Wood burning impact on PM10 in three Austrian regions

Anhydrosugars (levoglucosan, mannosan and galactosan) were investigated during one year in three Austrian regions at three types of sites (city-heavy traffic-impacted, city-residential and background) in order to assess the magnitude of the contribution of wood smoke to the particulate matter load and its organic fraction. The annually averaged concentrations of levoglucosan ranged from 0.12 to 0.48 μg m^?3. The levoglucosan concentration exhibited a strong annual cycle with higher concentrations in the cold season. The minor anhydrosugars had a similar annual trend, but their concentrations were lower by a factor of about 5 and about 25 in the cold season for mannosan and galactosan, respectively. Levoglucosan concentrations were higher at the inner-urban as compared to rural sites. The contribution of wood smoke to organic carbon and PM₁₀ levels was calculated using a constant ratio of levoglucosan and OC, respectively PM₁₀ as derived for fire wood typical for Alpine European regions [Schmidl, C., Marr, I.L., Caseiro, A.e, Kotianová, P., Berner, A., Bauer, H., Kasper-Giebl, A., Puxbaum, H., 2008a. Chemical characterisation of fine particle emissions from wood stove combustion of common woods growing in mid-European Alpine regions. Atmospheric Environment 42, 126–141]. The estimated contribution of wood smoke-OC to the OC of PM₁₀ ranged from one third to more than half in the cold season with higher contributions up to 70% in winter (December, January and February) in the smaller cities and the rural background. This indicates, that wood smoke is the predominant source of organic material at rural and small urban sites in central Europe. Consistently, wood smoke was an important contributor to PM₁₀ during the cold season, with contributions of around 10% in the Vienna larger region and around 20% at rural sites in the densely forested regions of Salzburg and Styria during the winter months. In those regions residential sites exhibited highest relative wood smoke contents in PM₁₀ during autumn (September till November), indicating the use of wood stoves for auxiliary heating in the transition of warm to cold season. Using the relationships between the different anhydrosugars the combustion of softwood was found to be dominant for the wood smoke occurrence in ambient air at the investigated sites. Potassium, a commonly used tracer for biomass burning, correlated well to levoglucosan, with a mass ratio of around 0.80 in the cold season.     

Quantification of Monosaccharide Anhydrides by Liquid Chromatography Combined with Mass Spectrometry: Application to Aerosol Samples from an Urban and a Suburban Site Influenced by Small-Scale Wood Burning

Abstract

Levels of the monosaccharide anhydride (MA) levoglucosan and its isomeric compounds galactosan and mannosan were quantified in the PM₁₀ fraction (particulate matter ≤10 µm in aerodynamic diameter) of ambient aerosols from an urban (Oslo) and a suburban (Elverum) site in Norway, both influenced by small-scale wood burning. MAs are degradation products of cellulose and hemicellulose, and levoglucosan is especially emitted in high concentrations during pyrolysis and combustion of wood, making it a potential tracer of primary particles emitted from biomass burning. MAs were quantified using a novel high-performance liquid chromatography/ high-resolution mass spectrometry-time of flight method. This approach distinguishes between the isomeric compounds of MAs and benefits from the limited sample preparation required before analysis, and no extensive derivatization step is needed. The highest concentrations of levogucosan, galactosan, and mannosan (∑MA) were recorded in winter because of wood burning for residential heating (∑MA_MAX = 1,240 ng m^-3). This finding was substantiated by a relatively high correlation (R² = 0.64) between the levoglucosan concentration and decreasing ambient temperature. At the suburban site, ∑MA accounted for 3.1% of PM₁₀, whereas the corresponding level at the urban site was 0.6%. The mass size distribution of MAs associated with atmospheric aerosols was measured using a Berner cascade impactor. The size distribution was characterized with a single mode at 561 nm. Ninety-five percent of the mass concentration of the MAs was found to be associated with particles <2 µm. A preliminary attempt to estimate the contribution of wood burning to the mass concentration of PM₁₀ in Oslo using levoglucosan as a tracer indicates that 24% comes from wood burning. This is approximately a factor of 2 lower than estimated by the AirQUIS dispersion model.     

