scholarly journals A dominant contribution to light absorption by methanol-insoluble brown carbon produced in the combustion of biomass fuels typically consumed in wildland fires in the United States

2022 ◽  
Author(s):  
Khairallah Atwi ◽  
Charles Perrie ◽  
Zezhen Cheng ◽  
Omar El Hajj ◽  
Rawad Saleh
Keyword(s):  
United States ◽  
Solvent Extraction ◽  
Light Absorption ◽  
The United States ◽  
Extraction Methods ◽  
Wildland Fires ◽  
Dominant Contribution ◽  
Biomass Fuels ◽  
Absorption Properties ◽  
Brown Carbon

The light-absorption properties of brown carbon (BrC) are often estimated using offline, solvent-extraction methods. However, recent studies have found evidence of insoluble species of BrC which are unaccounted for in...

Light absorption properties of elemental carbon (EC) and water-soluble brown carbon (WS–BrC) in the Kathmandu Valley, Nepal: A 5-year study

2020 ◽  
Vol 261 ◽  
pp. 114239 ◽  
Author(s):  
Pengfei Chen ◽  
Shichang Kang ◽  
Lekhendra Tripathee ◽  
Kirpa Ram ◽  
Maheswar Rupakheti ◽  
...  
Keyword(s):  
Light Absorption ◽  
Elemental Carbon ◽  
Water Soluble ◽  
Kathmandu Valley ◽  
Absorption Properties ◽  
Brown Carbon

Light absorption properties of brown carbon over the southeastern Tibetan Plateau

2018 ◽  
Vol 625 ◽  
pp. 246-251 ◽  
Author(s):  
Chong-Shu Zhu ◽  
Jun-Ji Cao ◽  
Ru-Jin Huang ◽  
Zhen-Xing Shen ◽  
Qi-Yuan Wang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Light Absorption ◽  
Absorption Properties ◽  
Brown Carbon ◽  
Southeastern Tibetan Plateau

Evolution of the light-absorption properties of combustion brown carbon aerosols following reaction with nitrate radicals

2020 ◽  
Vol 54 (7) ◽  
pp. 849-863 ◽  
Author(s):  
Zezhen Cheng ◽  
Khairallah M. Atwi ◽  
Zhenhong Yu ◽  
Anita Avery ◽  
Edward C. Fortner ◽  
...  
Keyword(s):  
Light Absorption ◽  
Absorption Properties ◽  
Brown Carbon ◽  
Nitrate Radicals ◽  
Carbon Aerosols

Light absorption properties, chromophore composition and sources of brown carbon aerosol in Xi’an, Northwest China

2020 ◽  
Author(s):  
Ru-Jin Huang ◽  
Wei Yuan ◽  
Lu Yang ◽  
Jie Guo ◽  
Jing Duan ◽  
...  
Keyword(s):  
Light Absorption ◽  
Coal Combustion ◽  
Radiative Forcing ◽  
Northwest China ◽  
Absorption Efficiency ◽  
Vehicular Emissions ◽  
Absorption Properties ◽  
Seasonal Differences ◽  
Brown Carbon ◽  
The Impact

<p>The impact of brown carbon aerosol (BrC) on the Earth’s radiative forcing balance has been widely recognized but remains uncertain, mainly because the relationships among BrC sources, chromophores, and optical properties of aerosol are poorly understood (Feng et al., 2013; Laskin et al., 2015). In this work, the light absorption properties and chromophore composition of BrC were investigated for samples collected in Xi’an, Northwest China from 2015 to 2016. Both absorption Ångström exponent and mass absorption efficiency show distinct seasonal differences, which could be attributed to the differences in sources and chromophore composition of BrC. Three groups of light-absorbing organics were found to be important BrC chromophores, including those show multiple absorption peaks at wavelength > 350 nm (12 polycyclic aromatic hydrocarbons and their derivatives) and those show single absorption peak at wavelength < 350 nm (10 nitrophenols and nitrosalicylic acids and 3 methoxyphenols). These measured BrC chromophores show distinct seasonal differences and contribute on average about 1.1% and 3.3% of light absorption of methanol-soluble BrC at 365 nm in summer and winter, respectively, about 7 and 5 times higher than the corresponding mass fractions in total organic carbon. The sources of BrC were resolved by positive matrix factorization (PMF) using these chromophores instead of commonly used non-light absorbing organic markers as model inputs. Our results show that in spring vehicular emissions and secondary formation are major sources of BrC (~70%), in fall coal combustion and vehicular emissions are major sources (~70%), in winter biomass burning and coal combustion become major sources (~80%), while in summer secondary BrC dominates (~60%).</p><p> </p><p>References:</p><p>Feng, Y., V. Ramanathan, and V. R. Kotamarthi: Brown carbon: A significant atmospheric absorber of solar radiation?, Atmos. Chem. Phys., 13, 8607-8621, doi:10.5194/acp-13-8607-2013, 2013.</p><p>Laskin, A., J. Laskin, and S. A. Nizkorodov: Chemistry of atmospheric brown carbon, Chem. Rev., 115, 4335-4382, doi:10.1021/cr5006167, 2015.</p>

Brown carbon in atmospheric fine particles in Yangzhou, China: Light absorption properties and source apportionment

