scholarly journals Exploiting multi-wavelength aerosol absorption coefficients in a multi-time source apportionment study to retrieve source-dependent absorption parameters

2019 ◽  
Author(s):  
Alice C. Forello ◽  
Vera Bernardoni ◽  
Giulia Calzolai ◽  
Franco Lucarelli ◽  
Dario Massabò ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
Source Apportionment ◽  
Biomass Burning ◽  
Fossil Fuel ◽  
Optical Parameters ◽  
Bootstrap Analysis ◽  
Mass Absorption ◽  
Aerosol Absorption ◽  
Multi Wavelength ◽  
Fossil Fuel Emissions

Abstract. In this paper, a new methodology coupling aerosol optical and chemical parameters in the same source apportionment study is reported. This approach gives additional relevant information such as estimates for the atmospheric Ångström Absorption Exponent (α) of the sources and Mass Absorption Coefficient (MAC) for fossil fuel emissions at different wavelengths. A multi-time source apportionment study using Multilinear Engine ME-2 was performed on a PM10 dataset with different time resolution (24 hours, 12 hours, and 1 hour) collected during two different seasons in Milan (Italy) in 2016. Samples were optically analysed to retrieve the aerosol absorption coefficient bap (in Mm−1) at four wavelengths (λ = 405 nm, 532 nm, 635 nm and 780 nm) and chemically characterised for elements, ions, levoglucosan, and carbonaceous components. Time-resolved chemically speciated data were coupled with bap multi-wavelength measurements and introduced as input data in the multi-time receptor model; this approach was proven to strengthen the identification of sources being particularly useful when important chemical markers (e.g. levoglucosan, elemental carbon, ...) are not available. The final solution consisted in 8 factors (nitrate, sulphate, resuspended dust, biomass burning, construction works, traffic, industry, aged sea salt); the implemented constraints led to a better physical description of factors and the bootstrap analysis supported the goodness of the solution. As for bap apportionment, consistently to what expected, the two factors assigned to biomass burning and traffic were the main contributors to aerosol absorption in atmosphere. A relevant feature of the approach proposed in this work is the possibility of retrieving many other information about optical parameters; for example, opposite to the more traditional approach used by optical source apportionment models, here we obtained the atmospheric Ångström Absorption Exponent (α) of the sources (α biomass burning = 1.83 and α fossil fuels = 0.80), without any a priori assumption. In addition, an estimate for the Mass Absorption Cross section (MAC) for fossil fuel emissions at four wavelengths was obtained and found to be consistent with literature ranges.

scholarly journals Exploiting multi-wavelength aerosol absorption coefficients in a multi-time resolution source apportionment study to retrieve source-dependent absorption parameters

2019 ◽  
Vol 19 (17) ◽  
pp. 11235-11252 ◽  
Author(s):  
Alice Corina Forello ◽  
Vera Bernardoni ◽  
Giulia Calzolai ◽  
Franco Lucarelli ◽  
Dario Massabò ◽  
...  
Keyword(s):  
Source Apportionment ◽  
Biomass Burning ◽  
Time Resolution ◽  
Fossil Fuel ◽  
Traditional Approach ◽  
Optical Data ◽  
Optical Parameters ◽  
Bootstrap Analysis ◽  
Aerosol Absorption ◽  
Fossil Fuel Emissions

Abstract. In this paper, a new methodology coupling aerosol optical and chemical parameters in the same source apportionment study is reported. In addition to results on source contributions, this approach provides information such as estimates for the atmospheric absorption Ångström exponent (α) of the sources and mass absorption cross sections (MACs) for fossil fuel emissions at different wavelengths. A multi-time resolution source apportionment study using the Multilinear Engine (ME-2) was performed on a PM10 dataset with different time resolutions (24, 12, and 1 h) collected during two different seasons in Milan (Italy) in 2016. Samples were optically analysed by an in-house polar photometer to retrieve the aerosol absorption coefficient bap (in Mm−1) at four wavelengths (λ=405, 532, 635, and 780 nm) and were chemically characterized for elements, ions, levoglucosan, and carbonaceous components. The dataset joining chemically speciated and optical data was the input for the multi-time resolution receptor model; this approach was proven to strengthen the identification of sources, thus being particularly useful when important chemical markers (e.g. levoglucosan, elemental carbon) are not available. The final solution consisted of eight factors (nitrate, sulfate, resuspended dust, biomass burning, construction works, traffic, industry, aged sea salt); the implemented constraints led to a better physical description of factors and the bootstrap analysis supported the goodness of the solution. As for bap apportionment, consistent with what was expected, biomass burning and traffic were the main contributors to aerosol absorption in the atmosphere. A relevant feature of the approach proposed in this work is the possibility of retrieving a lot of other information about optical parameters; for example, in contrast to the more traditional approach used by optical source apportionment models, here we obtained source-dependent α values without any a priori assumption (α biomass burning =1.83 and α fossil fuels =0.80). In addition, the MACs estimated for fossil fuel emissions were consistent with literature values. It is worth noting that the approach presented here can also be applied using more common receptor models (e.g. EPA PMF instead of multi-time resolution ME-2) if the dataset comprises variables with the same time resolution as well as optical data retrieved by widespread instrumentation (e.g. an Aethalometer instead of in-house instrumentation).

