Chemical and physical transformations of organic aerosol from the photo-oxidation of open biomass burning emissions in an environmental chamber
TL;DR: In this paper, the chemical and physical transformations of organic aerosol (OA) during photo-oxidation of open biomass burning emissions were investigated in the US Forest Service Fire Science Laboratory as part of the third Fire Lab at Missoula Experiment (FLAME III).
Abstract: . Smog chamber experiments were conducted to investigate the chemical and physical transformations of organic aerosol (OA) during photo-oxidation of open biomass burning emissions. The experiments were carried out at the US Forest Service Fire Science Laboratory as part of the third Fire Lab at Missoula Experiment (FLAME III). We investigated emissions from 12 different fuels commonly burned in North American wildfires. The experiments feature atmospheric and plume aerosol and oxidant concentrations; aging times ranged from 3 to 4.5 h. OA production, expressed as a mass enhancement ratio (ratio of OA to primary OA (POA) mass), was highly variable. OA mass enhancement ratios ranged from 2.9 in experiments where secondary OA (SOA) production nearly tripled the POA concentration to 0.7 in experiments where photo-oxidation resulted in a 30 % loss of the OA mass. The campaign-average OA mass enhancement ratio was 1.7 ± 0.7 (mean ± 1σ); therefore, on average, there was substantial SOA production. In every experiment, the OA was chemically transformed. Even in experiments with net loss of OA mass, the OA became increasingly oxygenated and less volatile with aging, indicating that photo-oxidation transformed the POA emissions. Levoglucosan concentrations were also substantially reduced with photo-oxidation. The transformations of POA were extensive; using levoglucosan as a tracer for POA, unreacted POA only contributed 17 % of the campaign-average OA mass after 3.5 h of exposure to typical atmospheric hydroxyl radical (OH) levels. Heterogeneous reactions with OH could account for less than half of this transformation, implying that the coupled gas-particle partitioning and reaction of semi-volatile vapors is an important and potentially dominant mechanism for POA processing. Overall, the results illustrate that biomass burning emissions are subject to extensive chemical processing in the atmosphere, and the timescale for these transformations is rapid.
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TL;DR: The aim of this work was to comprehensively review most of the studies published on this topic in China, including literature concerning field measurements, laboratory studies and the impacts of BB indoors and outdoors in China to provide a basis for formulation of policies and regulations by policy makers in China.
772 citations
Cites methods from "Chemical and physical transformatio..."
...…g/cm3 for temperate forest fire; Levin et al. (2010) calculated bulk densities of various BB aerosol from chemical compositions to be 1.2–1.9 g/cm3; Hennigan et al. (2011) assumed smoke aerosol density to be 1.3 g/cm3 throughout photo-oxidation process; while Li et al. (2015, 2016a) reported…...
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TL;DR: The literature on atmospheric particulate maffer (PM), or atmospheric aerosol, has increased enormously over the last 2 decades and amounts now to some 1500-2000 papers per year in the refereed literature.
Abstract: The literature on atmospheric particulate maffer (PM), or atmospheric aerosol, has increased enormously over the last 2 decades and amounts now to some 1500—2000 papers per year in the refereed literature. This is in part due to the enormous advances in measurement technologies, which have allowed for an increasingly accurate understanding of the chemical composition and of the physical properties of atmospheric particles and of their processes in the atmosphere. The growing scientific interest in atmospheric aerosol particles is due to their high importance for environmental policy. In fact, particulate maffer constitutes one of the most challenging problems both for air quality and for climate change policies. In this context, this paper reviews the most recent results within the atmospheric aerosol sciences and thepoticy needs, which have driven much ofthe increase in monitoring and mechanistic research over the last 2 decades. The synthesis reveals many new processes and developments in the science underpinning climate—aerosol interactions and effects of PM on human health and the environment. However, while airborne particulate matter is responsible for globally important influences on premature human mortality, we stijl do not know the relative importance of the different chemical components of PM for these effects. Likewise, the magnitude of the overall effects of PM on climate remains highly uncertain. Despite the uncertainty there are many things that could be done to mitigate local and global problems of atmospheric PM. Recent analyses have shown that reducing black carbon (BC) emissions, using known control measures, would reduce global wanning and delay the time when anthropogenic effects on global temperature would exceed 2°C. Likewise, cost-effective control measures on ammonia, an important agricultural precursor gas for secondary inorganic aerosols (SlA), would reduce regional eutrophication and PM concentrations in large areas of Europe, China and the USA. Thus, there is much that could be done to reduce the effects of atmospheric PM on the climate and the health of the environment and the human population. A prioritized list of actions to mitigate the full range of effects ofPM is currently undeliverable due to shortcomings in the knowledge of aerosol science; among the shortcomings, the roles of PM in global climate and the relative roles of different PM precursor sources and their response to climate and land use change over the remaining decades of this century are prominent. In any case, the evidence from this paper strongly advocates for an integrated approach to air quality and climate policies.