Seasonal variations of monosaccharide anhydrides in PM1 and PM2.5 aerosol in urban areas

The concentrations of monosaccharide anhydrides (levoglucosan, mannosan, galactosan) in PM1 and PM2.5 aerosol samples were measured in Brno and ?lapanice in the Czech Republic in winter and summer 2009. 56 aerosol samples were collected together at both sites to investigate the different sources that contribute to aerosol composition in studied localities. Daily PM1 and PM2.5 aerosol samples were collected on pre-fired quartz fibre filters.The sum of average atmospheric concentration of levoglucosan, mannosan and galactosan in PM1 aerosol in ?lapanice and Brno during winter was 513 and 273 ng m^?3, while in summer the sum of average atmospheric concentration of monosaccharide anhydrides (MAs) was 42 and 38 ng m^?3, respectively. The sum of average atmospheric concentration of MAs in PM1 aerosol formed 71 and 63% of the sum of MA concentration in PM2.5 aerosol collected in winter in ?lapanice and Brno, whereas in summer the sum of average atmospheric concentration of MAs in PM1 aerosol formed 45 and 43% of the sum of MA concentration in PM2.5 aerosol in ?lapanice and Brno, respectively.In winter, the sum of MAs contributed significantly to PM1 mass ranging between 1.37% and 2.67% of PM1 mass (Brno – ?lapanice), while in summer the contribution of the sum of MAs was smaller (0.28–0.32%). Contribution of the sum of MAs to PM2.5 mass is similar both in winter (1.37–2.71%) and summer (0.44–0.55%).The higher concentrations of monosaccharide anhydrides in aerosols in ?lapanice indicate higher biomass combustion in this location than in Brno during winter season. The comparison of levoglucosan concentration in PM1 and PM2.5 aerosol shows prevailing presence of levoglucosan in PM1 aerosol both in winter (72% on average) and summer (60% on average).The aerosol samples collected in ?lapanice and Brno in winter and summer show comparable contributions of levoglucosan, mannosan and galactosan to the total amount of monosaccharide anhydrides in both aerosol size fractions. Levoglucosan was the most abundant monosaccharide anhydride with a relative average contribution to the total amount of MAs in the range of 71–82% for PM1 aerosols and 52–79% for PM2.5 aerosols.     

Quantification of monosaccharide anhydrides by liquid chromatography combined with mass spectrometry: application to aerosol samples from an urban and a suburban site influenced by small-scale wood burning

Levels of the monosaccharide anhydride (MA) levoglucosan and its isomeric compounds galactosan and mannosan were quantified in the PM10 fraction (particulate matter < or = 10 microm in aerodynamic diameter) of ambient aerosols from an urban (Oslo) and a suburban (Elverum) site in Norway, both influenced by small-scale wood burning. MAs are degradation products of cellulose and hemicellulose, and levoglucosan is especially emitted in high concentrations during pyrolysis and combustion of wood, making it a potential tracer of primary particles emitted from biomass burning. MAs were quantified using a novel high-performance liquid chromatography/ high-resolution mass spectrometry-time of flight method. This approach distinguishes between the isomeric compounds of MAs and benefits from the limited sample preparation required before analysis, and no extensive derivatization step is needed. The highest concentrations of levogucosan, galactosan, and mannosan (sigmaMA) were recorded in winter because of wood burning for residential heating (sigmaMA(MAX) = 1,240 ng m(-3)). This finding was substantiated by a relatively high correlation (R2 = 0.64) between the levoglucosan concentration and decreasing ambient temperature. At the suburban site, sigmaMA accounted for 3.1% of PM10, whereas the corresponding level at the urban site was 0.6%. The mass size distribution of MAs associated with atmospheric aerosols was measured using a Berner cascade impactor. The size distribution was characterized with a single mode at 561 nm. Ninety-five percent of the mass concentration of the MAs was found to be associated with particles < 2 micro.m. A preliminary attempt to estimate the contribution of wood burning to the mass concentration of PM10 in Oslo using levoglucosan as a tracer indicates that 24% comes from wood burning. This is approximately a factor of 2 lower than estimated by the AirQUIS dispersion model.     

