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

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.

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

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-6221-2011 ◽

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.

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

10.5194/egusphere-egu21-14205 ◽

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

The study investigates the chemical composition and source of aerosol origin at a semi-urban (Kharagpur&#8211;Kgp) and urban (Kolkata&#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&#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&#8211;K+), a biomass burning tracer was found higher at Kol than at Kgp. Sum of secondary aerosols sulphate (SO42-), nitrate (NO3-) and ammonium (NH4+) was higher at Kol than Kgp with relative concentration of SO42- being higher than NO3- 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 > 2, indicating likely formation of secondary organic carbon formation. Seasonal influence of biomass burning inferred from nss&#8211;K+ (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.

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Fossil vs. non-fossil sources of fine carbonaceous aerosols in four Chinese cities during the extreme winter haze episode of 2013

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-1299-2015 ◽

2015 ◽

Vol 15 (3) ◽

pp. 1299-1312 ◽

Cited By ~ 113

Author(s):

Y.-L. Zhang ◽

R.-J. Huang ◽

I. El Haddad ◽

K.-F. Ho ◽

J.-J. Cao ◽

...

Keyword(s):

Particulate Matter ◽

Organic Carbon ◽

Biomass Burning ◽

Water Soluble ◽

Total Carbon ◽

World Health ◽

Biomass Combustion ◽

Carbonaceous Aerosols ◽

Haze Episode ◽

Mass Concentrations

Abstract. During winter 2013, extremely high concentrations (i.e., 4–20 times higher than the World Health Organization guideline) of PM2.5 (particulate matter with an aerodynamic diameter < 2.5 μm) mass concentrations (24 h samples) were found in four major cities in China including Xi'an, Beijing, Shanghai and Guangzhou. Statistical analysis of a combined data set from elemental carbon (EC), organic carbon (OC), 14C and biomass-burning marker measurements using Latin hypercube sampling allowed a quantitative source apportionment of carbonaceous aerosols. Based on 14C measurements of EC fractions (six samples each city), we found that fossil emissions from coal combustion and vehicle exhaust dominated EC with a mean contribution of 75 ± 8% across all sites. The remaining 25 ± 8% was exclusively attributed to biomass combustion, consistent with the measurements of biomass-burning markers such as anhydrosugars (levoglucosan and mannosan) and water-soluble potassium (K+). With a combination of the levoglucosan-to-mannosan and levoglucosan-to-K+ ratios, the major source of biomass burning in winter in China is suggested to be combustion of crop residues. The contribution of fossil sources to OC was highest in Beijing (58 ± 5%) and decreased from Shanghai (49 ± 2%) to Xi'an (38 ± 3%) and Guangzhou (35 ± 7%). Generally, a larger fraction of fossil OC was from secondary origins than primary sources for all sites. Non-fossil sources accounted on average for 55 ± 10 and 48 ± 9% of OC and total carbon (TC), respectively, which suggests that non-fossil emissions were very important contributors of urban carbonaceous aerosols in China. The primary biomass-burning emissions accounted for 40 ± 8, 48 ± 18, 53 ± 4 and 65 ± 26% of non-fossil OC for Xi'an, Beijing, Shanghai and Guangzhou, respectively. Other non-fossil sources excluding primary biomass burning were mainly attributed to formation of secondary organic carbon (SOC) from non-fossil precursors such as biomass-burning emissions. For each site, we also compared samples from moderately to heavily polluted days according to particulate matter mass. Despite a significant increase of the absolute mass concentrations of primary emissions from both fossil and non-fossil sources during the heavily polluted events, their relative contribution to TC was even decreased, whereas the portion of SOC was consistently increased at all sites. This observation indicates that SOC was an important fraction in the increment of carbonaceous aerosols during the haze episode in China.

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

10.5194/acp-2021-1045 ◽

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.

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

10.5194/egusphere-egu2020-611 ◽

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

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. The daily averaged BC increased 4 times during the BB regime (12.3 &#177; 3.9 &#956;g m-3) as compared to summer (4.2 &#177; 0.8 &#956;g m-3), 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 NO3- (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 (MAE250/MAE365). 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.

