scholarly journals Sources and mixing state of summertime background aerosol in the northwestern Mediterranean basin

2017 ◽  
Author(s):  
Jovanna Arndt ◽  
Jean Sciare ◽  
Marc Mallet ◽  
Greg C. Roberts ◽  
Nicolas Marchand ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Biomass Burning ◽  
Mediterranean Basin ◽  
Particle Number ◽  
Fossil Fuel ◽  
Western Mediterranean ◽  
Sea Salt ◽  
Quantitative Measurements ◽  
Combustion Particles ◽  
Mass Concentrations

Abstract. An aerosol time-of-flight mass spectrometer (ATOFMS) was employed to provide real-time single particle mixing state and thereby source information for aerosols impacting the western Mediterranean basin during the ChArMEx-ADRIMED and SAF-MED campaigns in summer 2013. The ATOFMS measurements were made at a ground-based remote site on the northern tip of Corsica Island. 27 distinct ATOFMS particle classes were identified and subsequently grouped into 8 general categories: EC-rich (elemental carbon), K-rich, Na-rich, Amines, OC-rich (organic carbon), V-rich, Fe-rich and Ca-rich. Mass concentrations were reconstructed for the ATOFMS particle classes and found to be in good agreement with other co-located quantitative measurements (PM1, black carbon (BC), organic carbon, sulfate mass and ammonium mass). Total ATOFMS reconstructed mass (PM2.5) accounted for 70–90 % of measured PM10 mass and was comprised of regionally transported fossil fuel (EC-rich) and biomass burning (K-rich) particles. The accumulation of these transported particles was favoured by repeated and extended periods of air mass stagnation over the western Mediterranean during the sampling campaigns. The single particle mass spectra proved to be valuable source markers, allowing the identification of fossil fuel and biomass burning combustion sources, and therefore highly complementary to quantitative measurements made by particle-into-liquid sampler ion chromatography (PILS-IC) and an aerosol chemical speciation monitor (ACSM), which have demonstrated that PM1 and PM10 were comprised predominantly of sulfate, ammonium and OC. Good temporal agreement was observed between ATOFMS EC-rich and K-rich particle mass concentrations and combined mass concentrations of BC, sulfate, ammonium and low volatility oxygenated organic aerosol (LV-OOA). This combined information suggests that combustion of fossil fuels and biomass produced primary EC- and OC-containing particles, which then accumulated ammonium, sulfate and alkylamines during regional transport. Three other sources were also identified: local biomass burning, marine and shipping. Local combustion particles (emitted in Corsica) contributed little to PM2.5 particle number and mass concentrations but were easily distinguished from regional combustion particles. Marine emissions comprised fresh and aged sea salt; the former detected mostly during one 5-day event during which it accounted for 50–80 % of sea salt aerosol mass, while the latter detected throughout the sampling period. Dust was not efficiently detected by the ATOFMS, and support measurements showed that it was mainly in the PM2.5–10 fraction. Shipping particles, identified using markers for heavy fuel oil combustion, were associated with regional emissions, and represented only a small fraction of PM2.5 particle number and mass concentration at the site.

scholarly journals Sources and mixing state of summertime background aerosol in the north-western Mediterranean basin

2017 ◽  
Vol 17 (11) ◽  
pp. 6975-7001 ◽  
Author(s):  
Jovanna Arndt ◽  
Jean Sciare ◽  
Marc Mallet ◽  
Greg C. Roberts ◽  
Nicolas Marchand ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Mediterranean Basin ◽  
Particle Number ◽  
Fossil Fuel ◽  
Western Mediterranean ◽  
Sea Salt ◽  
Quantitative Measurements ◽  
Combustion Particles ◽  
Western Mediterranean Basin ◽  
Mass Concentrations

