scholarly journals Fossil and non-fossil sources of organic carbon (OC) and elemental carbon (EC) in Göteborg, Sweden

2008 ◽  
Vol 8 (4) ◽  
pp. 16255-16289 ◽  
Author(s):  
S. Szidat ◽  
M. Ruff ◽  
L. Wacker ◽  
H.-A. Synal ◽  
M. Hallquist ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Elemental Carbon ◽  
Latin Hypercube Sampling ◽  
Water Soluble ◽  
Rural Site ◽  
Urban Site ◽  
Winter Period ◽  
Back Trajectories ◽  
Relative Contribution ◽  
Wood Burning

Abstract. Particulate matter was collected at an urban site in Göteborg (Sweden) in February/March 2005 and in June/July 2006. Additional samples were collected at a rural site for the winter period. Elemental carbon (EC), organic carbon (OC), water-insoluble OC (WINSOC), and water-soluble OC (WSOC) were analyzed for 14C in order to distinguish fossil from non-fossil emissions. As wood burning is the single major source of non-fossil EC, its contribution can be quantified directly. For non-fossil OC, the wood burning fraction was determined independently by levoglucosan and 14C analysis and combined using Latin-hypercube sampling (LHS). For the winter period, the relative contribution of EC from wood burning to the total EC was >3 times higher at the rural site compared to the urban site, whereas the absolute concentrations of EC from wood burning were comparable at both sites. Thus, the urban site is substantially more influenced by fossil EC emissions. For summer, biogenic emissions dominated OC concentrations most likely due to secondary organic aerosol (SOA) formation. During both seasons, a more pronounced fossil signal was observed for Göteborg than has previously been reported for Zurich, Switzerland. Analysis of air mass origin using back trajectories suggests that the fossil impact was larger when local sources dominated, whereas long-range transport caused an enhanced non-fossil signal. In comparison to other European locations, concentrations of levoglucosan and other monosaccharide anhydrides were low for the urban and the rural site in the area of Göteborg during winter. The comparison of summer and winter results provides insight into the annual cycle of anthropogenic vs. biogenic contributions to the atmospheric aerosol.

scholarly journals Fossil and non-fossil sources of organic carbon (OC) and elemental carbon (EC) in Göteborg, Sweden

2009 ◽  
Vol 9 (5) ◽  
pp. 1521-1535 ◽  
Author(s):  
S. Szidat ◽  
M. Ruff ◽  
N. Perron ◽  
L. Wacker ◽  
H.-A. Synal ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Elemental Carbon ◽  
Latin Hypercube Sampling ◽  
Water Soluble ◽  
Total Carbon ◽  
Rural Site ◽  
Urban Site ◽  
Winter Period ◽  
Back Trajectories ◽  
Wood Burning

Abstract. Particulate matter was collected at an urban site in Göteborg (Sweden) in February/March 2005 and in June/July 2006. Additional samples were collected at a rural site for the winter period. Total carbon (TC) concentrations were 2.1–3.6 μg m−3, 1.8–1.9 μg m−3, and 2.2–3.0 μg m−3 for urban/winter, rural/winter, and urban/summer conditions, respectively. Elemental carbon (EC), organic carbon (OC), water-insoluble OC (WINSOC), and water-soluble OC (WSOC) were analyzed for 14C in order to distinguish fossil from non-fossil emissions. As wood burning is the single major source of non-fossil EC, its contribution can be quantified directly. For non-fossil OC, the wood-burning fraction was determined independently by levoglucosan and 14C analysis and combined using Latin-hypercube sampling (LHS). For the winter period, the relative contribution of EC from wood burning to the total EC was >3 times higher at the rural site compared to the urban site, whereas the absolute concentrations of EC from wood burning were elevated only moderately at the rural compared to the urban site. Thus, the urban site is substantially more influenced by fossil EC emissions. For summer, biogenic emissions dominated OC concentrations most likely due to secondary organic aerosol (SOA) formation. During both seasons, a more pronounced fossil signal was observed for Göteborg than has previously been reported for Zurich, Switzerland. Analysis of air mass origin using back trajectories suggests that the fossil impact was larger when local sources dominated, whereas long-range transport caused an enhanced non-fossil signal. In comparison to other European locations, concentrations of levoglucosan and other monosaccharide anhydrides were low for the urban and the rural site in the area of Göteborg during winter.