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Chemical composition and light absorption of brown carbon emitted from residential coal combustion in China

10.5194/egusphere-egu2020-6259 ◽

2020 ◽

Author(s):

Jianzhong Song ◽

Meiju Li ◽

Xingjun Fan ◽

Peng'an Peng

Keyword(s):

Organic Carbon ◽

Organic Compounds ◽

Biomass Burning ◽

Light Absorption ◽

Coal Combustion ◽

Extraction Methods ◽

Water Soluble ◽

Brown Carbon ◽

Smoke Particles ◽

Soluble Organic Carbon

Brown carbon (BrC) is a type of light-absorbing organic compounds with a high capacity to absorb light in the low-wavelength visible and near-ultraviolet regions, which is ubiquitous in atmospheric aerosols, rainwater, and cloudwater samples. BrC can not only alter the light absorption and radiative forcing of aerosols but can also influence the formation of cloud condensation nuclei; therefore, it has a potential impact on atmospheric chemistry and climate change. Numerous studies have demonstrated that combustion processes are significant sources of atmospheric BrC, however most of these studies were focused on the emissions of biomass burning. Knowledge of primary BrC from coal combustion is still limited. In the study, smoke particles emitted from the combustion of residential coals with different geological maturity were collected in a combustion system. Then BrC fractions, including water soluble organic carbon (WSOC), water soluble humic-like substances (HULISw), alkaline soluble organic carbon (ASOC) and methanol soluble organic carbon (MSOC) were extracted and characterized for their abundances, chemical, and light absorption properties.&#160;Our results showed that the abundance and light absorption of the coal combustion-derived BrC fractions were strongly dependent on the extraction methods used and the coal maturity. The abundances of MSOC fraction was significantly higher than WSOC and ASOC fractions and even higher than the sum of WSOC and ASOC, indicating that most organic compounds in smoke particles were soluble in pure methanol. The WSOC and MSOC fractions from the combustion of low maturity coal had relatively low SUVA254 and MAE365 values, indicated that they had relatively low levels of aromatic structures and light absorption.&#160;The WSOC and MSOC fractions were characterized by ultrahigh-resolution mass spectrometry. The results showed that S-containing compounds (CHOS and CHONS) are found to be the dominant components of the WSOC, whereas CHO and CHON compounds make a great contribution to the MSOC samples. Noted that a greater abundance of S-containing compounds was found in the smoke produced from coal combustion compared to biomass burning and atmospheric samples, indicated that coal combustion could be an important source of atmospheric S-containing compounds in certain areas. The findings also suggest that organic molecules with a high aromaticity index and low polarity showed stronger light absorption. In summary, our study indicated that coal combustion is a potential source of atmospheric BrC and their abundance, chemical, and light absorption were strongly dependent on the extraction methods used and the coal maturity.

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Fossil vs. non-fossil sources of fine carbonaceous aerosols in four Chinese cities during the extreme winter haze episode in 2013

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-14-26257-2014 ◽

2014 ◽

Vol 14 (19) ◽

pp. 26257-26296 ◽

Cited By ~ 2

Author(s):

Y.-L. Zhang ◽

R.-J. Huang ◽

I. El Haddad ◽

K.-F. Ho ◽

J.-J. Cao ◽

...

Keyword(s):