scholarly journals Six-year source apportionment of submicron organic aerosols from near-continuous measurements at SIRTA (Paris area, France)

2019 ◽  
Author(s):  
Yunjiang Zhang ◽  
Olivier Favez ◽  
Jean-Eudes Petit ◽  
Francesco Canonaco ◽  
Francois Truong ◽  
...  
Keyword(s):  
Source Apportionment ◽  
Biomass Burning ◽  
Ambient Air ◽  
Carbonaceous Aerosols ◽  
Time Resolved ◽  
Pronounced Increase ◽  
Paris Area ◽  
Multi Wavelength ◽  
High Concentrations

Abstract. 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.

Source apportionment of black carbon (BC) from fossil fuel and biomass burning in metropolitan Milan, Italy

2019 ◽  
Vol 203 ◽  
pp. 252-261 ◽  
Author(s):  
Amirhosein Mousavi ◽  
Mohammad H. Sowlat ◽  
Christopher Lovett ◽  
Martin Rauber ◽  
Soenke Szidat ◽  
...  
Keyword(s):  
Black Carbon ◽  
Source Apportionment ◽  
Biomass Burning ◽  
Fossil Fuel

scholarly journals Global combustion: the connection between fossil fuel and biomass burning emissions (1997–2010)

2016 ◽  
Vol 371 (1696) ◽  
pp. 20150177 ◽  
Author(s):  
Jennifer K. Balch ◽  
R. Chelsea Nagy ◽  
Sally Archibald ◽  
David M. J. S. Bowman ◽  
Max A. Moritz ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Urban Areas ◽  
Fossil Fuel ◽  
Global Scale ◽  
Fossil Fuel Burning ◽  
Annual Carbon ◽  
Global Modelling ◽  
Human Use ◽  
Global Data ◽  
Fossil Fuel Emissions

Humans use combustion for heating and cooking, managing lands, and, more recently, for fuelling the industrial economy. As a shift to fossil-fuel-based energy occurs, we expect that anthropogenic biomass burning in open landscapes will decline as it becomes less fundamental to energy acquisition and livelihoods. Using global data on both fossil fuel and biomass burning emissions, we tested this relationship over a 14 year period (1997–2010). The global average annual carbon emissions from biomass burning during this time were 2.2 Pg C per year (±0.3 s.d.), approximately one-third of fossil fuel emissions over the same period (7.3 Pg C, ±0.8 s.d.). There was a significant inverse relationship between average annual fossil fuel and biomass burning emissions. Fossil fuel emissions explained 8% of the variation in biomass burning emissions at a global scale, but this varied substantially by land cover. For example, fossil fuel burning explained 31% of the variation in biomass burning in woody savannas, but was a non-significant predictor for evergreen needleleaf forests. In the land covers most dominated by human use, croplands and urban areas, fossil fuel emissions were more than 30- and 500-fold greater than biomass burning emissions. This relationship suggests that combustion practices may be shifting from open landscape burning to contained combustion for industrial purposes, and highlights the need to take into account how humans appropriate combustion in global modelling of contemporary fire. Industrialized combustion is not only an important driver of atmospheric change, but also an important driver of landscape change through companion declines in human-started fires. This article is part of the themed issue ‘The interaction of fire and mankind’.

scholarly journals Sources and transport of Δ<sup>14</sup>C on CO<sub>2</sub> within the Mexico City Basin and vicinity

2009 ◽  
Vol 9 (2) ◽  
pp. 7213-7237 ◽  
Author(s):  
S. A. Vay ◽  
S. C. Tyler ◽  
Y. Choi ◽  
D. R. Blake ◽  
N. J. Blake ◽  
...  
Keyword(s):  
Mexico City ◽  
Biomass Burning ◽  
North American ◽  
Nuclear Power ◽  
Fossil Fuel ◽  
Co2 Flux ◽  
Waste Incineration ◽  
Background Value ◽  
The North ◽  
Fossil Fuel Emissions