scholarly journals Size-resolved measurements of brown carbon and estimates of their contribution to ambient fine particle light absorption based on water and methanol extracts

2013 ◽  
Vol 13 (7) ◽  
pp. 18233-18276 ◽  
Author(s):  
J. Liu ◽  
M. Bergin ◽  
H. Guo ◽  
L. King ◽  
N. Kotra ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Light Absorption ◽  
Fine Particle ◽  
Elemental Carbon ◽  
Fine Particles ◽  
Water Soluble ◽  
Rural Site ◽  
Brown Carbon ◽  
Methanol Extracts ◽  
Carbon Absorption

Abstract. Light absorbing organic carbon, often termed brown carbon, has the potential to significantly contribute to the visible light absorption budget, particularly at shorter wavelengths. Currently, the relative contributions of particulate brown carbon to light absorption, as well as the sources of brown carbon are poorly understood. With this in mind field measurements were made at both urban (Atlanta), and rural (Yorkville) sites in Georgia. Measurements in Atlanta were made at both a central site and a road side site adjacent to a main highway near the city center. Fine particle brown carbon optical absorption is estimated based on Mie calculations using direct size resolved measurements of chromophores in filter extracts. Size-resolved atmospheric aerosol samples were collected using a cascade impactor and analyzed for water-soluble organic carbon (WSOC), organic and elemental carbon (OC and EC), and solution light absorption spectra of water and methanol extracts. Methanol extracts were more light-absorbing than water extracts for all size ranges and wavelengths. Absorption refractive indices of the organic extracts were calculated from solution measurements for a range of wavelengths and used with Mie theory to predict the light absorption by fine particles comprised of these components, under the assumption that brown carbon and other aerosol components were externally mixed. For all three sites, chromophores were predominately in the accumulation mode with an aerodynamic mean diameter of 0.5 μm, an optically effective size range resulting in predicted particle light absorption being a factor of 2 higher than bulk solution absorption. Fine particle absorption was also measured with a Multi-Angle Absorption Photometer (MAAP) and seven-wavelength Aethalometer. Scattering-corrected aethalometer and MAAP absorption were in good agreement at 670 nm and Mie-estimated absorption based on size-resolved EC data were within 30% of these optical instruments. When applied to solution measurements, at all sites, Mie-predicted brown carbon absorption at 350 nm contributed a significant fraction (20 to 40%) relative to total light absorption, with highest contributions at the rural site where organic to elemental carbon ratios were highest. Brown carbon absorption, however, was highest by the roadside site due to vehicle emissions. The multi-wavelength aethalometer did not detect brown carbon, having an absorption Ångstrom exponent near one. Although the results are within the estimated Aethalometer uncertainties, the direct measurement of brown carbon in solution definitively shows that it is present and this Mie analysis suggests it is optically important in the near UV range in both a rural and urban environment during summer when biomass burning emissions are low.

scholarly journals Contributions of biomass/biofuel burning to organic aerosols and particulate matter in Tanzania, East Africa, based on analyses of ionic species, organic and elemental carbon, levoglucosan and mannosan

2013 ◽  
Vol 13 (20) ◽  
pp. 10325-10338 ◽  
Author(s):  
S. L. Mkoma ◽  
K. Kawamura ◽  
P. Q. Fu
Keyword(s):  
Particulate Matter ◽  
Organic Carbon ◽  
East Africa ◽  
Biomass Burning ◽  
Elemental Carbon ◽  
Dry Season ◽  
Water Soluble ◽  
Total Carbon ◽  
Rural Site ◽  
Pm2.5 And Pm10

