Major secondary aerosol formation in southern African open biomass burning plumes

Vakkari, Ville; Beukes, Johan P.; Maso, Miikka Dal; Aurela, Mika; Josipovic, Miroslav; Zyl, Pieter G. van

doi:10.1038/s41561-018-0170-0

Cited by 93 publications

(146 citation statements)

References 46 publications

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“…There are regions within our parameter space of our sensitivity studies in which intermediate plumes do not increase in normalized OA mass (Figures S15 and S17 in the supporting information). Further, some field experiments have seen factors of 2-3 in mass enhancements (Vakkari et al, 2014(Vakkari et al, , 2018Yokelson et al, 2009), higher than observed in this study, and this discrepancy could be related to differences in particle and (Table 1). Warm colors indicate an increase in ΔOA/ΔCO after 4 hr of aging, and cool colors represent a decrease.…”

Section: Smoke Mass Aging Depends On Fire Size Dilution Evaporationcontrasting

confidence: 83%

“…There are regions within our parameter space of our sensitivity studies in which intermediate plumes do not increase in normalized OA mass (Figures S15 and S17 in the supporting information). Further, some field experiments have seen factors of 2–3 in mass enhancements (Vakkari et al, , ; Yokelson et al, ), higher than observed in this study, and this discrepancy could be related to differences in particle and precursor‐vapor emissions, in‐plume oxidant concentrations (Yokelson et al, ), or other factors not explored in this study. The differences in our model results here and previously observed measurements should be investigated in a future study in order to attempt to discern what other factors are strongly controlling net OA mass, especially in larger fires.…”

Section: Resultscontrasting

confidence: 63%

“…Discrepancies between our results here and observational studies (section 3.1) indicate that our current modeling framework still requires further improvements in future studies. For example, some studies have seen much higher mass enhancements than any of the cases modeled here, indicated potentially a missing major OA source for those specific systems (Vakkari et al, 2014(Vakkari et al, , 2018Yokelson et al, 2009). We fix many aerosol/plume properties that are likely to vary across real plumes.…”

Section: Synthesis Recommendations and Conclusionmentioning

confidence: 98%

“…A large number of field campaigns have analyzed the aging of various normalized biomass burning aerosol properties within the plume. In this study, normalized refers to correcting a property for dilution and background concentrations by subtracting off the background value and then dividing the property by a conserved quantity, usually an effectively inert species, such as CO. Studies focusing on the aging of organic aerosol mass report a range of changes to the net (difference between total secondary organic aerosol [SOA] production and OA evaporation) normalized OA within the plume (Shrivistava et al, 2017): some of these studies reported an OA gain (Alvarado & Prinn, 2009;Cachier et al, 1995;Formenti et al, 2003;Liu et al, 2016;Reid et al, 1998;Vakkari et al, 2014Vakkari et al, , 2018Yokelson et al, 2009), some an OA loss (Akagi et al, 2012;Forrister et al, 2015;Hobbs et al, 2003;Jolleys et al, 2012Jolleys et al, , 2015May et al, 2015), and others showed no significant change in OA (Brito et al, 2014;Capes et al, 2008;Collier et al, 2016;Cubison et al, 2011;Hecobian et al, 2011;Liu et al, 2016;May et al, 2015;Nance et al, 1993;Sakamoto et al, 2015;Zhou et al, 2017). However, sampling noise due to different sampling times, collection efficiencies, and other issues can also make it ambiguous whether net normalized OA increased in a single fire (e.g., the analysis of Alvarado and Prinn (2009) of the Timbavati fire from Hobbs et al (2003)).…”

Section: Introductionmentioning

confidence: 99%

“…The evolution of the total number of particles from biomass burning emissions is controlled by coagulation (Akagi et al, 2012;Capes et al, 2008;Formenti et al, 2003;Radke et al, 1995;Ramnarine et al, 2018;Sakamoto et al, 2016), although deposition plays a minor role early in the plume, and nucleation may contribute to number in some cases (e.g., Andreae et al, 2001;Hennigan et al, 2012;Hobbs et al, 2003;Vakkari et al, 2018). The rate of coagulation is proportional to the square of the particle number concentration for particles of fixed sizes.…”

Section: Introductionmentioning

confidence: 99%

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More Than Emissions and Chemistry: Fire Size, Dilution, and Background Aerosol Also Greatly Influence Near‐Field Biomass Burning Aerosol Aging