Particulate Matter ◽

Organic Carbon ◽

Source Apportionment ◽

Biomass Burning ◽

Crop Residues ◽

Water Soluble ◽

World Health ◽

Biomass Combustion ◽

Carbonaceous Aerosols ◽

Haze Episode

Abstract. During winter 2013, extremely high concentrations (i.e. 4–20 times higher than the World Health Organization guideline) of PM2.5 (particulate matter with an aerodynamic diameter <2.5 μm) were reported in several large cities in China. In this work, source apportionment of fine carbonaceous aerosols during this haze episode was conducted at four major cities in China including Xian, Beijing, Shanghai and Guangzhou. An effective statistical analysis of a combined dataset from elemental carbon (EC) and organic carbon (OC), radiocarbon (14C) and biomass-burning marker measurements using Latin-hypercube sampling allowed a quantitative source apportionment of carbonaceous aerosols. We found that fossil emissions from coal combustion and vehicle exhaust dominated EC with a mean contribution of 75 ± 8% at all sites. The remaining 25 ± 8% was exclusively attributed to biomass combustion, consistent with the measurements of biomass-burning markers such as anhydrosugars (levoglucosan and mannosan) and water-soluble potassium (K+). With a combination of the levoglucosan-to-mannosan and levoglucosan-to-K+ ratios, the major source of biomass burning in winter in China is suggested to be combustion of crop residues. The contribution of fossil sources to OC was highest in Beijing (58 ± 5%) and decreased from Shanghai (49 ± 2%) to Xian (38 ± 3%) and Guangzhou (35 ± 7%). Generally, a larger fraction of fossil OC was rather from secondary origins than primary sources for all sites. Non-fossil sources accounted on average for 55 ± 10% and 48 ± 9% of OC and TC, respectively, which suggests that non-fossil emissions were very important contributors of urban carbonaceous aerosols in China. The primary biomass-burning emissions accounted for 40 ± 8%, 48 ± 18%, 53 ± 4% and 65 ± 26% of non-fossil OC for Xian, Beijing, Shanghai and Guangzhou, respectively. Other non-fossil sources excluding primary biomass-burning were mainly attributed to formation of secondary organic carbon (SOC) from non-fossil precursors such as biomass-burning emissions. For each site, we also compared samples from moderately with heavily polluted days according to particulate matter mass. Despite a significant increase of absolute mass concentrations of primary emissions from both, fossil and non-fossil sources, during the heavily polluted events, their relative contribution to TC was even decreased, whereas the portion of SOC was consistently increased at all sites. This observation indicates that SOC was an important fraction in the increment of carbonaceous aerosols during the haze episode in China.

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Thermal Distribution of Size-resolved Carbonaceous Aerosols and Water Soluble Organic Carbon in Emissions from Biomass Burning

Asian Journal of Atmospheric Environment ◽

10.5572/ajae.2013.7.2.095 ◽

2013 ◽

Vol 7 (2) ◽

pp. 95-104 ◽

Cited By ~ 7

Author(s):

Min-Suk Bae ◽

Seung-Shik Park

Keyword(s):

Organic Carbon ◽

Biomass Burning ◽

Water Soluble ◽

Carbonaceous Aerosols ◽

Thermal Distribution ◽

Water Soluble Organic Carbon ◽

Soluble Organic Carbon

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Chemical composition and light absorption of carbonaceous aerosols emitted from crop residue burning: influence of combustion efficiency

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-13721-2020 ◽

2020 ◽

Vol 20 (22) ◽

pp. 13721-13734

Author(s):

Yujue Wang ◽

Min Hu ◽

Nan Xu ◽

Yanhong Qin ◽

Zhijun Wu ◽

...

Keyword(s):