Abstract. Atmospheric aerosol samples of PM2.5 and PM10 were collected at a rural site in Tanzania, East Africa, in 2011 during wet and dry seasons and were analysed for carbonaceous components, levoglucosan, mannosan and water-soluble inorganic ions. The contributions of biomass/biofuel burning to the organic carbon (OC) and particulate matter (PM) mass were estimated to be 46–52% and 87–13%, respectively. The mean mass concentrations of PM2.5 and PM10 were 28 ± 6 μg m−3 and 47 ± 8 μg m−3 in wet season, and 39 ± 10 μg m−3 and 61 ± 19 μg m−3 in dry season, respectively. Total carbon (TC) accounted for 16–19% of the PM2.5 mass and 13–15% of the PM10 mass. On average, 86 to 89% of TC in PM2.5 and 87 to 90% of TC in PM10 was OC, of which 67–72% and 63% was found to be water-soluble organic carbon (WSOC) in PM2.5 and PM10, respectively. We found that concentrations of levoglucosan and mannosan (specific organic tracers of pyrolysis of cellulose) well correlated with non-sea-salt potassium (nss-K+) (r2 = 0.56–0.75), OC (r2 = 0.75–0.96) and WSOC (r2 = 0.52–0.78). The K+ / OC ratios varied from 0.06 to 0.36 in PM2.5 and from 0.03 to 0.36 in PM10 with slightly higher ratios in dry season. Mean percent ratios of levoglucosan and mannosan to OC were found to be 3–4% for PM2.5 and PM10 in both seasons. We found lower levoglucosan / K+ ratios and higher K+ / EC (elemental carbon) ratios in the biomass-burning aerosols from Tanzania than those reported from other regions. This feature is consistent with the high levels of potassium reported in the soils of Morogoro, Tanzania, suggesting an importance of direct emission of potassium by soil resuspension although K+ is present mostly in fine particles. It is also likely that biomass burning of vegetation of Tanzania emits high levels of potassium that may be enriched in plant tissues. The present study demonstrates that emissions from mixed biomass- and biofuel-burning activities largely influence the air quality in Tanzania.

scholarly journals Size-resolved measurements of brown carbon in water and methanol extracts and estimates of their contribution to ambient fine-particle light absorption

2013 ◽  
Vol 13 (24) ◽  
pp. 12389-12404 ◽  
Author(s):  
J. Liu ◽  
M. Bergin ◽  
H. Guo ◽  
L. King ◽  
N. Kotra ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Light Absorption ◽  
Fine Particle ◽  
Elemental Carbon ◽  
Rural Site ◽  
Urban Site ◽  
Brown Carbon ◽  
Methanol Extracts ◽  
Direct Measurements ◽  
Carbon Absorption

Abstract. Light absorbing organic carbon, often called brown carbon, has the potential to significantly contribute to the visible light-absorption budget, particularly at shorter wavelengths. Currently, the relative contributions of particulate brown carbon to light absorption, as well as the sources of brown carbon, are poorly understood. With this in mind size-resolved direct measurements of brown carbon were made at both urban (Atlanta), and rural (Yorkville) sites in Georgia. Measurements in Atlanta were made at both a representative urban site and a road-side site adjacent to a main highway. Fine particle absorption was measured with a multi-angle absorption photometer (MAAP) and seven-wavelength Aethalometer, and brown carbon absorption was estimated based on Mie calculations using direct size-resolved measurements of chromophores in solvents. Size-resolved samples were collected using a cascade impactor and analyzed for water-soluble organic carbon (WSOC), organic and elemental carbon (OC and EC), and solution light-absorption spectra of water and methanol extracts. Methanol extracts were more light-absorbing than water extracts for all size ranges and wavelengths. Absorption refractive indices of the organic extracts were calculated from solution measurements for a range of wavelengths and used with Mie theory to predict the light absorption by fine particles comprised of these components, under the assumption that brown carbon and other aerosol components were externally mixed. For all three sites, chromophores were predominately in the accumulation mode with an aerodynamic mean diameter of 0.5 μm, an optically effective size range resulting in predicted particle light absorption being a factor of 2 higher than bulk solution absorption. Mie-predicted brown carbon absorption at 350 nm contributed a significant fraction (20 to 40%) relative to total light absorption, with the highest contributions at the rural site where organic to elemental carbon ratios were highest. Brown carbon absorption, however, was highest by the roadside site due to vehicle emissions. The direct size-resolved measurement of brown carbon in solution definitively shows that it is present and optically important in the near-UV range in both a rural and urban environment during the summer when biomass burning emissions are low. These results allow estimates of brown carbon aerosol absorption from direct measurements of chromophores in aerosol extracts.