2020 ◽  
Vol 244 ◽  
pp. 105028 ◽  
Author(s):  
Yanfang Chen ◽  
Xinchun Xie ◽  
Zhan Shi ◽  
Yilin Li ◽  
Xinyu Gai ◽  
...  
Keyword(s):  
Source Apportionment ◽  
Light Absorption ◽  
Fine Particles ◽  
Absorption Properties ◽  
Brown Carbon

Discrepancies between brown carbon light-absorption properties retrieved from online and offline measurements

2020 ◽  
Vol 55 (1) ◽  
pp. 92-103 ◽  
Author(s):  
Zezhen Cheng ◽  
Khairallah Atwi ◽  
Omar El Hajj ◽  
Ifeoma Ijeli ◽  
D. Al Fischer ◽  
...  
Keyword(s):  
Light Absorption ◽  
Absorption Properties ◽  
Brown Carbon

scholarly journals Contributions of nitrated aromatic compounds to the light absorption of water-soluble and particulate brown carbon in different atmospheric environments in Germany and China

2016 ◽  
Author(s):  
Monique Teich ◽  
Dominik van Pinxteren ◽  
Michael Wang ◽  
Simonas Kecorius ◽  
Zhibin Wang ◽  
...  
Keyword(s):  
Light Absorption ◽  
Strong Influence ◽  
Water Soluble ◽  
Absorption Properties ◽  
Brown Carbon ◽  
Light Absorption Coefficient ◽  
Alkaline Conditions ◽  
Acidic Conditions ◽  
The Mean ◽  
Biogenic Aerosols

Abstract. The relative contribution of eight nitrated aromatic compounds (NACs, nitrophenols + nitrated salicylic acids) to the light absorption of aqueous particle extracts and particulate brown carbon were determined from aerosol particle samples collected in Germany and China. High-volume filter samples were collected during six campaigns, performed at five locations in two seasons: (I) two campaigns with strong influence of biomass burning (BB) aerosol – at the TROPOS institute (winter, 2014, urban background, Leipzig, Germany) and the Melpitz research site (winter, 2014, rural background); (II) two campaigns with strong influence from biogenic emissions – at Melpitz (summer, 2014) and the forest site Waldstein (summer, 2014, Fichtelgebirge, Germany), and (III) two CAREBeijing-NCP campaigns – at Xianghe (summer, 2013, anthropogenic polluted background) and Wangdu (summer, 2014, anthropogenic polluted background with a distinct BB-episode), both in the North China Plain. The filter samples were analyzed for NAC concentrations and the light absorption of aqueous filter extracts was determined. Light absorption properties of particulate brown carbon were derived from a seven-wavelength Aethalometer during the campaigns at TROPOS (winter) and Waldstein (summer). The light absorption of the aqueous filter extracts was found to be pH dependent: at pH 10, the aqueous light absorption coefficient Abs370 and the mass absorption efficiency (MAE370) at 370 nm were a factor of 1.6 and 1.4 larger than at pH 2, respectively. In general, Abs370 ranged from 0.21–21.8 Mm−1 under acidic conditions and 0.63–27.2 Mm−1 under alkaline conditions, over all campaigns. The observed MAE370 was in a range of 0.10–1.79 m2 g−1 and 0.24–2.57 m2 g−1 for acidic and alkaline conditions, respectively. For MAE370 and Abs370, the observed values were higher in winter than in summer, in agreement with other studies. Furthermore, it was found that the MAE370 values in winter in Germany exceeded those of the Chinese summer background stations (average of 0.85±0.24 m2 g−1 compared to 0.47±0.15 m2 g−1). The lowest MAE was observed for the Waldstein (summer) campaign (average of 0.17±0.03 m2 g−1), indicating that freshly emitted biogenic aerosols are only weakly absorbing. In contrast, a strong relationship was found between the light absorption properties and the concentrations of levoglucosan, corroborating findings from other studies. Regarding the particulate light absorption at 370 nm, a mean particulate light absorption coefficient babs,370 of 54 Mm−1 and 6.0 Mm−1 was determined for the TROPOS (winter) and Waldstein (summer) campaigns, respectively, with average contributions of particulate brown carbon to babs,370 of 46 % at TROPOS (winter) and 15 % at Waldstein (summer). The absorption Ångström exponent of the ambient aerosol during the campaigns at TROPOS (winter) and Waldstein (summer) was found to be 1.5±0.1 and 1.2±0.3, respectively. Thus, the Aethalometer measurements support the findings from aqueous filter extracts of only weakly absorbing biogenic aerosols in comparison to the more polluted and BB influenced aerosol at TROPOS (winter). The mean contribution of NACs to the aqueous extract light absorption over all campaigns ranged from 0.10 %–1.25 % under acidic conditions and 0.13 %–3.71 % under alkaline conditions. The high variability among the measurement sites showed that the emission strengths of light absorbing compounds and the composition of brown carbon were very different for each site. The mean contribution of NACs to the particulate brown carbon light absorption was 0.10±0.06 % (acidic conditions) and 0.13±0.09 % (alkaline conditions) during the Waldstein (summer) campaign and 0.25±0.21 % (acidic conditions) and 1.13±1.03 % (alkaline conditions) during the TROPOS (winter) campaign. A correlation of NAC concentrations with Abs370 was observed for the BB-influenced campaigns at TROPOS (winter) and Melpitz (winter). The average contribution of NACs to the aqueous extract light absorption over all campaigns was found to be 5 times higher than their mass contribution to water-soluble organic carbon indicating that even small amounts of light-absorbing compounds can have a disproportionately high impact on the light absorption properties of particles.

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