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Abstract

Although particulate emissions from residential wood burning have become a subject of great scientific concern for a few years, data related to their impact on the air quality of large European urban centres are still missing. In the present study, we investigated the chemical and optical properties of fine (PM2.5) carbonaceous aerosols in Paris during the 2005 winter season in order to track the presence of wood burning emissions in such a large city. The use of a seven wavelength Aethalometer allowed us to document shortwave light absorption by brown-carbon-containing organic aerosols of biomass burning origin. In particular, a well-marked diurnal pattern of the spectral dependence of light absorption, with maxima during the night, could be observed every day of the campaign and attributed to wood burning emissions. Relatively high absorption Ångstrom exponents and WSOC/OC ratios (respectively 1.25 and 0.35 on average for the period of study) also indicated the importance of biomass burning aerosols in the Paris atmosphere in winter. Finally, a rough estimate of the contribution of wood burning carbonaceous aerosols to PM2.5 could be achieved. This contribution was found to be as high as 20 ± 10% on average at the Paris background site investigated here.

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... Globally, open biomass burning (e.g., fire emissions) was reported as an important BrC source (Saleh et al., 2015). In particular, residential wood burning -which is now recognized as a predominant wintertime OA source in Western Europe within emission inventories (Denier van der Gon et al., 2015) -has been assessed as a major source of BrC at various urban (Favez et al., 2009;Moschos et al., 2018;Zhang et al., 2018) and rural (Golly et al., 2019) environments. Moreover, a growing number of studies are also indicating significant contributions of secondary organic aerosols (SOA) to BrC concentrations, while comprehensive source apportionment exercises of light absorbing OA are still needed Gilardoni et al., 2016;Kumar et al., 2018;Lambe et al., 2013;Moise et al., 2015;Moschos et al., 2018;Xie et al., 2020). ...
... Furthermore, the diel variations of brown carbon (see Fig. 3)which are characterized by evident late evening peaks at all sampling sitescould further support important contribution of local emissions to brown carbon. These diel cycle patterns is also consistent with the variations of wood-burning aerosols (e.g., BBOA and eBC wb ) reported by some previous studies at various sites during cold months in France (Favez et al., 2009;Favez et al., 2010;Languille et al., 2020;Weber et al., 2019;Zhang et al., 2019), as well as the funding in this study (see Fig. 6). Interestingly, the BrC PSCF patterns described above seems coherent with the spatialized emission inventories available for residential wood burning in France (Denier van der Gon et al., 2015). ...
Article
Brown carbon (BrC) is known to absorb light at subvisible wavelengths but its optical properties and sources are still poorly documented, leading to large uncertainties in climate studies. Here, we show its major wintertime contribution to total aerosol absorption at 370 nm (18–42%) at 9 different French sites. Moreover, an excellent correlation with levoglucosan (r² = 0.9 and slope = 22.2 at 370 nm), suggesting important contribution of wood burning emissions to ambient BrC aerosols in France. At all sites, BrC peaks were mainly observed during late evening, linking to local intense residential wood burning during this time period. Furthermore, the geographic origin analysis also highlighted the high potential contribution of local and/or small-regional emissions to BrC. Focusing on the Paris region, twice higher BrC mass absorption efficiency value was obtained for less oxidized biomass burning organic aerosols (BBOA) compared to more oxidized BBOA (e.g., about 4.9 ± 0.2 vs. 2.0 ± 0.1 m² g⁻¹, respectively, at 370 nm). Finally, the BBOA direct radiative forcing effect was found to be 40% higher when these two fractions are treated as light-absorbing species, compared to the non-absorbing BBOA scenario.
... This is a useful property for the separation of fossil fuel and biomass burning contributions to ambient BC concentrations, through application of the Aethalometer model for example (Sandradewi et al., 2008a). This model was first used to estimate the relative contribution of fossil fuel and biomass burning contributions to ambient BC mass concentrations at sites in Europe impacted by residential wood combustion emissions (Sandradewi et al., 2008a(Sandradewi et al., , 2008bFavez et al., 2009Favez et al., , 2010Herich et al., 2011;Sciare et al., 2011). However, the model has seen increased use in recent years, as Aethalometer instrumentation coverage increases globally (Tiwari et al., 2015;Briggs and Long, 2016;Healy et al., 2017;Helin et al., 2018;Mousavi et al., 2018Mousavi et al., , 2019Zheng et al., 2019). ...
... However, in the work of Zotter et al. (2017) all measurements were performed in Switzerland, where residential wood combustion is the dominant biomass burning BC source. AAE values for biomass burning aerosol vary depending on the fuel burned, the efficiency of combustion and the extent of atmospheric processing (Favez et al., 2009;Sciare et al., 2011;Saleh et al., 2013;Fuller et al., 2014;McMeeking et al., 2014;Forrister et al., 2015;Teich et al., 2017;Helin et al., 2018;Bhattarai et al., 2018;Cappa et al., 2019;Satish and Rastogi, 2019). In the absence of radiocarbon measurements in this work to constrain AAE, we applied AAE values of 0.9 and 2.09 to the hourly averaged absorption data collected at each site. ...
Article
Exposure to wildfire smoke is a public health issue of increasing prominence in North America, particularly in western states and provinces. In this study, Aethalometer data collected at six sites in the Lower Fraser Valley (LFV), British Columbia, from September 2016 through August 2017 were analyzed to investigate the relative importance of fossil fuel and biomass burning contributions to black carbon (BC) in the region. Annual mean BC mass concentrations were in the range 0.3–0.8 μg m⁻³, and BC was apportioned to fossil fuel and biomass burning sources at hourly resolution using the dual-wavelength Aethalometer model, applying a typical a priori assumed biomass burning Absorption Ångström Exponent (AAE) value close to 2. However, this approach was found to underestimate biomass contributions to BC mass by up to a factor of three during wildfire events that impacted air quality throughout the region in July and August 2017. Hourly resolution PM2.5 concentrations in excess of 100 μg m⁻³ were recorded at multiple sites and mean ambient PM2.5 concentrations for the wildfire smoke periods were up to nine times higher than mean concentrations for the remainder of the summer. A background extraction approach was applied to optimize BC source apportionment during these events and to enable the calculation of wildfire aerosol AAE, with similar values for the latter determined across all six sites (1.35 ± 0.09). The relatively low AAE values observed suggest that evaporation and/or photobleaching of brown carbon occurred during transport of wildfire aerosol to the receptor sites. From an exposure perspective, for the sites investigated, up to 69 ± 20% (±1σ) of ambient BC is attributed to wildfires during these events. On an annual scale, however, fossil fuel combustion and residential/agricultural biomass burning are estimated to be more important contributors to ambient BC mass concentrations at every site.
... That slope was very similar to reported ratios (10.3-10.8) of wood-burning organics to levoglucosan (Sciare et al., 2011;Favez et al., 2010), while Harrison et al. (2012) used a similar conversion PM 2.5 /Lev factor of 11.2 to estimate PM 2.5 -BB concentrations in UK cities. However, the slope value in Ioannina was lower (7.88 ± 0.31) (Fig. 5a), likely attributed to limited oxidation of levoglucosan and to low PM 2.5 contributions from sources other than BB, opposite to that found in Greek and European cities (Favez et al., 2009;Costabile et al., 2017;Grivas et al., 2018). Therefore, a lower (PM 2.5 /Lev) BB ratio in the order of 8, like in Ioannina, could be suggested for sites highly impacted by local fresh hardwood burning and low contributions from other sources. ...
... Since gas-phase photo-oxidation of levoglucosan was shown to be limited in Ioannina, heterogeneous reactions on cloud droplets or fog should be considered. Even lower WSOC/OC values (0.35-0.40) were found in Paris (Favez et al., 2009;Sciare et al., 2011) and Beijing (Cheng et al., 2016) during wintertime. Furthermore, the WSOC/OC fractions were much higher than those reported for vehicular emissions (Yan et al., 2015), suggesting higher solubility for fast-oxidized BB aerosols. ...
Article
This study examines the concentrations and characteristics of carbonaceous aerosols (including saccharides) and inorganic species measured by PM2.5 filter sampling and a multi-wavelength Aethalometer during two campaigns in a mountainous, medium-sized, Greek city (Ioannina). The first campaign was conducted in summer and used as a baseline of low concentrations, while the second took place in winter under intensive residential wood burning (RWB) emissions. Very high winter-mean OC concentrations (26.0 μg m⁻³) were observed, associated with an OC/EC ratio of 9.9, and mean BCwb and PM2.5 levels of 4.5 μg m⁻³ and 57.5 μg m⁻³, respectively. Simultaneously, record-high levoglucosan (Lev) concentrations (mean: 6.0 μg m⁻³; max: 15.9 μg m⁻³) were measured, revealing a severely biomass burning (BB)-laden environment. The water-soluble OC component (WSOC) accounted for 56 ± 9% of OC in winter, exhibiting high correlations (R² = 0.93–0.97) with BB tracers (nss-K⁺, BCwb, Lev), nitrate and light absorption, potentially indicating the formation of water-soluble brown carbon (BrC) from fast oxidation processes. The examination of diagnostic ratios involving BB tracers indicated the prevalence of hardwood burning, while the mean Lev/OC ratio (22%) was remarkably higher than literature values. Applying a mono-tracer method based on levoglucosan, we estimated very high BB contributions to OC (∼92%), EC (∼64%) and WSOC (∼87%) during winter. On the contrary, low levels were registered during summer for all carbonaceous components, with winter/summer ratios of 4–5 for PM2.5 and BC, 10 for OC, 30 for BCwb and ∼1100 for levoglucosan. The absence of local BB sources in summer, combined with the photochemical processing and aging of regional organic aerosols, resulted in higher WSOC/OC fractions (64 ± 13%). The results indicate highly soluble fine carbonaceous aerosol fraction year-round, which when considered alongside the extreme concentration levels in winter can have important implications for short- and long-term health effects.
... By contrast, AE33 can provide direct information on solid fuel and liquid fuel combustions. Indeed, for French urban environments, eBCff has been shown to be predominantly related to road transport emissions, while eBCwb is mainly originating from wood burning for residential heating in cold seasons [50], [51]. These fractions can then be used to estimate PM loadings that may be attributable to both sources (i.e., PMff and PMwb, respectively), using conversion factors such as: PMff = a x eBCff and PMwb = b x eBCwb, where a and b can be retrieved from the literature and/or further site-specific a priori knowledge. ...
... Wood burning has been described as a major source of wintertime PM pollution in some of the largest French cities for more than ten years [50], [51], [72], [73]. Yet, it is still a subject of great scientific and political concern, notably due to possible conflicting interest in policy strategies promoting the use of renewable energies. ...
Preprint
Full-text available
The CARA program has been developed since 2008 by the French reference laboratory for air quality monitoring (LCSQA) and the regional monitoring networks to gain a better knowledge at the national level on the particulate matter (PM) chemistry and its diverse origins in urban environments. It results of strong collaborations with international-level academic partners, allowing to bring state-of-the-art, straightforward and robust results and methodologies within operational air quality stakeholders (and subsequently, decision makers). Here, we illustrate some of the main outputs obtained over the last decade thanks to this program, regarding methodological aspects (both in terms of measurement techniques and data treatment procedures) as well as acquired knowledge on the predominant PM sources. Offline and online methods are used following well-suited quality assurance and quality control procedures, notably including inter-laboratory comparison exercises. Source apportionment studies are conducted using various receptor modeling approaches. Overall, the results presented herewith underline the major influences of residential wood burning (during the cold period) and road transport emissions (exhaust and non-exhaust ones, all along the year), as well as substantial contributions of mineral dust and primary biogenic particles (mostly during the warm period). Long-range transport phenomena, e.g., advection of secondary inorganic aerosols from the European continental sector and of Saharan dust into the French West Indies, are also discussed in this paper. Finally, we briefly address the use of stable isotope measurements (δ15N) and of various organic molecular markers for a better understanding of the origins of ammonium and of the different organic aerosol fractions, respectively.
... The estimated AAE average (1.3 ± 0.7) represents urban pollution (Backman et al., 2014); including biofuel-burning aerosols (Srivastava et al., 2012;Stockwell et al., 2016;Dumka et al., 2018;Liakakou et al., 2020). Favez et al. (2009) also found a similar AAE value (1.25) which was associated with domestic solid-fuel combustion particles. ...
... The analysis of AAE is wavelength pair-specific (Favez et al., 2009;Dumka et al, 2018). For instance, AAE values measured at short wavelengths are relatively higher (AAE >1.5) than those measured at longer wavelengths (Fig. 7), indicating the significant contributions of BrC possibly from wood/biomass burning and agricultural waste. ...
Article
Full-text available
Light-absorbing aerosols, particularly black carbon (BC), have significant impacts on human health and the climate. They are also the least-studied fraction of atmospheric particles, particularly in residential areas of southern Africa. The optical characteristics of ground-based light-absorbing aerosols from Kwadela Township in South Africa are investigated in this study. Daily averaged ambient PM2.5 highest levels were 51.39 µg m–3 and 32.18 µg m–3, whereas hourly averages peaked at 61.31 µg m–3 and 34.69 µg m–3 during winter and summer, respectively. Levels of daily averaged light-absorbing aerosols were 2.9 times higher (1.89 ± 0.5 µg m–3) in winter 2014 than in summer 2015 (0.66 ± 0.2 µg m–3). In both seasons, hourly averaged levels showed bimodal diurnal cycles, which correlated with the PM2.5 diurnal patterns that indicated distinct peaks in the morning and evening. These diurnal cycle peak periods corresponded with the times of increased solid domestic fuel usage, road traffic, and also shallower boundary layer. On average, light-absorbing aerosols contributed a larger proportion of total ambient PM2.5 levels in winter (6.5 ± 1.0%) than in summer (3.4 ± 1.0%). The winter average Absorption Ångstrӧm exponent AAE(370/880 nm) (1.7± 0.5), indicated the dominance of brown carbon (BrC) from biofuel/biomass burning and/or low-quality coal combustion emissions. In summer, the average AAE(370/950 nm) (1.3 ± 0.7), suggested the presence of BC and BrC in the mornings and evenings possibly from fossil fuel combustion sources. At midday and at night in summer, the AAE was close to 1, suggesting more BC contributions from sources such as diesel emissions during this time. A combination of BC and BrC particulates dominated on 50% and 5% of the summer days, respectively, whereas fresh BC were only measured in summer days (23%). Residential solid-fuel and/biomass combustion are important sources of light-absorbing aerosols in this study region, with concomitant human health and environmental impacts.
... By contrast, AE33 can provide direct information on solid fuel and liquid fuel combustions. Indeed, for French urban environments, eBCff has been shown to be predominantly related to road transport emissions, while eBCwb mainly originates from wood burning for residential heating in cold seasons [50,51]. These fractions can then be used to estimate PM loadings that may be attributable to both sources (i.e., PMff and PMwb,, respectively), using conversion factors, such as: PMff = a × eBCff and PMwb = b × eBCwb, where a and b can be retrieved from the literature and/or further site-specific a priori knowledge. ...
... Wood burning has been described as a major source of wintertime PM pollution in some of the largest French cities for more than ten years [50,51,72,73]. Yet, it is still a subject of great scientific and political concern, notably due to possible conflicting interest in policy strategies promoting the use of renewable energies. ...
Article
Full-text available
The CARA program has been running since 2008 by the French reference laboratory for air quality monitoring (LCSQA) and the regional monitoring networks, to gain better knowledge—at a national level—on particulate matter (PM) chemistry and its diverse origins in urban environments. It results in strong collaborations with international-level academic partners for state-of-the-art, straightforward, and robust results and methodologies within operational air quality stakeholders (and subsequently, decision makers). Here, we illustrate some of the main outputs obtained over the last decade, thanks to this program, regarding methodological aspects (both in terms of measurement techniques and data treatment procedures) as well as acquired knowledge on the predominant PM sources. Offline and online methods are used following well-suited quality assurance and quality control procedures, notably including inter-laboratory comparison exercises. Source apportionment studies are conducted using various receptor modeling approaches. Overall, the results presented herewith underline the major influences of residential wood burning (during the cold period) and road transport emissions (exhaust and non-exhaust ones, all throughout the year), as well as substantial contributions of mineral dust and primary biogenic particles (mostly during the warm period). Long-range transport phenomena, e.g., advection of secondary inorganic aerosols from the European continental sector and of Saharan dust into the French West Indies, are also discussed in this paper. Finally, we briefly address the use of stable isotope measurements (δ15N) and of various organic molecular markers for a better understanding of the origins of ammonium and of the different organic aerosol fractions, respectively.
