Optical properties of atmospheric brown carbon (BrC) for photochemical and biomass burning-dominated aerosol regimes in India.

2020 ◽  
Author(s):  
Archita Rana ◽  
Supriya Dey ◽  
Sayantan Sarkar
Keyword(s):  
Optical Properties ◽  
Biomass Burning ◽  
Global Climate ◽  
Strong Association ◽  
Absorption Efficiency ◽  
Water Soluble ◽  
Tropospheric Chemistry ◽  
Gangetic Plain ◽  
Brown Carbon ◽  
Fluorescence Measurements

<p>Black and brown carbon (BC and BrC) are potent climate forcing agents with pronounced effects on global climate and tropospheric chemistry. Given the large heterogeneities in BC emission inventories from India and the paucity of studies on BrC characteristics, field-based measurements of BC and BrC sources and optical properties are essential to understand their impacts on regional climate. To address this issue, we report the first ground-based measurements of BC and BrC from a rural location in the highly polluted eastern Indo-Gangetic Plain (IGP) during May-November 2018 encompassing the photochemistry-dominated summer (May-June) and regional biomass burning (BB)-dominated post-monsoon (October-November) periods. A 7-wavelength Aethalometer was used for time-resolved measurements of BC mass and was supplemented by UV-Vis and fluorescence measurements of time-integrated (24 h) aqueous and organic BrC fractions, and measurements of OC, EC, WSOC, and ionic species.<br>The daily averaged BC increased 4 times during the BB regime (12.3 ± 3.9 μg m<sup>-3</sup>) as compared to summer (4.2 ± 0.8 μg m<sup>-3</sup>), while aqueous and organic BrC fractions demonstrated light absorption (babs_365) enhancements of 3-5 times during BB. For aqueous BrC, the averaged AE of 5.9-6.2 and a prominent fluorescence peak at ~420 nm suggested the presence of humic-like substances (HULIS), potentially from secondary photochemical formation during summer and primary emission during BB periods. Fluorescence and UV-Vis spectra also indicated the presence of nitroaromatic compounds, presumably from OH oxidation in summer and nighttime NO3- oxidation in the presence of enhanced NOx and precursor emission during BB. The latter was supported by the strong association between water-soluble organic carbon (WSOC; a proxy for aqueous BrC) and aerosol NO<sub>3</sub><sup>-</sup> (r=0.70, p<0.05). During BB, the fraction of water-insoluble (i.e., organic) BrC increased from 41% at 330 nm to 59 % at 550 nm while during the photochemistry-dominated summer period, the water-insoluble BrC fraction decreased from 73% at 400 nm to 41% at 530 nm, possibly due to photobleaching in the presence of OH. The BB-related BrC aerosol was also characterized by higher aromaticity and increased molecular weights of organic components as evidenced by mass absorption efficiency (MAE) ratios (MAE<sub>250</sub>/MAE<sub>365</sub>). Overall, this study established that BrC is a significant component of light-absorbing aerosol in the eastern IGP and that BrC optical properties may vary significantly in this region depending on the relative dominance of aerosol emissions and atmospheric processes.</p>

scholarly journals Chemical and optical properties of carbonaceous aerosols in Nanjing, eastern China: regionally transported biomass burning contribution

2019 ◽  
Vol 19 (17) ◽  
pp. 11213-11233 ◽  
Author(s):  
Xiaoyan Liu ◽  
Yan-Lin Zhang ◽  
Yiran Peng ◽  
Lulu Xu ◽  
Chunmao Zhu ◽  
...  
Keyword(s):  
Optical Properties ◽  
Organic Carbon ◽  
Solar Energy ◽  
Energy Absorption ◽  
Biomass Burning ◽  
Eastern China ◽  
Water Soluble ◽  
Carbonaceous Aerosols ◽  
Southeastern China ◽  
Brown Carbon