Abstract. An aerosol time-of-flight mass spectrometer (ATOFMS) was employed to provide real-time single particle mixing state and thereby source information for aerosols impacting the western Mediterranean basin during the ChArMEx-ADRIMED and SAF-MED campaigns in summer 2013. The ATOFMS measurements were made at a ground-based remote site on the northern tip of Corsica. Twenty-seven distinct ATOFMS particle classes were identified and subsequently grouped into eight general categories: EC-rich (elemental carbon), K-rich, Na-rich, amines, OC-rich (organic carbon), V-rich, Fe-rich and Ca-rich particles. Mass concentrations were reconstructed for the ATOFMS particle classes and found to be in good agreement with other co-located quantitative measurements (PM1, black carbon (BC), organic carbon, sulfate mass and ammonium mass). Total ATOFMS reconstructed mass (PM2. 5) accounted for 70–90 % of measured PM10 mass and was comprised of regionally transported fossil fuel (EC-rich) and biomass burning (K-rich) particles. The accumulation of these transported particles was favoured by repeated and extended periods of air mass stagnation over the western Mediterranean during the sampling campaigns. The single particle mass spectra proved to be valuable source markers, allowing the identification of fossil fuel and biomass burning combustion sources, and was therefore highly complementary to quantitative measurements made by Particle into Liquid Sampler ion chromatography (PILS-IC) and an aerosol chemical speciation monitor (ACSM), which have demonstrated that PM1 and PM10 were comprised predominantly of sulfate, ammonium and OC. Good temporal agreement was observed between ATOFMS EC-rich and K-rich particle mass concentrations and combined mass concentrations of BC, sulfate, ammonium and low volatility oxygenated organic aerosol (LV-OOA). This combined information suggests that combustion of fossil fuels and biomass produced primary EC- and OC-containing particles, which then accumulated ammonium, sulfate and alkylamines during regional transport. Three other sources were also identified: local biomass burning, marine and shipping. Local combustion particles (emitted in Corsica) contributed little to PM2. 5 particle number and mass concentrations but were easily distinguished from regional combustion particles. Marine emissions comprised fresh and aged sea salt: the former was detected mostly during a 5-day event during which it accounted for 50–80 % of sea salt aerosol mass, while the latter was detected throughout the sampling period. Dust was not efficiently detected by the ATOFMS, and support measurements showed that it was mainly in the PM2. 5–10 fraction. Shipping particles, identified using markers for heavy fuel oil combustion, were associated with regional emissions and represented only a small fraction of PM2. 5 particle number and mass concentration at the site.

scholarly journals Sources and mixing state of size-resolved elemental carbon particles in a European megacity: Paris

2012 ◽  
Vol 12 (4) ◽  
pp. 1681-1700 ◽  
Author(s):  
R. M. Healy ◽  
J. Sciare ◽  
L. Poulain ◽  
K. Kamili ◽  
M. Merkel ◽  
...  
Keyword(s):  
Mass Spectrometer ◽  
Biomass Burning ◽  
Single Particle ◽  
Mass Concentration ◽  
Elemental Carbon ◽  
Fossil Fuel ◽  
Time Of Flight ◽  
Particle Mass ◽  
Mass Size ◽  
Mass Concentrations