... Previous studies focused on the impact of wood burning on air quality in Île-de-France, which unanimously highlighted the significance of this source. For instance, Favez et al. (2009) demonstrated that carbonaceous aerosols from wood burning represent on average 20 % of the total PM 2.5 in Paris city during the winter season. Similar wintertime contributions to PM 2.5 (22-24 %) were obtained by Bressi et al. (2014) at different locations across Île-de-France. ...
... The 7-wavelength measurements not only allowed us to estimate total black carbon concentrations but also to roughly apportion the contribution of the two major BC sources: fossil fuel and biomass burning (Drinovec et al., 2015). This source apportionment model was developed by Sandradewi et al. (2008) and was successfully used in numerous studies afterwards (e.g., Favez et al., 2009;Sciare et al., 2011;Petit et al., 2014Petit et al., , 2015Kalogridis et al., 2018). Based on these studies, the two BC fractions were used here as tracers for traffic (BC traffic ) and wood burning (BC wb ) emissions, respectively. ...
Article
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Wood burning is widely used for domestic heating and has been identified as a ubiquitous pollution source in urban areas, especially during cold months. The present study is based on a three and a half winter months field campaign in the Paris region measuring Volatile Organic Compounds (VOCs) by Proton Transfer Reaction Mass Spectrometry (PTR-MS) in addition to Black Carbon (BC). Several VOCs were identified as strongly wood burning-influenced (e.g., acetic acid, furfural), or traffic-influenced (e.g., toluene, C8-aromatics). Methylbutenone, benzenediol and butandione were identified for the first time as wood burning-related in ambient air. A Positive Matrix Factorization (PMF) analysis highlighted that wood burning is the most important source of VOCs during the winter season. (47%). Traffic was found to account for about 22% of the measured VOCs during the same period, whereas solvent use plus background accounted altogether for the remaining fraction. The comparison with the regional emission inventory showed good consistency for benzene and xylenes but revisions of the inventory should be considered for several VOCs such as acetic acid, C9-aromatics and methanol. Finally, complementary measurements acquired simultaneously at other sites in Île-de-France (the Paris region) enabled evaluation of spatial variabilities. The influence of traffic emissions on investigated pollutants displayed a clear negative gradient from roadside to suburban stations, whereas wood burning pollution was found to be fairly homogeneous over the region.
... Based on these differences in optical properties, a growing number of studies recently used multi-wavelength Aethalometers to detect and/or apportion wood burning carbonaceous aerosols in ambient air (e.g. Jeong et al., 2004;Sandradewi et al., 2008aSandradewi et al., , 2008bYang et al., 2009;Favez et al., 2009). In particular, Sandradewi et al. (2008b) introduced a methodology to quantitatively assess the contribution of wood burning and fossil fuel to the absorption coefficients (babs) measured by a multi-wavelength Aethalometer. ...
Technical Report
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This report contains a guide and a European harmonised protocol prepared within the framework of the Working Group 3 on source apportionment of the Forum for Air Quality Modelling in Europe (FAIRMODE). It has been initiated as a JRC initiative for the harmonisation of source apportionment with receptor models, in collaboration with FAIRMODE as well as with the European networks in the field of air quality measurements (AQUILA), and then further with the European COLOSSAL (Chemical On-Line cOmpoSition and Source Apportionment of fine aerosol) COST action. The JRC initiative also included a review of the methodologies used in Europe for source identification and intercomparison exercises for the quantitative assessment of the performance of source apportionment models. The document, drafted and then revised by a group of international experts, is organised following the logical sequence of steps to be carried out in a source apportionment study. Sections with increasing levels of complexity make it accessible to readers with different degrees of familiarity with this topic, from air quality managers to air pollution experts and modellers. It has been conceived as a reference document that includes tutorials, technical recommendations and check lists.
... This result indicates that BC wb was undervalued by the model applied in our study, in contrary to theZotter et al. (2016) model especially in spring and autumn. exponent Another important factor for the characterization of the source of measured BC during the year of study is the Angstrom exponent (α).Favez et al., (2009) revealed a low spectral dependence of black carbon light absorption (α ~ 1), in contrast, it is much higher for other aerosol components, i.e. hematite and brown carbon.Sandradewi et al. (2008) recorded light absorption exponents of 1.1 for traffic and 1.8-1.9 for wood burning, calculated from the light absorption at 470 and 950 nm.Soni et al. (2011) observed minimum values of the Angstrom exponent during May and maximum values during the winter period (December and January), related to a gradual decrease in the coarse particle concentration from summer to winter months. The Angstrom exponent (calculated at 470 and 950nm) shown in ...
Article
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This study aims to investigate, for the first time in Algeria, the atmospheric black carbon (BC) concentrations over one year measured at the Scientific Observatory of Algiers and to compare their concentration levels with other Mediterranean cities (i.e., Athens and Crete). The diurnal cycles as well as seasonal variations of BC concentrations were evaluated and attributed to their emission sources (fossil fuel: BCff and wood burning: BC wb). The annual mean concentrations of BC, BCff and BCwb were 1.113±2.030, 1.064±2.002 and 0.049±0.262 µgm -3 , respectively. The highest seasonal mean concentrations were recorded in summer and autumn with 1.283±1.346 and 1.209±1.149 µgm -3 for BC and 1.217±1.431 and 1.177±1.151 µgm -3 for BCff, respectively. However, the lowest mean concentrations were recorded in winter and spring with 1.023±1.189 and 0.966±0.964 µgm -3 for BC and 0.933±1.177 and 0.956±0.874 µgm -3 for BCff, respectively. For BCwb, the highest mean concentrations were reached in winter and summer with 0.090±0.055 and 0.066±0.050 µgm -3 , respectively, very likely due to the forest fires and long-range transport of air pollution from Europe. The lowest mean concentrations of BCwb were recorded in autumn and spring with 0.032±0.033 and 0.010±0.021 µgm -3 , respectively. Seggregating BC levels into eight wind sectors, showed that the prevailing BC pollution with concentrations reaching up to 5.000 µgm-3 originated from the North-West wind sector. A source apportionment of BC for the wet and dry period was also perfomed followed by a back trajectory cluster analysis for long-range transport.
... Most notably, woodburning particles, i.e. wood smoke, generally contains a rich organic component which is very effective at absorbing light in the UV range while diesel soot shows a weaker spectral dependence (Kirchstetter et al., 2004) (Fig. 1). The different spectral dependences between these sources can be leveraged with a data processing technique called the aethalometer model, first reported by but used many times since in many locations; for examples, see ; Favez et al. (2009); 5 Herich et al. (2011);Fuller et al. (2014). In routine aethalometer use, only the 880 nm absorption wavelength is used with a fixed coefficient (called a mass absorption coefficient) which is the strict definition of BC. ...
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Abstract. Black carbon (BC) or soot is a constituent of particulate matter (PM) which is relevant for negative human health and climate effects, and despite the lack of legal limits, it is recognised as an important atmospheric pollutant to monitor, understand, and control. Aethalometers are instruments which continuously monitor BC by measuring absorption at a number of distinct wavelengths. If collocated elemental carbon (EC) observations are used to transform these values into BC mass, by convention, the result is named equivalent black carbon (EBC). BC emitted by different combustion processes have different optical absorption characteristics and this can be used to apportion EBC mass into traffic (EBC<sub>TR</sub>) and woodburning (EBC<sub>WB</sub>) components with a data processing technique known as the aethalometer model. The aethalometer model was applied to six EBC monitoring sites across Switzerland (using data between 2008 and 2018) and was evaluated by investigating diurnal cycles, model coefficients, and ambient temperature dependence of the two EBC components. For one monitoring site, San Vittore, the aethalometer model failed to produce plausible outputs. The reason for this failure was likely due to a high load of freshly emitted wood smoke during the winter which should be thought of as a third distinct emission source. After model evaluation, the trend analysis indicated that EBC<sub>TR</sub> concentrations at the remaining five locations significantly decreased between 2008 and 2018 illustrating the successful widespread installation of diesel particulate filters (DPF) within the vehicle fleet. EBC<sub>WB</sub> also demonstrated significant deceases in most monitoring locations, but not at a monitoring site south of the Alps with a high PM load sourced from biomass burning. This indicated that the management of woodburning has be ineffective at reducing BC emissions and concentrations for this, likely representative location. The EBC/PM<sub>2.5</sub> ratios suggested that EBC contributes 6–13 % of the PM<sub>2.5</sub> mass in Switzerland which is important for soot and PM source management. The aethalometer model is a useful data analysis procedure, but can fail under certain conditions, thus, careful evaluation is required to ensure the method is robust and suitable in other locations.
... Recently, biomass combustion for residential heating has been promoted under the label of renewable fuel and additionally increased due to economic crises and increase in other fuel prices (Crilley et al., 2015;Denier van der Gon et al., 2015;Hovorka et al., 2015;Athanasopoulou et al., 2017). Although several studies report a significant role of wood burning emissions in BC concentrations in Alpine valleys (Sandradewi et al., 2008b;Favez et al., 2010;Herich et al., 2014) and Scandinavian rural areas (Ricard et al., 2002;Aurela et al., 2011), an increase in the contribution of wood smoke to fine PM was also noticed in several large urban areas (Favez et al., 2009;Crippa et al., 2013;Fuller et al., 2014;Denier van der Gon et al., 2015;Hovorka et al., 2015;Helin et al., 2018;Zhang et al., 2019). ...
Article
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We present a new method for the determination of the source-specific black carbon emission rates. The methodology was applied in two different environments: an urban location in Ljubljana and a rural one in the Vipava valley (Slovenia, Europe), which differ in pollution sources and topography. The atmospheric dynamics was quantified using the atmospheric radon (222Rn) concentration to determine the mixing layer height for periods of thermally driven planetary boundary layer evolution. The black carbon emission rate was determined using an improved box model taking into account boundary layer depth and a horizontal advection term, describing the temporal and spatial exponential decay of black carbon concentration. The rural Vipava valley is impacted by a significantly higher contribution to black carbon concentration from biomass burning during winter (60 %) in comparison to Ljubljana (27 %). Daily averaged black carbon emission rates in Ljubljana were 210 ± 110 and 260 ± 110 µgm-2h-1 in spring and winter, respectively. Overall black carbon emission rates in Vipava valley were only slightly lower compared to Ljubljana: 150 ± 60 and 250 ± 160 µgm-2h-1 in spring and winter, respectively. Different daily dynamics of biomass burning and traffic emissions was responsible for slightly higher contribution of biomass burning to measured black carbon concentration, compared to the fraction of its emission rate. Coupling the high-time-resolution measurements of black carbon concentration with atmospheric radon concentration measurements can provide a useful tool for direct, highly time-resolved measurements of the intensity of emission sources. Source-specific emission rates can be used to assess the efficiency of pollution mitigation measures over longer time periods, thereby avoiding the influence of variable meteorology.
... Although, the precise contribution shows considerable variation in time and space, the results of the studies demonstrate a large influence of RWC on ambient OC, thus, during colder seasons RWC comprised more than 40% OC in PM 10 ( Bari et al., 2009;Maenhaut et al., 2012;Piazzalunga et al., 2013) and in PM 2.5 (Favez et al., 2009;Gelencsér et al., 2007;Saarikoski et al., 2008;Golly et al., 2019). In the OC fraction, submicron Biomass Burning Organic Aerosols (BBOA) (see section S2.5) are typically in the order of 10-40% in European rural and urban background (Table 3). ...
Article
In recent years, residential wood combustion (RWC) has become a major source of ambient particulate matter (PM) in many developed countries, and in some of these countries even the largest source of primary particle emissions. While other sources of PM have been regulated intensively during the past decades, RWC has been subject to only minor regulation despite of its impact on climate and health. This review covers recent research publications on RWC contributions to ambient PM in different regions of Europe, North America and Australasia, and on key species associated with RWC. Furthermore, factors governing emissions from wood stoves (as the typical appliance used in residential heating) are evaluated. State-of-the-art methods for estimating RWC as a source of ambient PM are discussed. We conclude by highlighting important areas for future research and policies.
... CC BY 4.0 License. the label of renewable fuel and additionally increased due to economic crises and increase of other fuel prices (Crilley et al., 2015;Denier van der Gon et al., 2015;Hovorka et al., 2015;Athanasopoulou et al., 2017). Although several studies report significant role of wood burning emissions on BC concentrations in Alpine valleys (Sandradewi et al., 2008b;Favez et al., 2010;Herich et al., 2014) and Scandinavian rural areas (Ricard et al., 2002;Aurela et al., 2011), increase in contribution of wood smoke to fine PM was noticed also in several large urban areas (Favez et al., 2009;Crippa et al., 2013;Fuller et al., 5 2014;Denier van der Gon et al., 2015;Hovorka et al., 2015;Helin et al., 2018;Zhang et al., 2019). Notable contribution of wood smoke was observed also in Slovenian urban (Ogrin et al., 2016) and rural areas (Wang et al., 2019), responsible for air quality deterioration especially in geographically constrained areas such as valleys and basins. ...
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Abstract. We present a new method for the determination of the source specific black carbon emission rates. The methodology was applied in two different environments: an urban location in Ljubljana and a rural one in the Vipava valley (Slovenia, Europe), which differ in pollution sources and topography. The atmospheric dynamics was quantified using the atmospheric radon (<sup>222</sup>Rn) concentration to determine the mixing layer height for periods of thermally driven planetary boundary layer evolution. The black carbon emission rate was determined using an improved box model taking into account boundary layer depth and a horizontal advection term, describing the temporal and spatial exponential decay of black carbon concentration. The rural Vipava valley is impacted by a significantly higher contribution to black carbon concentration from biomass burning during winter (62 %) in comparison to Ljubljana (31 %). Results of the calculated black carbon emission rates in Ljubljana were in the range from 280 to 300 μg m<sup>−2</sup> h<sup>−1</sup> in spring and winter, respectively. Overall black carbon emission rate in Vipava valley were only 25 % lower compared to Ljubljana and were in the range from 210 to 240 μg m<sup>−2</sup> h<sup>−1</sup> in spring and winter, respectively. As expected, black carbon emissions from traffic prevail in Ljubljana and account for 80 % of emissions during winter; the traffic contribution in the Vipava valley was only 42 %. Different daily dynamics of biomass burning and traffic emissions was responsible for higher contribution of biomass burning to measured black carbon concentration, compared to the fraction of its emission rate. Coupling the high time resolution measurements of black carbon concentration with atmospheric radon concentration measurements can provide a useful tool for direct, highly time resolved measurements of the intensity of emission sources. Source specific emission rates can be used to assess the efficiency of pollution mitigation measures over longer time periods, thereby avoiding the influence of variable meteorology.
... Samples were collected for four sequential 12 h durations starting at either 06:00 or 18:00 PST on days when forecasts indicated that PM 2.5 concentrations would be high on a particular day. Daytime (06:00 or 18:00) and nighttime (18:00 to 06:00) samples were taken, since mobile source emissions are relatively higher in daytime, and residential wood burning emissions are higher in nighttime [25,26,37]. Thus, a comparison of daytime to nighttime concentrations can show which source type contributes more to ambient HAPs. ...
Article
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Ambient air monitoring and phone survey data were collected in three environmental justice (EJ) and three non-EJ communities in Sacramento County during winter 2016–2017 to understand the differences in air toxics and in wood smoke pollution among communities. Concentrations of six hazardous air pollutants (HAPs) and black carbon (BC) from fossil fuel (BCff) were significantly higher at EJ communities versus non-EJ communities. BC from wood burning (BCwb) was significantly higher at non-EJ communities. Correlation analysis indicated that the six HAPs were predominantly from fossil fuel combustion sources, not from wood burning. The HAPs were moderately variable across sites (coefficient of divergence (COD) range of 0.07 for carbon tetrachloride to 0.28 for m- and p-xylenes), while BCff and BCwb were highly variable (COD values of 0.46 and 0.50). The BCwb was well correlated with levoglucosan (R2 of 0.68 to 0.95), indicating that BCwb was a robust indicator for wood burning. At the two permanent monitoring sites, wood burning comprised 29–39% of the fine particulate matter (PM2.5) on nights when PM2.5 concentrations were forecasted to be high. Phone survey data were consistent with study measurements; the only significant difference in the survey results among communities were that non-EJ residents burn with indoor devices more often than EJ residents.