scholarly journals Spatio-Temporal Variation of Atmospheric Gaseous and Particulate Reactive Nitrogen over Northern India

2021 ◽  
Vol Special Issue (1) ◽  
pp. 53-67
Author(s):  
Manisha Mishra ◽  
Umesh C Kulshrestha
Keyword(s):  
Source Parameters ◽  
Ambient Air ◽  
Water Soluble ◽  
Rural Site ◽  
Urban Site ◽  
Local Source ◽  
Reactive Nitrogen ◽  
Gangetic Plain ◽  
Reactive N ◽  
Spatio Temporal

The present study reports spatio-temporal distribution pattern of major gaseous (NH3 and NO2) and particulate water soluble total nitrogen (pWSTN) in the ambient air to explore the seasonal variation, major interactions and dominating sources. Considering the major hotspot of atmospheric reactive nitrogen (N) emission, three sites in Indo-Gangetic plain (IGP) were selected based on different local source parameters. Results have shown that gas phase reactive N contribute up to 90% of total analyzed reactive N, where NH3 imparted highest at all the three sites. Prayagraj, a fast growing urban site, has shown highest concentrations of NH3 (72.0 μg m−3), followed by Madhupur rural site (57.7 μg m−3) and Delhi, an urban megacity site (35.8 μg m−3). As compared to previous studies conducted at different sites of IGP, NH3 concentrations were reported to be the highest at the former two sites. However, unlike NH3, NO2 levels were recorded lower at Madhupur (3.1 μg m−3) and Prayagraj (9.4 μg m−3) sites as compared to Delhi (13.4 μg m−3). Similarly, pWSTN concentrations were in the order of Madhupur (6.6 μg m−3) < Prayagraj (10.0 μg m−3) < Delhi (10.1 μg m−3). A strong correlation of NO2 with pWSTN at urban sites has shown the crucial role of NO2 in the formation of nitrogenous aerosols. Significant spatial variation can be attributed to varying local emission sources ranging from microbial emission from improper sewage treatment and open waste dumping at Prayagraj, agricultural activities at Madhupur and vehicular exhausts at Delhi site.

scholarly journals An optimized tracer-based approach for estimating organic carbon emissions from biomass burning in Ulaanbaatar, Mongolia

2020 ◽  
Vol 20 (5) ◽  
pp. 3231-3247 ◽  
Author(s):  
Jayant Nirmalkar ◽  
Tsatsral Batmunkh ◽  
Jinsang Jung
Keyword(s):  
Organic Carbon ◽  
Biomass Burning ◽  
Quantitative Estimation ◽  
Water Soluble ◽  
Atmospheric Particulate Matter ◽  
Coefficient Of Determination ◽  
Urban Site ◽  
Air Sampler ◽  
Novel Approach ◽  
The Impact