Levoglucosan,a tracer for cellulose in biomass burning and atmospheric particles

The major organic components of smoke particles from biomass burning are monosaccharide derivatives from the breakdown of cellulose, accompanied by generally lesser amounts of straight-chain, aliphatic and oxygenated compounds and terpenoids from vegetation waxes, resins/gums, and other biopolymers. Levoglucosan and the related degradation products from cellulose can be utilized as specific and general indicator compounds for the presence of emissions from biomass burning in samples of atmospheric fine particulate matter. This enables the potential tracking of such emissions on a global basis. There are other compounds (e.g. amyrones, friedelin, dehydroabietic acid, and thermal derivatives from terpenoids and from lignin—syringaldehyde, vanillin, syringic acid, vanillic acid), which are additional key indicators in smoke from burning of biomass specific to the type of biomass fuel. The monosaccharide derivatives (e.g. levoglucosan) are proposed as specific indicators for cellulose in biomass burning emissions. Levoglucosan is emitted at such high concentrations that it can be detected at considerable distances from the original combustion source.     

Temporal variation and impact of wood smoke pollution on a residential area in southern Germany

This paper is a continuation of our previous publication (Bari, M.A., Baumbach, G., Kuch, B., Scheffknecht, G., 2009. Wood smoke as a source of particle-phase organic compounds in residential areas. Atmospheric Environment 43, 4722–4732) and describes a detailed characterisation of different particle-phase wood smoke tracer compounds in order to find out the impact of wood-fired heating on ambient PM₁₀ pollution in a residential area near Stuttgart in southern Germany. The results from previous flue gas measurements help distinguishing different tracer compounds in ambient PM₁₀ samples. In the residential area, significant amounts of hardwood markers (syringaldehyde, acetosyringone, propionylsyringol, sinapylaldehyde) and low concentrations of softwood markers (vanillin, acetovanillone, coniferyldehyde, dehydroabietic acid, retene) were found in the ambient air. The general wood combustion markers Levoglucosan, mannosan and galactosan were detected in high concentrations in all particle-phase PM₁₀ samples. To find out the size distribution of ambient particles, cascade impactor measurements were carried out. It was found that more than 70% of particulate matter was in the particle diameter of less than 1 μm. Using emission ratio of levoglucosan to PM₁₀, it can be demonstrated that during winter months 59% of ambient PM₁₀ pollution could be attributed to residential wood-fired heating.     

Chemical speciation,transport and contribution of biomass burning smoke to ambient aerosol in Guangzhou,a mega city of China

Intensive measurements of aerosol (PM₁₀) and associated water-soluble ionic and carbonaceous species were conducted in Guangzhou, a mega city of China, during summer 2006. Elevated levels of most chemical species were observed especially at nighttime during two episodes, characterized by dramatic build-up of the biomass burning tracers levoglucosan and non-sea-salt potassium, when the prevailing wind direction had changed due to two approaching tropical cyclones. High-resolution air mass back trajectories based on the MM5 model revealed that air masses with high concentrations of levoglucosan (43–473 ng m^?3) and non-sea-salt potassium (0.83–3.2 μg m^?3) had passed over rural regions of the Pearl River Delta and Guangdong Province, where agricultural activities and field burning of crop residues are common practices. The relative contributions of biomass burning smoke to organic carbon in PM₁₀ were estimated from levoglucosan data to be on average 7.0 and 14% at daytime and nighttime, respectively, with maxima of 9.7 and 32% during the episodic transport events, indicating that biomass and biofuel burning activities in the rural parts of the Pearl River Delta and neighboring regions could have a significant impact on ambient urban aerosol levels.     

Anhydrosugar and sugar alcohol organic markers associated with carboxylic acids in particulate matter from incense burning