648 citations
Cites background from "Chemical and physical transformatio..."
...The aging of emissions from open biomass combustion yielded OA enhancement ratios ranging from 0.7 to 2.9, depending on fuel type and burn conditions (Hennigan et al., 2011; Ortega et al., 2013)....
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...Residential wood burning and wildfires are also significant sources of SOA precursors (e.g. Grieshop et al., 2009; Hennigan et al., 2011)....
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University of Colorado Boulder1, Cooperative Institute for Research in Environmental Sciences2, Pennsylvania State University3, National Center for Atmospheric Research4, Langley Research Center5, Harvard University6, Florida State University7, Georgia Institute of Technology8, University of Innsbruck9, University of Miami10, National Institute of Aerospace11
TL;DR: In this paper, the authors investigated the physical and chemical evolution of biomass burning (BB) organic aerosols (POA and SOA) using the Aerodyne Aerosol Mass Spectrometer.
Abstract: . Biomass burning (BB) is a large source of primary and secondary organic aerosols (POA and SOA). This study addresses the physical and chemical evolution of BB organic aerosols. Firstly, the evolution and lifetime of BB POA and SOA signatures observed with the Aerodyne Aerosol Mass Spectrometer are investigated, focusing on measurements at high-latitudes acquired during the 2008 NASA ARCTAS mission, in comparison to data from other field studies and from laboratory aging experiments. The parameter f 60 , the ratio of the integrated signal at m/z 60 to the total signal in the organic component mass spectrum, is used as a marker to study the rate of oxidation and fate of the BB POA. A background level of f 60 ~0.3% ± 0.06% for SOA-dominated ambient OA is shown to be an appropriate background level for this tracer. Using also f 44 as a tracer for SOA and aged POA and a surrogate of organic O:C, a novel graphical method is presented to characterise the aging of BB plumes. Similar trends of decreasing f 60 and increasing f 44 with aging are observed in most field and lab studies. At least some very aged BB plumes retain a clear f 60 signature. A statistically significant difference in f 60 between highly-oxygenated OA of BB and non-BB origin is observed using this tracer, consistent with a substantial contribution of BBOA to the springtime Arctic aerosol burden in 2008. Secondly, a summary is presented of results on the net enhancement of OA with aging of BB plumes, which shows large variability. The estimates of net OA gain range from ΔOA/ΔCO(mass) = −0.01 to ~0.05, with a mean ΔOA/POA ~19%. With these ratios and global inventories of BB CO and POA a global net OA source due to aging of BB plumes of ~8 ± 7 Tg OA yr −1 is estimated, of the order of 5 % of recent total OA source estimates. Further field data following BB plume advection should be a focus of future research in order to better constrain this potentially important contribution to the OA burden.
495 citations
Cites background or result from "Chemical and physical transformatio..."
...Results from laboratory studies of the aging of open BB emissions mirror these findings, demonstrating a wide range of measured net OA production depending on, among other factors, the fuel and burning conditions (Hennigan et al., 2011; Ortega et al., 2010)....