Abstract. Radiocarbon samples taken over Mexico City and the surrounding region during the MILAGRO field campaign in March 2006 exhibited an unexpected distribution: (1) relatively few samples (23%) were below the North American free tropospheric background value (57‰) despite the fossil fuel emissions from one of the world's most highly polluted environments; and (2) frequent enrichment well above the background value was observed. Correlate source tracer species and air transport characteristics were examined to elucidate influences on the radiocarbon distribution. Our analysis suggests that a combination of radiocarbon sources biased the "regional radiocarbon background" above the North American value thereby decreasing the apparent fossil fuel signature. These sources included the release of bomb or "hot" radiocarbon sequestered in plant carbon pools via the ubiquitous biomass burning in the region as well as the direct release of radiocarbon as CO2. Plausible large local perturbations include the burning of hazardous waste in cement kilns; medical waste incineration; and emissions from the Laguna Verde Nuclear Power Plant. These observations provide insight into the use of Δ14CO2 to constrain fossil fuel emissions in the megacity environment, indicating that underestimation of the fossil fuel contribution to the CO2 flux is likely wherever biomass burning coexists with urban emissions. Our findings increase the complexity required to quantify fossil fuel-derived CO2 in source-rich environments characteristic of megacities, and have implications for the use of Δ14CO2 observations in evaluating bottoms-up emission inventories and their reliability as a tool for validating national emission claims of CO2 within the framework of the Kyoto Protocol.

scholarly journals Modeled source apportionment of black carbon particles coated with a light-scattering shell

2020 ◽  
Author(s):  
Aki Virkkula
Keyword(s):  
Black Carbon ◽  
Biomass Burning ◽  
Fossil Fuel ◽  
Size Distributions ◽  
Core Size ◽  
Carbon Particles ◽  
Aerosol Mass ◽  
Measured Absorption ◽  
Absorbing Material ◽  
Fossil Fuel Emissions

Abstract. The Aethalometer model been used widely for estimating the contributions of fossil fuel emissions and biomass burning to equivalent black carbon (eBC). The calculation is based on measured absorption Ångström exponents (αabs). The interpretation αabs is ambiguous since it is well-known that it not only depends on the dominant absorber but also on the size and internal structure of the particles, core size and shell thickness. In this work the uncertainties of the Aethalometer-model-derived apparent fractions of absorption by eBC from fossil fuel and biomass burning are evaluated with a core-shell Mie model. Biomass-burning fractions (BB(%)) were calculated for pure and coated single BC particles, for lognormal unimodal and bimodal size distributions of BC cores coated with ammonium sulfate, a scattering-only material. BB(%) was very seldom 0 % even though BC was the only absorbing material in the simulations. The shape of size distribution plays an important role. Narrow size distributions result in higher αabs and BB(%) values than wide size distributions. The sensitivity of αabs and BB(%) to variations in shell volume fractions is the highest for accumulation mode particles. This is important because that is where the largest aerosol mass is. For the interpretation of absorption Ångström exponents it would be very good to measure BC size distributions and shell thicknesses together with the wavelength dependency of absorption.

Spatio-temporal trends and source apportionment of fossil fuel and biomass burning black carbon (BC) in the Los Angeles Basin

2018 ◽  
Vol 640-641 ◽  
pp. 1231-1240 ◽  
Author(s):  
Amirhosein Mousavi ◽  
Mohammad H. Sowlat ◽  
Sina Hasheminassab ◽  
Andrea Polidori ◽  
Constantinos Sioutas
Keyword(s):  
Los Angeles ◽  
Black Carbon ◽  
Source Apportionment ◽  
Biomass Burning ◽  
Fossil Fuel ◽  
Temporal Trends ◽  
Los Angeles Basin ◽  
Spatio Temporal

scholarly journals Inter-comparison of source apportionment models for the estimation of wood burning aerosols during wintertime in an Alpine city (Grenoble, France)

2010 ◽  
Vol 10 (1) ◽  
pp. 559-613 ◽  
Author(s):  
O. Favez ◽  
I. El Haddad ◽  
C. Piot ◽  
A. Boréave ◽  
E. Abidi ◽  
...  
Keyword(s):  
Source Apportionment ◽  
Fossil Fuel ◽  
Winter Season ◽  
Organic Aerosols ◽  
Receptor Site ◽  
Ambient Air ◽  
Aerosol Mass ◽  
Wood Burning ◽  
Study Results ◽  
Fossil Fuel Emissions