Aerosol from the burning two types of sandalwood-based incense, Hsing Shan and Lao Shan, was analyzed to characterize the chemical profile of total particulate matter emitted. The total particulate matter (PM) mass emission factors were 46.3 ± 2.68 mg g^?1 of Hsing Shan incense and 43.7 ± 1.08 mg g^?1 of Lao Shan incense. Chemical analysis of emissions from the two types of incense revealed that of the 25 components in four groups characterized, anhydrosugars formed the major group, at 46.7–52.2% w/w of the identified particulate and 1078.3–1169.8 μg g^?1 of incense, followed by inorganic salts at 30.4–31.8% w/w of identified particulate and 681.6–734.0 μg g^?1 of incense, carboxylic acids at 12.0–17.1% w/w of the identified particulate and 268.6–392.8 μg g^?1 of incense, and sugar alcohols at 4.44–5.38% w/w of the identified particulate and 102.3–120.6 μg g^?1 of incense. More anhydrosugars and sugar alcohols were emitted from Lao Shan incense than from Hsing Shan incense whereas more carboxylic acids and organic salts were emitted from Hsing Shan than from Lao Shan. These differences were due to structural and functional differences in the young sandalwood used to make Hsing Shan and the aged sandalwood used to make Lao Shan. The anhydrosugar levoglucosan, used as a marker of biomass burning, was always the most abundant species in emitted PM for both incenses (Lao Shan 21.7 mg g^?1 of PM and Hsing Shan 18.7 mg g^?1). K⁺ and Cl^? were the second most abundant components (K⁺ and Cl^? were summed), accounting for 10.6 mg g^?1 of Hsing Shan PM and 9.85 mg g^?1 of Lao Shan PM. The most abundant carboxylic acids in the emissions were formic, acetic, succinic, glutaric and phthalic acid. The latter is a fragrance ingredient and a potential health hazard and was twice as prevalent in Lao Shan emissions. Xylitol was the most prevalent of the sugar alcohols at 35.7–36.6% w/w of total identified sugar alcohols. These abundant species are potential markers for incense burning. K⁺, levoglucosan, mannosan and xylitol are already reported in discriminator ratios for wood burning and it is proposed here that these can and should also apply to incense burning. The calculated discriminator ratios for two types of incense burning reported here are 0.229–0.288 for K/Levo, 12.5–13.5 for Levo/Manno, and 21.5–23.7 for the novel discriminator ratio Levo/Xylitol.     

Characterization and seasonal variations of levoglucosan in fine particulate matter in Xi’an,China

PM_2.5 (particulate matter with an aerodynamic diameter <2.5 μm) samples (n = 58) collected every sixth day in Xi’an, China, from 5 July 2008 to 27 June 2009 are analyzed for levoglucosan (1,6-anhydro-β-d-glucopyranose) to evaluate the impacts of biomass combustion on ambient concentrations. Twenty-four-hour levoglucosan concentrations displayed clear summer minima and winter maxima that ranged from 46 to 1889 ng m^?3, with an average of 428 ± 399 ng m^?3. Besides agricultural burning, biomass/biofuel combustion for household heating with straws and branches appears to be of regional importance during the heating season in northwestern China. Good correlations (0.70 < R < 0.91) were found between levoglucosan relative to water-soluble K⁺, Cl^?, organic carbon (OC), elemental carbon (EC), and glyoxal. The highest levoglucosan/OC ratio of 2.3% was found in winter, followed by autumn (1.5%). Biomass burning contributed to 5.1–43.8% of OC (with an average of 17.6 ± 8.4%).

Implications:?PM_2.5 levoglucosan concentrations and the correlation between levoglucosan relative to other compounds during four seasons in Xi’an showed that the influence of biomass burning is maximum during the residential heating season (winter), although some important influences may be detected in spring (field preparation burnings) and autumn (corn stalks and wheat straw burning, fallen dead leaves burning) at Xi’an and surrounding areas. Household heating with biomass during winter was quite widespread in Guanzhong Plain. Therefore, the control of biomass/biofuel combustion could be an effective method to reduce pollutant emission on a regional scale.     

