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

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.

Download Full-text

Ambient measurements and source apportionment of fossil fuel and biomass burning black carbon in Ontario

Atmospheric Environment ◽

10.1016/j.atmosenv.2017.04.034 ◽

2017 ◽

Vol 161 ◽

pp. 34-47 ◽

Cited By ~ 57

Author(s):

R.M. Healy ◽

U. Sofowote ◽

Y. Su ◽

J. Debosz ◽

M. Noble ◽

...

Keyword(s):

Black Carbon ◽

Source Apportionment ◽

Biomass Burning ◽

Fossil Fuel ◽

Ambient Measurements

Download Full-text

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

10.5194/acp-2020-451 ◽

2020 ◽

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 ◽

East Central ◽

Coastal City ◽

Source Contributions

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) were 2932 ± 1444 ng m−3 and 1340 ± 542 ng m−3, contributing 66.7 % and 33.3 % to total BC, respectively. BCbb contribution exhibited clear diurnal cycle with the highest level (37.9 %) in the evening rush hour and 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 for 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 biomass burning and fossil fuel combustion identified by the source-oriented model and observation-based method were in good agreement. The source-oriented model also captured the majority of seasonal variations in source contributions. The findings provide solid supports for controlling fossil fuel sources to limit the impacts of BC on climate change and environmental degradation in the relatively clean region in China.

Download Full-text

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

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-11235-2019 ◽

2019 ◽

Vol 19 (17) ◽

pp. 11235-11252 ◽

Cited By ~ 3

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).

Download Full-text

Source apportionment and organic compound characterization of ambient ultrafine particulate matter (PM) in the Los Angeles Basin

Atmospheric Environment ◽

10.1016/j.atmosenv.2013.07.040 ◽

2013 ◽

Vol 79 ◽

pp. 529-539 ◽

Cited By ~ 50

Author(s):

Sina Hasheminassab ◽

Nancy Daher ◽

James J. Schauer ◽

Constantinos Sioutas

Keyword(s):

Particulate Matter ◽

Los Angeles ◽

Organic Compound ◽

Source Apportionment ◽

Los Angeles Basin ◽

Ultrafine Particulate Matter

Download Full-text

Diurnal tracking of anthropogenic CO<sub>2</sub> emissions in the Los Angeles basin megacity during spring, 2010

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-5771-2012 ◽

2012 ◽

Vol 12 (2) ◽

pp. 5771-5801 ◽

Cited By ~ 12

Author(s):

S. Newman ◽

S. Jeong ◽

M. L. Fischer ◽

X. Xu ◽

C. L. Haman ◽

...

Keyword(s):

Los Angeles ◽

Fossil Fuel ◽

Simple Technique ◽

Anthropogenic Emissions ◽

Fossil Fuel Combustion ◽

Planetary Boundary Layer Height ◽

Los Angeles Basin ◽

Boundary Layer Height ◽

Anthropogenic Component

Abstract. Attributing observed CO2 variations to human or natural cause is critical to deducing and tracking emissions from observations. We have used in situ CO2, CO, and planetary boundary layer height (PBLH) measurements recorded during the CalNex-LA (CARB et al., 2008) ground campaign of 15 May–15 June 2010, in Pasadena, CA, to deduce the diurnally varying anthropogenic component of observed CO2 in the megacity of Los Angeles (LA). This affordable and simple technique, validated by carbon isotope observations, is shown to robustly attribute observed CO2 variation to anthropogenic or biogenic origin. During CalNex-LA, local fossil fuel combustion contributed up to ~50 % of the observed CO2 enhancement overnight, and ~100 % during midday. This suggests midday column observations over LA, such as those made by satellites relying on reflected sunlight, can be used to track anthropogenic emissions.

Download Full-text

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

10.5194/amt-2020-438 ◽

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.

Download Full-text

Sources and contributions of wood smoke during winter in London: assessing local and regional influences

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-14-27459-2014 ◽

2014 ◽

Vol 14 (19) ◽

pp. 27459-27530 ◽

Cited By ~ 3

Author(s):

L. R. Crilley ◽

W. J. Bloss ◽

J. Yin ◽

D. C. S. Beddows ◽

R. M. Harrison ◽

...

Keyword(s):

Black Carbon ◽

Source Apportionment ◽

Biomass Burning ◽

Traffic Emissions ◽

Total Carbon ◽

Local Source ◽

Wood Smoke ◽

Biomass Smoke ◽

Domestic Heating ◽

Wood Burning

Abstract. Determining the contribution of wood smoke to air pollution in large cities such as London is becoming increasingly important due to the changing nature of domestic heating in urban areas. During winter, biomass burning emissions can exceed the contributions from traffic emissions, and have been identified as a major cause of exceedences of European air quality limits. The aim of this work was to quantify the contribution of biomass burning in London to concentrations of PM2.5 and determine whether local emissions or regional contributions were the main source of biomass smoke. To achieve this, a number of biomass burning chemical tracers were analysed at a site within central London and two sites in surrounding rural areas. Concentrations of levoglucosan, elemental carbon (EC), organic carbon (OC) and K+ were generally well correlated across the three sites. At all the sites, biomass burning was found to be a source of OC and EC, with the largest contribution of EC from traffic emissions, while for OC the dominant fraction likely included contributions from secondary organic aerosols, primary biogenic and cooking sources. Source apportionment of the EC and OC using average source ratios from published data was found to give reasonable estimation of the total carbon from non-fossil and fossil fuel sources based upon comparison with estimates derived from 14C analysis. Black carbon (BC) data from 2 and 7 wavelength Aethalometers were also apportioned into the contributions from biomass burning and traffic, based upon the enhanced absorption of wood smoke at UV wavelengths compared to BC. While the source apportionment of BC using this approach found similar trends to that observed for EC, higher percentage contributions of wood burning to BC were estimated. Based on a wood smoke mass conversion factor for levoglucosan, mean wood smoke mass at the sites was found to range from 0.78–1.0 μg m−3 during the campaign in January–February 2012. Measurements on a 160 m tower in London suggested a similar ratio of brown to black carbon (reflecting wood burning and traffic respectively) in regional and London air. Peaks in the levoglucosan and K+ concentrations were observed to coincide with low ambient temperature, consistent with domestic heating as a major contributing local source in London. Overall, the source of biomass smoke in London was concluded to be a background regional source overlaid by contributions from local domestic burning emissions. This could have implications when considering future emission control strategies during winter and may be the focus of future work in order to better determine the contributing local sources.

Download Full-text