... Urban forests can also help supply affordable energy to people that need it(FAO, 2016). It is important to note, however, that burning wood is a large contributor to air pollution in urban environments(Favez, Cachier, Sciare, Sarda- Estève, & Martinon, 2009). Therefore, if wood is used for fuel, it should be burned in such a way that the benefits outweigh the ...
Article
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We live in an era influenced by humans to the point that the Earth's systems are now altered. In addition, a majority of the world's population live in cities. To meet the needs of people in a changing world, The United Nations General Assembly created the United Nations Sustainable Development Goals (UN SDG) to improve the quality of life for people. These broad goals outline the greatest challenges of our time. An effective strategy to assist in meeting these goals is to plant and protect trees, especially in cities where the majority of people live. This paper serves as a critical review of the benefits of trees. Trees promote health and social well‐being by removing air pollution, reducing stress, encouraging physical activity, and promoting social ties and community. Children with views of trees are more likely to succeed in school. Trees promote a strong economy and can provide numerous resources to the people that need them. While cities are getting hotter, trees can reduce urban temperatures. They provide habitat and food for animals. Finally, trees are valuable green infrastructure to manage stormwater. Money spent on urban forestry has a high return on investment. As we navigate this human‐dominated era, we need skilled people who understand the nuances of the built environment and trees as we strategically plan the cities of the future. The overwhelming evidence from the scientific literature suggests that investing in trees is an investment in meeting the UN SDG, and ultimately an investment for a better world.
... BrC in particulate matters can be measured by optical instruments, such as particle-soot absorption photometer, aethalometer, multi-angle absorption photometer, and photo-acoustic soot spectrometer (Favez et al., 2009;Healy et al., 2015). However, it is a challenge to separate BrC from other components that could absorb or scatter light in particulate matters (Coen et al., 2010). ...
Article
Water-soluble brown carbon (BrC) plays an important role in climate change by influencing aerosol radiative forcing. There is little information on aerosol BrC over the South China Sea (SCS). In this study, water-soluble organic carbon (WSOC) in a round-year set of aerosol samples from a remote island in the northern SCS were characterized for optical properties. In-depth information about the sources and input pathways of water-soluble BrC was obtained using molecular markers and statistic tools. The highest WSOC concentrations, light absorption coefficients at 365 nm (Abs365) and mass absorption efficiencies at 365 nm (MAE365) were observed in winter, when atmospheric outflow from mainland China and the northern Indo-China Peninsula prevailed. Through the year, primary emissions from biomass burning and urban secondary organic aerosols (SOA) & waste combustion, respectively, were observed to be associated with higher MAE365 (2.47 m² g⁻¹ and 1.97 m² g⁻¹) and to be the main contributors to Abs365 (31.6% and 22.0%), while biogenic SOA showed little contribution. For the first time, microorganism/plankton primary emissions (MAE365 0.98 m² g⁻¹), mainly from the sea, was identified to be an important contributor to water-soluble BrC in spring (31% of Abs365) and summer (19% of Abs365). This implies that emissions from microorganism/plankton warrants carefully consideration in the assessment of global aerosol light absorbance.
... Cette étude novatrice a permis d'illustrer l'intérêt de ce type de travaux, indiquant des contributions à la matière organique de l'ordre de 20 à 50%, selon les sites, au cours de l'hiver 2006-2007 [3]. Toutes les études réalisées depuis, ont confirmé que le chauffage résidentiel au bois constitue une source majeure de PM 10 dans les différentes agglomérations françaises ayant pu être investiguées (e.g., Clermont-Ferrand, Paris, Grenoble, Rouen, Lens, Bordeaux, Lyon) [4][5][6][7][8][9], et que cette source peut expliquer la survenue d'importants épisodes de pollution en début d'hiver [8][9][10]. ...
Technical Report
Cette étude s’inscrit dans la continuité des travaux menés depuis une dizaine d’années par le LCSQA (en étroite collaboration avec des laboratoires de recherche, dont le LGGE) afin de mieux évaluer l’impact du chauffage résidentiel au bois sur les niveaux de PM10 enregistrés sur différentes stations du dispositif national de surveillance. Pour réaliser ce type d’étude, il est généralement recouru à l’analyse de marqueurs organiques spécifiques, tel que le levoglucosan, prélevés sur filtres. Il est ensuite possible d’estimer la quantité de matière particulaire (PM) provenant de la combustion de biomasse en appliquant différents facteurs multiplicatifs aux concentrations obtenues pour ces marqueurs. Ces dernières années ont également vu l’émergence d’analyseurs automatiques de la composition chimique des particules permettant notamment l’identification et la mesure en temps réel des particules liées à cette source. En particulier, de récents tests en AASQA ont permis de vérifier la robustesse et la fiabilité de l’Aethalomètre multi-longueurs d’onde de type AE33, conduisant à son implantation sur différents sites urbains de fond du dispositif national entre 2013 et 2014. Dans le cadre de ses travaux pour le LCSQA, l’INERIS a alors proposé de réaliser une étude combinant des mesures sur filtres et des mesures par AE33 au cours de l’hiver 2014-2015. Le présent rapport rend compte des résultats obtenus à l’aide des mesures sur filtres, réalisées pour 10 sites de fond urbain du programme CARA au sein de grandes agglomérations françaises (constituant à ce jour le plus large panel de sites étudiés simultanément en France). Les prélèvements ont été réalisés sur une période hivernale élargie s’étendant de mi-novembre 2014 à mi-avril 2015. Sur cette période, les contributions journalières moyennes aux PM10 de la combustion de biomasse sont globalement comprises entre 18% et 36%, les plus faibles niveaux étant obtenus pour Marseille et les plus élevés pour Grenoble. Parmi les autres agglomérations étudiées, Bordeaux et Poitiers présentent également des contributions journalières très élevées (environ 30%). Pour les autres sites (Rouen, Reims, Strasbourg, Nantes, Lyon, et Nice), cette contribution est estimée à environ 20%. Ces résultats sont en bon accord avec ceux obtenus précédemment, pour certains de ces sites ou pour d’autres agglomérations françaises, confirmant l’importance de l’influence du chauffage résidentiel au bois sur la qualité de l’air de l’ensemble du territoire métropolitain en hiver. Les résultats obtenus dans le cadre decette étude permettront d’affiner la méthodologie d’exploitation des données issues de la mesure automatique.
... Similar winter concentrations were obtained in Aveiro (Portugal) in 2002-2003 and 2003-2004. Nevertheless, winter levels of levoglucosan in Fos-sur-Mer remain lower than those detected in winter in French and Swiss alpine valleys, which suffer from strong pollution periods due to biomass combustion (Bonvalot et al., 2016;Favez et al., 2009;Zotter et al., 2014). These alpine valleys are enclosed between steep slopes and are characterized by temperature inversions which limit atmospheric mixing during winter. ...
Article
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Located in the Mediterranean Basin and close to Marseille (France), Fos-sur-Mer is situated in the vicinity of industrial harbor and agricultural lands. Its location makes it prone to mixed pollution contributions, combining the influence of residential, industrial, agricultural, maritime road and traffic sources. For this study, the origins of carbonaceous particles sampled over several months are investigated by a coupled approach based on analyses of radiocarbon (¹⁴C), elemental to total carbon ratio (EC/TC) and various molecular tracers (levoglucosan, methoxyphenols, malic and glyceric acids), giving information about their background origins. Accelerator mass spectrometry with a gas ion source give the opportunity to quantify the fossil and non-fossil fractions for each individual sample, avoiding to pool them. Analyzing ¹⁴C in micro-samples (down to a few μg of carbon) complements the approach based on chemical tracers, which are useful to identify sources, but insufficient to quantify accurately the modern and fossil carbon fractions. The measurements in about 30 samples collected during summer and fall/winter 2013, allow the detection of a strong seasonality of the pollution: the fall/winter PM2.5 fraction concentration equals to three times the summer concentration and we observe a significant fluctuation of the relative contributions of fossil and non-fossil fractions (fNF is ≈ 0.83 for fall/winter samples and ≈0.59 for summer samples). Significant correlations between ¹⁴C, levoglucosan and different methoxyphenols, allow the identification and quantification of a major influence of biomass burning emissions during fall and winter. Biomass burning organic carbon (OCBB) and elemental carbon (ECBB) contribute to 45% and 8% of the TC, respectively, whereas their total contribution is only 3% in summer samples. Biogenic emissions from the vegetation are the main sources of carbon during summer (≈57%). Significant correlations between summer OCbio and malic acid and DL glyceric acid suggest a secondary origin for this fraction. The total fossil carbon concentration (ECF and OCF) from vehicular, shipping and industrial sources is constant throughout the year, which is compatible with intense road and maritime traffics and industrial activity during both seasons. Overall, our study based on ¹⁴C and molecular tracers illustrates the power of a coupled approach in order to both identify and quantify biomass burning, biogenic, traffic and industrial sources of carbonaceous aerosols, forming a complex mix of background PM origins in a typical industrious harbor of the Mediterranean region.
... In the recent years, partly because of the rising cost of fossil fuels (Rao et al., 2018), the combustion of wood-2 based biomass has encountered a wide diffusion (Favez et al., 2009). Wood/pellet burning has become a 3 common practice even in mild climates, where conventional heating systems based on natural-gas (NG) boilers 4 had been normally employed in the past (Perrino et al., 2019). ...
Article
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The combustion of wood-based biomass for domestic heating, which is common in rural and mountainous regions of Europe, entails significant local impacts on air quality. Worse conditions occur in low-income countries where the use of coal in household stoves is a common practice. The present paper aims at demonstrating that the combination of waste-to-energy (WtE) plants (based on direct or indirect waste combustion technologies) and direct electric heating (DEH) would be beneficial to reduce air pollution and, meanwhile, optimize the local waste management. Specifically, a WtE plant powering a DEH network will be compared with two reference scenarios of domestic heating: the use of wood/pellet stoves and coal stoves. The results show that shifting to a DEH system, powered by the nearby WtE plant, would reduce the emissions of total suspended particles, NOx, CO, VOCs, dioxins, PAHs and heavy metals by >99%, 27%, 97%, 96%, 93%, 94% and 32%, respectively, with respect to the use of solid fuel in household stoves. In addition, the higher degree of atmospheric dispersion of the off-gas from the stack of the WtE plant is expected to further reduce the impacts in terms of air quality, as estimated by an approach based on the concept of dilution factors. The avoided transportation of waste to other waste facilities outside the region would reduce the greenhouse gas emissions with respect to coal combustion and biomass burning, by 63% and 3%, respectively. The integration of local WtE and DEH could be also “mild”, opening to scenarios that could improve the local air quality without renouncing totally to the habits of domestic wood combustion in mountainous regions. Mild-DEH could be designed to integrate the domestic use of wood with electrical heaters, reducing fuel use and air pollution.
... Smoke produced by biomass (wood) combustion besides BC also contains organics that strongly absorb in the blue and ultraviolet (UV) part of the light spectrum which increases Ångström exponent. For wood smoke or smoke resulting from biomass combustion, the Ångström exponent is expected to be higher than about 1.7 (Favez et al., 2009;Sandradewi et al., 2008a;Sandradewi et al., 2008b;Saleh et al., 2013;Zotter et al., 2017). ...
Article
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The paper presents a study of air pollution caused by black carbon (BC) and fine particulate matter (PM) carried out in the rural area of the municipality of Loški Potok in the winter season of 2017/2018. Measurements of pollutants were performed at two different locations, one at Retje, a village at the bottom of a karst depression, and the other on the top of the Tabor hill in settlement Hrib. The measurement results exposed the main sources of black carbon air pollution in this area: domestic heating with biomass (almost 80% of all black carbon emissions) and unfavorable meteorological conditions for dilution of pollutants during temperature inversions. Three times higher concentrations were measured at Retje during temperature inversions than in the days of mixed atmosphere. In the winter of 2017/18, the average concentrations in the Retje hollow were even higher than those of Ljubljana, which calls attention to the problem of polluted air in rural areas too.
... Then, assuming that prior PMF analysis should add additional errors, the relative uncertainties of OA factors were set to 30 %. Similarly, for BC wb and BC ff , a relative uncertainty of 40 % was used as an extended uncertainty applied to the 20 % error of BC concentrations due to the Weingartner correction (Favez et al., 2009). Finally, a relative uncertainty of 50 % was set for potassium because major measurement artifacts with C 3 H + 3 fragment may occur (Ji et al., 2010) but are hardly quantifiable using unit-mass resolution ACSM data. ...
Article
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Online non-refractory submicron Aerosol Mass Spectrometer (AMS) measurements in urban areas have successfully allowed the apportionment of specific sources and/or physical and chemical properties of the organic fraction. However, in order to be fully representative of PM pollution, a comprehensive source apportionment analysis is needed by taking into account all major components of submicron aerosols, creating strengthened bonds between the organic components and pollution sources. We present here a novel two-step methodology to perform such an analysis, by taking advantage of high time resolution of monitoring instruments: the Aerosol Chemical Speciation Monitor (ACSM) and the multi-wavelength absorption measurements (Aethalometer AE31) in Paris, France. As a first step, organic aerosols (OA) were deconvoluted to hydrocarbon-like OA (HOA), Biomass Burning OA (BBOA) and Oxygenated OA (OOA) with Positive Matrix Factorization, and black carbon was deconvolved into its wood burning and fossil fuel combustion fractions. A second PMF analysis was then carried out with organic factors, BC fractions and inorganic species (nitrate, sulfate, ammonium, chloride), leading to a~four-factor solution allowing real-time characterization of the major sources of PM1. Outputs of this PMF2 include two dominant combustion sources (wood burning and traffic) as well as semi-volatile and low-volatile secondary aerosols. While HOA is found to be emitted by both wood burning and traffic, the latter sources occurred to significantly contribute also to OOA.
... The comparison of E abs at 880 nm (E abs_880 ) and E abs at 370 nm (E abs_370 ) indicated the role of brown carbon on E abs (Zhang et al., 2018a;Yus-Díez et al., 2022). In Fig. S6, a slightly higher E abs_370 (1.47 ± 0.39) than E abs_880 (1.36 ± 0.35) by 8.09% in summer suggested a negligible contribution of brown carbon to the total absorption at UV light ranges (Favez et al., 2009;Sciare et al., 2011;Zhang et al., 2018a). In winter, E abs_370 (1.33 ± 0.27) was much higher than E abs_880 (1.17 ± 0.24) by 13.7%, implying a higher contribution of brown carbon to the total absorption, which maybe related to the abundant biomass burning emissions during winter in Wuhan Zheng et al., 2020bZheng et al., , 2021. ...
Article
High uncertainty in simulating the climate effect of black carbon (BC)-containing particles can be raised by an important parameter: light absorption enhancement (Eabs), which was impacted by the morphology of BC, its mixing state with coating materials, and the aging process, etc. By a statistical approach called minimum R square (MRS), this study investigated the influence of aerosol chemical compositions on Eabs with on-line observational datasets during summer (June 2018) and winter (December 2018) at an urban site in Wuhan, Central China. The Eabs at 880 nm (Eabs_880) showed a moderate enhancement with a mean value of 1.36 ± 0.35 in summer, which was significantly (p < 0.001) higher than that in winter (1.17 ± 0.24). A proxy defined as the mass ratio of non-refractory chemical components to BC (RBC) was used to link the thickness of BC-containing particles and aerosol chemical compositions with Eabs. With the increase of RBC from 16.4 to 51.3 in summer and from 18.3 to 53.3 in winter, Eabs_880 values amplified by 15.3% and 38.3%, respectively. The statistical and sensitivity analysis indicated that secondary inorganic aerosols (SIA) contributed most to Eabs_880 during summer (92.6%) and winter (71.2%) in Wuhan. Given the dominant mass percentages of SIA in particle chemical compositions and their important role to Eabs, reducing their precursors would benefit to alleviate the particle pollution and the warming effect of BC synergistically. The comparison of Eabs with previous studies suggested that despite the MRS method in this study had some limitations, this method can be widely used in other regions with similar datasets.