Abstract. An Aerosol Time-Of-Flight Mass Spectrometer (ATOFMS) was deployed to investigate the size-resolved chemical composition of single particles at an urban background site in Paris, France, as part of the MEGAPOLI winter campaign in January/February 2010. ATOFMS particle counts were scaled to match coincident Twin Differential Mobility Particle Sizer (TDMPS) data in order to generate hourly size-resolved mass concentrations for the single particle classes observed. The total scaled ATOFMS particle mass concentration in the size range 150–1067 nm was found to agree very well with the sum of concurrent High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and Multi-Angle Absorption Photometer (MAAP) mass concentration measurements of organic carbon (OC), inorganic ions and black carbon (BC) (R2 = 0.91). Clustering analysis of the ATOFMS single particle mass spectra allowed the separation of elemental carbon (EC) particles into four classes: (i) EC attributed to biomass burning (ECbiomass), (ii) EC attributed to traffic (ECtraffic), (iii) EC internally mixed with OC and ammonium sulfate (ECOCSOx), and (iv) EC internally mixed with OC and ammonium nitrate (ECOCNOx). Average hourly mass concentrations for EC-containing particles detected by the ATOFMS were found to agree reasonably well with semi-continuous quantitative thermal/optical EC and optical BC measurements (r2 = 0.61 and 0.65–0.68 respectively, n = 552). The EC particle mass assigned to fossil fuel and biomass burning sources also agreed reasonably well with BC mass fractions assigned to the same sources using seven-wavelength aethalometer data (r2 = 0.60 and 0.48, respectively, n = 568). Agreement between the ATOFMS and other instrumentation improved noticeably when a period influenced by significantly aged, internally mixed EC particles was removed from the intercomparison. 88% and 12% of EC particle mass was apportioned to fossil fuel and biomass burning respectively using the ATOFMS data compared with 85% and 15% respectively for BC estimated from the aethalometer model. On average, the mass size distribution for EC particles is bimodal; the smaller mode is attributed to locally emitted, mostly externally mixed EC particles, while the larger mode is dominated by aged, internally mixed ECOCNOx particles associated with continental transport events. Periods of continental influence were identified using the Lagrangian Particle Dispersion Model (LPDM) "FLEXPART". A consistent minimum between the two EC mass size modes was observed at approximately 400 nm for the measurement period. EC particles below this size are attributed to local emissions using chemical mixing state information and contribute 79% of the scaled ATOFMS EC particle mass, while particles above this size are attributed to continental transport events and contribute 21% of the EC particle mass. These results clearly demonstrate the potential benefit of monitoring size-resolved mass concentrations for the separation of local and continental EC emissions. Knowledge of the relative input of these emissions is essential for assessing the effectiveness of local abatement strategies.

scholarly journals Fossil vs. non-fossil sources of fine carbonaceous aerosols in four Chinese cities during the extreme winter haze episode of 2013

2015 ◽  
Vol 15 (3) ◽  
pp. 1299-1312 ◽  
Author(s):  
Y.-L. Zhang ◽  
R.-J. Huang ◽  
I. El Haddad ◽  
K.-F. Ho ◽  
J.-J. Cao ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Organic Carbon ◽  
Biomass Burning ◽  
Water Soluble ◽  
Total Carbon ◽  
World Health ◽  
Biomass Combustion ◽  
Carbonaceous Aerosols ◽  
Haze Episode ◽  
Mass Concentrations

Abstract. During winter 2013, extremely high concentrations (i.e., 4–20 times higher than the World Health Organization guideline) of PM2.5 (particulate matter with an aerodynamic diameter < 2.5 μm) mass concentrations (24 h samples) were found in four major cities in China including Xi'an, Beijing, Shanghai and Guangzhou. Statistical analysis of a combined data set from elemental carbon (EC), organic carbon (OC), 14C and biomass-burning marker measurements using Latin hypercube sampling allowed a quantitative source apportionment of carbonaceous aerosols. Based on 14C measurements of EC fractions (six samples each city), we found that fossil emissions from coal combustion and vehicle exhaust dominated EC with a mean contribution of 75 ± 8% across all sites. The remaining 25 ± 8% was exclusively attributed to biomass combustion, consistent with the measurements of biomass-burning markers such as anhydrosugars (levoglucosan and mannosan) and water-soluble potassium (K+). With a combination of the levoglucosan-to-mannosan and levoglucosan-to-K+ ratios, the major source of biomass burning in winter in China is suggested to be combustion of crop residues. The contribution of fossil sources to OC was highest in Beijing (58 ± 5%) and decreased from Shanghai (49 ± 2%) to Xi'an (38 ± 3%) and Guangzhou (35 ± 7%). Generally, a larger fraction of fossil OC was from secondary origins than primary sources for all sites. Non-fossil sources accounted on average for 55 ± 10 and 48 ± 9% of OC and total carbon (TC), respectively, which suggests that non-fossil emissions were very important contributors of urban carbonaceous aerosols in China. The primary biomass-burning emissions accounted for 40 ± 8, 48 ± 18, 53 ± 4 and 65 ± 26% of non-fossil OC for Xi'an, Beijing, Shanghai and Guangzhou, respectively. Other non-fossil sources excluding primary biomass burning were mainly attributed to formation of secondary organic carbon (SOC) from non-fossil precursors such as biomass-burning emissions. For each site, we also compared samples from moderately to heavily polluted days according to particulate matter mass. Despite a significant increase of the absolute mass concentrations of primary emissions from both fossil and non-fossil sources during the heavily polluted events, their relative contribution to TC was even decreased, whereas the portion of SOC was consistently increased at all sites. This observation indicates that SOC was an important fraction in the increment of carbonaceous aerosols during the haze episode in China.