Abstract. Biomass burning can significantly impact the chemical and optical properties of carbonaceous aerosols. Here, the biomass burning impacts were studied during wintertime in a megacity of Nanjing, eastern China. The high abundance of biomass burning tracers such as levoglucosan (lev), mannosan (man), galactosan (gal) and non-sea-salt potassium (nss-K+) was found during the studied period with the concentration ranges of 22.4–1476 ng m−3, 2.1–56.2 ng m−3, 1.4–32.2 ng m−3 and 0.2–3.8 µg m−3, respectively. The significant contribution of biomass burning to water-soluble organic carbon (WSOC; 22.3±9.9 %) and organic carbon (OC; 20.9±9.3 %) was observed in this study. Backward air mass origin analysis, potential emission sensitivity of elemental carbon (EC) and MODIS fire spot information indicated that the elevations of the carbonaceous aerosols were due to the transported biomass-burning aerosols from southeastern China. The characteristic mass ratio maps of lev∕man and lev∕nss-K+ suggested that the biomass fuels were mainly crop residuals. Furthermore, the strong correlation (p < 0.01) between biomass burning tracers (such as lev) and light absorption coefficient (babs) for water-soluble brown carbon (BrC) revealed that biomass burning emissions played a significant role in the light-absorption properties of carbonaceous aerosols. The solar energy absorption due to water-soluble brown carbon and EC was estimated by a calculation based on measured light-absorbing parameters and a simulation based on a radiative transfer model (RRTMG_SW). The solar energy absorption of water-soluble BrC in short wavelengths (300–400 nm) was 0.8±0.4 (0.2–2.3) W m−2 (figures in parentheses represent the variation range of each parameter) from the calculation and 1.2±0.5 (0.3–1.9) W m−2 from the RRTMG_SW model. The absorption capacity of water-soluble BrC accounted for about 20 %–30 % of the total absorption of EC aerosols. The solar energy absorption of water-soluble BrC due to biomass burning was estimated as 0.2±0.1 (0.0–0.9) W m−2, considering the biomass burning contribution to carbonaceous aerosols. Potential source contribution function model simulations showed that the solar energy absorption induced by water-soluble BrC and EC aerosols was mostly due to the regionally transported carbonaceous aerosols from source regions such as southeastern China. Our results illustrate the importance of the absorbing water-soluble brown carbon aerosols in trapping additional solar energy in the low-level atmosphere, heating the surface and inhibiting the energy from escaping the atmosphere.

scholarly journals Measurement Report: Optical properties and sources of water-soluble brown carbon in Tianjin, North China: insights from organic molecular compositions

2022 ◽  
Author(s):  
Junjun Deng ◽  
Hao Ma ◽  
Xinfeng Wang ◽  
Shujun Zhong ◽  
Zhimin Zhang ◽  
...  
Keyword(s):  
Optical Properties ◽  
Biomass Burning ◽  
Light Absorption ◽  
Radiative Forcing ◽  
North China ◽  
Water Soluble ◽  
Formation Mechanisms ◽  
Chemical Compositions ◽  
Brown Carbon ◽  
Near Ultraviolet

Abstract. Brown carbon (BrC) aerosols exert vital impacts on climate change and atmospheric photochemistry due to their light absorption in the wavelength range from near-ultraviolet (UV) to visible light. However, the optical properties and formation mechanisms of ambient BrC remain poorly understood, limiting the estimation of their radiative forcing. In the present study, fine aerosols (PM2.5) were collected during 2016–2017 on a day/night basis over urban Tianjin, a megacity in North China, to obtain seasonal and diurnal patterns of atmospheric water-soluble BrC. There were obvious seasonal but no evident diurnal variations in light absorption properties of BrC. In winter, BrC showed much stronger light absorbing ability since mass absorption efficiency at 365 nm (MAE365) (1.54 ± 0.33 m2 g−1), which was 1.8 times larger than that (0.84 ± 0.22 m2 g−1) in summer. Direct radiative effects by BrC absorption relative to black carbon in the UV range were 54.3 ± 16.9 % and 44.6 ± 13.9 %, respectively. In addition, five fluorescent components in BrC, including three humic-like fluorophores and two protein-like fluorophores were identified with excitation-emission matrix fluorescence spectrometry and parallel factor (PARAFAC) analysis. The lowly-oxygenated components contributed more to winter and nighttime samples, while more-oxygenated components increased in summer and daytime samples. The higher humification index (HIX) together with lower biological index (BIX) and fluorescence index (FI) suggest that the chemical compositions of BrC were associated with a high aromaticity degree in summer and daytime due to photobleaching. Fluorescent properties indicate that wintertime BrC were predominantly affected by primary emissions and fresh secondary organic aerosol (SOA), while summer ones were more influenced by aging processes. Results of source apportionments using organic molecular compositions of the same set of aerosols reveal that fossil fuel combustion and aging processes, primary bioaerosol emission, biomass burning, and biogenic and anthropogenic SOA formation were the main sources of BrC. Biomass burning contributed much larger to BrC in winter and at nighttime, while biogenic SOA contributed more in summer and at daytime. Especially, our study highlights that primary bioaerosol emission is an important source of BrC in urban Tianjin in summer.

