite data from the Visible Infrared Imaging Radiometer Suite (VIIRS) and the Moderate-Resolution Imaging Spectroradiometer (MODIS). PM2.5 increased by a factor of 2 at some monitoring sites, and ozone concentration increased to 40 % in Mexico City during the poor air quality episode. Our results indicate that over 50 % of the fire activity observed during the 2019 fire season was concentrated in May in Central Mexico. The burning activity was mainly seen over shrubland and forest between 10 and 15 May. Moreover, the fire radiative power analysis indicates that most energy was associated with burning shrubland and forests. Organic carbon emissions were estimated highest on 14 and 15 May, coinciding with the largest number of fires. Back trajectory analysis indicates that enhanced concentration of air pollutants in Mexico City originated from biomass burning detected in neighboring states: Guerrero, Michoacán, and the State of Mexico. Smoke from fires on the specific vegetation cover was advected into Mexico City and contributed to the bad air quality episode. Further meteorological analysis evidenced that the fire intensity and emissions were worsened by low humidity and the late onset of the rainy season in Central Mexico.
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•An increase in the burned area and their intensity was observed during May 2019.•Backtrajectory showed that air pollutants were created from fires in nearby states.•Low humidity and the late onset of the rainy season led to more intense fires.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Every year in the post-monsoon season, ~1.7 billion tons of paddy stubble is burnt openly in the Indo-Gangetic Plain (IGP) producing persistent smog and air quality deterioration that affects the ...entire IGP. Information concerning the identity, amounts and spatial distribution of volatile organic compounds (VOCs) which drive ozone and aerosol formation is still largely unknown as existing global emission inventories have poor VOC speciation and rely on limited satellite overpasses for mapping burnt areas. Here, emission factors (EFs) of 77 VOCs were measured from paddy fire smoke and combined with 1 km × 1 km stubble burning activity constrained by annual crop production yields and detected fires to compile a new gridded emission inventory for 2017. Our results reveal a large source of acetaldehyde (37.5 ± 9.6 Ggy−1), 2-furaldehyde (37.1 ± 12.5 Ggy−1), acetone (34.7 ± 13.6 Ggy−1), benzene (9.9 ± 2.8 Ggy−1) and isocyanic acid (0.4 ± 0.2 Ggy−1) that are not accounted for by existing emission inventories (GFED, GFAS, FINv2.1). During October–November, these emissions (346 ± 65 Ggy−1 NMVOC; 38 ± 8 Ggy−1 NOx; 16 ± 4 Ggy−1 NH3; 129 ± 9 Ggy−1 PM2.5; 22,125 ± 3674 Ggy−1 GHG CO2 equivalents) are more than 20 times larger than corresponding emissions from traffic and municipal waste burning over north-west India. Mitigation of this source alone can therefore yield massive air-quality climate co-benefits for more than 500 million people.
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•Emission factors (EFs) of 77 VOCs were measured from paddy fire smoke over NW India.•First 1 km × 1 km gridded emission CRB inventory of speciated VOCs and air pollutants•Emissions of paddy stubble burning source were 20 times greater than other sources.•Furaldehyde was major emission that was completely missing from existing inventories.•New more accurate emission inventory will improve air quality modelling efforts.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Biomass burning (BB) emissions significantly deteriorate air quality in many regions worldwide, impact human health and perturbing Earth's radiation budget and climate. South America is one of ...largest contributors to BB emissions globally. After Amazonia, BB emissions from open and agricultural fires of Northern South America (NSA) are the most significant. Recent evidence shows a strong correlation between fire counts in NSA and Brown Carbon in some Colombian cities, suggesting a substantial seasonal contribution of regional BB sources to air pollution levels in the densely populated areas of NSA. In this work we use the atmospheric regional chemical transport model WRF-Chem to assess the contribution of open BB events to pollutant concentration and to estimate potential health impacts associated with wildfire events in NSA. Three nested domains are used to simulate atmospheric composition in the Northern part of South America and the Caribbean. Simulations included biogenic and anthropogenic emissions from a global emission inventory merged with local emissions for the city of Bogotá. Two modelling scenarios were considered, a base case without BB emissions (NO_FIRE) and a sensitivity scenario with BB emissions. Simulations were carried out for periods of strong BB activity in NSA. In the NO_FIRE scenario, aerosol concentrations are unrealistically low. When BB emissions are is included background PM2.5 concentrations increase 80%. The increment in aerosol concentrations is mainly driven by Secondary Organic Aerosols. In the case of Bogotá, the most densely populated city in the domain, monthly mean increase in PM2.5 is 3.3 μg m−3 and 4.3 ppb for O3. Modeled meteorological and air pollution fields are in better agreement with observations when high spatial resolution (3 × 3 km) is used in the simulations. The total estimated short-term all-cause mortality associated to BB during February in the region is 171 cases, 88 PM2.5-related and 83 O3-related mortality.