... One of the most critical PM sources in ambient air is biomass burning notably in winter period when wood burning is used for residential heating purposes. Many previous studies have already shown the major impact of this source on ambient air PM concentration levels in rural, suburban and urban areas worldwide (Chen et al., 2017;Crippa et al., 2013;Denier van der Gon et al., 2015;Favez et al., 2009Favez et al., , 2010Fuller et al., 2014;Herich et al., 2014;Kotchenruther, 2016;Lanz et al., 2010;Maenhaut et al., 2012;Petit et al., 2014;Puxbaum et al., 2007;Saarikoski et al., 2008;Srivastava et al., 2018;Viana et al., 2016;Vicente and Alves, 2018;Weber et al., 2019;Zhang et al., 2019Zhang et al., , 2020. The apportionment of biomass burning sources is usually achieved thanks to typical source marker (tracer) species such as levoglucosan, potassium or retene (Bhattarai et al., 2019;Hopke et al., 2020;Karagulian et al., 2015;Ramdahl, 1983;Simoneit et al., 1999). ...
Article
This work provides an evaluation of the emission factors (EFs) of typical garden waste burning (fallen leaves and hedge trimming) in terms of particulate matter (PM), elemental and organic carbon (EC-OC) together with a detailed chemical characterization of 88 particle-bound organic species including polycyclic aromatic hydrocarbons (PAHs), levoglucosan and its isomers, lignin breakdown products (methoxyphenols), cholesterol, alkanes, polyols and sugars. Furthermore, wood-log based burning experiments have been performed to highlight key indicators or chemical patterns of both, green waste and wood burning (residential heating) sources, that may be used for PM source apportionment purposes. Two residential log wood combustion appliances, wood stove (RWS) and fireplace, under different output conditions (nominal and reduced) and wood log moisture content (mix of beech, oak and hornbeam), have been tested. Open wood burning experiments using wood logs were also performed. Green waste burning EFs obtained were comparable to the available literature data for open-air biomass burning. For PM and for most of the organic species studied, they were about 2 to 30 times higher than those observed for wood log combustion experiments. Though, poor performance wood combustions (open-air wood log burning, fireplace and RWS in reduced output) showed comparable EFs for levoglucosan and its isomers, methoxyphenols, polyols, PAHs and sugars. Toxic PAH equivalent benzo[a]pyrene EFs were even 3–10 times higher for the fireplace and open-air wood log burning. These results highlighted the impact of the nature of the fuel burnt and the combustion performances on the emissions. Different chemical fingerprints between both biomass burning sources were highlighted with notably a predominance of odd high-molecular weight n-alkanes (higher carbon preference index, CPI), lower levoglucosan/mannosan ratio and lower sinapylaldehyde abundance for green waste burning. However, the use of such indicators seems limited, especially if applied alone, for a clear discrimination of both sources in ambient air.
... For example, Vicente and co-workers reported that the total carbon represented 54e73 wt% of the particulate matter emitted from the wood stove, regardless of wood type or operating conditions tested [11]. The emissions of carbonaceous particles from wood stoves, especially under partial-load conditions and intermittent combustion phases are high and contribute significantly to overall carbonaceous particulate emissions in Europe [1,12]. ...
Article
Particulate matter (PM) generated by residential wood combustion is a major environmental concern in Europe. This study focuses on the influence of potassium chloride (KCl) on fine particle emissions from a modern wood stove. Wood logs with and without KCl impregnation were subjected to batch combustion and emission measurements. A bi-modal particle number-size distribution characterized by a nucleation mode and an accumulation mode was identified for all types of wood fuel. However, in the presence of KCl, a lower number emission of ultrafine particles and a higher number emission of larger particles (size ∼200-500 nm) were observed. In addition, the emission factor of condensed organic compounds (COC) increased with increasing KCl content, from 0.16 g/kg dry wood for normal wood (NW) to 0.48 g/kg dry wood for wood impregnated with the 2 mol/L KCl solution (HKW), most likely due to the facilitated heterogeneous condensation of semi-volatile hydrocarbons on pre-existing ash particles. In addition, the emission factor of soot particles also increased slightly when the KCl content was high, from 1.47 g/kg dry wood for NW to 2.23 g/kg dry wood for HKW.
... Based on these differences in optical properties, a growing number of studies recently used multi-wavelength Aethalometers to detect and/or apportion wood burning carbonaceous aerosols in ambient air (e.g. Jeong et al., 2004;Sandradewi et al., 2008aSandradewi et al., , 2008bYang et al., 2009;Favez et al., 2009). In particular, Sandradewi et al. (2008b) introduced a methodology to quantitatively assess the contribution of wood burning and fossil fuel to the absorption coefficients (babs) measured by a multi-wavelength Aethalometer. ...
Book
This report contains a guide and a European harmonised protocol prepared within the framework of the Working Group 3 on source apportionment of the Forum for Air Quality Modelling in Europe (FAIRMODE). It has been initiated as a JRC initiative for the harmonisation of source apportionment with receptor models, in collaboration with FAIRMODE as well as with the European networks in the field of air quality measurements (AQUILA), and then further with the European COLOSSAL (Chemical On-Line cOmpoSition and Source Apportionment of fine aerosol) COST action. The JRC initiative also included a review of the methodologies used in Europe for source identification and intercomparison exercises for the quantitative assessment of the performance of source apportionment models. The document, drafted and then revised by a group of international experts, is organised following the logical sequence of steps to be carried out in a source apportionment study. Sections with increasing levels of complexity make it accessible to readers with different degrees of familiarity with this topic, from air quality managers to air pollution experts and modellers. It has been conceived as a reference document that includes tutorials, technical recommendations and check lists.
... Biomass burning SOA is not estimated using the traditional SOA-tracer method. Neglecting this SOA source might lead to significant underestimation of the total wintertime SOC concentrations in Europe due to relatively high contributions (up to 70%) of residential wood burning during the cold season (Ciarelli et al., 2017;Denier van der Gon et al., 2015;Favez et al., 2009;Petit et al., 2014;Puxbaum et al., 2007;Srivastava et al., 2018c;Weber et al., 2019;Zhang et al., 2019). Here, the biomass burning SOA fraction was evaluated using the measured concentrations of methylnitrocatechols, previously demonstrated as secondary photooxidation products of phenolic compounds (e.g., cresols, methoxyphenols) (Iinuma et al., 2010) and known to account for a major fraction of SOA biomass burning (Bruns et al., 2016). ...
Article
Twenty-five biogenic and anthropogenic secondary organic aerosol (SOA) markers have been measured over a one-year period in both gaseous and PM10 phases in the Paris region (France). Seasonal and chemical patterns were similar to those previously observed in Europe, but significantly different from the ones observed in America and Asia due to dissimilarities in source precursor emissions. Nitroaromatic compounds showed higher concentrations in winter due to larger emissions of their precursors originating from biomass combustion used for residential heating purposes. Among the biogenic markers, only isoprene SOA marker concentrations increased in summer while pinene SOA markers did not display any clear seasonal trend. The measured SOA markers, usually considered as semi-volatiles, were mainly associated to the particulate phase, except for the nitrophenols and nitroguaiacols, and their gas/particle partitioning (GPP) showed a low temperature and OM concentrations dependency. An evaluation of their GPP with thermodynamic model predictions suggested that apart from equilibrium partitioning between organic phase and air, the GPP of the markers is affected by processes suppressing volatility from a mixed organic and inorganic phase, such as enhanced dissolution in aerosol aqueous phase and non-equilibrium conditions. SOA marker concentrations were used to apportion secondary organic carbon (SOC) sources applying both, an improved version of the SOA-tracer method and positive matrix factorization (PMF) Total SOC estimations agreed very well between both models, except in summer and during a highly processed Springtime PM pollution event in which systematic underestimation by the SOA tracer method was evidenced. As a first approach, the SOA-tracer method could provide a reliable estimation of the average SOC concentrations, but it is limited due to the lack of markers for aged SOA together with missing SOA/SOC conversion fractions for several sources.
... The results indicate that AAE ff and AAE mixed have a limited magnitude of 1.15 ± 0.05 and 1.29 ± 0.05, respectively, while AAE bb has a larger magnitude of 1.56 ± 0.14. Becerril-Valle et al. (2017) observed similar AAE profiles in Madrid, Spain, with a relatively flat trend in an urban background (1.05 ± 0.05 in spring and 1.07 ± 0.06 in autumn) and in the urban center (1.16 ± 0.08 in spring and 1.07 ± 0.07 in autumn), while in Paris, France, AAE values of 1.02 ± 0.04 (summer) during peak morning traffic and 1.08 ± 0.04 during the evening/night periods were reported in another study (Favez et al., 2009). In both cases, the seasons are characterized by the predominance of vehicular traffic as a significant source. ...
Article
Black carbon (BC) is one of the short-lived air pollutants that contributes significantly to aerosol radiative forcing and global climate change. It is emitted by the incomplete combustion of fossil fuels, biofuels, and biomass. Urban environments are quite complex and thus, the use of mobile jointly with fixed monitoring provides a better understanding of the dynamics of BC distribution in such areas. The present study addresses the measurement of BC concentration using real-time mobile and ambient monitoring in Barranquilla, an industrialized urban area of the Colombian Caribbean. A microaethalometer (MA200) and an aethalometer (AE33) were used for measuring the BC concentration. The absorption Ångström exponent (AAE) values were determined for the study area, for identifying the BC emission sources. The results of the ambient sampling show that vehicle traffic emissions prevail; however, the influence of biomass burning was also observed. The mean ambient BC concentration was found to be 1.04 ± 1.03 μg/m 3 and varied between 0.5 and 4.0 μg/m 3. From the mobile measurements obtained in real traffic conditions on the road, a much higher average value of 16.1 ± 16.5 μg/m 3 was measured. Many parts of the city showed BC concentrations higher than 20 μg/m 3. The spatial distribution of BC concentration shows that vehicle emissions and traffic jams, a consequence of road and transport infrastructure, are the factors that most affect the BC concentration. A comparison of results obtained from two aethalometers indicates that the concentrations measured by MA200 are 9% lower than those measured by AE33. The AAE obtained was found to vary between 1.1 and 1.6, indicating vehicular emissions as the most crucial source. In addition, it was observed that the BC concentration on working days was 2.5 times higher than on the weekends in the case of mobile monitoring and 1.5 times higher in the case of ambient monitoring.
... Clegg et al., 1998;Pay et al., 2012;Bressi et al., 2013;Petetin et al., 2014;Petit et al., 2015). The increase in organic matter and BCwb concentrations at low temperatures (Fig. 5g) is likely related to the emission intensity, as biomass burning is often used for domestic heating in the study area (Favez et al., 2009;Sciare et al., 2010;Healy et al., 2012;Jiang et al., 2019). In addition, organic matter concentrations are linked to the condensation of semi-volatile organic species at low temperatures (Putaud et al., 2004;Bressi et al., 2013). ...
Article
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Air pollution, in particular high concentrations of particulate matter smaller than 1 µm in diameter (PM1), continues to be a major health problem, and meteorology is known to substantially influence atmospheric PM concentrations. However, the scientific understanding of the ways in which complex interactions of meteorological factors lead to high-pollution episodes is inconclusive. In this study, a novel, data-driven approach based on empirical relationships is used to characterize and better understand the meteorology-driven component of PM1 variability. A tree-based machine learning model is set up to reproduce concentrations of speciated PM1 at a suburban site southwest of Paris, France, using meteorological variables as input features. The model is able to capture the majority of occurring variance of mean afternoon total PM1 concentrations (coefficient of determination (R2) of 0.58), with model performance depending on the individual PM1 species predicted. Based on the models, an isolation and quantification of individual, season-specific meteorological influences for process understanding at the measurement site is achieved using SHapley Additive exPlanation (SHAP) regression values. Model results suggest that winter pollution episodes are often driven by a combination of shallow mixed layer heights (MLHs), low temperatures, low wind speeds, or inflow from northeastern wind directions. Contributions of MLHs to the winter pollution episodes are quantified to be on average ∼5 µg/m3 for MLHs below
... À elle seule, elle constitue en moyenne 45% en masse de l'aérosol non-réfractaire. Favez et al., 2009;Kleindienst et al., 2010;Liu et al., 2012). Les fractions de l'AOP émises par ces sources seront désignées respectivement par les acronymes HOA (Hydrocarbon-like Organic Aerosol), BBOA (Biomass Burning Organic Aerosol) et COA (Cooking Organic Aerosol) (Aiken et al., 2010;Allan et al., 2010;Crippa et al., 2013;Freutel et al., 2013). ...
Thesis
L’aérosol organique secondaire (AOS) est reconnu pour avoir un impact sur la qualité de l’air et le changement climatique mais ses quantités atmosphériques restent encore aujourd’hui mal représentées, aussi bien en région source qu’en région de transport. Les principales causes sont la méconnaissance des sources et de la nature des composés organiques gazeux (COG) précurseurs de l’AOS, d’une part, et des mécanismes de formation de l’AOS, d’autre part. Les travaux présentés dans ce mémoire de thèse ont ainsi pour objectif (i) de caractériser les sources des COG, parmi lesquels d’importants précurseurs d’AOS, en zone urbaine, et (ii) d’estimer l’impact des COG sur la formation d’AOS en zone urbaine. Pour répondre à ces objectifs, ce travail s’appuie sur les mesures des COG en deux sites périurbains de deux mégapoles, Paris et Los Angeles, dans le cadre des programmes MEGAPOLI (été 2009 et hiver 2010) et CALNEX (printemps 2010). En combinant l’analyse de la composition de la fraction organique des phases gazeuse et particulaire à celle d’indicateurs de la qualité de l’air et aux données météorologiques, nous avons (i) identifié les déterminants des COG, (ii) identifié et estimé l’importance relative des sources d’émissions des COG, en fonction de la saison, par application du modèle sources-récepteur PMF, (iii) estimé l’impact des COG sur la formation d’AOS, avec un intérêt particulier porté aux Composés Organiques à la Volatilité Intermédiaire (COV-I) qui ont été mesurés dans le cadre du projet MEGAPOLI. En été comme en hiver, les COG mesurés au site périurbain de l’agglomération parisienne sont fortement associés au profil de source des émissions lointaines ainsi qu’à celui des COVO. Les COG mesurés dans l’agglomération de Los Angeles sont majoritairement associés aux profils de sources anthropiques primaires. Pour ce qui est de la formation d’AOS, ces travaux ont pour la première fois permis de mettre en évidence l’importance des COV-I dans la formation d’AOS à partir de leur mesure in-situ.
... Biomass burning contribution to BC concentration at the urban site is in the range of those observed in other European cities. Indeed, a biomass burning contribution of about 25% has been reported for urban and suburban areas in Paris (Favez et al., 2009), 24% in Zurich (Herich et al., 2011) and 23% in London (Fuller et al., 2014). On the other hand, the biomass burning contribution to BC concentration at the suburban station is in the range of those reported for other European metropolitan areas highly influenced by biomass burning like Helsinki (Helin et al., 2018) or those observed in rural areas in Switzerland (Herich et al., 2011), with contributions of 40% and 33%, respectively. ...