scholarly journals Optical properties of elemental carbon and water-soluble organic carbon in Beijing, China

2011 ◽  
Vol 11 (2) ◽  
pp. 6221-6258
Author(s):  
Y. Cheng ◽  
K.-B. He ◽  
M. Zheng ◽  
F.-K. Duan ◽  
Y.-L. Ma ◽  
...  
Keyword(s):  
Optical Properties ◽  
Organic Carbon ◽  
Biomass Burning ◽  
Light Absorption ◽  
Elemental Carbon ◽  
Water Soluble ◽  
Brown Carbon ◽  
Sulphate Concentration ◽  
Water Soluble Organic Carbon ◽  
Soluble Organic Carbon

Abstract. The mass absorption cross-section (MAC) of elemental carbon (EC) in Beijing was quantified using a thermal-optical carbon analyzer and the influences of mixing state and sources of carbonaceous aerosol were investigated. The MAC measured at 632 nm was 29.0 and 32.0 m2 g−1 during winter and summer respectively. MAC correlated well with the organic carbon (OC) to EC ratio (R2 = 0.91) which includes important information about the extent of secondary organic aerosol (SOA) production, indicating the enhancement of MAC by coating with SOA. The extrapolated MAC value was 10.5 m2 g−1 when the OC to EC ratio is zero, which was 5.6 m2 g−1 after correction by the enhancement factor (1.87) caused by the artifacts associated with the "filter-based" methods. The MAC also increased with sulphate (R2 = 0.84) when the sulphate concentration was below 10 μg m−3, whereas MAC and sulphate were only weekly related when the sulphate concentration was above 10 μg m−3, indicating the MAC of EC was also enhanced by coating with sulphate. Based on a converting approach that accounts for the discrepancy caused by measurements methods of both light absorption and EC concentration, previously published MAC values were converted to the "equivalent MAC", which is the estimated value if using the same measurement methods as used in this study. The "equivalent MAC" was found to be much lower in the regions heavily impacted by biomass burning (e.g., India), probably due to the influence of brown carbon. Optical properties of water-soluble organic carbon (WSOC) in Beijing were also presented. Light absorption by WSOC exhibited strong wavelength (λ) dependence such that absorption varied approximately as λ−7, which was characteristic of the brown carbon spectra. The mass absorption efficiency (σabs) of WSOC (measured at 365 nm) was 1.83 and 0.70 m2 g−1 during winter and summer respectively. The seasonal pattern of σabs was attributed to the difference in the precursors of SOA, because WSOC in Beijing has been demonstrated to be strongly linked to SOA. Moreover, the σabs of WSOC in Beijing was much higher than results from the southeastern United States which were obtained using the same method as used in this study, perhaps due to the influence of biomass burning.

scholarly journals Modelling the optical properties of fresh biomass burning aerosol produced in a smoke chamber: results from the EFEU campaign

