Light-absorbing organic carbon from prescribed and laboratory biomass burning and gasoline vehicle emissions

Xie, Mingjie; Hays, Michael D.; Holder, Amara L.

doi:10.1038/s41598-017-06981-8

Cited by 117 publications

(171 citation statements)

References 54 publications

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“…3 shows the normalized absorbance for polar and non-polar extracts of fresh and aged BB aerosols. While most previous studies have focused on light absorption by the watersoluble fraction of BB aerosols (Hecobian et al, 2010;Xie et al, 2017;Zhang et al, 2013b), very little attention was given to the light absorption by the water-insoluble part of BB aerosols (Chen and Bond,10 2010) Our results suggest that for fresh aerosols from all fuels except for Siberian peat, non-polar (hexane) extracts absorb more than polar (water) extracts (Fig. 3).…”

Section: Resultsmentioning

confidence: 50%

Light absorption by polar and non-polar aerosol compounds from laboratory biomass combustion

Sengupta¹,

Samburova²,

Bhattarai³

et al. 2018

Preprint

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Abstract. Fresh and atmospherically aged biomass-burning (BB) aerosol mass is mostly comprised of black carbon (BC) and organic carbon (OC) with its light-absorbing fraction -brown carbon (BrC). 10There is a lack of data on the physical and chemical properties of atmospheric BB aerosols, leading to high uncertainties in estimates of the BB impact on air quality and climate, especially for BrC. The polarity of chemical compounds influences their fate in the atmosphere including wet/dry deposition and chemical and physical processing. So far, most of the attention has been given to the water-soluble (polar) fraction of BrC, while the non-polar BrC fraction has been largely ignored. In the present study, 15 the light absorption properties of polar and non-polar fractions of fresh and aged BB emissions were examined to estimate the contribution of different-polarity organic compounds to the light absorption properties of BB aerosols.In our experiments, four globally and regionally important fuels were burned under flaming and smoldering conditions in DRI's combustion chamber. To mimic atmospheric oxidation processes (5-7 20 days), BB emissions were aged using an oxidation flow reactor (OFR). Fresh and OFR-aged BB aerosols were collected on filters and extracted with water and hexane to study absorption properties of polar and non-polar organic species. Spectrophotometric measurements over the 190 to 900 nm wavelength range showed that the non-polar (hexane-soluble) fraction is 2-3 times more absorbing than the polar (water-soluble) fraction. However, an increased absorbance was observed for the water 25 extracts of oxidized/aged emissions while the absorption of the hexane extracts was lower for the aged emissions. Comparing the absorption Ångström Exponent (AAE) values, we observed changes in the light absorption properties of BB aerosols with aging that was dependent on the fuel types. The light Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2018-161 Manuscript under review for journal Atmos. Chem. Phys.

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Section: Resultsmentioning

confidence: 50%

Light absorption by polar and non-polar aerosol compounds from laboratory biomass combustion

Sengupta¹,

Samburova²,

Bhattarai³

et al. 2018

Preprint

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“…On the other hand, r liq.fossil of 0.85 ± 0.16 was applied without considering its seasonal variations. However, it is found that r liq.fossil is lower in summer compared with other seasons, which is related to increased volatilization of semivolatile organic compounds and faster catalyst and engine warm-up times in summer (Xie et al, 2017). X. H. H. found OC/EC ratios from fresh vehicular emissions in summer to be ∼ 80 % of the yearly average, based on the lowest 5 % OC/EC ratios measured in a roadside environment in Hongkong, China.…”

Section: Differences Between Observed and Estimated Primary Oc Concenmentioning

confidence: 99%

Source apportionment of carbonaceous aerosols in Xi'an, China: insights from a full year of measurements of radiocarbon and the stable isotope <sup>13</sup>C

Huang

Cao

et al. 2018

Atmos. Chem. Phys.

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Sources of organic carbon (OC) and elemental carbon (EC) in Xi'an, China, are investigated based on 1year radiocarbon and stable carbon isotope measurements. The radiocarbon results demonstrate that EC is dominated by fossil sources throughout the year, with a mean contribution of 83 ± 5 % (7 ± 2 µg m −3 ). The remaining 17 ± 5 % (1.5 ± 1 µg m −3 ) is attributed to biomass burning, with a higher contribution in the winter (∼ 24 %) compared to the summer (∼ 14 %). Stable carbon isotopes of EC (δ 13 C EC ) are enriched in winter (−23.2 ± 0.4 ‰) and depleted in summer (−25.9 ± 0.5 ‰), indicating the influence of coal combustion in winter and liquid fossil fuel combustion in summer. By combining radiocarbon and stable carbon signatures, relative contributions from coal combustion and liquid fossil fuel combustion are estimated to be 45 % (median; 29 %-58 %, interquartile range) and 31 % (18 %-46 %) in winter, respectively, whereas in other seasons more than one half of EC is from liquid fossil combustion. In contrast with EC, the contribution of non-fossil sources to OC is much larger, with an annual average of 54 ± 8 % (12 ± 10 µg m −3 ). Clear seasonal variations are seen in OC concentrations both from fossil and non-fossil sources, with maxima in winter and minima in summer because of unfavorable meteorological conditions coupled with enhanced fossil and non-fossil activities in winter, mainly biomass burning and domestic coal burning. δ 13 C OC exhibited similar values to δ 13 C EC , and showed strong correlations (r 2 = 0.90) in summer and autumn, indicating similar source mixtures with EC. In spring, δ 13 C OC is depleted (1.1 ‰-2.4 ‰) compared to δ 13 C EC , indicating the importance of secondary formation of OC (e.g., from volatile organic compound precursors) in addition to primary sources. Modeled mass concentrations and source contributions of primary OC are compared to the measured mass and source contributions. There is strong evidence that both secondary formation and photochemical loss processes influence the final OC concentrations.

