TY  - JOUR
AB  - Black carbon (BC) particles produced by incomplete combustion of biomass and fossil fuels warm the atmosphere and decrease the reflectivity of snow and ice, hastening their melt. Although the significance of BC in Arctic climate change is widely acknowledged, observations on its deposition and sources are few. We present BC source types in a 300-year (1700–2005) Svalbard ice core by analysis of particle-bound organic compounds, radiocarbon, and trace elements. According to the radiocarbon results, 58% of the deposited elemental carbon (EC, thermal-optical proxy of BC) is of non-fossil origin throughout the record, while the organic compounds suggest a higher percentage (68%). The contribution of fossil fuels to EC is suggested to have been elevated between 1860 and 1920, particularly based on the organics and trace element data. A second increase in fossil fuel sources seems to have occurred near the end of the record: according to radiocarbon measurements between 1960 and 1990, while the organics and trace element data suggest that the contribution of fossil fuels has increased since the 1970s to the end of the record, along with observed increasing EC deposition. Modeled atmospheric transport between 1948 and 2004 shows that increasing EC deposition observed at the glacier during that period can be associated with increased atmospheric transport from Far East Asia. Further observational BC source data are essential to help target climate change mitigation efforts. The combination of robust radiocarbon with organic compound analyses requiring low sample amounts seems a promising approach for comprehensive Arctic BC source apportionment.
AU  - Ruppel, M.M.*
AU  - Khedr, M.
AU  - Liu, X.
AU  - Beaudon, E.*
AU  - Szidat, S.*
AU  - Tunved, P.*
AU  - Ström, J.*
AU  - Koponen, H.*
AU  - Sippula, O.*
AU  - Isaksson, E.*
AU  - Gallet, J.C.*
AU  - Hermanson, M.*
AU  - Manninen, S.*
AU  - Schnelle-Kreis, J.
C1  - 68364
C2  - 53639
CY  - 2000 Florida Ave Nw, Washington, Dc 20009 Usa
TI  - Organic compounds, radiocarbon, trace elements and atmospheric transport illuminating sources of elemental carbon in a 300-year svalbard ice core.
JO  - J. Geophys. Res. Atmos.
VL  - 128
IS  - 16
PB  - Amer Geophysical Union
PY  - 2023
SN  - 2169-897X
ER  - 

TY  - JOUR
AB  - The absorption Ångström exponent (AAE) describes the spectral dependence of light absorption by aerosols. AAE is typically used to differentiate between different aerosol types for example., black carbon, brown carbon, and dust particles. In this study, the variation of AAE was investigated mainly in fresh aerosol emissions from different fuel and combustion types, including emissions from ships, buses, coal-fired power plants, and residential wood burning. The results were assembled to provide a compendium of AAE values from different emission sources. A dual-spot aethalometer (AE33) was used in all measurements to obtain the light absorption coefficients at seven wavelengths (370–950 nm). AAE  varied greatly between the different emission sources, ranging from −0.2 ± 0.7 to 3.0 ± 0.8. The correlation between the AAE  and AAE  results was good (R  = 0.95) and the mean bias error between these was 0.02. In the ship engine exhaust emissions, the highest AAE  values (up to 2.0 ± 0.1) were observed when high sulfur content heavy fuel oil was used, whereas low sulfur content fuels had the lowest AAE  (0.9–1.1). In the diesel bus exhaust emissions, AAE  increased in the order of acceleration (0.8 ± 0.1), deceleration (1.1 ± 0.1), and steady driving (1.2 ± 0.1). In the coal-fired power plant emissions, the variation of AAE  was substantial (from −0.1 ± 2.1 to 0.9 ± 1.6) due to the differences in the fuels and flue gas cleaning conditions. Fresh wood-burning derived aerosols had AAE  from 1.1 ± 0.1 (modern masonry heater) to 1.4 ± 0.1 (pellet boiler), lower than typically associated with wood burning, while the burn cycle phase affected AAE variation. 470/950 470/950 370-950 470/950 470/950 470/950 470/950 470/950 2
AU  - Helin, A.*
AU  - Virkkula, A.*
AU  - Backman, J.*
AU  - Pirjola, L.*
AU  - Sippula, O.*
AU  - Aakko-Saksa, P.*
AU  - Väätäinen, S.*
AU  - Mylläri, F.*
AU  - Järvinen, A.*
AU  - Bloss, M.*
AU  - Aurela, M.*
AU  - Jakobi, G.
AU  - Karjalainen, P.*
AU  - Zimmermann, R.
AU  - Jokiniemi, J.*
AU  - Saarikoski, S.*
AU  - Tissari, J.*
AU  - Rönkkö, T.J.*
AU  - Niemi, J.V.*
AU  - Timonen, H.*
C1  - 62170
C2  - 50675
CY  - 2000 Florida Ave Nw, Washington, Dc 20009 Usa
TI  - Variation of absorption Ångström exponent in aerosols from different emission sources.
JO  - J. Geophys. Res. Atmos.
VL  - 126
IS  - 10
PB  - Amer Geophysical Union
PY  - 2021
SN  - 2169-897X
ER  - 

