The importance of burning conditions on the composition of domestic biomass burning organic aerosol and the impact of atmospheric aging (original) (raw)
Related papers
2020
Semivolatile organic compounds (SVOCs) emitted from open biomass burning (BB) can contribute to chemical and physical properties of atmospheric aerosols and also may cause adverse health effects. The polar fraction of SVOCs is a prominent part of BB organic aerosols, and thus it is important to characterize the chemical composition and reactivity of this fraction. In this study, globally and regionally important representative fuels (Alaskan peat, Moscow peat, Pskov peat, eucalyptus, Malaysian peat, and Malaysian agricultural peat) were burned under controlled conditions using the combustion chamber facility at the Desert Research Institute (DRI). Gas-and particle-phase biomassburning emissions were aged in an oxidation flow reactor (OFR) to mimic 5-7 d of atmospheric aging. Fresh and OFRaged biomass-burning aerosols were collected on Teflonimpregnated glass fiber filters (TIGF) in tandem with XAD resin media for organic carbon speciation. The polar fraction extracted with dichloromethane and acetone was analyzed with gas chromatography mass spectrometry (GC-MS) for 84 polar organic compounds-including mono-and dicarboxylic acids, methoxylated phenols, aromatic acids, anhydrosugars, resin acids, and sterols. For all these compounds, fuel-based emission factors (EFs) were calculated for fresh and OFR-aged samples. The carbon mass of the quantified polar compounds was found to constitute 5 % to 7 % of the total organic compound mass. A high abundance of methoxyphenols (239 mg kg −1 for Pskov peat; 22.6 % of total GC-MS characterized mass) and resin acids (118 mg kg −1 for Alaskan peat; 14.5 % of total GC-MS characterized mass) was found in peat-burning emissions (smoldering combustion). The concentration of some organic compounds (e.g., tetracosanoic acid) with a molecular weight (MW) above 350 g mol −1 decreased after OFR aging, while abundances of low-MW compounds (e.g., hexanoic acid) increased. This indicated a significant extent of fragmentation reactions in the OFR. Methoxyphenols decreased after OFR aging, while a significant increase (3.7 to 8.6 times) in the abundance of dicarboxylic acids emission factors (EFs), especially maleic acid (10 to 60 times), was observed. EFs for fresh and ratios from fresh-to-aged BB samples reported in this study can be used to perform source apportionment and predict processes occurring during atmospheric transport.
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 SOAdominated 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 Correspondence to:
Journal of Geophysical Research: Atmospheres, 2019
After smoke from burning biomass is emitted into the atmosphere, chemical and physical processes change the composition and amount of organic aerosol present in the aged, diluted plume. During the fourth Fire Lab at Missoula Experiment, we performed smog-chamber experiments to investigate formation of secondary organic aerosol (SOA) and multiphase oxidation of primary organic aerosol (POA). We simulated atmospheric aging of diluted smoke from a variety of biomass fuels while measuring particle composition using high-resolution aerosol mass spectrometry. We quantified SOA formation using a tracer ion for low-volatility POA as a reference standard (akin to a naturally occurring internal standard). These smoke aging experiments revealed variable organic aerosol (OA) enhancements, even for smoke from similar fuels and aging mechanisms. This variable OA enhancement correlated well with measured differences in the amounts of emitted volatile organic compounds (VOCs) that could subsequently be oxidized to form SOA. For some aging experiments, we were able to predict the SOA production to within a factor of 2 using a fuel-specific VOC emission inventory that was scaled by burn-specific toluene measurements. For fires of coniferous fuels that were dominated by needle burning, volatile biogenic compounds were the dominant precursor class. For wiregrass fires, furans were the dominant SOA precursors. We used a POA tracer ion to calculate the amount of mass lost due to gas-phase oxidation and subsequent volatilization of semivolatile POA. Less than 5% of the POA mass was lost via multiphase oxidation-driven evaporation during up to 2 hr of equivalent atmospheric oxidation. Plain Language Summary We measured aging of biomass-burning smoke at the Missoula Fire Laboratory. The smoke was from various fuels containing green foliage as well as some grasses. We observed significant changes in the mass spectra from the particles, and were also in many cases able to describe formation of additional (secondary) mass to within about a factor of 2 based on measured emissions of volatile organic compounds. However, we show that the amount of secondary mass depends heavily on the type of biomass fuel (green foliated branches vs dried firewood vs grasses, etc).