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...…with two different experimental setups also resulted in a highly variable net OA enhancement, depending (among other parameters) on fuel type and burn conditions (Hennigan et al., 2011; Ortega, 2010), which appears consistent with the large degree of variability observed in the ambient datasets....
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Pacific Northwest National Laboratory1, University of California, Davis2, University of California, Berkeley3, University of California, Irvine4, Cooperative Institute for Research in Environmental Sciences5, Brookhaven National Laboratory6, Harvard University7, Georgia Institute of Technology8, University of Helsinki9, Colorado State University10, Lund University11, California Institute of Technology12, University of Washington13
TL;DR: In this paper, a review summarizes some of the important developments during the past decade in understanding secondary organic aerosol (SOA) formation, including formation of extremely low volatility organics in the gas phase, acid-catalyzed multiphase chemistry of isoprene epoxydiols, particle-phase oligomerization, and physical properties such as volatility and viscosity.
Abstract: Anthropogenic emissions and land use changes have modified atmospheric aerosol concentrations and size distributions over time. Understanding preindustrial conditions and changes in organic aerosol due to anthropogenic activities is important because these features (1) influence estimates of aerosol radiative forcing and (2) can confound estimates of the historical response of climate to increases in greenhouse gases. Secondary organic aerosol (SOA), formed in the atmosphere by oxidation of organic gases, represents a major fraction of global submicron-sized atmospheric organic aerosol. Over the past decade, significant advances in understanding SOA properties and formation mechanisms have occurred through measurements, yet current climate models typically do not comprehensively include all important processes. This review summarizes some of the important developments during the past decade in understanding SOA formation. We highlight the importance of some processes that influence the growth of SOA particles to sizes relevant for clouds and radiative forcing, including formation of extremely low volatility organics in the gas phase, acid-catalyzed multiphase chemistry of isoprene epoxydiols, particle-phase oligomerization, and physical properties such as volatility and viscosity. Several SOA processes highlighted in this review are complex and interdependent and have nonlinear effects on the properties, formation, and evolution of SOA. Current global models neglect this complexity and nonlinearity and thus are less likely to accurately predict the climate forcing of SOA and project future climate sensitivity to greenhouse gases. Efforts are also needed to rank the most influential processes and nonlinear process-related interactions, so that these processes can be accurately represented in atmospheric chemistry-climate models.
467 citations
TL;DR: In this article, the absorption properties of brown carbon aerosols from biomass burning are linked to their black carbon content, and they showed that the absorption property of aerosols can exert an important influence on Earth's climate.
Abstract: Atmospheric aerosols can exert an important influence on Earth’s climate. Combustion chamber experiments reveal that the absorption properties of brown carbon aerosols from biomass burning are linked to their black carbon content.
415 citations
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TL;DR: In this article, the authors present a set of emission factors for a large variety of species emitted from biomass fires, where data were not available, they have proposed estimates based on appropriate extrapolation techniques.
Abstract: A large body of information on emissions from the various types of biomass burning has been accumulated over the past decade, to a large extent as a result of International Geosphere-Biosphere Programme/International Global Atmospheric Chemistry research activities. Yet this information has not been readily accessible to the atmospheric chemistry community because it was scattered over a large number of publications and reported in numerous different units and reference systems. We have critically evaluated the presently available data and integrated these into a consistent format. On the basis of this analysis we present a set of emission factors for a large variety of species emitted from biomass fires. Where data were not available, we have proposed estimates based on appropriate extrapolation techniques. We have derived global estimates of pyrogenic emissions for important species emitted by the various types of biomass burning and compared our estimates with results from inverse modeling studies.
3,556 citations
"Chemical and physical transformatio..." refers background in this paper
...While variable, the range of OC and EC emission factors are consistent with laboratory (McMeeking et al., 2009) and field data (Andreae and Merlet, 2001)....
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...They are also comparable with emission factors from field studies of open biomass burning (Andreae and Merlet, 2001)....