scholarly journals The EMEP Intensive Measurement Period campaign, 2008–2009: Characterizing the carbonaceous aerosol at nine rural sites in Europe

2018 ◽  
Author(s):  
Karl Espen Yttri ◽  
David Simpson ◽  
Robert Bergström ◽  
Gyula Kiss ◽  
Sönke Szidat ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Biomass Burning ◽  
Fossil Fuel ◽  
Carbonaceous Aerosol ◽  
Anthropogenic Sources ◽  
Anthropogenic Source ◽  
Emission Inventories ◽  
Model Calculations ◽  
Natural Sources ◽  
Wood Burning

Abstract. Source apportionment (SA) of carbonaceous aerosol was performed as part of the EMEP Intensive Measurement Periods (EIMPs), conducted in fall 2008 and winter/spring 2009. Levels of elemental carbon (EC), particulate organic carbon (OCp), particulate total carbon (TCp), levoglucosan and 14C in PM10, observed at nine European rural background sites, were used as input for the SA, whereas Latin Hypercube Sampling (LHS) was used to statistically treat the multitude of possible combinations resulting when ambient concentrations were combined with appropriate emission ratios. Five predefined sources/subcategories of carbonaceous aerosol were apportioned: Elemental and organic carbon from combustion of biomass (ECbb and OCbb) and from fossil fuel (ECff and OCff) sources, as well as remaining non-fossil organic carbon (OCrnf), typically dominated by natural sources. The carbonaceous aerosol concentration decreased from South to North, as did the concentration of the apportioned carbonaceous aerosol. OCrnf was more abundant in fall compared to winter/spring, reflecting the vegetative season, and made a larger contribution to TCp than anthropogenic sources (here: ECbb, OCbb, ECff and OCff) at four of the sites, whereas anthropogenic sources dominated at all but one sites in winter/spring. Levels of OCbb and ECbb were typically higher in winter/spring than in fall, due to larger residential wood burning emissions in the heating season, whereas there was no consistent seasonal pattern for fossil fuel emissions. Biomass burning (OCbb + ECbb) was the major anthropogenic source at the Central European sites in fall, whereas fossil fuel sources dominated at the southernmost and the two northernmost sites. In winter/spring, biomass burning was the major anthropogenic source at all but two sites. Addressing EC in particular, fossil fuel sources dominated at all sites in fall, whereas there was as shift towards biomass burning in winter/spring for the southernmost sites. Influence of residential wood burning emissions was substantial already in the first week of sampling in fall, constituting 30–50 % of TCp at most sites, showing that this source can be dominating even at a time of the year when the ambient temperature in Europe is still rather high. Model calculations were made, attempting to reproduce LHS-derived OCbb and ECbb, using two different residential wood burning emission inventories. Both simulations strongly under-predicted the LHS-derived values at most sites outside Scandinavia. Emissions based on a consistent bottom-up inventory for residential combustion (and including intermediate volatility compounds, IVOC) improved model results at most sites compared to the base-case emissions (based mainly on officially reported national emissions), but at the three southernmost sites the modelled OCbb and ECbb concentrations were still much lower than the LHS source apportioned results. The current study shows that natural sources is a major contributor to the carbonaceous aerosol in Europe even in fall and in winter/spring, and that residential wood burning emissions can be equally large or larger than that of fossil fuel sources, depending on season and region. Our results suggest that residential wood burning emissions are still poorly constrained for large parts of Europe. The need to improve emission inventories is obvious, with harmonization of emission factors between countries likely being the most important step to improve model calculations, not only for biomass burning emissions, but for European PM2.5 concentrations in general.

scholarly journals Fossil versus contemporary sources of fine elemental and organic carbonaceous particulate matter during the DAURE campaign in Northeast Spain