Wood smoke as a source of particle-phase organic compounds in residential areas

The objective of this study was to investigate the organic composition of wood smoke emissions and ambient air samples in order to determine the wood smoke contribution to the ambient air pollution in the residential areas. From November 2005 to March 2006 particle-phase PM₁₀ samples were collected in the residential town Dettenhausen surrounded by forests near Stuttgart in southern Germany. Samples collected on pre-baked glass fibre filters were extracted using toluene with ultrasonic bath and analysed by gas chromatography mass spectrometry (GC-MS). 21 polycyclic aromatic hydrocarbons (PAH) including 16 USEPA priority pollutants, different organic wood smoke tracers, primarily 21 species of syringol and guaiacol derivatives, levoglucosan and its isomers mannosan, galactosan and dehydroabietic acid were detected and quantified in this study. The concentrations of these compounds were compared with the fingerprints of emissions from hardwood and softwood combustion carried out in test facilities at Universitaet Stuttgart and field investigations at a wood stove during real operation in Dettenhausen. It was observed that the combustion derived PAH was detected in higher concentrations than other PAH in the ambient air PM₁₀ samples. Syringol and its derivatives were found in large amounts in hardwood burning but were not detected in softwood burning emissions. On the other hand, guaiacol and its derivatives were found in both softwood and hardwood burning emissions, but the concentrations were higher in the softwood smoke compared to hardwood smoke. So, these compounds can be used as typical tracer compounds for the different types of wood burning emissions. In ambient air samples both syringol and guaiacol derivatives were found which indicates the wood combustion contribution to the PM load in such residential areas. Levoglucosan was detected in high concentrations in all ambient PM₁₀ samples. A source apportionment modelling, Positive Matrix Factorization (PMF) was implemented to quantify the wood smoke contribution to the ambient PM₁₀ bound organic compounds in the residential area.     

Influence of combustion conditions on yields of solvent-extractable anhydrosugars and lignin phenols in chars: Implications for characterizations of biomass combustion residues

Anhydrosugars, such as levoglucosan and its isomers (mannosan, galactosan), as well as the solvent-extractable lignin phenols (methoxylated phenols) are thermal degradation products of cellulose/hemicellulose and lignin, respectively. These two groups of biomarkers are often used as unique tracers of combusted biomass inputs in diverse environmental media. However, detailed characterization of the relative proportion and signatures of these compounds in highly heterogeneous plant-derived chars are still scarce. Here we conducted a systematic study to investigate the yields of solvent-extractable anhydrosugars and lignin phenols in 25 lab-made chars produced from different plant materials under different combustion conditions. Solvent-extractable anhydrosugars and lignin phenols were only observed in chars formed below 350 °C and yields were variable across different combustion temperatures. The yields of mannosan (M) and galactosan (G) decreased more rapidly than those of levoglucosan (L) under increasing combustion severity (temperature and duration), resulting in variable L/M and L/(M + G) ratios, two diagnostic ratios often used for identification of combustion sources (e.g. hardwoods vs. softwoods vs. grasses). Our observations thus may provide an explanation for the wide ranges of values reported in the literature for these two ratios. On the other hand, the results of this study suggest that the ratios of the major solvent-extractable lignin phenols (vanillyls (V), syringyls (S), cinnamyls (C)) provide additional source reconstruction potential despite observed variations with combustion temperature. We thus propose using a property-property plot (L/M vs. S/V) as an improved means for source characterization of biomass combustion residues. The L/M-S/V plot has shown to be effective in environmental samples (soil organic matter, atmospheric aerosols) receiving substantial inputs of biomass combustion residues.     

Water-soluble organic compounds at a mountain-top site in Colorado,USA

Water extracts of atmospheric particulate matter (PM_2.5) collected at the Storm Peak Laboratory (SPL) (3210 MSL, 40.45° N, 106.74° W) were analyzed for a wide variety of polar organic compounds. The unique geographical character of SPL allows for extended observations/sampling of the free tropospheric interface. Under variable meteorological conditions between January 9th and January14th 2007, the most abundant compounds were levoglucosan (9–72 ng m^?3), palmitic acid (10–40 ng m^?3) and succinic acid (18–27 ng m^?3). Of 84 analytes included in the GC–MS method, over 50 individual water extractable polar organic compounds (POC) were present at concentrations greater than 0.1 ng m^?3. During a snow event (Jan. 11th–13th), the concentrations of several presumed atmospheric transformation compounds (dicarboxylic acids) were reduced. Lower actinic flux, reduced transport distance, and ice crystal scavenging may explain this variability. Diurnal averages over the sampling period revealed a higher total concentration of water extractable POC at night, 211 ng m^?3 (105–265 ng m^?3), versus day, 160 ng m^?3 (137–205 ng m^?3), which suggests a more aged nighttime aerosol character. This may be due to the increased daytime convective mixing of local primary emissions from the Yampa Valley. XAD resin extracts revealed a gas-phase partitioning of several compounds, and analysis of cloud water collected at this site in 2002 revealed a similar compound abundance trend. Levoglucosan, a wood smoke tracer was generally found to be the most abundant compound in both aerosol and cloud water samples. Variations in meteorological parameters and local/regional transport analysis play an important interpretive role in understanding these results.     