Atmospheric Chemistry and Physics, 2011
A series of photo-oxidation smog chamber experiments were performed to investigate the primary emissions and secondary aerosol formation from two different log wood burners and a residential pellet burner under different burning conditions: starting and flaming phase. Emissions were sampled from the chimney and injected into the smog chamber leading to primary organic aerosol (POA) concentrations comparable to ambient levels. The composition of the aerosol was measured by an Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS) and black carbon (BC) instrumentation. The primary emissions were then exposed to xenon light to initiate photo-chemistry and subsequent secondary organic aerosol (SOA) production. After correcting for wall losses, the average increase in organic matter (OM) concentrations by SOA formation for the starting and flaming phase experiments with the two log wood burners was found to be a factor of 4.1±1.4 after five hours of aging. No SOA formation was observed for the stable burning phase of the pellet burner. The startup emissions of the pellet burner showed an increase in OM concentration by a factor of 3.3. Including the measured SOA formation potential, average emission factors of BC+POA+SOA, calculated from CO 2 emission, were found to be in the range of 0.04 to 3.9 g/kg wood for the stable burning pellet burner and an old log wood burner during startup respectively. SOA contributed significantly to the ion C 2 H 4 O + 2 at mass to charge ratio m/z 60, a commonly used
Science of The Total Environment, 2019
The combustion of spruce logwood in a modern residential stove was found to emit polycyclic aromatic hydrocarbons (PAH) and oxygenated polycyclic aromatic hydrocarbons (OPAH) with emission factors of 404 μg MJ −1 of 35 analysed PAH, 317 μg MJ −1 of 11 analysed Oxy-PAH and 12.5 μg MJ −1 of 5 analysed OH-PAH, most of which are known as potential mutagens and carcinogens. Photochemical ageing in an oxidation flow reactor (OFR) degraded particle-bound PAH, which was also reflected in declining PAH toxicity equivalent (PAH-TEQ) values by 45 to 80% per equivalent day of photochemical ageing in the atmosphere. OPAH concentrations decreased less than PAH concentrations during photochemical ageing, supposedly due to their secondary formation, while 1-hydroxynaphthalene, 1,5-dihydroxynaphthalene and 1,8-naphthalaldehydic acid were significantly increased after ageing. Furthermore, secondary organic aerosol (SOA) formation and aromatic compounds not included in targeted analysis were investigated by thermal-optical carbon analysis (TOCA) hyphenate to resonance-enhanced multi-photon ionisation time-of-flight mass spectrometry (REMPI-TOFMS). The commonly used PAH-source indicators phenanthrene/anthracene, fluoranthene/pyrene, retene/chrysene, and indeno[cd]pyrene/benzo[ghi]perylene remained stable during photochemical ageing, enabling identification of wood combustion emissions in ambient air. On the other hand, benz[a]pyrene/benz[e]pyrene and benz[a]anthracene/chrysene were found to decrease with increasing photochemical age. Retene/chrysene was not a proper classifier for the wood combustion emissions of this study, possibly due to more efficient combustion than in open wood burning, from which this diagnostic ratio was initially derived. This study motivates in-depth investigation of degradation kinetics of particle-bound species on different combustion aerosol as well as the consequences of photochemical ageing on toxicity and identification of wood combustion emissions in ambient air.
Smoke aerosol chemistry and aging of Siberian biomass burning emissions in a large aerosol chamber
Atmospheric Environment, 2018
Vegetation open fires constitute a significant source of particulate pollutants on a global scale and play an important role in both atmospheric chemistry and climate change. To better understand the emission and aging characteristics of smoke aerosols, we performed small-scale fire experiments using the Large Aerosol Chamber (LAC, 1800 m 3) with a focus on biomass burning from Siberian boreal coniferous forests. A series of burn experiments were conducted with typical Siberian biomass (pine and debris), simulating separately different combustion conditions, namely, flaming, smoldering and mixed phase. Following smoke emission and dispersion in the combustion chamber, we investigated aging of aerosols under dark conditions. Here, we present experimental data on emission factors of total, elemental and organic carbon, water-soluble carbon as well as individual organic compounds, such as anhydrosugars, phenolic and dicarboxylic acids. We found that total carbon accounts for up to 80 % of the fine mode (PM 2.5) smoke aerosol. Higher PM 2.5 emission factors were observed in the smoldering compared to flaming phase and in pine compared to debris smoldering phase. For lowtemperature combustion, organic carbon (OC) contributed to more than 90 % of total carbon, whereas elemental carbon (EC) dominated the aerosol composition in flaming burns with a 60-70 % contribution to the total carbon mass. For all smoldering burns, levoglucosan (LG), a cellulose decomposition product, was the most abundant organic species (average LG/OC=0.26 for pine smoldering), followed by its isomer mannosan or dehydroabietic acid (DA), an important constituent of conifer resin (DA/OC = 0.033). A levoglucosan-to-mannosan ratio of about 3 was observed, which is consistent with ratios reported for coniferous biomass and more generally softwood. The rate of aerosol removal for OC and individual organic compounds were investigated during aging in the chamber in terms of mass concentration loss rates over time under dark conditions and