2007 ◽  
Vol 7 (4) ◽  
pp. 12657-12686 ◽  
Author(s):  
K. Hungershöfer ◽  
K. Zeromskiene ◽  
Y. Iinuma ◽  
G. Helas ◽  
J. Trentmann ◽  
...  
Keyword(s):  
Optical Properties ◽  
Biomass Burning ◽  
Atmospheric Chemistry ◽  
Absorption Efficiency ◽  
Max Planck ◽  
Fresh Biomass ◽  
Biomass Burning Aerosol ◽  
Smoke Chamber ◽  
The Impact ◽  
Mass Absorption Efficiency

Abstract. A better characterisation of the optical properties of biomass burning aerosol as a function of the burning conditions is required in order to quantify their effects on climate and atmospheric chemistry. Controlled laboratory combustion experiments with different fuel types were carried out at the combustion facility of the Max Planck Institute for Chemistry (Mainz, Germany) as part of the 'Impact of Vegetation Fires on the Composition and Circulation of the Atmosphere' (EFEU) project. Using the measured size distributions as well as mass scattering and absorption efficiencies, Mie calculations provided mean effective refractive indices of 1.60−0.010i and 1.56−0.010i (λ=0.55 μm) for smoke particles emitted from the combustion of savanna grass and an African hardwood (musasa), respectively. The relatively low imaginary parts suggest that the light-absorbing carbon of the investigated fresh biomass burning aerosol is only partly graphitized, resulting in strongly scattering and less absorbing particles. While the observed variability in mass scattering efficiencies was consistent with changes in particle size, the changes in the mass absorption efficiency can only be explained, if the chemical composition of the particles varies with combustion conditions.

Investigation of atmospheric aerosols over semi-urban and urban areas in Eastern Indo-Gangetic Plain: seasonal variability and source apportionment using PMF

2021 ◽  
Author(s):  
Kanishtha Dubey ◽  
Shubha Verma
Keyword(s):  
Organic Carbon ◽  
Biomass Burning ◽  
Atmospheric Aerosols ◽  
Urban Areas ◽  
Relative Concentration ◽  
Road Dust ◽  
Water Soluble ◽  
Carbonaceous Aerosols ◽  
Gangetic Plain ◽  
Brick Kilns

&lt;p&gt;The study investigates the chemical composition and source of aerosol origin at a semi-urban (Kharagpur&amp;#8211;Kgp) and urban (Kolkata&amp;#8211;Kol) region during the period February 2015 to January 2016 and September 2010 to August 2011 respectively. Major water-soluble inorganic aerosols (WSII) were determined using Ion chromatography and carbonaceous aerosols (CA) using OC&amp;#8211;EC analyser. A multivariate factor analysis Positive Matrix Factorization (PMF) was used in resolving source of aerosols at the study locations. Seasonal analysis of WSII at Kgp and Kol indicated relative dominance of calcium at both the places followed by sodium, chloride, and magnesium ions. Non-sea salt potassium (nss&amp;#8211;K&lt;sup&gt;+&lt;/sup&gt;), a biomass burning tracer was found higher at Kol than at Kgp. Sum of secondary aerosols sulphate (SO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt;), nitrate (NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;) and ammonium (NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;) was higher at Kol than Kgp with relative concentration of SO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt; being higher than NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt; at Kgp which was vice-versa at Kol. Examination of carbonaceous aerosols showed three times higher concentration of organic carbon (OC) than elemental carbon (EC) with monthly mean of OC/EC ratio &gt; 2, indicating likely formation of secondary organic carbon formation. Seasonal influence of biomass burning inferred from nss&amp;#8211;K&lt;sup&gt;+&lt;/sup&gt; (OC/EC) ratio relationship indicated dissimilarity in seasonality of biomass burning at Kgp (Kol). PMF resolved sources for Kgp constituted of secondary aerosol emissions, biomass burning, fugitive dust, marine aerosols, crustal dust and emissions from brick kilns while for Kol factors constituted of burning of waste, resuspended paved road dust, coal combustion, sea spray aerosols, vehicular emissions and biomass burning.&lt;/p&gt;