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In this study, we propose a new approach to determine the contributions of primary vehicle exhaust (N1ff), primary biomass burning (N1bb) and secondary (N2) particles to mode segregated particle number concentrations. We used simultaneous measurements of aerosol size distribution in the 12-600 nm size range and black carbon (BC) concentration obtained during winter period at urban and suburban sites influenced by biomass burning (BB) emissions. As expected, larger aerosol number concentrations in the 12-25 and 25-100 nm size ranges are observed at the urban site compared to the suburban site. However, similar concentrations of BC are observed at both sites due to the larger contribution of BB particles to the observed BC at suburban (34%) in comparison to urban site (23%). Due to this influence of BB emissions in our study area, the application of the Rodríguez and Cuevas (2007) method, which was developed for areas mainly influenced by traffic emissions, leads to an overestimation of the primary vehicle exhaust particles concentrations by 18% and 26% in urban and suburban sites, respectively, as compared to our new proposed approach. The results show that (1) N2 is the main contributor in all size ranges at both sites, (2) N1ff is the main contributor to primary particles (>70%) in all size ranges at both sites and (3) N1bb contributes significantly to the primary particles in the 25-100 and 100-600 nm size ranges at the suburban (24% and 28%, respectively) and urban (13% and 20%, respectively) sites. At urban site, the N1ff contribution shows a slight increase with the increase of total particle concentration, reaching a contribution of up to 65% at high ambient aerosol concentrations. New particle formation events are an important aerosol source during summer noon hours but, on average, these events do not implicate a considerable contribution to urban particles.
... The results indicate that AAE ff and AAE mixed have a limited magnitude of 1.15 ± 0.05 and 1.29 ± 0.05, respectively, while AAE bb has a larger magnitude of 1.56 ± 0.14. Becerril-Valle et al. (2017) observed similar AAE profiles in Madrid, Spain, with a relatively flat trend in an urban background (1.05 ± 0.05 in spring and 1.07 ± 0.06 in autumn) and in the urban center (1.16 ± 0.08 in spring and 1.07 ± 0.07 in autumn), while in Paris, France, AAE values of 1.02 ± 0.04 (summer) during peak morning traffic and 1.08 ± 0.04 during the evening/night periods were reported in another study (Favez et al., 2009). In both cases, the seasons are characterized by the predominance of vehicular traffic as a significant source. ...
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Black carbon (BC) is one of the short-lived air pollutants that contributes significantly to aerosol radiative forcing and global climate change. It is emitted by the incomplete combustion of fossil fuels, biofuels, and biomass. Urban environments are quite complex and thus, the use of mobile jointly with fixed monitoring provides a better understanding of the dynamics of BC distribution in such areas. The present study addresses the measurement of BC concentration using real-time mobile and ambient monitoring in Barranquilla, an industrialized urban area of the Colombian Caribbean. A microaethalometer (MA200) and an aethalometer (AE33) were used for measuring the BC concentration. The absorption Ångström exponent (AAE) values were determined for the study area, for identifying the BC emission sources. The results of the ambient sampling show that vehicle traffic emissions prevail; however, the influence of biomass burning was also observed. The mean ambient BC concentration was found to be 1.04 ± 1.03 μg/m³ and varied between 0.5 and 4.0 μg/m³. From the mobile measurements obtained in real traffic conditions on the road, a much higher average value of 16.1 ± 16.5 μg/m³ was measured. Many parts of the city showed BC concentrations higher than 20 μg/m³. The spatial distribution of BC concentration shows that vehicle emissions and traffic jams, a consequence of road and transport infrastructure, are the factors that most affect the BC concentration. A comparison of results obtained from two aethalometers indicates that the concentrations measured by MA200 are 9% lower than those measured by AE33. The AAE obtained was found to vary between 1.1 and 1.6, indicating vehicular emissions as the most crucial source. In addition, it was observed that the BC concentration on working days was 2.5 times higher than on the weekends in the case of mobile monitoring and 1.5 times higher in the case of ambient monitoring.
... The source apportionment of eBC was performed using the two-component model described by Sandradewi et al. [8], using light absorption measurements at 470 nm and 950 nm [27,28], since eBC from fossil fuel has a weak dependence on wavelength (i.e., AAE~1), whereas eBC from biomass burning features a stronger absorption spectral dependence and shows enhanced absorption at a shorter wavelength (i.e., AAE > 1) [29,30]. The absorption at 470 nm was used, instead of the UV channel at 370 nm, to minimize the interferences introduced by types of organic compounds, based on the sensitivity of the aethalometer model due to different wavelength combinations carried out by Zotter et al. [31]. ...
Article
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Light-absorbing carbonaceous aerosols (including black carbon (BC)) pose serious health issues and play significant roles in atmospheric radiative properties. Two-year measurements (2015–2016) of aerosol light absorption, combined with measurements of sub-micrometric particles, were continuously conducted in A Coruña (northwest (NW) Spain) to determine their light absorption properties: absorption coefficients (σabs) and the absorption Ångström exponent (AAE). The mean and standard deviation of equivalent black carbon (eBC) during the period of study were 0.85 ± 0.83 µg m−3, which are lower than other values measured in urban areas of Spain and Europe. High eBC concentrations found in winter are associated with an increase in emissions from anthropogenic sources in combination with lower mixing layer heights and frequent stagnant conditions. The pronounced diurnal variability suggests a strong influence from local sources. AAE had an average value of 1.26 ± 0.22 which implies that both fossil fuel combustion and biomass burning influenced optical aerosol properties. This also highlights biomass combustion in suburban areas, where the use of wood for domestic heating is encouraged, as an important source of eBC. All data treatment was gathered using SCALA© as atmospheric aerosol data management support software program.
... The parameter describing the exponential wavelength dependence is the absorption Ångström exponent (α). This wavelength dependence is different for particles from different pollution sources, enabling separation of traffic and biomass burning for domestic heating (Favez et al., 2009;Sandradewi et al., 2008a;Sandradewi et al., 2008b;Saleh et al., 2013;Zotter et al., 2017). ...
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Air pollution is not an exclusively urban problem as wood burning is a widespread practice in rural areas. As we lack information on the air quality situation in rural mountainous regions, our aim is to examine equivalent black carbon (eBC) pollution in a typical rural karst area in the settlement of Loški Potok (Slovenia). eBC mass concentrations were measured by Aethalometer (AE-33) at two sites in Retje karst depression. The rural village station was located at the bottom of the karst depression whereas the rural background station was positioned at the top of the hill. We show the diurnal variation of equivalent black carbon mass concentrations for different seasons. In the populated karst depression, the major source of eBC pollution are households using wood as a heating fuel reaching the highest mass concentrations in winter. Diurnal pattern of eBC from biomass burning and traffic differ due to different source activity and it is influenced by typical formation of a cold air pool from late afternoon until late morning, restricting the dispersion of local emissions. The large difference in mass concentrations between the lowest part of the village (rural station) and the top of the hill (rural background station) indicates that in a vertically stratified and stable atmosphere local sources of black carbon have a major impact on air quality conditions in the area studied. Since in Alpine and Dinaric regions there are many similar inhabited areas, we can expect similar air quality conditions also in other rural hilly areas with limited self-cleaning air capacity.
... Biomass burning contribution to BC concentration at the urban site is in the range of those observed in other European cities. Indeed, a biomass burning contribution of about 25% has been reported for urban and suburban areas in Paris(Favez et al., 2009), 24% in Zurich(Herich et al., 2011) and 23% in London(Fuller et al., 2014). On the other hand, the biomass burning contribution to BC concentration at the suburban station is in the range of those reported for other European metropolitan areas highly influenced by biomass burning like Helsinki(Helin et al., 2018) or those observed in rural areas in Switzerland(Herich et al., 2011), with contributions of 40% and 33%, respectively. ...
Thesis
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This PhD dissertation focuses on the characterization of fine atmospheric aerosol particles emission sources (their strength, spatial and temporal variability) at different environments by means of ground-based in-situ techniques. To this end, the aerosol microphysical and optical properties obtained by state-of-the-art instrumentation in multiple experimental campaigns performed at different environments (urban, suburban and remote high-altitude) in the southeast of the Iberian Peninsula have been analyzed and discussed. In order to take insight about the sources of fine atmospheric aerosol, their diurnal, weekly, seasonal and spatial variability in the Granada urban area, the aerosol number flux and concentration of fine particles obtained by eddy covariance technique are examined during the period from Nov/2016 to Apr/2018. The results show that the majority of aerosol number flux values are positive, suggesting that the urban site acts as a net source of aerosol particles to the atmosphere at different time scales. Concerning aerosol emissions sources, road traffic is identified as the main source in Granada urban area in all seasons. During winter, domestic heating and agricultural waste burning emissions are additional aerosol sources, while during spring and summer new particle formation processes contribute significantly to ultrafine aerosol particles. Wind sector analysis shows that the impact of domestic heating emissions from the urban area, especially at night, is much stronger than the impact of agricultural waste burning emissions from the suburban sector. With the aim to disentangle the contribution of the different aerosol sources to the total aerosol number concentration at sites influenced by biomass burning emissions, a new approach based on the Rodriguez and Cuevas (2007) and Sandradewi et al. (2008) methods has been developed. This new approach has been used to determine the contributions of both vehicle and biomass burning primary emissions and secondary aerosol to the size-segregated particle number concentrations at urban and suburban sites. This method has been applied to simultaneous measurements of aerosol number size distribution in the 12–600 nm size range and black carbon (BC) concentration obtained at both sites during winter season, when the study area is usually influenced by biomass burning emissions from domestic heating and agricultural waste burning. The results show that (1) secondary aerosol is the main contributor to the particle number concentration in all size ranges at both sites, (2) primary vehicle exhaust is the main source of primary particles with contributions >70% in all size ranges at both sites and (3) primary biomass burning particles contribute significantly to the primary particles concentrations in the 25–100 and 100–600 nm size ranges at the suburban (24% and 28%, respectively) and urban (13% and 20%, respectively) sites. In addition, new particle formation (NPF) events have been found to be an important aerosol source during summer noon hours but, on average, these events do not implicate a considerable contribution to urban particles. Despite this low contribution of NPF events to the total particle number concentration in Granada urban area, these events are of great importance for the production of cloud condensation nuclei (CCN), affecting clouds formation. Therefore, the characterization of NPF vertical distribution is of special interest. To this end, a detailed investigation of the NPF characteristics and the different factors that promote/inhibit NPF processes has been performed at two contrastive sites: urban and high-altitude remote sites. For this, simultaneous measurements of aerosol size distributions (4-500 nm) measured at both sites have been used. The analysis shows that, with NPF event frequency >70% at both sites, nucleation mode particles highly contribute to the total aerosol number concentration in summer (47 % and 48 % at mountain and urban sites, respectively). At the high-altitude remote site, NPF events have been found to be associated with the transport of gaseous precursors from lower altitudes by orographic buoyant upward flows. Nevertheless, NPF events at the high-altitude remote site have been always observed from the smallest measured sizes of the aerosol size distribution (4 nm), implying that NPF takes place in or in the vicinity of the high-altitude remote station rather than being transported from lower altitudes. Although NPF events at the mountain site seem to be connected with those occurring at the urban site, growth rates (GRs) at mountain site are higher than those at the urban site. The analysis of sulfuric acid (H2SO4) shows that the concentrations of H2SO4 can explain a minimal contribution of the observed GRs at both sites (< 1 % and < 10 % for the 7–25 and 4–7 nm size ranges, respectively), indicating that other condensing vapours are responsible for the majority of particle growth, as well as the differing growth rates between the two sites. The results also show that the condensation sink (CS) does not play a relevant role in NPF processes at both sites and points to the availability of volatile organic compounds (VOCs) as one of the main factors controlling the NPF events at the urban and high-altitude remote sites investigated.
Article
A field measurement campaign was carried out during the late winter and early spring of 2015 in Budapest, the capital of Hungary. The size distribution (SD) and optical absorption of carbonaceous particulate matter (CPM) was measured online using a Scanning Mobility Particle Sizer (SMPS), a 7λ-aethalometer and an inhouse developed 4λ-Photoacoustic Spectrometer. Based on the SD data, the measurement period could be classified into days with and without new particle formation events (normal days and nucleation days), although particular nucleation-like events were observed on normal days as well. Three characteristic size modes were observed with CMDs of circa 15, 25 and 110 nm that corresponded to the nucleation, traffic and heating modes. Based on the temporal behavior of these modes both types of days were divided into distinctive daily periods (heating hours, traffic hours and nucleation hours). The optical absorption spectra (OAC and AAE) also displayed the same part of day behavior to that of SD. That way this paper is among the first to assess the optical response of urban nucleation events. Due to the simultaneous measurement of OAC by the 7λ-aethalometer and a 4λ-Photoacoustic Spectrometer, OAC was measured overall at 11 wavelengths. That way aethalometer correction factors (f and C) were determined at all aethalometer wavelengths using in situ reference photoacoustic measurements. Correction factors were found to have both wavelength and time of the day variation. In the case of f, no clear trend could be observed, however, Cref values increased both as a function of wavelength.
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A two-month sampling campaign was carried out from 1 November to 30 December 2019, to investigate the light absorption of aerosols at coastal sites in Qingdao. The average values and standard deviations of the absorption coefficient (OAC) at λ = 1064 nm during the measurement period were 18.52 ± 13.31 Mm−1. Combined with the backward trajectory model, the aerosol absorption coefficient and gas pollution concentration of six possible air mass trajectories were obtained and calculated. The maximum absorption coefficient of local air masses was approximately 20.4 Mm−1 and anthropogenic pollution originated from mainly local sources in the Jiaozhou area. In our measurements at this site, the results also showed that there was a positive correlation between relative humidity (RH) and aerosol absorption. Without considering other factors, the size of aerosol particles grew with the increasing of RH, which changed the nonlinear relationship between the size and the absorption cross section of aerosol particles subsequently. In addition, the correlations between gas pollutants and OAC were calculated. The atmospheric environment is complex in sea–land intersection areas, especially in coastal cities. Analysis of various aerosol sources, meteorological conditions, and gas precursors enhances the study of aerosol optical absorption.
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Health effects from long- and short-term exposure to fine particulate matter (PM 2.5 )have resulted in an annual average PM 2.5 standard across Europe and World Health Organisation guidelines for annual (10 μg m ⁻³ )and 24 h PM 2.5 concentrations (25 μg m ⁻³ ). Developing strategies to reduce both annual and 24 h average PM 2.5 requires that the conditions that produce the magnitude of these metrics are understood. This paper presents a standard and replicable set of statistics that link the magnitude of annual and daily PM 2.5 metrics to variation in i)hourly PM 2.5 concentrations, ii)geographic regions traversed by air mass back trajectories, and iii)the ‘urban increment’ and ‘regional contribution’ to urban PM 2.5 concentrations. These statistics are calculated between 2009 and 2018 at monitoring sites across Paris and the Île-de-France region, France, where there is a national objective to achieve the WHO annual PM 2.5 guideline, and where short-term PM 2.5 episodes still occur. The aim is to investigate changes in the conditions producing annual average, and 24 h PM 2.5 concentrations exceeding 25 μg m ⁻³ , and how these long- and short-term metrics could be reduced further. The statistics indicate that reductions between 2009 and 2018 in both annual PM 2.5 concentrations (PM 2.5AA , −0.79 μg m ⁻³ y ⁻¹ averaged across 3 urban background sites (33% average 2009–2018 reduction))and the number of days with 24 h PM 2.5 concentrations above 25 μg m ⁻³ (D24h25, -6 days y ⁻¹ (62% average 2009–2018 reduction)), were driven by reductions in local emissions in Paris and the Île-de-France region. For example, reduction in PM 2.5AA and D24h25 were greater at urban traffic sites, and between 2009 and 2018 the highest hourly PM 2.5 concentrations occurred less frequently during rush hour periods, while the lowest hourly PM 2.5 concentrations occurred more frequently during the day. In addition, when relatively moderate and high hourly PM 2.5 concentrations were measured, air mass back trajectories spent more time (during the 4 preceding days)over European geographic regions, compared to the ocean indicating an increased relative contribution from regional transport to these hourly PM 2.5 concentrations. Consequently, there is now a greater difference in the contribution of different hourly PM 2.5 concentrations to annual and 24 h PM 2.5 compared with 2009, with relatively high hourly PM 2.5 concentrations having a larger contribution to D24h25, and moderate hourly PM 2.5 concentrations having a larger contribution to PM 2.5AA . Strategies to reduce PM 2.5 concentrations in Paris should consider how mitigation measures will affect different ranges of hourly PM 2.5 concentrations to understand the (potentially differing)effect on long- and short-term PM 2.5 impact metrics. Comparison of hourly PM 2.5 concentrations at urban sites and upwind rural sites showed regional contributions to PM 2.5AA of approximately 50% and 70% at urban traffic and urban background sites, respectively. The largest regional contributions were also estimated for the highest hourly PM 2.5 concentrations, compared to moderate hourly PM 2.5 concentrations. Regional emission reductions could therefore make a substantial contribution to achieving the WHO air quality guidelines in Paris.