2011 ◽  
Vol 11 (8) ◽  
pp. 23573-23618 ◽  
Author(s):  
M. C. Minguillón ◽  
N. Perron ◽  
X. Querol ◽  
S. Szidat ◽  
S. M. Fahrni ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Organic Carbon ◽  
Source Apportionment ◽  
Biomass Burning ◽  
Atmospheric Aerosols ◽  
Fine Particulate Matter ◽  
Western Mediterranean ◽  
Carbonaceous Aerosol ◽  
Carbonaceous Aerosols ◽  
Background Site

Abstract. We present results from the international field campaign DAURE (Determination of the sources of atmospheric Aerosols in Urban and Rural Environments in the western Mediterranean), with the objective of apportioning the sources of fine carbonaceous aerosols. Submicron fine particulate matter (PM1) samples were collected during February-March 2009 and July 2009 at an urban background site in Barcelona (BCN) and at a forested regional background site in Montseny (MSY). We present radiocarbon (14C) analysis for elemental and organic carbon (EC and OC) and source apportionment for these data. We combine the results with those from component analysis of aerosol mass spectrometer (AMS) measurements, and compare to levoglucosan-based estimates of biomass burning OC, source apportionment of filter data with inorganic+EC+OC speciation, submicron bulk potassium (K) concentrations, and gaseous acetonitrile concentrations. At BCN, 87 % and 91 % of the EC on average, in winter and summer, respectively, had a fossil origin, whereas at MSY these fractions were 66 % and 79 %. The contribution of fossil sources to organic carbon (OC) at BCN was 40 % and 48 %, in winter and summer, respectively, and 31 % and 25 % at MSY. The combination of results obtained using the 14C technique, AMS data, and the correlations between fossil OC and fossil EC imply that the fossil OC at Barcelona is ~65 % primary whereas at MSY the fossil OC is mainly secondary (~85 %). Day-to-day variation in total carbonaceous aerosol loading and the relative contributions of different sources predominantly depended on the meteorological transport conditions. The estimated biogenic secondary OC at MSY only increased by ~40 % compared to the order-of-magnitude increase observed for biogenic volatile organic compounds (VOCs) between winter and summer, which highlights the uncertainties in the estimation of that component. Biomass burning contributions estimated using the 14C technique ranged from similar to higher than when estimated using other techniques, and the different estimations were highly or moderately correlated. Differences can be explained by the contribution of secondary organic matter (not included in the primary biomass burning source estimates), and/or by an overestimation of the biomass burning OC contribution by the 14C technique if the estimated biomass burning EC/OC ratio used for the calculations is too high for this region. Acetonitrile concentrations correlate well with the biomass burning EC determined by 14C. K is a noisy tracer for biomass burning.

scholarly journals Aerosols at the Poles: An AeroCom Phase II multi-model evaluation

2017 ◽  
Author(s):  
Maria Sand ◽  
Bjørn H. Samset ◽  
Yves Balkanski ◽  
Susanne Bauer ◽  
Nicolas Bellouin ◽  
...  
Keyword(s):  
Phase Ii ◽  
Biomass Burning ◽  
Radiative Forcing ◽  
Fossil Fuel ◽  
Organic Aerosols ◽  
Global Climate Models ◽  
Sea Salt ◽  
The Arctic ◽  
Anthropogenic Aerosols ◽  
The Antarctic