Organic Carbon ◽

Biomass Burning ◽

Light Absorption ◽

Combustion Efficiency ◽

Emission Factors ◽

Absorption Efficiency ◽

Water Soluble ◽

Radiation Budget ◽

Carbonaceous Aerosols ◽

Flaming Combustion

Abstract. Biomass burning is one of the major sources of carbonaceous aerosols, which affects air quality, the radiation budget and human health. Field straw residue burning is a widespread type of biomass burning in Asia, while its emissions are poorly understood compared with wood burning emissions. In this study, lab-controlled straw (wheat and corn) burning experiments were designed to investigate the emission factors and light absorption properties of different biomass burning organic aerosol (BBOA) fractions, including water-soluble organic carbon (WSOC), humic-like substances (HULIS) and water-insoluble organic carbon (WISOC). The influences of biofuel moisture content and combustion efficiency on emissions are comprehensively discussed. The emission factors of PM2.5, organic carbon (OC) and elemental carbon (EC) were 9.3±3.4, 4.6±1.9 and 0.21±0.07 g kg−1 for corn burning and 8.7±5.0, 3.9±2.8 and 0.22±0.05 g kg−1 for wheat burning, generally lower than wood or forest burning emissions. Though the mass contribution of WISOC to OC (32 %–43 %) was lower than WSOC, the light absorption contribution of WISOC (57 %–84 % at 300–400 nm) surpassed WSOC due to the higher mass absorption efficiency (MAE) of WISOC. The results suggested that BBOA light absorption would be largely underestimated if only the water-soluble fractions were considered. However, the light absorption of WSOC in the near-UV range, occupying 39 %–43 % of the total extracted OC absorption at 300 nm, cannot be negligible due to the sharper increase of absorption towards shorter wavelengths compared with WISOC. HULIS were the major light absorption contributors to WSOC, due to the higher MAE of HULIS than other high-polarity WSOC components. The emission levels and light absorption of BBOA were largely influenced by the burning conditions, indicated by modified combustion efficiency (MCE) calculated by measured CO and CO2 in this study. The emission factors of PM2.5, OC, WSOC, HULIS and organic acids were enhanced under lower MCE conditions or during higher moisture straw burning experiments. Light absorption coefficients of BBOA at 365 nm were also higher under lower MCE conditions, which was mainly due to the elevated mass emission factors. Our results suggested that the influence of varied combustion efficiency on particle emissions could surpass the differences caused by different types of biofuels. Thus, the burning efficiency or conditions should be taken into consideration when estimating the influence of biomass burning. In addition, we observed that the ratios of K+/OC and Cl-/OC increased under higher MCE conditions due to the enhancement of potassium and chlorine released under higher fire temperatures during flaming combustion. This indicates that the potassium ion, as a commonly used biomass burning tracer, may lead to estimation uncertainty if the burning conditions are not considered.

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Source apportionment and dynamic changes of carbonaceous aerosols during the haze bloom–decay process in China based on radiocarbon and organic molecular tracers

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-34949-2015 ◽

2015 ◽

Vol 15 (23) ◽

pp. 34949-34979 ◽

Cited By ~ 1

Author(s):

J. Liu ◽

J. Li ◽

D. Liu ◽

P. Ding ◽

C. Shen ◽

...

Keyword(s):

Organic Carbon ◽

Source Apportionment ◽

Biomass Burning ◽

South China ◽

Fossil Fuel ◽

Decay Process ◽

Water Soluble ◽

Total Carbon ◽

Carbonaceous Aerosols ◽

Fossil Carbon

Abstract. Fine carbonaceous aerosols (CAs) is the key factor influencing the currently filthy air in megacities of China, yet seldom study simultaneously focuses on the origins of different CAs species using specific and powerful source tracers. Here, we present a detailed source apportionment for various CAs fractions, including organic carbon (OC), water-soluble OC (WSOC), water-insoluble OC (WIOC), elemental carbon (EC) and secondary OC (SOC) in the largest cities of North (Beijing, BJ) and South China (Guangzhou, GZ), respectively, using the measurements of radiocarbon and anhydrosugars. Results show that non-fossil fuel sources such as biomass burning and biogenic emission make a significant contribution to the total CAs in Chinese megacities: 56 ± 4 % in BJ and 46 ± 5 % in GZ, respectively. The relative contributions of primary fossil carbon from coal and liquid petroleum combustions, primary non-fossil carbon and secondary organic carbon (SOC) to total carbon are 19, 28 and 54 % in BJ, and 40, 15 and 46 % in GZ, respectively. Non-fossil fuel sources account for 52 % in BJ and 71 % in GZ of SOC, respectively. These results suggest that biomass burning has a greater influence on regional particulate air pollution in North China than in South China. We observed an unabridged haze bloom–decay process in South China, which illustrates that both primary and secondary matter from fossil sources played a key role in the blooming phase of the pollution episode, while haze phase is predominantly driven by fossil-derived secondary organic matter and nitrate.

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