Abstract. The emission of organic aerosols (OA) in the ambient air by residential wood burning is nowadays a subject of great scientific concern and a growing number of studies aim at apportioning the influence of such emissions on urban air quality. In the present study, results obtained using two commonly-used source apportionment models, i.e., Chemical Mass Balance (CMB, performed with off-line filter measurements) and Positive Matrix Factorization (PMF, applied to aerosol mass spectrometer measurements), as well as using the recently-proposed aethalometer model (based on the measurement of the aerosol light absorption at different wavelengths) are inter-compared. This work is performed using field data obtained during the winter season (14 to 30 January 2009) at an urban background site of a French Alpine city (Grenoble). Converging results from the different models indicate a major contribution of wood burning organic aerosols (OMwb) to the organic fraction, with mean OMwb contributions to total OA of about 67%, 60% and 38% for the CMB, the aethalometer and the AMS-PMF models, respectively. Quantitative discrepancies might notably be due to the overestimation of OMwb calculated by the CMB due to the loss of semi-volatile compounds from sources to receptor site, as well as to the accounting of oxidized primary wood burning organic (OPOAwb) aerosols within the Oxygenated Organic Aerosol (OOA) PMF-factor. This OOA factor accounts on average for about 50% of total OM, while non-combustion sources contribute to about 25% and 28% of total OM according to the CMB and aethalometer models, respectively. Each model suggests a mean contribution of fossil fuel emissions to total OM of about 10%. A good agreement is also obtained for the source apportionment of elemental carbon (EC) by both the CMB and aethalometer models, with fossil fuel emissions representing on average more than 80% of total EC.

scholarly journals Source apportionment of black carbon aerosols from light absorption observation and source-oriented modeling: an implication in a coastal city in China

2020 ◽  
Vol 20 (22) ◽  
pp. 14419-14435
Author(s):  
Junjun Deng ◽  
Hao Guo ◽  
Hongliang Zhang ◽  
Jialei Zhu ◽  
Xin Wang ◽  
...  
Keyword(s):  
Climate Change ◽  
Black Carbon ◽  
Source Apportionment ◽  
Biomass Burning ◽  
Light Absorption ◽  
Fossil Fuel ◽  
Central China ◽  
Fossil Fuel Combustion ◽  
East Central ◽  
Coastal City

Abstract. Black carbon (BC) is the most important light-absorbing aerosol in the atmosphere. However, sources of atmospheric BC aerosols are largely uncertain, making it difficult to assess its influence on radiative forcing and climate change. In this study, year-round light-absorption observations were conducted during 2014 using an aethalometer in Xiamen, a coastal city in Southeast China. Source apportionment of BC was performed and temporal variations in BC sources were characterized based on both light absorption measurements and a source-oriented air quality model. The annual average concentrations of BC from fossil fuel (BCff) and biomass burning (BCbb) by the aethalometer method were 2932 ± 1444 ng m−3 and 1340 ± 542 ng m−3, contributing 66.7 % and 33.3 % to total BC, respectively. A sensitivity analysis was performed with different absorption Ångström exponent (AAE) values of fossil fuel combustion (αff) and biomass burning (αbb), suggesting that the aethalometer method was more sensitive to changes in αbb than αff. BCbb contribution exhibited a clear diurnal cycle, with the highest level (37.9 %) in the evening rush hour and a seasonal pattern with the maximum (39.9 %) in winter. Conditional probability function (CPF) analysis revealed the large biomass-burning contributions were accompanied by east-northeasterly and northerly winds. Backward trajectory indicated that air masses from North and East–Central China were associated with larger biomass-burning contributions. Potential source contribution function (PSCF) and concentration-weighted trajectory (CWT) suggested that North and East–Central China and Southeast Asia were potential sources of both BCff and BCbb. The source-oriented modeling results showed that transportation, residential and open biomass burning accounting for 45.3 %, 30.1 % and 17.6 % were the major BC sources. Among the three fuel catalogs, liquid fossil fuel (46.5 %) was the largest source, followed by biomass burning (32.6 %) and coal combustion (20.9 %). Source contributions of fossil fuel combustion and biomass burning identified by the source-oriented model were 67.4 % and 32.6 %, respectively, close to those obtained by the aethalometer method. The findings provide solid support for controlling fossil fuel sources to limit the impacts of BC on climate change and environmental degradation in the relatively clean region in China.

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