Abstract. Atmospheric aerosols from anthropogenic and natural sources reach the Polar Regions through long-range transport. Such transport is however poorly constrained in present day global climate models, and few multi-model evaluations of Polar anthropogenic aerosol radiative forcing exist. Here we compare the aerosol optical depth (AOD) at 550 nm from simulations with 16 global aerosol models from the AeroCom phase II model inter-comparison project with available observations at both Poles. We show that the annual mean multi-model median is representative of the observations in Arctic, but that the inter-model spread is large. We also document the geographical distribution and seasonal cycle of the AOD for the individual aerosol species; black carbon (BC) from fossil fuel and biomass burning, sulfate, organic aerosols (OA), dust and sea-salt. For a subset of models that represent nitrate and secondary organic aerosols (SOA), we document the role of these aerosols at high latitudes. The seasonal dependence of natural and anthropogenic aerosols differs with natural aerosols peaking in the winter (sea-salt) and spring (dust), whereas AOD from anthropogenic aerosols peaks during late spring/summer. The models produce a median annual mean (AOD) of 0.07 in the Arctic (defined here as north of 60° N). The models also predict a noteworthy aerosol transport to the Antarctic (south of 70° S) with a resulting AOD varying between 0.01–0.02. The models have also estimated the shortwave anthropogenic radiative forcing contributions to the direct aerosol effect (DAE) associated with BC and OA from fossil fuel and biofuel (FF), sulfate, SOA, nitrate, and biomass burning from BC and OA emissions combined. The Arctic modeled annual mean DAE is slightly negative (−0.12 W m−2), dominated by a positive BC FF DAE during spring and a negative sulfate DAE during summer. The Antarctic DAE is governed by BC FF. We perform sensitivity experiments with one of the AeroCom models (GISS modelE) to investigate how regional emissions of BC and sulfate and the lifetime of BC influence the Arctic and Antarctic AOD. A doubling of emissions in East Asia, result in a 33 % increase in Arctic AOD of BC. However, radical changes such as reducing the e-folding lifetime by half or doubling it, still fall within the AeroCom model range.

scholarly journals A new method to quantify mineral dust and other aerosol species from aircraft platforms using single-particle mass spectrometry

2019 ◽  
Vol 12 (11) ◽  
pp. 6209-6239 ◽  
Author(s):  
Karl D. Froyd ◽  
Daniel M. Murphy ◽  
Charles A. Brock ◽  
Pedro Campuzano-Jost ◽  
Jack E. Dibb ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Biomass Burning ◽  
Single Particle ◽  
Atmospheric Aerosol ◽  
Mineral Dust ◽  
Sea Salt ◽  
Particle Mass ◽  
Mode Analysis ◽  
Single Particle Mass Spectrometry ◽  
Mass Concentrations

Abstract. Single-particle mass spectrometry (SPMS) instruments characterize the composition of individual aerosol particles in real time. Their fundamental ability to differentiate the externally mixed particle types that constitute the atmospheric aerosol population enables a unique perspective into sources and transformation. However, quantitative measurements by SPMS systems are inherently problematic. We introduce a new technique that combines collocated measurements of aerosol composition by SPMS and size-resolved absolute particle concentrations on aircraft platforms. Quantitative number, surface area, volume, and mass concentrations are derived for climate-relevant particle types such as mineral dust, sea salt, and biomass burning smoke. Additionally, relative ion signals are calibrated to derive mass concentrations of internally mixed sulfate and organic material that are distributed across multiple particle types. The NOAA Particle Analysis by Laser Mass Spectrometry (PALMS) instrument measures size-resolved aerosol chemical composition from aircraft. We describe the identification and quantification of nine major atmospheric particle classes, including sulfate–organic–nitrate mixtures, biomass burning, elemental carbon, sea salt, mineral dust, meteoric material, alkali salts, heavy fuel oil combustion, and a remainder class. Classes can be sub-divided as necessary based on chemical heterogeneity, accumulated secondary material during aging, or other atmospheric processing. Concentrations are derived for sizes that encompass the accumulation and coarse size modes. A statistical error analysis indicates that particle class concentrations can be determined within a few minutes for abundances above ∼10 ng m−3. Rare particle types require longer sampling times. We explore the instrumentation requirements and the limitations of the method for airborne measurements. Reducing the size resolution of the particle data increases time resolution with only a modest increase in uncertainty. The principal limiting factor to fast time response concentration measurements is statistically relevant sampling across the size range of interest, in particular, sizes D < 0.2 µm for accumulation-mode studies and D > 2 µm for coarse-mode analysis. Performance is compared to other airborne and ground-based composition measurements, and examples of atmospheric mineral dust concentrations are given. The wealth of information afforded by composition-resolved size distributions for all major aerosol types represents a new and powerful tool to characterize atmospheric aerosol properties in a quantitative fashion.

scholarly journals Fossil versus contemporary sources of fine elemental and organic carbonaceous particulate matter during the DAURE campaign in Northeast Spain