Long-range transport episodes of fine particles in southern Finland during 1999–2007

The frequency, strength and sources of long-range transport (LRT) episodes of fine particles (PM_2.5) were studied in southern Finland using air quality monitoring results, backward air mass trajectories, remote sensing of fire hot spots, transport and dispersion modelling of smoke and chemical analysis of particle samples (black carbon, monosaccharide anhydrides, oxalate, succinate, malonate, SO₄^2?, NO₃^?, K⁺ and NH₄⁺). At an urban background site in Helsinki, the daily WHO guideline value (24-h PM_2.5 mean 25 μg m^?3) was exceeded during 1–7 LRT episodes per year in 1999–2007. The 24-h mean maximum concentrations varied between 25 and 49 μg m^?3 during the episodes, which was 3–6 times higher than the local mean concentration (8.7 μg m^?3) in 1999–2007. The highest particle concentrations (max. 1-h mean 163 μg m^?3) and the longest episodes (max. 9 days) were mainly caused by the emissions from open biomass burning, especially during springs and late-summers in 2002 and 2006. During the period 2001–2007, the satellite remote sensing of active fire hot spots and transport and dispersion modelling of smoke indicated that approximately half of the episodes were caused partly by the emissions from wildfires and/or agricultural waste burning in fields in Eastern Europe, especially in Russia, Belarus and Ukraine. Other episodes were mainly caused by the LRT of ordinary anthropogenic pollutants, e.g. from energy production, traffic, industry and wood combustion. During those ‘other episodes’, air masses also arrived from Eastern Europe, including Poland. The highest concentrations of biomass-burning tracers, such as monosaccharide anhydrides (levoglucosan + mannosan + galactosan) and K⁺, were observed during open biomass-burning episodes, but quite high values were also measured during some winter episodes due to wood combustion emissions. Our results indicate that open biomass burning in Eastern Europe causes high fine particle concentration peaks in large areas of Europe almost every year.     

Aerosol transport model evaluation of an extreme smoke episode in Southeast Asia

Biomass burning is one of many sources of particulate pollution in Southeast Asia, but its irregular spatial and temporal patterns mean that large episodes can cause acute air quality problems in urban areas. Fires in Sumatra and Borneo during September and October 2006 contributed to 24-h mean PM₁₀ concentrations above 150 μg m^?3 at multiple locations in Singapore and Malaysia over several days. We use the FLAMBE model of biomass burning emissions and the NAAPS model of aerosol transport and evolution to simulate these events, and compare our simulation results to 24-h average PM₁₀ measurements from 54 stations in Singapore and Malaysia. The model simulation, including the FLAMBE smoke source as well as dust, sulfate, and sea salt aerosol species, was able to explain 50% or more of the variance in 24-h PM₁₀ observations at 29 of 54 sites. Simulation results indicated that biomass burning smoke contributed to nearly all of the extreme PM₁₀ observations during September–November 2006, but the exact contribution of smoke was unclear because the model severely underestimated total smoke emissions. Using regression analysis at each site, the bias in the smoke aerosol flux was determined to be a factor of between 2.5 and 10, and an overall factor of 3.5 was estimated. After application of this factor, the simulated smoke aerosol concentration averaged 20% of observed PM₁₀, and 40% of PM₁₀ for days with 24-h average concentrations above 150 μg m^?3. These results suggest that aerosol transport models can aid analysis of severe pollution events in Southeast Asia, but that improvements are needed in models of biomass burning smoke emissions.     

Emission factors and particulate matter size distribution of polycyclic aromatic hydrocarbons from residential coal combustions in rural Northern China