et al. 2019

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Biomass burning emits particles (black carbon and primary organic aerosol) and precursor vapors to the atmosphere that chemically and physically age in the atmosphere. This theoretical study explores the relationships between fire size (determining the initial plume width and concentration), dilution rate, and entrainment of background aerosol on particle coagulation, organic aerosol (OA) evaporation, and secondary organic aerosol (SOA) condensation in smoke plumes. We examine the impacts of these processes on aged smoke OA mass, geometric mean diameter (Dg), peak lognormal modal width (σg), particle extinction (E), and cloud condensation nuclei (CCN) concentrations. In our simulations, aging OA mass is controlled by competition between OA evaporation and SOA condensation. Large, slowly diluting plumes evaporate little in our base set of simulations, which may allow for net increases in mass, E, CCN , and Dg from SOA condensation. Smaller, quickly diluting fire plumes lead to faster evaporation, which favors decreases in mass, E, CCN, and Dg. However, the SOA fraction of the smoke OA increases more rapidly in smaller fires due to faster primary organic aerosol evaporation leading to more SOA precursors. Net mass changes for smaller fires depend on background OA concentrations; increasing background aerosol concentrations decrease evaporation rates. Although coagulation does not change mass, it can decrease the number of particles in large/slowly diluting plumes, increasing Dg and E, and decreasing σg. While our conclusions are limited by being a theoretical study, we hope they help motivate future smoke‐plume analyses to consider the effects of fire size, meteorology, and background OA concentrations.

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Section: Smoke Mass Aging Depends On Fire Size Dilution Evaporationcontrasting

confidence: 83%

“…There are regions within our parameter space of our sensitivity studies in which intermediate plumes do not increase in normalized OA mass (Figures S15 and S17 in the supporting information). Further, some field experiments have seen factors of 2–3 in mass enhancements (Vakkari et al, , ; Yokelson et al, ), higher than observed in this study, and this discrepancy could be related to differences in particle and precursor‐vapor emissions, in‐plume oxidant concentrations (Yokelson et al, ), or other factors not explored in this study. The differences in our model results here and previously observed measurements should be investigated in a future study in order to attempt to discern what other factors are strongly controlling net OA mass, especially in larger fires.…”

Section: Resultscontrasting

confidence: 63%

Section: Synthesis Recommendations and Conclusionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

More Than Emissions and Chemistry: Fire Size, Dilution, and Background Aerosol Also Greatly Influence Near‐Field Biomass Burning Aerosol Aging

et al. 2019

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Non-reversible aging increases the solar absorptivity of African biomass burning plumes

Dobracki

Howell

Saide

et al. 2021

Preprint

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Biomass-burning emissions impact almost all of the radiative forcing terms considered by the IPCC, yet little is known about smoke aerosol aging in nature beyond a few days. The marine southeast Atlantic free-troposphere is a natural testbed for examining aging through photolysis/oxidation of African continental fire emissions advected westward. In-situ measurements primarily from September, 2016 indicate highly-oxidized aerosol with minimal primary source signatures after 4-9 modelpredicted days since emission. Aerosol loses approximately one-half of its organic aerosol over the ocean. The organic aerosol to black carbon mass ratios decrease from 14 to 10, significantly lower than many model predictions. This mass loss, combined with stability in black carbon, supports an observed 20% increase in solar absorptivity. The decreased single scattering albedos, reaching 0.83 at 9 days, arguably represent the lowest values measured globally. The relationship of the aerosol properties to model-derived time since emission suggests a useful new modeling constraint.

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Fresh organic and soot particles from crop straw burning: Morphology, composition and size distribution

Li,

Shao,

Wang

et al. 2023

Geological Journal

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Particulate matter from biomass burning is considered to be one of the major sources of air pollution in China. To examine the characteristics of the particles emitted from the burning of crop straw, an open burning experiment is designed. Individual particles are collected in the flaming and smouldering stages, and analysed by individual particle analyses represented by high‐resolution transmission electron microscopy equipped with the energy‐dispersive X‐ray spectrometer. Five types of particles are identified, namely, pure organic particle, organic particle‐K (OP‐K), tar ball, K‐rich and soot particles. Of these, the OP‐K particles have the highest relative number percentage in all analysed particles in both the flaming and smouldering stages. Interestingly, the microscopic morphology of organic particles is completely different in the flaming and smouldering stages, being near‐spherical in the flaming stage and gel‐like in the smouldering stage. According to the elemental compositions, most of OP‐K particles contained potassium compounds in the form of KCl and K2SO4. High combustion efficiency and temperature promote the formation of crystal structure, resulting in the onion‐like microstructure of soot particles. Apparently, the soot microstructure is a fingerprint feature that helps identify combustion sources. In addition, the particles emitted in the flaming stage are smaller than those in the smouldering stage, implying that high temperature combustion tends to be associated with high combustion efficiency. The relationship between burning temperatures and particle sizes can help to understand the emission of particles from crop straw burning and find new ways to solve the problems caused by straw burning. The results of this study can provide more detailed ‘fingerprint’ characteristics of the particulate matter emitted from biomass‐burning sources, and an understanding of their potential impact on the atmospheric environment.

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Major secondary aerosol formation in southern African open biomass burning plumes

Cited by 93 publications

References 46 publications

More Than Emissions and Chemistry: Fire Size, Dilution, and Background Aerosol Also Greatly Influence Near‐Field Biomass Burning Aerosol Aging

More Than Emissions and Chemistry: Fire Size, Dilution, and Background Aerosol Also Greatly Influence Near‐Field Biomass Burning Aerosol Aging

Non-reversible aging increases the solar absorptivity of African biomass burning plumes

Fresh organic and soot particles from crop straw burning: Morphology, composition and size distribution

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