2011 ◽  
Vol 11 (23) ◽  
pp. 12067-12084 ◽  
Author(s):  
M. C. Minguillón ◽  
N. Perron ◽  
X. Querol ◽  
S. Szidat ◽  
S. M. Fahrni ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Organic Carbon ◽  
Source Apportionment ◽  
Biomass Burning ◽  
Atmospheric Aerosols ◽  
Fine Particulate Matter ◽  
Western Mediterranean ◽  
Carbonaceous Aerosol ◽  
Carbonaceous Aerosols ◽  
Background Site

Abstract. We present results from the international field campaign DAURE (Determination of the sources of atmospheric Aerosols in Urban and Rural Environments in the Western Mediterranean), with the objective of apportioning the sources of fine carbonaceous aerosols. Submicron fine particulate matter (PM1) samples were collected during February–March 2009 and July 2009 at an urban background site in Barcelona (BCN) and at a forested regional background site in Montseny (MSY). We present radiocarbon (14C) analysis for elemental and organic carbon (EC and OC) and source apportionment for these data. We combine the results with those from component analysis of aerosol mass spectrometer (AMS) measurements, and compare to levoglucosan-based estimates of biomass burning OC, source apportionment of filter data with inorganic composition + EC + OC, submicron bulk potassium (K) concentrations, and gaseous acetonitrile concentrations. At BCN, 87 % and 91 % of the EC on average, in winter and summer, respectively, had a fossil origin, whereas at MSY these fractions were 66 % and 79 %. The contribution of fossil sources to organic carbon (OC) at BCN was 40 % and 48 %, in winter and summer, respectively, and 31 % and 25 % at MSY. The combination of results obtained using the 14C technique, AMS data, and the correlations between fossil OC and fossil EC imply that the fossil OC at Barcelona is ∼47 % primary whereas at MSY the fossil OC is mainly secondary (∼85 %). Day-to-day variation in total carbonaceous aerosol loading and the relative contributions of different sources predominantly depended on the meteorological transport conditions. The estimated biogenic secondary OC at MSY only increased by ∼40 % compared to the order-of-magnitude increase observed for biogenic volatile organic compounds (VOCs) between winter and summer, which highlights the uncertainties in the estimation of that component. Biomass burning contributions estimated using the 14C technique ranged from similar to slightly higher than when estimated using other techniques, and the different estimations were highly or moderately correlated. Differences can be explained by the contribution of secondary organic matter (not included in the primary biomass burning source estimates), and/or by an overestimation of the biomass burning OC contribution by the 14C technique if the estimated biomass burning EC/OC ratio used for the calculations is too high for this region. Acetonitrile concentrations correlate well with the biomass burning EC determined by 14C. K is a noisy tracer for biomass burning.

scholarly journals Effect of vehicular traffic, remote sources and new particle formation on the activation properties of cloud condensation nuclei in the megacity of São Paulo, Brazil

2016 ◽  
Vol 16 (22) ◽  
pp. 14635-14656 ◽  
Author(s):  
Carlos Eduardo Souto-Oliveira ◽  
Maria de Fátima Andrade ◽  
Prashant Kumar ◽  
Fábio Juliano da Silva Lopes ◽  
Marly Babinski ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Particle Number ◽  
Cloud Condensation Nuclei ◽  
Activation Parameters ◽  
Particle Formation ◽  
Sea Salt ◽  
Vehicular Emissions ◽  
Vehicular Traffic ◽  
Condensation Nuclei ◽  
The Impact