Coal consumption is one important contributor to energy production, and is regarded as one of the most important sources of air pollutants that have considerable impacts on human health and climate change. Emissions of polycyclic aromatic hydrocarbons (PAHs) from coal combustion were studied in a typical stove. Emission factors (EFs) of 16 EPA priority PAHs from tested coals ranged from 6.25 ± 1.16 mg kg^?1 (anthracite) to 253 ± 170 mg kg^?1 (bituminous), with NAP and PHE dominated in gaseous and particulate phases, respectively. Size distributions of particulate phase PAHs from tested coals showed that they were mostly associated with particulate matter (PM) with size either between 0.7 and 2.1 μm or less than 0.4 μm (PM_0.4). In the latter category, not only were more PAHs present in PM_0.4, but also contained higher fractions of high molecular weight PAHs. Generally, there were more than 89% of total particulate phase PAHs associated with PM_2.5. Gas-particle partitioning of freshly emitted PAHs from residential coal combustions were thought to be mainly controlled by absorption rather than adsorption, which is similar to those from other sources. Besides, the influence of fuel properties and combustion conditions was further investigated by using stepwise regression analysis, which indicated that almost 57 ± 10% of total variations in PAH EFs can be accounted for by moisture and volatile matter content of coal in residential combustion.     

Chemical composition of aerosols during a major biomass burning episode over northern Europe in spring 2006: Experimental and modelling assessments

The long-range transported smokes emitted by biomass burning had a strong impact on the PM_2.5 mass concentrations in Helsinki over the 12 days period in April and May 2006. To characterize aerosols during this period, the real-time measurements were done for PM_2.5, PM_2.5–10, common ions and black carbon. Moreover, the 24-h PM₁ filter samples were analysed for organic and elemental carbon (OC and EC), water-soluble organic carbon (WSOC), ions and levoglucosan. The Finnish emergency and air quality modelling system SILAM was used for the forecast of the PM_2.5 concentration generated by biomass burning. According to the real-time PM_2.5 data, the investigated period was divided into four types of PM situations: episode 1 (EPI-1; 25–29 April), episode 2 (EPI-2; 1–5 May), episode 3 (EPI-3; 5–6 May) and a reference period (REF; 24 March–24 April). EPI-3 included a local warehouse fire and therefore it is discussed separately. The PM₁ mass concentrations of biomass burning tracers—levoglucosan, potassium and oxalate—increased during the two long-range transport episodes (EPI-1 and EPI-2). The most substantial difference between the episodes was exhibited by the sulphate concentration, which was 4.9 (±1.4) μg m⁻³ in EPI-2 but only 2.4 (±0.31) μg m⁻³ in EPI-1 being close to that of REF (1.8±0.54 μg m⁻³). The concentration of particulate organic matter in PM₁ was clearly higher during EPI-1 (11±3.3 μg m⁻³) and EPI-2 (9.7±4.0 μg m⁻³) than REF (1.3±0.45 μg m⁻³). The long-range transported smoke had only a minor impact on the WSOC-to-OC ratio. According to the model simulations, MODIS detected the fires that caused the first set of concentration peaks (EPI-1) and the local warehouse fire (EPI-3), but missed the second one (EPI-2) probably due to dense frontal clouds.     

Emission factors and exposures from ground-level pyrotechnics

Potential exposures from ground-level pyrotechnics were assessed by air monitoring and developing emission factors. Total particulate matter, copper and SO₂ exposures exceeded occupational health guidelines at two outdoor performances using consumer pyrotechnics. Al, Ba, B, Bi, Mg, Sr, Zn, and aldehyde levels were elevated, but did not pose a health hazard based on occupational standards. Emission factors for total particulate matter, metals, inorganic ions, aldehydes, and polyaromatic hydrocarbons (PAHs) were determined for seven ground-supported pyrotechnics through air sampling in an airtight room after combustion. Particle generation ranged from 5 to 13% of the combusted mass. Emission factors (g Kg^?1) for metals common to pyrotechnics were also high: K, 23–45; Mg, 1–7; Cu, 0.05–7; and Ba, 0.03–6. Pb emission rates of 1.6 and 2.7% of the combusted mass for two devices were noteworthy. A high correlation (r² ≥ 0.89) between metal concentrations in pyrotechnic compositions and emission factors were noted for Pb, Cr, Mg, Sb, and Bi, whereas low correlations (r² ≤ 0.1) were observed for Ba, Sr, Fe, and Zn. This may be due to the inherent heterogeneity of multi-effect pyrotechnics. The generation of inorganic nitrogen in both the particulate (NO₂^?, NO₃^?) and gaseous (NO, NO₂) forms varied widely (<0.1–1000 mg Kg^?1). Aldehyde emission factors varied by two orders of magnitude even though the carbon source was carbohydrates and charcoal for all devices: formaldehyde (<7.0–82 mg Kg^?1), acetaldehyde (43–210 mg Kg^?1), and acrolein (1.9–12 mg Kg^?1). Formation of lower molecular weight PAHs such as naphthalene and acenaphthylene were favored, with their emission factors being comparable to that from the combustion of household refuse and agricultural debris. Ba, Sr, Cu, and Pb had emission factors that could produce exposures exceeding occupational exposure guidelines. Sb and unalloyed Mg, which are banned from consumer fireworks in the US, were present in significant amounts.     