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•We used WRF-Chem to model the transport of Biomass Burning plumes in Northern South America.•Regional aerosol background concentrations are dominated by biomass burning during the dry season.•SOA contributes a substantial fraction of biomass burning smoke in the region.•Regional Ozone background levels are strongly impacted during the Biomass burning season.•Nearly 170 excess deaths can be associated with biomass burning PM2.5 and O3 increases during February, often the most affected by fires.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Chamber oxidation experiments conducted at the Fire Sciences Laboratory in 2016 are evaluated to identify important chemical processes contributing to the hydroxy radical (OH) chemistry of biomass ...burning non-methane organic gases (NMOGs). Based on the decay of primary carbon measured by proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS), it is confirmed that furans and oxygenated aromatics are among the NMOGs emitted from western United States fuel types with the highest reactivities towards OH. The oxidation processes and formation of secondary NMOG masses measured by PTR-ToF-MS and iodide-clustering time-of-flight chemical ionization mass spectrometry (I-CIMS) is interpreted using a box model employing a modified version of the Master Chemical Mechanism (v. 3.3.1) that includes the OH oxidation of furan, 2-methylfuran, 2,5-dimethylfuran, furfural, 5-methylfurfural, and guaiacol. The model supports the assignment of major PTR-ToF-MS and I-CIMS signals to a series of anhydrides and hydroxy furanones formed primarily through furan chemistry. This mechanism is applied to a Lagrangian box model used previously to model a real biomass burning plume. The customized mechanism reproduces the decay of furans and oxygenated aromatics and the formation of secondary NMOGs, such as maleic anhydride. Based on model simulations conducted with and without furans, it is estimated that furans contributed up to 10 % of ozone and over 90 % of maleic anhydride formed within the first 4 h of oxidation. It is shown that maleic anhydride is present in a biomass burning plume transported over several days, which demonstrates the utility of anhydrides as markers for aged biomass burning plumes.
Biomass burning (BB) is a major source of air pollution from local to global scale, having variable effects on air quality, human health, and climate system. Therefore, the source identification and ...characterization of BB-derived aerosols and tracer gases in the ambient environment is crucial. This review provides recent updates on the applicability of levoglucosan as a BB tracer in different environmental matrices such as aerosols, marine, snow and ice-cores etc. Among several tracer of BB emissions, levoglucosan has recently received widespread attention due to its unique origin solely from the pyrolysis of cellulose and hemicellulose, making it as a robust marker for characterization and quantification of BB throughout the world. This review first summarizes the established and emerging analytical methods, and their advantages and disadvantages for measurement of levoglucosan. Second, we discuss the formation mechanism, lifetime and its stability in different environmental conditions. In addition, we also try to deliberate on the application of ratios of levoglucosan with different organic components such as mannosan (M) and organic carbon (OC) for better identification of emission sources. Spatial distributions of levoglucosan in different locations (e.g., urban, rural, forest, marine, poles and higher altitude) are discussed scrupulously and meticulously on a global scale. We also reviewed the distributions of levoglucosan in snow, ice core and sediments to understand its applicability to construct paleofire records. Finally, we propose some key recommendations for future work in different ambient environmental conditions by utilizing the ratios of levoglucosan with other compounds (not limited only to M and OC) and the use of levoglucosan to reconstruct the paleo-historical records of fire-activity.