TY  - JOUR
AB  - We characterized the chemical composition and optical properties of particulate matter (PM) emitted by a marine diesel engine operated on heavy fuel oil (HFO), marine gas oil (MGO), and diesel fuel (DF). For all three fuels, ∼80% of submicron PM was organic (and sulfate, for HFO at higher engine loads). Emission factors varied only slightly with engine load. Refractory black carbon (rBC) particles were not thickly coated for any fuel; rBC was therefore externally mixed from organic and sulfate PM. For MGO and DF PM, rBC particles were lognormally distributed in size (mode at drBC≈120 nm). For HFO, much larger rBC particles were present. Combining the rBC mass concentrations with in situ absorption measurements yielded an rBC mass absorption coefficient MACBC,780nm of 7.8 ± 1.8 m2/g at 780 nm for all three fuels. Using positive deviations of the absorption Ångström exponent (AAE) from unity to define brown carbon (brC), we found that brC absorption was negligible for MGO or DF PM (AAE(370,880 nm)≈1.0 ± 0.1) but typically 50% of total 370‐nm absorption for HFO PM. Even at 590 nm, ∼20  of the total absorption was due to brC. Using absorption at 880 nm as a reference for BC absorption and normalizing to organic PM mass, we obtained a MACOM,370nm of 0.4 m2/g at typical operating conditions. Furthermore, we calculated an imaginary refractive index of (0.045 ± 0.025)(λ/370nm)−3 for HFO PM at 370 nm>λ > 660 nm, more than twofold greater than previous recommendations. Climate models should account for this substantial brC absorption in HFO PM.
AU  - Corbin, J.C.*
AU  - Pieber, S.M.*
AU  - Czech, H.*
AU  - Zanatta, M.*
AU  - Jakobi, G.
AU  - Massabò, D.*
AU  - Orasche, J.
AU  - El Haddad, I.*
AU  - Mensah, A.A.*
AU  - Stengel, B.*
AU  - Drinovec, L.*
AU  - Močnik, G.*
AU  - Zimmermann, R.
AU  - Prévôt, A.S.H.*
AU  - Gysel, M.*
C1  - 53829
C2  - 45059
CY  - Po Box 211, 1000 Ae Amsterdam, Netherlands
SP  - 6175-6195
TI  - Brown and black carbon emitted by a marine engine operated on heavy fuel oil and distillate fuels: Optical properties, size distributions, emission factors.
JO  - J. Geophys. Res. Atmos.
VL  - 123
IS  - 11
PB  - Elsevier Science Bv
PY  - 2018
SN  - 2169-897X
ER  - 

TY  - JOUR
AB  - Radiocarbon (14C) analysis is a unique tool to distinguish fossil/nonfossil sources of carbonaceous aerosols. We present 14C measurements of organic carbon (OC) and total carbon (TC) on highly time resolved filters (3-4 h, typically 12 h or longer have been reported) from 7 days collected during California Research at the Nexus of Air Quality and Climate Change (CalNex) 2010 in Pasadena. Average nonfossil contributions of 58%+/- 15% and 51%+/- 15% were found for OC and TC, respectively. Results indicate that nonfossil carbon is a major constituent of the background aerosol, evidenced by its nearly constant concentration (2-3 gC m-3). Cooking is estimated to contribute at least 25% to nonfossil OC, underlining the importance of urban nonfossil OC sources. In contrast, fossil OC concentrations have prominent and consistent diurnal profiles, with significant afternoon enhancements (similar to 3 gC m-3), following the arrival of the western Los Angeles (LA) basin plume with the sea breeze. A corresponding increase in semivolatile oxygenated OC and organic vehicular emission markers and their photochemical reaction products occurs. This suggests that the increasing OC is mostly from fresh anthropogenic secondary OC (SOC) from mainly fossil precursors formed in the western LA basin plume. We note that in several European cities where the diesel passenger car fraction is higher, SOC is 20% less fossil, despite 2-3 times higher elemental carbon concentrations, suggesting that SOC formation from gasoline emissions most likely dominates over diesel in the LA basin. This would have significant implications for our understanding of the on-road vehicle contribution to ambient aerosols and merits further study.
AU  - Zotter, P.*
AU  - El-Haddad, I.*
AU  - Zhang, Y.*
AU  - Hayes, P.L.*
AU  - Zhang, X.*
AU  - Lin, Y.*
AU  - Wacker, L.*
AU  - Schnelle-Kreis, J.
AU  - Abbaszade, G.
AU  - Zimmermann, R.
AU  - Surratt, J.D.*
AU  - Weber, R.*
AU  - Jimenez, J.L.*
AU  - Szidat, S.*
AU  - Baltensperger, U.*
AU  - Prevot, A.S.H.*
C1  - 31819
C2  - 34793
CY  - Washington
SP  - 6818-6835
TI  - Diurnal cycle of fossil and nonfossil carbon using radiocarbon analyses during CalNex.
JO  - J. Geophys. Res. Atmos.
VL  - 119
IS  - 11
PB  - Amer Geophysical Union
PY  - 2014
SN  - 2169-897X
ER  -