Biomass burning as the main source of organic aerosol particulate matter in Malaysia during haze episodes

The haze episodes that occurred in Malaysia in September-October 1991, August-October 1994 and September-October 1997 have been attributed to suspended smoke particulate matter from biomass burning in southern Sumatra and Kalimantan, Indonesia. In the present study, polar organic compounds in aerosol particulate matter from Malaysia are converted to their trimethylsilyl derivatives and analyzed by gas chromatography-mass spectrometry in order to better assess the contribution of the biomass burning component during the haze episodes. On the basis of this analysis, levoglucosan was found to be the most abundant organic compound detected in almost all samples. The monosaccharides, alpha- and beta-mannose, the lignin breakdown products, vanillic and syringic acids and the minor steroids, cholesterol and beta-sitosterol were also present in some samples. The presence of the tracers from smoke overwhelmed the typical signatures of emissions from traffic and other anthropogenic activities in the urban areas.     

Characterization of organic compounds and molecular tracers from biomass burning smoke in South China I: Broad-leaf trees and shrubs

Biomass burning smoke constituents are worthy of concern due to its influence on climate and human health. The organic constituents and distributions of molecular tracers emitted from burning smoke of six natural vegetations including monsoon evergreen broad-leaf trees and shrubs in South China were determined in this study. The gas and particle samples were collected and analyzed by gas chromatography–mass spectrometry. The major organic components in these smoke samples are methoxyphenols from lignin and saccharides from cellulose. Polycyclic aromatic hydrocarbons (PAHs) are also present as minor constituents. Furanose, pyranose and their dianhydrides are the first reported in the biomass burning smoke. Some unique biomarkers were detected in this study which may be useful as specific tracers. The corresponding tracer/OC ratios are used as indicators for the two types of biomass burning. U/R (1.06–1.72) in the smoke samples may be used as parameters to distinguish broad-leaf trees and shrubs from fossil fuel. Other useful diagnostic ratios such as methylphenanthrene to phenanthrene (MPhe/Phe), phenanthrene to phenanthrene plus anthracene (Phe/(Phe + Ant)) and fluoranthene to fluoranthene plus pyrene (Flu/(Flu + Pyr)) and octadecenoic acid/OC are also identified in this study. These results are useful in efforts to better understand the emission characterization of biomass burning in South China and the contribution of regional biomass burning to global climate change.     

Physical characterization of the fine particle emissions from commercial aircraft engines during the Aircraft Particle Emissions eXperiment (APEX) 1–3

The fine particulate matter (PM) emissions from nine commercial aircraft engine models were determined by plume sampling during the three field campaigns of the Aircraft Particle Emissions Experiment (APEX). Ground-based measurements were made primarily at 30 m behind the engine for PM mass and number concentration, particle size distribution, and total volatile matter using both time-integrated and continuous sampling techniques. The experimental results showed a PM mass emission index (EI) ranging from 10 to 550 mg kg^?1 fuel depending on engine type and test parameters as well as a characteristic U-shaped curve of the mass EI with increasing fuel flow for the turbofan engines tested. Also, the Teflon filter sampling indicated that ～40–80% of the total PM mass on a test-average basis was comprised of volatile matter (sulfur and organics) for most engines sampled. The number EIs, on the other hand, varied from ～10¹⁵ to 10¹⁷ particles kg^?1 fuel with the turbofan engines exhibiting a logarithmic decay with increasing fuel flow. Finally, the particle size distributions of the emissions exhibited a single primary mode that were lognormally distributed with a minor accumulation mode also observed at higher powers for all engines tested. The geometric (number) mean particle diameter ranged from 9.4 to 37 nm and the geometric standard deviation ranged from 1.3 to 2.3 depending on engine type, fuel flow, and test conditions.