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“…Figure 3 shows the normalized absorbance for polar and non-polar extracts of fresh and aged BB aerosols. While most previous studies have focused on light absorption by the water-soluble fraction of BB aerosols (Hecobian et al, 2010;Xie et al, 2017;Zhang et al, 2013), very little attention has been given to the light absorption by the water-insoluble part of BB aerosols (Chen and Bond, 2010). Our results demonstrate that for fresh aerosols from all fuels, non-polar (hexane) extracts absorb more than polar (water) extracts (Fig.…”

Section: Absorbance Of Polar and Non-polar Fractionsmentioning

confidence: 99%

Light absorption by polar and non-polar aerosol compounds from laboratory biomass combustion

et al. 2018

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Abstract. Fresh and atmospherically aged biomass-burning (BB) aerosol mass is mostly comprised of strongly lightabsorbing black carbon (BC) and of organic carbon (OC) with its light-absorbing fraction -brown carbon (BrC). There is a lack of data on the physical and chemical properties of atmospheric BB aerosols, leading to high uncertainties in estimates of the BB impact on air quality and climate, especially for BrC. The polarity of chemical compounds influences their fate in the atmosphere including wet/dry deposition and chemical and physical processing. So far, most of the attention has been given to the water-soluble (polar) fraction of BrC, while the non-polar BrC fraction has been largely ignored. In the present study, the light absorption properties of polar and non-polar fractions of fresh and aged BB emissions were examined to estimate the contribution of differentpolarity organic compounds to the light absorption properties of BB aerosols.In our experiments, four globally and regionally important fuels were burned under flaming and smoldering conditions in the Desert Research Institute (DRI) combustion chamber. To mimic atmospheric oxidation processes (5-7 days), BB emissions were aged using an oxidation flow reactor (OFR). Fresh and OFR-aged BB aerosols were collected on filters and extracted with water and hexane to study absorption properties of polar and non-polar organic species. Results of spectrophotometric measurements (absorption weighted by the solar spectrum and normalized to mass of fuel consumed) over the 190 to 900 nm wavelength range showed that the non-polar (hexane-soluble) fraction is 2-3 times more absorbing than the polar (water-soluble) fraction. However, for emissions from fuels that undergo flaming combustion, an increased absorbance was observed for the water extracts of oxidized/aged emissions while the absorption of the hexane extracts was lower for the aged emissions for the same type of fuels. Absorption Ångström exponent (AAE) values, computed based on absorbance values from spectrophotometer measurements, were changed with aging and the nature of this change was fuel dependent. The light absorption by humic-like substances (HULIS) was found to be higher in fuels characteristic of the southwestern USA. The absorption of the HULIS fraction was lower for OFR-aged BB emissions. Comparison of the light absorption properties of different-polarity extracts (water, hexane, HULIS) provides insight into the chemical nature of BB BrC and its transformation during oxidation processes.

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Light-absorbing organic carbon from prescribed and laboratory biomass burning and gasoline vehicle emissions

Cited by 117 publications

References 54 publications

Light absorption by polar and non-polar aerosol compounds from laboratory biomass combustion

Light absorption by polar and non-polar aerosol compounds from laboratory biomass combustion

Source apportionment of carbonaceous aerosols in Xi'an, China: insights from a full year of measurements of radiocarbon and the stable isotope <sup>13</sup>C

Light absorption by polar and non-polar aerosol compounds from laboratory biomass combustion

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Light-absorbing organic carbon from prescribed and laboratory biomass burning and gasoline vehicle emissions

Cited by 117 publications

References 54 publications

Light absorption by polar and non-polar aerosol compounds from laboratory biomass combustion

Light absorption by polar and non-polar aerosol compounds from laboratory biomass combustion

Source apportionment of carbonaceous aerosols in Xi'an, China: insights from a full year of measurements of radiocarbon and the stable isotope &lt;sup&gt;13&lt;/sup&gt;C

Light absorption by polar and non-polar aerosol compounds from laboratory biomass combustion

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Source apportionment of carbonaceous aerosols in Xi'an, China: insights from a full year of measurements of radiocarbon and the stable isotope <sup>13</sup>C