Natural organic compounds as tracers for biomass combustion in aerosols
1995
Biomass combustion is an important primary source of carbonaceous particles in the global atmosphere. Although various molecular markers have already been proposed for this process, additional specific organic tracers need to be characterized. The injection of natural product organic tracers to smoke occurs primarily by direct volatilizatiodsteam stripping and by thermal alteration based on combustion temperature. The degree of alteration increases as the bum temperature rises and the moisture content of the fuel decreases. Although the molecular composition of organic matter in smoke particles is highly variable, the molecular structures of the tracers are generally source specific. The homologous compound series and biomarkers present in smoke particles are derived directly from plant wax, gum and resin by volatilization and secondarily from pyrolysis of biopolymers (e.g., cellulose, lignin, cutin, suberin), wax, gum and resin. The complexity of the organic components of smoke aerosol is illustrated with examples from controlled burns of temperate and tropical biomass fuels. Burning of biomass from temperate regions (Le., conifers) yields characteristic tracers from diterpenoids as well as phenolics and other oxygenated species, which are recognizable in urban airsheds. The major organic components of smoke particles from tropical biomass are straight-chain, aliphatic and oxygenated compounds and triterpenoids. Several compounds (e.g., amyrones, friedelin, aromatic A-noroleananes and other thermal derivatives from triterpenoids, lignin phenols) are potential key indicators for smoke components from combustion of such biomass. The precursor to product approach of organic geochemistry can be applied successfully to provide tracers for studying smoke plume chemistry and dispersion.
Environmental Science & Technology, 2020
Biomass burning is the largest combustionrelated source of volatile organic compounds (VOCs) to the atmosphere. We describe the development of a state-of-the-science model to simulate the photochemical formation of secondary organic aerosol (SOA) from biomass burning emissions observed in dry (RH<20%) environmental chamber experiments. The modeling is supported by (i) new oxidation chamber measurements, (ii) detailed concurrent measurements of SOA precursors in biomass burning emissions, and (iii) development of SOA parameters for heterocyclic and oxygenated aromatic compounds based on historical chamber experiments. We find that oxygenated aromatic compounds, including phenols and methoxyphenols, account for slightly less than 60% of the SOA formed and help our model explain the variability in the organic aerosol mass (R 2 =0.68) and O:C (R 2 =0.69) enhancement ratios observed across eleven chamber experiments. Despite abundant emissions,
2012
Indoor solid fuel combustion is a dominant source of polycyclic aromatic hydrocarbons (PAHs) and oxygenated PAHs (OPAHs) and the latter are believed to be more toxic than the former. However, there is limited quantitative information on the emissions of OPAHs from solid fuel combustion. In this study, emission factors of OPAHs (EF OPAH ) for nine commonly used crop residues and five coals burnt in typical residential stoves widely used in rural China were measured under simulated kitchen conditions. The total EF OPAH ranged from 2.8±0.2 to 8.1±2.2 mg/kg for tested crop residues and from 0.043 to 71 mg/kg for various coals and 9-fluorenone was the most abundant specie. The EF OPAH for indoor crop residue burning were 1~2 orders of magnitude higher than those from open burning, and they were affected by fuel properties and combustion conditions, like moisture and combustion efficiency. For both crop residues and coals, significantly positive correlations were found between EFs for the individual OPAHs and the parent PAHs. An oxygenation rate, R o , was defined as the ratio of the EFs between the oxygenated and parent PAH species to describe the formation potential of OPAHs. For the studied OPAH/ PAH pairs, mean R o values were 0.16 ~ 0.89 for crop residues and 0.03 ~ 0.25 for coals. R o for crop residues burned in the cooking stove were much higher than those for open burning and much lower than those in ambient air, indicating the influence of secondary formation of OPAH and loss of PAHs. In comparison with parent PAHs, OPAHs showed a higher tendency to be associated with particulate matter (PM), especially fine PM, and the dominate size ranges were 0.7 2.1 µm for crop residues and high caking coals and < 0.7 µm for the tested low caking briquettes.