Abstract. Atmospheric aerosol is the primary source of cloud condensation nuclei (CCN). The microphysics and chemical composition of aerosols can affect cloud development and the precipitation process. Among studies conducted in Latin America, only a handful have reported the impact of urban aerosol on CCN activation parameters such as activation ratio (AR) and activation diameter (Dact). With over 20 million inhabitants, the Metropolitan Area of São Paulo (MASP) is the largest megacity in South America. To our knowledge, this is the first study to assess the impact that remote sources and new particle formation (NPF) events have on CCN activation properties in a South American megacity. The measurements were conducted in the MASP between August and September 2014. We measured the CCN within the 0.2–1.0 % range of supersaturation, together with particle number concentration (PNC) and particle number distribution (PND), as well as trace-element concentrations and black carbon (BC). NPF events were identified on 35 % of the sampling days. Combining multivariate analysis in the form of positive matrix factorization (PMF) with an aerosol profile from lidar and HYSPLIT model analyses allowed us to identify the main contribution of vehicular traffic on all days and sea salt and biomass burning from remote regions on 28 and 21 % of the sampling days, respectively. The AR and Dact parameters showed distinct patterns for daytime with intense vehicular traffic and nighttime periods. For example, CCN activation was lower during the daytime than during the nighttime periods, a pattern that was found to be associated mainly with local road-traffic emissions. A decrease in CCN activation was observed on the NPF event days, mainly due to high concentrations of particles with smaller diameters. We also found that aerosols from sea salt, industrial emissions, and biomass burning had minor effects on Dact. For example, nights with biomass burning and vehicular emissions showed slightly lower CCN activation properties than sea-salt, industrial and non-event nights. Our results show that particulate matter from local vehicular emissions during the daytime has a greater effect on CCN activation parameters than that from remote sources.

scholarly journals Better constraints on sources of carbonaceous aerosols using a combined <sup>14</sup>C – macro tracer analysis in a European rural background site

2011 ◽  
Vol 11 (1) ◽  
pp. 2503-2547 ◽  
Author(s):  
S. Gilardoni ◽  
E. Vignati ◽  
F. Cavalli ◽  
J. P. Putaud ◽  
B. R. Larsen ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Biomass Burning ◽  
Elemental Carbon ◽  
Fossil Fuel ◽  
Carbonaceous Aerosol ◽  
Po Valley ◽  
Fossil Fuel Burning ◽  
Potential Source ◽  
Fuel Burning ◽  
Source Contributions

Abstract. The source contributions to carbonaceous PM2.5 aerosol were investigated at a European background site at the edge of the Po Valley, in Northern Italy, during the period January–December 2007. Carbonaceous aerosol was described as the sum of eight source components: primary (1) and secondary (2) biomass burning organic carbon, biomass burning elemental carbon (3), primary (4) and secondary (5) fossil fuel burning organic carbon, fossil fuel burning elemental carbon (6), primary (7) and secondary (8) biogenic organic carbon. The concentration of each component was quantified using a set of macro tracers (organic carbon OC, elemental carbon EC, and levoglucosan), micro tracers (arabitol and mannitol), and 14C measurements. This was the first time that 14C measurements were performed on a long time series of data able to represent the entire annual cycle. This set of 6 tracers, together with assumed uncertainty ranges of the ratios of OC-to-EC, and the fraction of modern carbon in the 8 source categories, provides strong constraints to the source contributions to carbonaceous aerosol. The uncertainty of contributions was assessed with a Quasi-Monte Carlo (QMC) method accounting for the variability of OC and EC emission factors, and the uncertainty of reference fractions of modern carbon. During winter biomass burning composed 50% of the total carbon (TC) concentration, while in summer secondary biogenic OC accounted for 45% of TC. The contribution of primary biogenic aerosol particles was negligible during the entire year. Moreover, aerosol associated with fossil fuel burning represented 26% and 43% of TC in winter and summer, respectively. The comparison of source apportionment results in different urban and rural areas showed that the sampling site was mainly affected by local aerosol sources during winter and regional air masses from the nearby Po Valley in summer. This observation was further confirmed by back-trajectory analysis applying the Potential Source Contribution Function method to identify potential source regions. The contribution of secondary organic aerosol (SOA) to the organic mass (OM) was significant during the entire year. SOA accounted for 23% and 83% of OM during winter and summer, respectively. While the summer SOA was dominated by biogenic sources, winter SOA was mainly due to biomass and fossil fuel burning. This indicates that the oxidation of intermediate volatility organic compounds co-emitted with primary organics is a significant source of SOA, as suggested by recent model results and Aerosol Mass Spectrometer measurements in urban regions. Comparison with previous global model simulations, indicates a strong underestimate of wintertime primary aerosol emissions in this region.

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