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Wood smoke contains large quantities of carbonaceous aerosols known to increase climate forcing and be detrimental to human health. This paper reports the findings from our ambient sampling of fresh residential wood combustion (RWC) plumes in two heating seasons (2015-2016, 2016-2017) in Upstate New York. An Aethalometer (AE33) and a pDR-1500 were employed to monitor residential wood smoke plumes in Ithaca, NY through a hybrid mobile-stationary method. Fresh wood smoke plumes were captured and characterized at 13 different RWC sources in the city, all without significant influence from other combustion sources or atmospheric aging. Wood smoke absorption Ångström exponent (AAE) was estimated using both a one-component model, AAEWB, and a two-component model, AAEBrC (assuming AAEBC = 1.0). Consistent with the recent laboratory studies, our results show that AAEs were highly variable for residential wood smoke for the same source and across different sources, with AAEWB values ranging from 1.3 to 5.0 and AAEBrC values ranging from 2.2 to 7.4. This finding challenges the use of using a single AAE wood smoke value within the range of 1 to 2.5 for source apportionment studies. Furthermore, the PM2.5/BC ratio measured using optical instruments was demonstrated to be potentially useful to characterize burning conditions. Different wood smoke sources can be distinguished by their PM2.5/BC ratio, which range between 15 and 150. This shows promise as an in-situ, cost-effective, ambient sampling-based method to characterize wood burning conditions.
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Organic aerosol (OA) particles are recognized as key factors influencing air quality and climate change. However, highly-time resolved year-round characterizations of their composition and sources in ambient air are still very limited due to challenging continuous observations. Here, we present an analysis of long-term variability of submicron OA using the combination of Aerosol Chemical Speciation Monitor (ACSM) and multi-wavelength aethalometer from November 2011 to March 2018 at a background site of the Paris region (France). Source apportionment of OA was achieved via partially constrained positive matrix factorization (PMF) using the multilinear engine (ME-2). Two primary OA (POA) and two oxygenated OA (OOA) factors were identified and quantified over the entire studied period. POA factors were designated as hydrocarbon-like OA (HOA) and biomass burning OA (BBOA). The latter factor presented a significant seasonality with higher concentrations in winter with significant monthly contributions to OA (18–33 %) due to enhanced residential wood burning emissions. HOA mainly originated from traffic emissions but was also influenced by biomass burning in cold periods. OOA factors were distinguished between their less- and more-oxidized fractions (LO-OOA and MO-OOA, respectively). These factors presented distinct seasonal patterns, associated with different atmospheric formation pathways. A pronounced increase of LO-OOA concentrations and contributions (50–66 %) was observed in summer, which may be mainly explained by secondary OA (SOA) formation processes involving biogenic gaseous precursors. Conversely high concentrations and OA contributions (32–62 %) of MO-OOA during winter and spring seasons were partly associated with anthropogenic emissions and/or long-range transport from northeastern Europe. The contribution of the different OA factors as a function of OA mass loading highlighted the dominant roles of POA during pollution episodes in fall and winter, and of SOA for highest springtime and summertime OA concentrations. Finally, long-term trend analyses indicated a decreasing feature (of about 200 ng m−3 yr−1) for MO-OOA, very limited or insignificant decreasing trends for primary anthropogenic carbonaceous aerosols (BBOA and HOA, along with the fossil fuel and biomass burning black carbon components), and no trend for LO-OOA over the 6⁺-year investigated period.
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Air pollutants are coemitted with carbon dioxide (CO2) during the combustion of carbon-based fuels used to generate energy. By reducing air pollution in cities, we can improve the quality of life for millions of people, reduce the number of premature deaths, and mitigate the climate impacts of CO2 emissions. Here, we discuss the links between CO2 and coemitted air pollutants released from fossil and biofuels in mobile and stationary combustion and the impact of these emissions on air quality in cities. We highlight important examples of how policies to reduce CO2 emissions can either degrade or improve urban air quality, depending on how they are implemented. Key recommendations are to (1) prioritize the removal of carbon-fuel based combustion, especially coal and wood burning; (2) electrify transportation, especially for colder climates and heavy-duty vehicles; (3) remove sulfur from all fuels; and (4) leverage existing air quality monitoring networks to increase density of CO2 concentration measurements in cities worldwide.
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Carbonaceous constituents have various adverse impacts on human health, visibility, and climate change. Although comprehensive studies on the characteristics of carbonaceous constituents have been conducted recently, systematic studies covering both the mass characteristics and light-absorption properties of carbonaceous constituents on a regional scale in China are quite limited. In this study, current seasonal measurements of organic carbon (OC) and elemental carbon (EC) in PM2.5 were investigated during autumn and winter (1–30 October 2017 and December 18, 2017 to January 17, 2018) in six selected cities located at the eastern foot of the Taihang Mountains: Beijing, Baoding, Shijiazhuang, Handan, Xinxiang, and Zhengzhou. Seasonal variations were similar when Beijing was excluded. The lowest concentrations of OC (18.33 ± 9.39 μg/m³) and EC (7.66 ± 5.64 μg/m³) were observed in Xinxiang (autumn) and Beijing (winter), respectively, while the highest concentrations of OC (38.43 ± 62.10 μg/m³) and EC (12.24 ± 24.67 μg/m³) occurred in Baoding during winter mainly due to elevated fuel combustion for space heating. The results of the potential source contribution function (PSCF) analysis suggested that border zones between several provinces in North China should be highlighted in order to strengthen pollution control. Moreover, by separating the optical properties of brown carbon from those of black carbon, we were able to estimate the contributions of brown carbon to the PM2.5 total light-absorption coefficient. The results show that the brown carbon absorption coefficient (at 405 nm) in winter at six sites accounted for 21.2%, 33.3%, 34.7%, 39.1%, 48.6%, and 23.3% of the PM2.5 light absorption, which are values that are comparable to the contribution of black carbon in Xinxiang. These results provide a more comprehensive understanding of carbonaceous constituents on a regional scale.
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Climate change evolution, joined by other environmental issues, will lead in the coming years to a rapid introduction of new actions and technologies. They will have to resolve, in the different economic sectors, one or more aspects of the current unsustainability. The relevant risk is that, in urgent conditions where the unreleased practices will be proposed, the assessment of their environmental impact will remain limited to their specificfield/sector. Therefore, the evaluation would not be extended to any wide-ranging environmental effects. Withoutan accurate assessment it would be impossible to determine whether the solution was more damaging and burdensometo the environment than the initial problem. Small-medium anthropic activities do not possess, from the economicpoint of view, the means and the duty to achieve an impact analysis ad hoc. This work aims to describe an analysis methodology developed for the environmental impact assessment of Small-Medium Enterprises. It is both exhaustive and easily applicable to small work activities and processes. This methodology is aimed both at business managers and at local authorities. The identified method of analysis allows an exhaustive evaluation of the whole forest energy chain and the identification of technical choice with less impact on the environment.
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Organic aerosol (OA) particles are recognized as key factors influencing air quality and climate change. However, highly time-resolved long-term characterizations of their composition and sources in ambient air are still very limited due to challenging continuous observations. Here, we present an analysis of long-term variability of submicron OA using the combination of an aerosol chemical speciation monitor (ACSM) and a multiwavelength Aethalometer from November 2011 to March 2018 at a peri-urban background site of the Paris region (France). Source apportionment of OA was achieved via partially constrained positive matrix factorization (PMF) using the multilinear engine (ME-2). Two primary OA (POA) and two oxygenated OA (OOA) factors were identified and quantified over the entire studied period. POA factors were designated as hydrocarbon-like OA (HOA) and biomass burning OA (BBOA). The latter factor presented a significant seasonality with higher concentrations in winter with significant monthly contributions to OA (18 %–33 %) due to enhanced residential wood burning emissions. HOA mainly originated from traffic emissions but was also influenced by biomass burning in cold periods. OOA factors were distinguished between their less- and more-oxidized fractions (LO-OOA and MO-OOA, respectively). These factors presented distinct seasonal patterns, associated with different atmospheric formation pathways. A pronounced increase in LO-OOA concentrations and contributions (50 %–66 %) was observed in summer, which may be mainly explained by secondary OA (SOA) formation processes involving biogenic gaseous precursors. Conversely, high concentrations and OA contributions (32 %–62 %) of MO-OOA during winter and spring seasons were partly associated with anthropogenic emissions and/or long-range transport from northeastern Europe. The contribution of the different OA factors as a function of OA mass loading highlighted the dominant roles of POA during pollution episodes in fall and winter and of SOA for highest springtime and summertime OA concentrations. Finally, long-term trend analyses indicated a decreasing feature (of about −175 ng m−3 yr−1) for MO-OOA, very limited or insignificant decreasing trends for primary anthropogenic carbonaceous aerosols (BBOA and HOA, along with the fossil-fuel and biomass-burning black carbon components) and no statistically significant trend for LO-OOA over the 6-year investigated period.
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Rural lower Yakima Valley, Washington is home to the reservation of the Confederated Tribes and Bands of the Yakama Nation, and is a major agricultural region. Episodic poor air quality impacts this area, reflecting sources of particulate matter with a diameter of less than 2.5 μm (PM2.5) that include residential wood smoke, agricultural biomass burning and other emissions, truck traffic, backyard burning, and wildfire smoke. University of Washington partnered with the Yakama Nation Environmental Management Program to investigate characteristics of PM2.5 using 9 months of data from a combination of low-cost optical particle counters and a 5-wavelength aethalometer (MA200 Aethlabs) over 4 seasons and an episode of summer wildfire smoke. The greatest percentage of hours sampled with PM2.5 >12 μg/m³ occurred during the wildfire smoke episode (59%), followed by fall (23%) and then winter (21%). Mean (SD) values of Delta-C (μg/m³), which has been posited as an indicator of wood smoke, and determined as the mass absorbance difference at 375–880 nm, were: summer – wildfire smoke 0.34 (0.52), winter 0.27 (0.32), fall 0.10 (0.22), spring 0.05 (0.11), and summer – no wildfire smoke 0.04 (0.14). Mean (95% confidence interval) values of the absorption Ångström exponent, an indicator of the wavelength dependence of the aerosol, were: winter 1.5 (1.2–1.8), summer – wildfire smoke 1.4 (1.0–1.8), fall 1.3 (1.1–1.4), spring 1.2 (1.1–1.4), and summer – no wildfire smoke 1.2 (1.0–1.3). The trends in Delta-C and absorption Ångström exponents are consistent with expectations that a higher value reflects more biomass burning. These results suggest that biomass burning is an important contributor to PM2.5 in the wintertime, and emissions associated with diesel and soot are important contributors in the fall; however, the variety of emissions sources and combustion conditions present in this region may limit the utility of traditional interpretations of aethalometer data. Further research on the interpretation of aethalometer data in regions with complex emissions would contribute to much-needed understanding in communities impacted by air pollution from agricultural as well as residential sources of combustion.
Thesis
La pollution atmosphérique résulte d’un mélange complexe de composés, des gaz et des particules, dont les effets sont notoirement néfastes. Les composés organiques volatils (COV) tiennent un rôle prépondérant dans la chimie atmosphérique et sont précurseurs d’ozone et d’aérosols organiques secondaires (AOS). En Île-de-France, l’exposition à la pollution est préoccupante ; or, des incertitudes significatives sont toujours associées aux sources de polluants, ainsi qu’à leur intensité et leurs variabilités à différentes échelles de temps et très peu d’investigations ont porté sur la quantification de l’exposition individuelle. Dans ce contexte, cette thèse a cherché à mieux caractériser les variabilités temporelle et spatiale de la pollution en Île-de-France.La fiabilité discutable des capteurs portables a été dépassée par l’élaboration d’un protocole de sélection et de qualification comprenant différents tests en mesures fixes, en chambre et en mobilité. Cette nouvelle méthodologie, basée notamment sur l’utilisation d’un outil combinant différents indicateurs statistiques, a été appliquée pour retenir l’AE51, le Cairclip et le Canarin, mesurant respectivement le carbone suie (BC), le dioxyde d’azote (NO2) et les particules (PM).Ces trois capteurs ont été déployés au cours de campagnes de mesures impliquant une trentaine de volontaires. L’exposition individuelle ainsi quantifiée est plus élevée à l’automne qu’au printemps et varie de manière substantielle en fonction des différents environnements fréquentés. La proximité de la circulation routière (pour le BC et le NO2) ainsi que les activités de cuisine et la fumée de tabac (pour les PM) présentent des contributions importantes à l’exposition totale (jusqu’à 34 %, 26 % et 44 % respectivement), alors même que le temps passé dans ces environnements est faible.En plus du trafic routier, le BC est traditionnellement imputé au feu de bois. Une campagne hivernale de mesures (3,5 mois) a permis d’imputer respectivement 22 % et 47 % des COV mesurés à ces deux sources. Certains composés ont été mesurés et associés au feu de bois pour la première fois en air ambiant comme le benzènediol et le méthylbutènone. Une comparaison avec l’inventaire régional des émissions a permis d’identifier des similitudes et des différences pour proposer des améliorations.
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Black carbon (BC) or soot is a constituent of particulate matter (PM) which is relevant for negative human health and climate effects, and despite the lack of direct legal limits, it is recognised as an important atmospheric pollutant to monitor, understand, and control. Aethalometers are instruments which continuously monitor BC by measuring absorption at a number of distinct wavelengths. If collocated elemental carbon (EC) observations are used to transform these values into BC mass, by convention, the result is named equivalent black carbon (EBC). BC emitted by different combustion processes has different optical absorption characteristics, and this can be used to apportion EBC mass into traffic (EBCTR) and woodburning (EBCWB) components with a data processing technique known as the aethalometer model. The aethalometer model was applied to six EBC monitoring sites across Switzerland (using data between 2008 and 2018) and was evaluated by investigating diurnal cycles, model coefficients, and ambient temperature dependence of the two EBC components. For one monitoring site, San Vittore, the aethalometer model failed to produce plausible outputs. The reason for this failure was likely due to a high load of freshly emitted wood smoke during the winter which should be thought of as a third distinct emission source. After model evaluation, the trend analysis indicated that EBCTR concentrations at the remaining five locations significantly decreased between 2008 and 2018. EBCWB also demonstrated significant decreases in most monitoring locations but not at a monitoring site south of the Alps with a high PM load sourced from biomass burning. Ratios of EBC and particulate matter with a diameter of less than 2.5 µm (PM2.5) suggested that EBC contributes 6 %–14 % of the PM2.5 mass in Switzerland. The aethalometer model is a useful data analysis procedure but can fail under certain conditions; thus, careful evaluation is required to ensure the method is robust and suitable in other locations.
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Severe haze in Beijing during February of 2020, corresponding to the pandemics of Covid-19, was ascribed to residential coal combustion, which is always air lean or of oxygen deficiency, for household heating in the rural areas around Beijing. In this study, a drop-tube furnace combustion system was employed, where five types of representative coal were burned under the conditions of three respective temperatures and an oxygen-deficient combustion condition to simulate different residential coal combustion regimes. The on-line number concentration distribution of particulate matters in flue gas emitted was obtained. By size-segregated particulate matters of PM1, PM2.5 and PM10 collected in a three-stage sampler during various coal burning, the mass of organic carbon (OC) and elemental carbon (EC) and optical properties of light-absorbing organic carbonaceous aerosol were measured extensively. The results indicated that high temperature encouraged the formation of sub-micron and ultra-micron particles. It was found that coal types had a great impact on the formation of EC aerosols, that is, the mass of EC decreased with increasing geological maturity. Besides, the formation of EC was also affected by temperature, that is, the lower the temperature was, the more EC components were generated. The optical properties of the aerosol particle extracted by methanol from PM1, PM2.5, and PM10 were measured and explored. The high values of absorption Ångström exponent (AAE) and mass absorption efficiency at the wavelength of 365 nm (MAE365) indicated the high wavelength-dependence characteristics and strong light absorbing abilities of brown carbon (BrC) from residential coal burning. AAE values from 1200 °C combustion emissions was observed to be diminishing with increasing fixed carbon to volatile matter ratio (FC/VM) and decreasing OC/(OC + EC). In addition, MAE365 values from low-temperature combustion were higher. These findings help us better understand the role that household coal burning plays in global BrC emission and its harm on the environment and human health.