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...For example, average OC emission factors for the biomass burning classes Savannah and Grasslands, Tropical Forests, Extra Tropical Forests, and Agricultural Residues are 3.4, 5.2, 8.6–9.7, and 3.3 g kg−1, respectively (Andreae and Merlet, 2001)....
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...…CO (74.9±24.8 g kg−1 (average±1σ)) and NOx (3.5 ± 1.8 g kg−1 (average±1σ)) emission factors were within the range of emission factors reported for previous laboratory-scale burns (e.g., Yokelson et al., 2008; McMeeking et al., 2009; Burling et al., 2010) and field data (Andreae and Merlet, 2001)....
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...Both the variable nature of biomass emissions (e.g., Andreae and Merlet, 2001) and the large uncertainties in SOA formation demonstrate the need to empirically characterize SOA from biomass burning....
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University of Gothenburg1, University College Cork2, Paul Scherrer Institute3, Weizmann Institute of Science4, Norwegian Meteorological Institute5, Chalmers University of Technology6, University of Antwerp7, Carnegie Mellon University8, Centre national de la recherche scientifique9, University of Lyon10, University of California, Berkeley11, University of York12, Leibniz Institute for Neurobiology13, University of Mainz14, University of Florida15, University of Colorado Boulder16, Forschungszentrum Jülich17, Ghent University18, University of Manchester19, Aix-Marseille University20, California Institute of Technology21
TL;DR: In this article, an overview of the atmospheric degradation mechanisms for SOA precursors, gas-particle partitioning theory and analytical techniques used to determine the chemical composition of SOA is presented.
Abstract: Secondary organic aerosol (SOA) accounts for a significant fraction of ambient tropospheric aerosol and a detailed knowledge of the formation, properties and transformation of SOA is therefore required to evaluate its impact on atmospheric processes, climate and human health. The chemical and physical processes associated with SOA formation are complex and varied, and, despite considerable progress in recent years, a quantitative and predictive understanding of SOA formation does not exist and therefore represents a major research challenge in atmospheric science. This review begins with an update on the current state of knowledge on the global SOA budget and is followed by an overview of the atmospheric degradation mechanisms for SOA precursors, gas-particle partitioning theory and the analytical techniques used to determine the chemical composition of SOA. A survey of recent laboratory, field and modeling studies is also presented. The following topical and emerging issues are highlighted and discussed in detail: molecular characterization of biogenic SOA constituents, condensed phase reactions and oligomerization, the interaction of atmospheric organic components with sulfuric acid, the chemical and photochemical processing of organics in the atmospheric aqueous phase, aerosol formation from real plant emissions, interaction of atmospheric organic components with water, thermodynamics and mixtures in atmospheric models. Finally, the major challenges ahead in laboratory, field and modeling studies of SOA are discussed and recommendations for future research directions are proposed.
3,324 citations
University of Colorado Boulder1, Carnegie Mellon University2, Paul Scherrer Institute3, University at Albany, SUNY4, University of California, Berkeley5, Swiss Federal Laboratories for Materials Science and Technology6, State University of New York System7, University of California, Davis8, University of Eastern Finland9, Finnish Meteorological Institute10, University of Helsinki11, Stockholm University12, Texas A&M University13, Max Planck Society14, University of Tokyo15, University of New Hampshire16, National Oceanic and Atmospheric Administration17
TL;DR: A unifying model framework describing the atmospheric evolution of OA that is constrained by high–time-resolution measurements of its composition, volatility, and oxidation state is presented, which can serve as a basis for improving parameterizations in regional and global models.
Abstract: Organic aerosol (OA) particles affect climate forcing and human health, but their sources and evolution remain poorly characterized. We present a unifying model framework describing the atmospheric evolution of OA that is constrained by high-time-resolution measurements of its composition, volatility, and oxidation state. OA and OA precursor gases evolve by becoming increasingly oxidized, less volatile, and more hygroscopic, leading to the formation of oxygenated organic aerosol (OOA), with concentrations comparable to those of sulfate aerosol throughout the Northern Hemisphere. Our model framework captures the dynamic aging behavior observed in both the atmosphere and laboratory: It can serve as a basis for improving parameterizations in regional and global models.