Brown carbon in the continental outflow to the North Indian Ocean

2019 ◽  
Vol 21 (6) ◽  
pp. 970-987 ◽  
Author(s):  
Srinivas Bikkina ◽  
Manmohan Sarin
Keyword(s):  
Indian Ocean ◽  
Soluble Fraction ◽  
North Indian Ocean ◽  
Water Soluble ◽  
Gangetic Plain ◽  
Brown Carbon ◽  
Water Soluble Fraction ◽  
The North ◽  
Continental Outflow ◽  
Indo Gangetic Plain

In this paper, we synthesize the size distribution and optical properties of the atmospheric water-soluble fraction of light-absorbing organic carbon (brown carbon; BrC) in the continental outflow from the Indo-Gangetic Plain (IGP) in South Asia to the North Indian Ocean.

Optical properties of aerosol brown carbon (BrC) in the eastern Indo-Gangetic Plain

2020 ◽  
Vol 716 ◽  
pp. 137102 ◽  
Author(s):  
Archita Rana ◽  
Supriya Dey ◽  
Prashant Rawat ◽  
Arya Mukherjee ◽  
Jingying Mao ◽  
...  
Keyword(s):  
Optical Properties ◽  
Gangetic Plain ◽  
Brown Carbon ◽  
Indo Gangetic Plain

scholarly journals The characteristics of atmospheric brown carbon in Xi'an, inland China: sources, size distributions and optical properties

2020 ◽  
Vol 20 (4) ◽  
pp. 2017-2030 ◽  
Author(s):  
Can Wu ◽  
Gehui Wang ◽  
Jin Li ◽  
Jianjun Li ◽  
Cong Cao ◽  
...  
Keyword(s):  
Optical Properties ◽  
Biomass Burning ◽  
Isotope Composition ◽  
Stable Carbon Isotope ◽  
Urban Atmosphere ◽  
Semiarid Region ◽  
Chemical Compositions ◽  
Brown Carbon ◽  
Polycyclic Aromatic ◽  
Fine Mode

Abstract. To investigate the characteristics of atmospheric brown carbon (BrC) in the semiarid region of East Asia, PM2.5 and size-resolved particles in the urban atmosphere of Xi'an, inland China, during the winter and summer of 2017 were collected and analyzed for optical properties and chemical compositions. Methanol extracts (MeOH extracts) were more light-absorbing than water extracts (H2O extracts) in the optical wavelength of 300–600 nm and well correlated with nitrophenols, polycyclic aromatic hydrocarbons (PAHs) and oxygenated PAHs (r > 0.78). The light absorptions (absλ=365 nm) of H2O extracts and MeOH extracts in winter were 28±16 and 49±32 M m−1, respectively, which are about 10 times higher than those in summer, mainly due to the enhanced emissions from biomass burning for house heating. Water-extracted BrC predominately occurred in the fine mode (< 2.1 µm) during winter and summer, accounting for 81 % and 65 % of the total absorption of BrC, respectively. The light absorption and stable carbon isotope composition measurements showed an increasing ratio of absλ=365 nm-MeOH to absλ=550 nm-EC along with an enrichment of 13C in PM2.5 during the haze development, indicating an accumulation of secondarily formed BrC (e.g., nitrophenols) in the aerosol aging process. Positive matrix factorization (PMF) analysis showed that biomass burning, fossil fuel combustion, secondary formation, and fugitive dust are the major sources of BrC in the city, accounting for 55 %, 19 %, 16 %, and 10 % of the total BrC of PM2.5, respectively.

Brown carbon aerosol in urban Beijing: Significant contributions from biomass burning and secondary formation

2020 ◽  
Author(s):  
Ting Wang ◽  
Rujin Huang ◽  
Lu Yang ◽  
Wei Yuan ◽  
Yuquan Gong
Keyword(s):  
Biomass Burning ◽  
Light Absorption ◽  
Coal Combustion ◽  
Absorption Efficiency ◽  
Traffic Emission ◽  
Brown Carbon ◽  
Factorization Model ◽  
Secondary Formation ◽  
Vis Spectroscopy ◽  
The Impact