•Analytical methods for levoglucosan and its applicability as a BB tracer in different environments are summarized.•The formation mechanism, lifetime and stability determine levoglucosan’s behaviour.•Spatial distributions of levoglucosan in worldwide locations are discussed.•Levoglucosan in ice core and sediments could be used to reconstruct the paleofire history.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Many studies have drawn attention to the associations of oxygenated polycyclic aromatic hydrocarbons (OPAHs) with harmful health effects, advocating for their systematic monitoring alongside simple ...PAHs to better understand the aerosol carcinogenic potential in urban areas. To address this need, this study conducted an extensive PM2.5 sampling campaign in Athens, Greece, at the Thissio Supersite of the National Observatory of Athens, from December 2018 to July 2021, aiming to characterize the levels and variability of polycyclic aromatic compounds (PACs), perform source apportionment, and assess health risk. Cumulative OPAH concentrations (Σ-OPAHs) were in the same range as Σ-PAHs (annual average 4.2 and 5.6 ng m−3, respectively). They exhibited a common seasonal profile with enhanced levels during the heating seasons, primarily attributed to residential wood burning (RWB). The episodic impact of biomass burning was also observed during a peri-urban wildfire event in May 2021, when PAH and OPAH concentrations increased by a factor of three compared to the monthly average. The study period also included the winter 2020–2021 COVID-19 lockdown, during which PAH and OPAH levels decreased by >50 % compared to past winters. Positive matrix factorization (PMF) source apportionment, based on a carbonaceous aerosol speciation dataset, identified PAC sources related to RWB, local traffic (gasoline vehicles) and urban traffic (including diesel emissions), as well as an impact of regional organic aerosol. Despite its seasonal character, RWB accounted for nearly half of Σ-PAH and over two-thirds of Σ-OPAH concentrations. Using the estimated source profiles and contributions, the source-specific carcinogenic potency of the studied PACs was calculated, revealing that almost 50 % was related to RWB. These findings underscore the urgent need to regulate domestic biomass burning at a European level, which can provide concrete benefits for improving urban air quality, towards the new stricter EU standards, and reducing long-term health effects.
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•OPAH levels were in the same order of magnitude as PAHs in urban background PM2.5.•The COVID-19 lockdown led to a reduction of Σ-PAH (54 %) and Σ-OPAH (52 %) concentrations.•PAC levels during a peri-urban wildfire were 3 times higher than the monthly average.•Residential biomass burning was the principal source of PAHs (44 %) and OPAHs (69 %).•The 2019 annual BaPeq of Σ53-PAC species was 2 times higher compared to Σ16-EPA PAHs.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Biomass burning in Peninsular Southeast Asia (BB–PSEA) affects the climate in downwind regions, especially precipitation (PRE) in southern China. However, the impact of BB–PSEA on the meteorological ...drought in Southwest China (SWC), where closes to PSEA and often occurs seasonal drought, have not been clear yet. We selected a severe drought event in SWC from January to April 2010 and conducted sensitivity simulations using WRF–Chem (Weather Research and Forecasting model coupled with Chemistry) to evaluate the impact of BB–PSEA on the meteorological drought in SWC. Comparisons with observations revealed that the model performed well in simulating the spatiotemporal evolution of the drought in SWC. BB–PSEA increased the drought severity by 0.01–0.75 levels, enlarged drought areas by about 10%, and prolonged the drought duration mainly by one month in SWC. The impact of BB–PSEA on the drought in SWC in March/April was almost tenfold that in January/February, due to the higher emissions of BB–PSEA in March/April. The mechanism that BB–PSEA influenced drought predominantly involved the reduction of PRE, potential evapotranspiration (PET), and moisture fluxes in SWC. BB–PSEA aerosols warmed the air at 600–800 hPa and cooled the air near the surface in SWC, which stabilized the atmosphere and suppressed PRE and reduced PET in SWC. BB–PSEA aerosols also increased the sea surface temperature in South China Sea and the geopotential heights in the north of the Bay of Bengal, where the moisture sources of SWC originated from. This perturbation reduced the moisture fluxes across the west and south boundaries of SWC, resulting in the reduction of the water vapor content and PRE in SWC. Through elucidating the impact of BB–PSEA on the drought in SWC, this study clarified how BB–PSEA affected the climate in the downwind region and provided new understanding for drought prediction in SWC.
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•Strong BB in PSEA coincided with severe drought in SWC in spring 2010.•BB–PSEA increased the severity, areas, and duration of drought in SWC.•BB–PSEA reduced rainfall, PET, and moisture fluxes in SWC.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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