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Many open questions exist about the importance of different sources of carbonaceous aerosol, which is a substantial contributor to the global aerosol budget and, therefore, to climate change and human mortality. In this work, 14C was determined in elemental carbon (EC) and different organic carbon (OC) fractions from ambient urban aerosols with aerodynamic diameter <10 μm collected in Zurich (Switzerland). This enabled a more detailed source attribution of the carbonaceous aerosol mass than is possible with other currently available methods. The three major sources, fossil fuel, wood combustion (both anthropogenic emissions), and biogenic emissions, were quantified, making specific regulatory air quality management measures possible, EC originates nearly exclusively from fossil fuel usage during summer, whereas biomass-burning emissions become substantial during winter with ∼25%, even though this source contributes only marginally to the local energy consumption. For OC, biogenic sources are dominant in summer with ∼60%, where secondary organic aerosol prevails. Wood combustion accounts for up to ∼41% of OC in winter. Fossil fuels represent ∼30% of OC throughout the year.
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Atmospheric levoglucosan has been determined as a proxy for '' biomass smoke '' in samples from six background stations on a west - east transect extending from the Atlantic ( Azores) to the mid- European background site KPZ ( K- Puszta, Hungary). Concentration levels of levoglucosan ( biannual averages) in the west - east transect range from 0.005 mu g/m(3) at the oceanic background site AZO ( Azores) to 0.52 mu g/m(3) at AVE ( Aveiro, Portugal). The atmospheric concentration of '' biomass smoke '' ( biannual averages) was derived from the levoglucosan data with wood- type- specific conversion factors. Annual averages of wood smoke levels ranged from 0.05 mu g/m(3) at AZO to 4.3 mu g m(3) at AVE. Winter ( DJF) averages at the low- level sites AVE and KPZ were 10.8 and 6.7 mu g/m(3), respectively. Relative contributions of biomass smoke to organic matter ( OM) range from around 9 - 11% at the elevated sites SIL, PDD and SBO, as well as for AZO, to 36% at the low- level site AVE and 28% at KPZ. Surprisingly high relative concentrations of biomass smoke in OM ( 68 and 47%) were observed for wintry conditions at the continental low- level CARBOSOL sites AVE and KPZ. Thus biomass smoke is a very important constituent of the organic material in the mid and west European background with summer contributions to organic matter of around 1 - 6% and winter levels of around 20% at the elevated mountain sites and 47 - 68% at rural flat terrain sites, not including secondary organic aerosol from biomass combustion sources.
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1] A dual-wavelength photoacoustic instrument operating at 405 and 870 nm was used during the 2006 Fire Lab at Missoula Experiment to measure light scattering and absorption by smoke from the combustion of a variety of biomass fuels. Simultaneous measurements of aerosol light scattering by reciprocal nephelometry within the instrument's acoustic resonator accompany photoacoustic aerosol light absorption measurements. Single scattering albedo values at 405 nm ranging from 0.37 to 0.95 were measured for different fuel types, and the spectral dependence of absorption was quantified using the Å ngström exponent of absorption. An absorption Å ngström exponent near unity is commonly observed for motor vehicle emission-generated black carbon aerosol. For biomass smoke, Å ngström exponents as high as 3.5 were found in association with smoke having single scattering albedo near unity. The measurements strongly suggest that light-absorbing organic material is present in wood smoke. A second single-wavelength photoacoustic instrument with reciprocal nephelometry was used to quantify aerosol scattering and absorption at 532 nm. Absorption Å ngström exponents calculated using 532 and 870 nm data were as large as 2.5 for smoke with single scattering albedos near unity. The spectral variation in optical properties provides insight into the differentiation of aerosols from mobile or industrial sources versus those from biomass burning. Optical properties of biomass smokes could be classified by general fuel type such as flowering shrubs versus pine needle litter., Strong spectral variation of biomass smoke light absorption and single scattering albedo observed with a novel dual-wavelength photoacoustic instrument, J. Geophys. Res., 113, D16203, doi:10.1029/2007JD009699.
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A source apportionment study was performed for particulate matter in the small village of Roveredo, Switzerland, where more than 70% of the households use wood burning for heating purposes. A two-lane trans-Alpine highway passes through the village and contributes to the total aerosol burden in the area. The village is located in a steep Alpine valley characterized by strong and persistent temperature inversions during winter, especially from December to February. During two winter and one early spring campaigns, a seven-wavelength aethalometer, high volume (HIVOL) samplers, an Aerodyne quadrupole aerosol mass spectrometer (AMS), an optical particle counter (OPC), and a Sunset Laboratory OCEC analyzer were deployed to study the contribution of wood burning and traffic aerosols to particulate matter. A linear regression model of the carbonaceous particulate mass in the submicrometer size range CM(PM1) as a function of aerosol light absorption properties measured by the aethalometer is introduced to estimate the particulate mass from wood burning and traffic (PM(wb), PM(traffic)). This model was calibrated with analyses from the 14C method using HIVOL filter measurements. These results indicate that light absorption exponents of 1.1 for traffic and 1.8-1.9 for wood burning calculated from the light absorption at 470 and 950 nanometers should be used to obtain agreement of the two methods regarding the relative wood burning and traffic emission contributions to CM(PM1) and also to black carbon. The resulting PM(wb) and PM(traffic) values explain 86% of the variance of the CM(PM1) and contribute, on average, 88 and 12% to CM(PM1), respectively. The black carbon is estimated to be 51% due to wood burning and 49% due to traffic emissions. The average organic carbon/total carbon (OC/TC) values were estimated to be 0.52 for traffic and 0.88 for wood burning particulate emissions.
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Semicontinuous measurements of submicron water-soluble organic carbon (WSOC) aerosol were made simultaneously with organic carbon (OC) and elemental carbon (EC) in the Tokyo urban area in winter, summer, and fall 2004. The measurements of WSOC and OC/EC were made every 6 min and 1 hour, respectively, using a particle-into-liquid sampler (PILS) with a total organic carbon (TOC) analyzer and with an EC-OC analyzer using a thermal-optical technique. The PILS and 12-hour integrated filter measurements of WSOC agreed to within 12%. The WSOC mass concentrations and WSOC/OC ratio showed diurnal variations with peaks at 1200–1400 LT in summer and later in the afternoon in winter. On average, the WSOC/OC ratio was 0.20 and 0.35 μg C/μg C for winter and summer/late fall, respectively. The difference in the winter and summer frequency distributions of the WSOC/OC ratio suggests that the sampled air masses in summer and fall were more photochemically processed than those in winter. Secondary organic carbon (SOC) concentrations were estimated using the EC-tracer method. The measured WSOC was highly correlated with the derived SOC (r2 = 0.61–0.79), with WSOC/SOC slopes of 0.67 to 0.75 μg C/μg C for each season. These results suggest that the WSOC and SOC were similar in their chemical characteristics in this study. Water-insoluble organic carbon (WIOC) ( = OC–WSOC) correlated well with EC and CO (r2 = 0.59–0.73). The diurnally averaged WIOC/EC ratios were nearly constant (1.1 ± 0.1 μg C/μg C) throughout the study periods, suggesting that motor vehicle emissions were an important source of WIOC. A dominant portion (about 90% or more) of the POC was water-insoluble, consistent with previous studies of POC.
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A recently developed algorithm (Zhang et al., 2005) has been applied to deconvolve the mass spectra of organic aerosols acquired with the Aerosol Mass Spectrometer (AMS) in Pittsburgh during September 2002. The results are used here to characterize the mass concentrations, size distributions, and mass spectra of hydrocarbon-like and oxygenated organic aerosol (HOA and OOA, respectively). HOA accounts for 34% of the measured organic aerosol mass and OOA accounts for 66%. The mass concentrations of HOA demonstrate a prominent diurnal profile that peaks in the morning during the rush hour and decreases with the rise of the boundary layer. The diurnal profile of OOA is relatively flat and resembles those of SO<sub>4</sub><sup>2?</sup> and NH<sub>4</sub><sup>+</sup>. The size distribution of HOA shows a distinct ultrafine mode that is commonly associated with fresh emissions while OOA is generally concentrated in the accumulation mode and appears to be mostly internally mixed with the inorganic ions, such as SO<sub>4</sub><sup>2?</sup> and NH<sub>4</sub><sup>+</sup>. These observations suggest that HOA is likely primary aerosol from local, combustion-related emissions and that OOA is secondary organic aerosol (SOA) influenced by regional contributions. There is strong evidence of the direct correspondence of OOA to SOA during an intense new particle formation and growth event, when condensational growth of OOA was observed. The mass spectrum of OOA of this new particle formation event is very similar to the OOA spectrum of the entire study, which strongly suggests that most OOA during this study is SOA. O<sub>3</sub> appears to be a poor indicator for SOA concentration while SO<sub>4</sub><sup>2?</sup> is a relatively good surrogate for this dataset. Since the diurnal averages of HOA tightly track those of CO during day time, oxidation/aging of HOA appears to be very small on the time scale of several hours. Based on extracted mass spectra and the likely elemental compositions of major m/z 's, the organic mass to organic carbon ratios (OM:OC) of HOA and OOA are estimated at 1.2 and 2.2 ?g/?g C, respectively, leading to an average OM:OC ratio of 1.8 for submicron OA in Pittsburgh during September. The C:O ratio of OOA is estimated at 1:0.8. The carbon contents in HOA and OOA calculated accordingly correlate well to primary and secondary organic carbon, respectively, estimated by the OC/EC tracer technique (assuming POC-to-EC ratio=1). In addition, the total carbon concentrations calculated from the AMS data agree well with those measured by the Sunset Laboratory Carbon analyzer ( r <sup>2</sup>=0.87; slope=1.01±0.11).
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Residential wood combustion has only recently been recognized as a major contributor to air pollution in Switzerland and in other European countries. A source apportionment method using the aethalometer light absorption parameters was applied to five winter campaigns at three sites in Switzerland: a village with high wood combustion activity in winter, an urban background site and a highway site. The particulate mass from traffic (PMtraffic) and wood burning (PMwb) emissions obtained with this model compared fairly well with results from the 14C source apportionment method. PMwb from the model was also compared to well known wood smoke markers such as anhydrosugars (levoglucosan and mannosan) and fine mode potassium, as well as to a marker recently suggested from the Aerodyne aerosol mass spectrometer (mass fragment m/z 60). Additionally the anhydrosugars were compared to the 14C results and were shown to be comparable to literature values from wood burning emission studies using different types of wood (hardwood, softwood). The levoglucosan to PMwb ratios varied much more strongly between the different campaigns (4–13%) compared to mannosan to PMwb with a range of 1–1.5%. Possible uncertainty aspects for the various methods and markers are discussed.
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Although the definition and measurement methods of atmospheric &apos;&apos;black carbon&apos;&apos; (&apos;&apos;BC&apos;&apos;) have long been subjects of scientific controversy, the recent discovery of light-absorbing carbon that is not black (&apos;&apos;brown carbon, Cbrown&apos;&apos;) makes it imperative to reassess and redefine the components that make up light-absorbing carbonaceous matter (LAC) in the atmosphere. Evidence for the atmospheric presence of Cbrown comes directly from aerosol absorption measurements near specific combustion sources, from observations of spectral properties of water extracts of continental aerosol, from laboratory studies indicating the formation of light-absorbing organic matter in the atmosphere, and indirectly from the chemical analogy of aerosol species to colored natural humic substances. We show that these species may severely bias measurements of &apos;&apos;BC&apos;&apos; and &apos;&apos;EC&apos;&apos; over vast parts of the troposphere, where mass concentration of Cbrown is high relative to that of combustion soot. We also imply that due to the strongly skewed absorption of Cbrown towards the UV, single-wavelength light absorption measurements may not be adequate for the assessment of absorption of solar radiation in the troposphere. The possible consequences of these effects on our understanding of tropospheric processes are discussed.
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Black carbon, brown carbon, and mineral dust are three of the most important light absorbing aerosols. Their optical properties differ greatly and are distinctive functions of the wavelength of light. Most optical instruments that quantify light absorption, however, are unable to distinguish one type of absorbing aerosol from another. It is thus instructive to separate total absorption from these different light absorbers to gain a better understanding of the optical characteristics of each aerosol type. During the EAST-AIRE (East Asian Study of Tropospheric Aerosols: an International Regional Experiment) campaign near Beijing, we measured light scattering using a nephelometer, and light absorption using an aethalometer and a particulate soot absorption photometer. We also measured the total mass concentrations of carbonaceous (elemental and organic carbon) and inorganic particulates, as well as aerosol number and mass distributions. We were able to identify periods during the campaign that were dominated by dust, biomass burning, fresh (industrial) chimney plumes, other coal burning pollution, and relatively clean (background) air for Northern China. Each of these air masses possessed distinct intensive optical properties, including the single scatter albedo and Ångstrom exponents. Based on the wavelength-dependence and particle size distribution, we apportioned total light absorption to black carbon, brown carbon, and dust; their mass absorption efficiencies at 550 nm were estimated to be 9.5, 0.5 (a lower limit value), and 0.03 m2/g, respectively. While agreeing with the common consensus that black carbon is the most important light absorber in the mid-visible, we demonstrated that brown carbon and dust could also cause significant absorption, especially at shorter wavelengths.
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During the major part of the Mediterranean Intensive Oxidant Study (MINOS) campaign (summer 2001, Crete Isl.), the Marine Boundary Layer (MBL) air was influenced by long range transport of biomass burning from the northern and western part of the Black Sea. During this campaign, carbonaceous aerosols were collected on quartz filters at a Free Tropospheric (FT) site, and at a MBL site together with size-resolved distribution of aerosols. Three Evolution Gas Analysis (EGA) protocols have been tested in order to better characterize the collected aged biomass burning smoke: A 2-step thermal method (Cachier et al., 1989) and a thermo-optical technique using two different temperature programs. The later temperature programs are those used for IMPROVE (Interagency Monitoring of Protected Visual Environments) and NIOSH 5040 (National Institute of Occupational Safety and Health). Artifacts were observed using the NIOSH temperature program and identified as interactions between carbon and dust deposited on the filter matrix at high temperature (T>550ºC) under the pure helium step of the analysis. During the MINOS campaign, Black Carbon (BC) and Organic Carbon (OC) mass concentrations were on average respectively 1.19±0.56 and 3.62±1.08 m gC/m<sup>3</sup> for the IMPROVE temperature program, and 1.09±0.36 and 3.75±1.24 m gC/m<sup>3</sup> for the thermal method. Though these values compare well on average and the agreement between the Total Carbon (TC) measurements sample to sample was excellent (slope=1.00, r <sup>2</sup>=0.93, n=56), important discrepancies were observed in determining BC concentrations from these two methods (average error of 33±22%). BC from the IMPROVE temperature program compared well with non-sea-salt potassium (nss-K) pointing out an optical sensitivity to biomass burning. On the other hand, BC from the thermal method showed a better agreement with non-sea-salt sulfate (nss-SO<sub>4</sub>), considered as a tracer for fossil fuel combustion during the MINOS campaign. The coupling between these two methods for determining BC brings here new insights on the origin of carbonaceous aerosols in a complex mixture of different sources. It brings also to our attention that important deviations in BC levels are observed using three widely used EGA's techniques and most probably none of the EGA tested here are well adapted to fully characterize this aerosol mixture. Spherical, smooth and silico-aluminated fly-ash observed by an Analytical Scanning Electron Microscope (ASEM) confirm the influence of coal combustion on the carbonaceous aerosol load throughout the campaign. A rough calculation based on a BC/nss-SO<sub>4</sub> mass ratio suggests that biomass burning could be responsible for half of the BC concentration recorded during the MINOS campaign. From the plot of BC as a function of TC, two linear correlations were observed corresponding to 2 times series (before and after 12 August). Such good correlations suggest, from a first look, that both BC and OC have similar origin and atmospheric transport. On the other hand, the plot of BC as a function of TC obtained from the 2-step thermal method applied to DEKATI Low Pressure Cascade Impactor samples does not show a similar correlation and points out a non conservative distribution of this ratio with 2 super micron modes enriched in OC, correlated with sea salt aerosols and probably originating from gas-to-particle conversion.