&lt;p&gt;Atmospheric brown carbon (BrC) has significant impact on Earth&amp;#8217;s radiative budget. However, due to our very limited knowledge about the relationship between BrC light absorption and the associated sources, the estimation for radiative effects of BrC is still largely constrained. In this study, we combine ultraviolet&amp;#8722;visible (UV&amp;#8722;vis) spectroscopy measurements and chemical analyses of BrC samples collected from January to December 2015 in urban Beijing, to investigated the sources of atmospheric BrC. The multiple liner regression model was applied to apportion the contributions of individual primary and secondary organic aerosol (OA) source components to light absorption of BrC. Our results indicated that biomass burning emission and secondary formation are highly absorbing up to 500 nm, and their contributions increased with the wavelengths. In contrast, the contribution of traffic emission and coal combustion to total absorption decreased with the wavelength and the large contributions were mostly found at shorter wavelengths. Then the mass absorption efficiency (MAE) of major light-absorbing components were estimated, which can provide a support to estimate the impact of BrC from these sources on the climate. The positive matrix factorization model were also used to verify the contributions of different source components of BrC absorption at 365 nm. The results consistently demonstrate that the biomass burning and secondary formation contributes significantly to the overall absorption, followed by coal combustion and traffic emission.&lt;/p&gt;

scholarly journals Physical and optical properties of aged biomass burning aerosol from wildfires in Siberia and the Western USA at the Mt. Bachelor Observatory

2016 ◽  
Vol 16 (23) ◽  
pp. 15185-15197 ◽  
Author(s):  
James R. Laing ◽  
Daniel A. Jaffe ◽  
Jonathan R. Hee
Keyword(s):  
Optical Properties ◽  
Pacific Northwest ◽  
Biomass Burning ◽  
Geometric Mean ◽  
Fine Particulate Matter ◽  
Single Scattering ◽  
Absorption Efficiency ◽  
Size Distributions ◽  
Scanning Mobility Particle Sizer ◽  
Scattering Coefficients

Abstract. The summer of 2015 was an extreme forest fire year in the Pacific Northwest. Our sample site at the Mt. Bachelor Observatory (MBO, 2.7 km a.s.l.) in central Oregon observed biomass burning (BB) events more than 50 % of the time during August. In this paper we characterize the aerosol physical and optical properties of 19 aged BB events during August 2015. Six of the 19 events were influenced by Siberian fires originating near Lake Baikal that were transported to MBO over 4–10 days. The remainder of the events resulted from wildfires in Northern California and Southwestern Oregon with transport times to MBO ranging from 3 to 35 h. Fine particulate matter (PM1), carbon monoxide (CO), aerosol light scattering coefficients (σscat), aerosol light absorption coefficients (σabs), and aerosol number size distributions were measured throughout the campaign. We found that the Siberian events had a significantly higher Δσabs∕ΔCO enhancement ratio, higher mass absorption efficiency (MAE; Δσabs∕ΔPM1), lower single scattering albedo (ω), and lower absorption Ångström exponent (AAE) when compared with the regional events. We suggest that the observed Siberian events represent that portion of the plume that has hotter flaming fire conditions and thus enabled strong pyroconvective lofting and long-range transport to MBO. The Siberian events observed at MBO therefore represent a selected portion of the original plume that would then have preferentially higher black carbon emissions and thus an enhancement in absorption. The lower AAE values in the Siberian events compared to regional events indicate a lack of brown carbon (BrC) production by the Siberian fires or a loss of BrC during transport. We found that mass scattering efficiencies (MSE) for the BB events ranged from 2.50 to 4.76 m2 g−1. We measured aerosol size distributions with a scanning mobility particle sizer (SMPS). Number size distributions ranged from unimodal to bimodal and had geometric mean diameters (Dpm) ranging from 138 to 229 nm and geometric standard deviations (σg) ranging from 1.53 to 1.89. We found MSEs for BB events to be positively correlated with the geometric mean of the aerosol size distributions (R2 = 0.73), which agrees with Mie theory. We did not find any dependence on event size distribution to transport time or fire source location.

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