Abstract. The impact of biomass burning (BB) on atmospheric particulate matter of <2.5 µm diameter (PM2.5) at Ulaanbaatar, Mongolia, was investigated using an optimized tracer-based approach during winter and spring 2017. Integrated 24 h PM2.5 samples were collected on quartz-fiber filters using a 30 L min−1 air sampler at an urban site in Ulaanbaatar. The aerosol samples were analyzed for organic carbon (OC) and elemental carbon (EC), anhydrosugars (levoglucosan, mannosan, and galactosan), and water-soluble ions. OC was found to be the predominant species, contributing 64 % and 56 % to the quantified aerosol components in PM2.5 in winter and spring, respectively. BB was identified as a major source of PM2.5, followed by dust and secondary aerosols. Levoglucosan ∕ mannosan and levoglucosan ∕ K+ ratios indicate that BB in Ulaanbaatar mainly originated from the burning of softwood. Because of the large uncertainty associated with the quantitative estimation of OC emitted from BB (OCBB), a novel approach was developed to optimize the OC ∕ levoglucosan ratio for estimating OCBB. The optimum OC ∕ levoglucosan ratio in Ulaanbaatar was obtained by regression analysis between OCnon-BB (OCtotal–OCBB) and levoglucosan concentrations that gives the lowest coefficient of determination (R2) and slope. The optimum OC ∕ levoglucosan ratio was found to be 27.6 and 18.0 for winter and spring, respectively, and these values were applied in quantifying OCBB. It was found that 68 % and 63 % of the OC were emitted from BB during winter and spring, respectively. This novel approach can also be applied by other researchers to quantify OCBB using their own chemical measurements. In addition to OCBB, sources of OCnon-BB were also investigated through multivariate correlation analysis. It was found that OCnon-BB originated mainly from coal burning, vehicles, and vegetative emissions.

scholarly journals High contributions of fossil sources to more volatile organic aerosol

2019 ◽  
Vol 19 (15) ◽  
pp. 10405-10422 ◽  
Author(s):  
Haiyan Ni ◽  
Ru-Jin Huang ◽  
Junji Cao ◽  
Wenting Dai ◽  
Jiamao Zhou ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Elemental Carbon ◽  
Organic Aerosol ◽  
Formation Mechanisms ◽  
Formation Processes ◽  
Combustion System ◽  
Relative Contribution ◽  
Custom Made ◽  
Volatile Organic ◽  
Volatile Carbon

Abstract. Sources of particulate organic carbon (OC) with different volatility have rarely been investigated, despite the significant importance for better understanding of the atmospheric processes of organic aerosols. In this study we develop a radiocarbon-based (14C) approach for source apportionment of more volatile OC (mvOC) and apply to ambient aerosol samples collected in winter in six Chinese megacities. mvOC is isolated by desorbing organic carbon from the filter samples in helium (He) at 200 ∘C in a custom-made aerosol combustion system for 14C analysis. Evaluation of this new isolation method shows that the isolated mvOC amount agrees very well with the OC1 fraction (also desorbed at 200 ∘C in He) measured by a thermal–optical analyzer using the EUSAAR_2 protocol. The mvOC, OC and elemental carbon (EC) of 13 combined PM2.5 samples in six Chinese cities are analyzed for 14C to investigate their sources and formation mechanisms. The relative contribution of fossil sources to mvOC is 59±11 %, consistently larger than the contribution to OC (48±16 %) and smaller than that to EC (73±9 %), despite large differences in fossil contributions in different cities. The average difference in the fossil fractions between mvOC and OC is 13 % (range of 7 %–25 %), similar to that between mvOC and EC (13 %, with a range 4 %–25 %). Secondary OC (SOC) concentrations and sources are modeled based on the 14C-apportioned OC and EC and compared with concentrations and sources of mvOC. SOC concentrations (15.4±9.0 µg m−3) are consistently higher than those of mvOC (3.3±2.2 µg m−3), indicating that only a fraction of SOC is accounted for by the more volatile carbon fraction desorbed at 200 ∘C. The fossil fraction in SOC is 43 % (10 %–70 %), lower than that in mvOC (59 %, with a range of 45 %–78 %). Correlation between mvOC and SOC from nonfossil sources (mvOCnf vs. SOCnf) and from fossil sources (mvOCfossil vs. SOCfossil) is examined to further explore sources and formation processes of mvOC and SOC.

scholarly journals Source apportionment of fine organic aerosol in Mexico City during the MILAGRO experiment 2006