3,104 citations
"Chemical and physical transformatio..." refers background or methods in this paper
...…phase of the experiment, an oxygenated organic aerosol (OOA) factor derived from ambient data collected in Pittsburgh (Zhang et al., 2005), and low-volatility OOA (LV-OOA) and semi-volatile OOA (SV-OOA) factors derived from the Pittsburgh OOA (Ulbrich et al., 2009; Jimenez et al., 2009)....
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...Figure 4 plots time series of the coefficient of determination values (R2) between each measured Q-AMS OA mass spectrum and different reference mass spectra, similar to Grieshop et al. (2009a) and Jimenez et al. (2009)....
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TL;DR: Widespread burning of biomass serves to clear land for shifting cultivation, to convert forests to agricultural and pastoral lands, and to remove dry vegetation in order to promote agricultural productivity and the growth of higher yield grasses, but it may also disturb biogeochemical cycles, especially that of nitrogen.
Abstract: The use of fire as a tool to manipulate the environment has been instrumental in the human conquest of Earth, the first evidence of the use of fires by early hominids dating back to 1–1.5 million years ago [1]. Even today, most human-ignited vegetation fires take place on the African continent, and its widespread, frequently burned savannas bear ample witness to this. Although natural fires can occur even in tropical forest regions [2, 3], the extent of fires has greatly expanded on all continents with the arrival of Homo sapiens. Measurements of charcoal in dated sediment cores have shown clear correlations between the rate of burning and human settlement [4]. Pollen records show a shift with human settlement from pyrophobic vegetation to pyrotolerant and pyrophilic species, testimony to the large ecological impact of human-induced fires.
2,424 citations
TL;DR: This article presented a bottom-up estimate of uncertainties in source strength by combining uncertainties in particulate matter emission factors, emission characterization, and fuel use, with uncertainty ranges of 4.3-22 Tg/yr for BC and 17-77 Tg /yr for OC.
Abstract: [1] We present a global tabulation of black carbon (BC) and primary organic carbon (OC) particles emitted from combustion. We include emissions from fossil fuels, biofuels, open biomass burning, and burning of urban waste. Previous ‘‘bottom-up’’ inventories of black and organic carbon have assigned emission factors on the basis of fuel type and economic sector alone. Because emission rates are highly dependent on combustion practice, we consider combinations of fuel, combustion type, and emission controls and their prevalence on a regional basis. Central estimates of global annual emissions are 8.0 Tg for black carbon and 33.9 Tg for organic carbon. These estimates are lower than previously published estimates by 25–35%. The present inventory is based on 1996 fuel-use data, updating previous estimates that have relied on consumption data from 1984. An offset between decreased emission factors and increased energy use since the base year of the previous inventory prevents the difference between this work and previous inventories from being greater. The contributions of fossil fuel, biofuel, and open burning are estimated as 38%, 20%, and 42%, respectively, for BC, and 7%, 19%, and 74%, respectively, for OC. We present a bottom-up estimate of uncertainties in source strength by combining uncertainties in particulate matter emission factors, emission characterization, and fuel use. The total uncertainties are about a factor of 2, with uncertainty ranges of 4.3–22 Tg/yr for BC and 17–77 Tg/yr for OC. Low-technology combustion contributes greatly to both the emissions and the uncertainties. Advances in emission characterization for small residential, industrial, and mobile sources and topdown analysis combining field measurements and transport modeling with iterative inventory development will be required to reduce the uncertainties further. INDEX TERMS: 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801); 0322 Atmospheric Composition and Structure: Constituent sources and sinks; 0345 Atmospheric Composition and Structure: Pollution—urban and regional (0305); 0360 Atmospheric Composition and Structure: Transmission and scattering of radiation; 0365 Atmospheric Composition and Structure: Troposphere—composition and chemistry; KEYWORDS: emission, black carbon, organic carbon, fossil fuel, biofuel, biomass burning
2,180 citations