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The contribution of air particles in human cardio-respiratory diseases has been enlightened by several epidemiological studies. However the respective involvement of coarse, fine and ultrafine particles in health effects is still unclear. The aim of the present study is to determine which size fraction from a chemically characterized background aerosol has the most important short term biological effect and to decipher the determinants of such a behaviour. Ambient aerosols were collected at an urban background site in Paris using four 13-stage low pressure cascade impactors running in parallel (winter and summer 2005) in order to separate four size-classes (PM0.03-0.17 (defined here as ultrafine particles), PM0.17-1 (fine), PM1-2.5(intermediate) and PM2.5-10 (coarse)). Accordingly, their chemical composition and their pro-inflammatory potential on human airway epithelial cells were investigated. Considering isomass exposures (same particle concentrations for each size fractions) the pro-inflammatory response characterized by Granulocyte Macrophage-Colony Stimulating Factor (GM-CSF) release was found to decrease with aerosol size with no seasonal dependency. When cells were exposed to isovolume of particle suspensions in order to respect the particle proportions observed in ambient air, the GM-CSF release was maximal with the fine fraction. In presence of a recombinant endotoxin neutralizing protein, the GM-CSF release induced by particles is reduced for all size-fractions, with exception of the ultra-fine fraction which response is not modified. The different aerosol size-fractions were found to display important chemical differences related to the various contributing primary and secondary sources and aerosol age. The GM-CSF release was correlated to the organic component of the aerosols and especially its water soluble fraction. Finally, Cytochrome P450 1A1 activity that reflects PAH bioavailability varied as a function of the season: it was maximal for the fine fraction in winter and for the ultrafine fraction in summer. In the frame of future regulations, a particular attention should thus be paid to the ultrafine/fine (here referred to as PM1) fraction due to their overwhelming anthropogenic origin and predominance in the urban aerosol and their pro-inflammatory potential.
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The wavelength dependence of light absorption by aerosols collected on filters is investigated throughout the near-ultraviolet to near-infrared spectral region. Measurements were made using an optical transmission method. Aerosols produced by biomass combustion, including wood and savanna burning, and by motor vehicles, including diesel trucks, are included in the analysis. These aerosol types were distinguished by different wavelength (λ) dependences in light absorption. Light absorption by the motor vehicle aerosols exhibited relatively weak wavelength dependence; absorption varied approximately as λ-1, indicating that black carbon (BC) was the dominant absorbing aerosol component. By contrast, the biomass smoke aerosols had much stronger wavelength dependence, approximately λ-2. The stronger spectral dependence was the result of enhanced light absorption at wavelengths shorter than 600 nm and was largely reduced when much of the sample organic carbon (OC) was extracted by dissolution in acetone. This indicates that OC in addition to BC in the biomass smoke aerosols contributed significantly to measured light absorption in the ultraviolet and visible spectral regions and that OC in biomass burning aerosols may appreciably absorb solar radiation. Estimated absorption efficiencies and imaginary refractive indices are presented for the OC extracted from biomass burning samples and the BC in motor vehicle-dominated aerosol samples. The uncertainty of these constants is discussed. Overall, results of this investigation show that low-temperature, incomplete combustion processes, including biomass burning, can produce light-absorbing aerosols that exhibit much stronger spectral dependence than high-temperature combustion processes, such as diesel combustion.
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In virtually all published literature wherein closure between gravimetric and chemical measurements is tested, the concentration of particulate organics is estimated by multiplying the measured concentration of organic carbon (micrograms carbon/cubic meter air) by a factor of 1.2-1.4. This factor, which is an estimate of the average molecular weight per carbon weight for the organic aerosol, stems from very limited theoretical and laboratory studies conducted during the 1970s. This investigation suggests that 1.4 is the lowest reasonable estimate for the organic molecular weight per carbon weight for an urban aerosol and that 1.4 does not accurately represent the average organic molecular weight per carbon weight for a nonurban aerosol. Based on the current evaluation, ratios of 1.6 ± 0.2 for urban aerosols and 2.1 ± 0.2 for nonurban aerosols appear to be more accurate. Measurements are recommended. Literature values also suggest that 1.2 g/cm3 is a reasonable estimate for the organic aerosol density. This quantity is needed to convert between geometric and aerodynamic size distributions (e.g., to predict aerosol optical properties and understand cloud nucleating properties).
Article
During summer, the Beijing urban area meets contrasting meteorological conditions including warm and humid monsoon winds from the southeast bringing high levels of pollution, with PM2.5 mass concentrations often exceeding 100 μg/m3. The specific weather conditions and aerosol chemical composition observed at that time offer a unique opportunity to address the question of the contribution of semi-volatile material (SVM) in the continuous PM records available for the south East Asian urban regions. Different PM2.5 measurements were evaluated during a 3-week field campaign performed in Beijing downtown during the summer 2004, and consisting of a Rupprecht & Patashnik (R&P TEOM) (heating air sample at 50°C), R&P TEOM-FDMS (enabling SVM measurement), optical GRIMM counter, and filter weighing. A good agreement was found between the different TEOM measurements during the campaign with the exception of the periods of high Relative Humidity (RH), which exhibited SVM levels (derived from PM2.5 loss in the TEOM heated at 50°C) as high as 140 μg/m3. Continuous artefact-free PM2.5 nitrate measurements were performed simultaneously and showed a close relationship with the TEOM-derived SVM, accounting for half of this SVM. To better document the role of RH on SVM, estimates of liquid water content (LWC) in aerosols were derived from light scattering coefficient and integrated aerosol volume measurements performed in the field at different RH. LWC is shown to be related in a quantitative way to the levels of SVM and nitrate in aerosols, and thus is believed to play a major role in the gas-particle partitioning of semi-volatile species in Beijing aerosols.
Article
Sampling and analysis of carbonaceous compounds in particulate matter presents a number of difficulties related to artefacts during sampling and to the distinction between organic (OC) and elementalcarbon (EC) during analysis. Our study reports on a comparativeanalysis of OC, EC and WSOC (water-soluble organiccarbon) concentrations, as well as sampling artefacts, for PM2.5 aerosol in threeEuropeancities (Amsterdam, Barcelona and Ghent) representing Southern and Western European urban environments. Comparability of results was ensured by using a single system for sample analysis from the different sites. OC and EC concentrations were higher in the vicinity of roads, thus having higher levels in Amsterdam (3.9–6.7 and 1.7–1.9 μg m−3, respectively) and Barcelona (3.6–6.9 and 1.5–2.6 μg m−3) than in Ghent (2.7–5.4 and 0.8–1.2 μg m−3). A relatively larger influence of secondary organicaerosols (SOA), as deduced from a larger OC/EC ratio, was observed in Ghent. In absolute sense, WSOC concentrations were similar at the three sites (1.0–2.3 μg m−3). Positive artefacts were higher in Southern (11–16% of the OC concentration in Barcelona) than in Western Europe (5–12% in Amsterdam, 5–7% in Ghent). During special episodes, the contribution of carbonaceousaerosols from non-local sources accounted for 67–69% of the OC concentration in Western Europe, and for 44% in Southern Europe.
Article
We present a study of aerosol light absorption using a multi-wavelength Aethalometer (l ¼ 370–950 nm) in an Alpine valley where the major local emissions of aerosols in winter are from domestic wood burning and traffic. The measurements were done in winter and summer periods in 2004 and 2005. Much stronger diurnal trends in CO, NOx and aerosol light absorption parameters were observed in winter than in summer. The average (71 S.D.) PM10 concentrations measured at this site were 31.5721.7 mgm�3 in winter and 15.8710.0 mgm�3 in summer. The highest PM10 concentrations were observed between 18:00 and 22:00 h CET in both campaigns, with 45.4721.0 mgm�3 for winter and 21.079.5 mgm�3 for summer. The average (71 S.D.) power law exponents of the absorption coefficients (also called absorption exponent) with l ¼ 370–950 nm, a370–950 nm were 1.670.25 in winter and 1.170.05 in summer. The calculation of a separately for lower and higher wavelengths (i.e., a370–520nm and a660–950 nm) provided a better description of the wavelength dependence from the UV- to the near-IR region. The highest mean values of a370–520 nm and a660–950nm were observed between 22:00 and 02:00 h CET in winter with 2.770.4 and 1.370.1, respectively. Comparison of a370–520 nm with CO and NOx data indicated that the relative contribution of wood burning versus traffic was responsible for the seasonal and diurnal variability of a. The seasonal and diurnal trends of a were not attributed to changes in the particle size since the aerosol volume size distributions (dV/d logD) were found to be similar in both campaigns.
Article
Bulk aerosols sampled on a weekly basis at two Cairo (Egypt) urban sites from January 2003 to May 2006 were analysed for their chemical composition of major aerosol species (elemental carbon, water soluble/insoluble organic carbon, nitrate, sulphate, ammonium, chloride, sodium and calcium). Data subsequently obtained constitute one of the longest and more detailed dataset related to Cairo aerosols, and offer the opportunity to investigate seasonal trends. Dust aerosols (derived from calcium measurements) displayed maximum concentrations in spring and winter, due to frequent dust storms, but also high background concentration levels (∼50 μg m−3) all year long. Within these particles, about 40% on average of Ca2+ was found to be associated with SO42−, NO3− and/or Cl−, pointing out “dust anthropization” processes and their subsequent climatic impact on a regional scale. Seasonal variations of non-dust aerosols, equally distributed between carbonaceous aerosols and ions, were also observed, with concentrations of the order of 100 μg m−3 in autumn and winter, and of 60 μg m−3 in spring and summer. High concentration levels of non-sea-salt chloride (up to 15 μg m−3 on a monthly basis), likely of industrial origin, were observed in autumn and winter. During the autumn “Black Cloud” event, biomass burning aerosols originating from rice straw burning in the Nile Delta have shown to account for 12%, 35% and 50% of Cairo EC, WIOC and WSOC mass concentrations, respectively. Finally, relatively low WSOC/OC ratios (∼1/3) were obtained all the year long, calling for more investigation on the water-solubility of organic aerosols originating from the burning of agricultural waste, and on that of secondary organic aerosols formed in dry urban atmospheres.
Article
During a soot aerosol measurement campaign the response of two different aethalometers (AE10 with white light and AE30 with multiwavelength capability) to several types of soot was investigated. Diesel soot, spark-generated carbon particles, and mixtures of these soot particles with ammonium sulfate and oxidation products of α-pinene were used in this evaluation. The determination of the particles light absorption coefficient (babs) with the AE10 aethalometer is a difficult task because of an ill-defined spectral sensitivity of this instrument. Provided that the proper numerical corrections are performed, the AE30 instrument allows for the measurement of babs over a wide spectral range (λ=450–). During all experiments it was found that with increasing filter load the optical path in the aethalometer filter decreased. As a result, an increased underestimation of the measured aethalometer signals (babs or black carbon mass concentrations) occurs with increasing filter loads. This effect, which is attributed to a “shadowing” of the particles in the fiber matrix, is very pronounced for “pure” soot particles while almost negligible for aged atmospheric aerosols. An empirical correction for this bias is presented and requires information on the light scattering behavior (i.e. light scattering coefficient) of the sampled particles. Without this additional information, the applicability of the instruments is limited. Comparison with a reference method shows that multiple scattering in the nearly unloaded fiber filter is responsible for enhanced light absorption by a factor of about 2.14.
Article
Collocated PM2.5 measurements using a conventional R&P TEOM (model 1400a) and a TEOM-FDMS were performed at a Paris urban background site during winter/summer field experiments. Results showed that conventional TEOM underestimates PM2.5 mass concentrations by about 50% in winter and 35% in summer. They also confirmed that this negative sampling artifact, due to the volatilization of semi-volatile material (SVM) inside the instrument, cannot be accurately accommodated by a single correction factor because of SVM routine fluctuations. A basic filter-based investigation of the SVM chemical composition also indicated that SVM, measured by the TEOM–FDMS, is mainly formed by ammonium nitrate in winter while significant contributions of semi-volatile organic matter were observed in summer. The latter species was found to possibly account for more than 50% of secondary organic aerosol formed during summer afternoons. These findings call for more investigation of the SVM chemical composition, particularly during the summer season, in Paris and in Europe.
Article
Cycas debaoensis is one of the critically endangered cycad species endemic to China. In this study, we described the development of six microsatellite markers from the genome of C. debaoensis using the protocol of fast isolation by AFLP of sequences containing repeats (FIASCO) and two microsatellite markers derived from the database of expressed sequence tags (dbEST). Polymorphism of each locus was assessed in 60 adult individuals of the cycad. The average allele number of the microsatellites was 2.6 per locus, ranging from two to five. The observed and expected heterozygosities varied from 0.0833 to 0.7333 and from 0.0805 to 0.7188, respectively. Despite its rarity, only one locus (Y177) deviated from Hardy-Weinberg equilibrium due to the excessive homozygosity. The marker transferability of the eight primer pairs was tested on other four congeneric species that also occur in China.
Article
This study presents a method for analyzing the black carbon (BC) mass loading on a quartz fiber filter using a modified thermal-optical analysis method, wherein light transmitted through the sample is measured over a spectral region instead of at a single wavelength. Evolution of the spectral light transmission signal depends on the relative amounts of light-absorbing BC and char, the latter of which forms when organic carbon in the sample pyrolyzes during heating. Absorption selectivities of BC and char are found to be distinct and are used to apportion the amount of light attenuated by each component in the sample. Light attenuation is converted to mass concentration on the basis of derived mass attenuation efficiencies (MAEs) of BC and char. The fractions of attenuation due to each component are scaled by their individual MAE values and added together as the total mass of light absorbing carbon (LAC). An iterative algorithm is used to find the MAE values for both BC and char that provide the best fit to the carbon mass remaining on the filter (derived from direct measurements of thermally evolved CO2) at temperatures higher than 480 degrees C. This method was applied to measure the BC concentration in precipitation samples collected in northern California. The uncertainty in the measured BC concentration of samples that contained a high concentration of organics susceptible to char ranged from 12% to 100%, depending on the mass loading of BC on the filter. The lower detection limit for this method was approximately 0.35 microg of BC, and the uncertainty approached 20% for BC mass loading greater than 1.0 microg of BC.
Article
An improved analytical method was developed and validated for the determination of the monosaccharide anhydrides levoglucosan, mannosan, and galactosan in atmospheric aerosol samples. The method uses an external recovery standard, extraction in dichloromethane, trimethylsilylation, addition of an internal standard (1-phenyl dodecane), and analysis by gas chromatography with flame ionization detection (GC-FID) and gas chromatography/mass spectrometry (GC/MS). As external recovery standard, we selected 1,2,3-trihydroxyhexane, which has a similar polarity as the monosaccharide anhydrides; furthermore, it was ensured that the trimethylsilylation step leads to complete derivatization into trimethylsilyl ethers. The reproducibility of the combined trimethylsilylation and analysis of levoglucosan was about 2% for standard solutions, whereas the precision of the entire method for the sum of all three monosaccharide anhydrides (MAs) in real aerosol filter samples was about 5%. The method was applied to aerosol samples from urban and tropical locations. The atmospheric concentration of the MAs in fine (<2.5 microm) aerosols at a primary forest site in Rondĵnia, Brazil, was on average 2.15 microg m(-3) during the dry season when intensive biomass burning occurs, which was almost 400 times higher than during the wet (nonburning) season. Urban total aerosols collected in Gent, Belgium, showed an average atmospheric concentration of MAs of 0.56 microg m(-3) for the winter season, which was a factor of 20 higher than for the summer season. The carbon in the MAs accounted on average for about 5.1% and 1.8% of the organic carbon in the Brazilian dry season and Gent winter aerosols, respectively. Levoglucosan was the major MA, with a relative abundance in the range of 76-93%.