2008 ◽  
Vol 8 (5) ◽  
pp. 1249-1259 ◽  
Author(s):  
E. A. Stone ◽  
D. C. Snyder ◽  
R. J. Sheesley ◽  
A. P. Sullivan ◽  
R. J. Weber ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Mexico City ◽  
Large Fraction ◽  
Optical Filter ◽  
Soxhlet Extraction ◽  
Water Soluble ◽  
Motor Vehicles ◽  
Balance Model ◽  
Urban Site ◽  
Peripheral Site

Abstract. Organic carbon (OC) comprises a large fraction of fine particulate matter (PM2.5) in Mexico City. Daily and select 12-h PM2.5 samples were collected in urban and peripheral sites in Mexico City from 17–30 March 2006. Samples were analyzed for OC and elemental carbon (EC) using thermal-optical filter-based methods. Real-time water-soluble organic carbon (WSOC) was collected at the peripheral site. Organic compounds, particularly molecular markers, were quantified by soxhlet extraction with methanol and dichloromethane, derivitization, and gas chromatography with mass spectrometric detection (GCMS). A chemical mass balance model (CMB) based on molecular marker species was used to determine the relative contribution of major sources to ambient OC. Motor vehicles, including diesel and gasoline, consistently accounted for 49% of OC in the urban area and 32% on the periphery. The daily contribution of biomass burning to OC was highly variable, and ranged from 5–26% at the urban site and 7–39% at the peripheral site. The remaining OC unapportioned to primary sources showed a strong correlation with WSOC and was considered to be secondary in nature. Comparison of temporally resolved OC showed that contributions from primary aerosol sources during daylight hours were not significantly different from nighttime. This study provides quantitative understanding of the important sources of OC during the MILAGRO 2006 field campaign.

scholarly journals Mass absorption efficiency of elemental carbon and water-soluble organic carbon in Beijing, China

2011 ◽  
Vol 11 (22) ◽  
pp. 11497-11510 ◽  
Author(s):  
Y. Cheng ◽  
K.-B. He ◽  
M. Zheng ◽  
F.-K. Duan ◽  
Z.-Y. Du ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Biomass Burning ◽  
Light Absorption ◽  
Elemental Carbon ◽  
Organic Aerosol ◽  
Absorption Efficiency ◽  
Water Soluble ◽  
Water Soluble Organic Carbon ◽  
Soluble Organic Carbon ◽  
Mass Absorption Efficiency

Abstract. The mass absorption efficiency (MAE) of elemental carbon (EC) in Beijing was quantified using a thermal-optical carbon analyzer. The MAE measured at 632 nm was 8.45±1.71 and 9.41±1.92 m2 g−1 during winter and summer respectively. The daily variation of MAE was found to coincide with the abundance of organic carbon (OC), especially the OC to EC ratio, perhaps due to the enhancement by coating with organic aerosol (especially secondary organic aerosol, SOA) or the artifacts resulting from the redistribution of liquid-like organic particles during the filter-based absorption measurements. Using a converting approach that accounts for the discrepancy caused by measurements methods of both light absorption and EC concentration, previously published MAE values were converted to the equivalent-MAE, which is the estimated value if using the same measurement methods as used in this study. The equivalent-MAE was found to be much lower in the regions heavily impacted by biomass burning (e.g., below 2.7 m2 g−1 for two Indian cities). Results from source samples (including diesel exhaust samples and biomass smoke samples) also demonstrated that emissions from biomass burning would decrease the MAE of EC. Moreover, optical properties of water-soluble organic carbon (WSOC) in Beijing were 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 MAE of WSOC (measured at 365 nm) was 1.79±0.24 and 0.71±0.20 m2 g−1 during winter and summer respectively. The large discrepancy between the MAE of WSOC during winter and summer was attributed to the difference in the precursors of SOA such that anthropogenic volatile organic compounds (AVOCs) should be more important as the precursors of SOA in winter. The MAE 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 stronger emissions of biomass burning in China.

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