TY  - JOUR
AB  - Aviation is an important source of urban air pollution, but the impacts of photochemical processing on the exhaust emissions remain insufficiently characterized. Here, the physical-chemical properties of fresh and photochemically aged emissions from a laboratory-scale jet engine burner operated with JP-8 kerosene were studied in detail with a range of online and offline methods. The fresh emissions contained high amounts of organic matter present predominantly in the gaseous phase. Photochemical aging in an oxidation flow reactor caused substantial formation of oxidized organic aerosol, increasing the particle mass approximately 300-fold. During aging, aromatic hydrocarbons and alkanes in the gas-phase decayed, while gas-phase oxidation products, such as small carbonyls and oxygenated aromatics, increased. The composition of organic matter became more complex by photochemical processing, with the average particulate carbon oxidation state increasingly growing throughout the addressed exposure range (equivalent to 0.2 to 7 d in the atmosphere) with a Delta H:C/Delta O:C slope of -0.54. Simultaneously, the near-UV wavelength absorption by the particles increased due to enhanced particulate mass. The imaginary refractory indices of organic particulate matter were 0.0071 and 0.00013 at the wavelength of 520 nm for the fresh and photochemically processed particles, respectively, indicating secondary production of weakly absorbing brown carbon. The direct radiative forcing by the exhaust particles was estimated by a Mie model, which revealed a prominent shift from a warming to cooling climate effect upon photochemical aging. The results highlight the importance of considering secondary aerosol formation when assessing the environmental impacts of aviation.
AU  - Hartikainen, A.*
AU  - Ihalainen, M.*
AU  - Shukla, D.
AU  - Rohkamp, M.*
AU  - Mukherjee, A.*
AU  - He, Q.*
AU  - Piel, S.
AU  - Virkkula, A.*
AU  - Li, D.*
AU  - Kokkola, T.*
AU  - Jeong, S.
AU  - Koponen, H.*
AU  - Etzien, U.*
AU  - Das, A.
AU  - Luoma, K.*
AU  - Schwalb, L.
AU  - Gröger, T.M.
AU  - Barth, A.*
AU  - Sklorz, M.
AU  - Streibel, T.*
AU  - Czech, H.
AU  - Gündling, B.*
AU  - Kalberer, M.*
AU  - Buchholz, B.*
AU  - Hupfer, A.*
AU  - Adam, T.*
AU  - Hohaus, T.*
AU  - Johan Øvrevik,*
AU  - Zimmermann, R.
AU  - Sippula, O.*
C1  - 75410
C2  - 57962
CY  - Bahnhofsallee 1e, Gottingen, 37081, Germany
SP  - 9275 - 9294
TI  - Photochemical aging of aviation emissions: Transformation of chemical and physical properties of exhaust emissions from a laboratory-scale jet engine combustion chamber.
JO  - Atmos. Chem. Phys.
VL  - 25
IS  - 16
PB  - Copernicus Gesellschaft Mbh
PY  - 2025
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - Residential biomass combustion significantly contributes to light-absorbing carbonaceous aerosols in the atmosphere, impacting the earth’s radiative balance at regional and global levels. This study investigates the contribution of brown carbon (BrC) to the total particulate light absorption in the wavelength range of 370–950 nm (BrC370–950) and the particulate absorption Ångström exponents (AAE470/950) in 15 different European residential combustion appliances using a variety of wood-based fuels. BrC370–950 was estimated to be from 1 % to 21 % for wood log stoves and 10 % for a fully automatized residential pellet boiler. Correlations between the ratio of organic to elemental carbon (OC /EC) and BrC370–950 indicated that a one-unit increase in OC /EC corresponded to approximately a 14 % increase in BrC370–950. Additionally, BrC370–950 was clearly influenced by the fuel moisture content and the combustion efficiency, while the effect of the combustion appliance type was less prominent. AAE470/950 of wood log combustion aerosols ranged from 1.06 to 1.61. By examining the correlation between AAE470/950 and OC /EC, an AAE470/950 close to unity was found for pure black carbon (BC) particles originating from residential wood combustion. This supports the common assumption used to differentiate light absorption caused by BC and BrC. Moreover, diesel aerosols exhibited an AAE470/950 of 1.02, with BrC contributing only 0.66 % to the total absorption, aligning with the assumption employed in source apportionment. These findings provide important data to assess the BrC from residential wood combustion with different emission characteristics and confirm that BrC can be a major contributor to particulate UV and near-UV light absorption for northern European wood stove emissions with relatively high OC /EC ratios.
AU  - Basnet, S.*
AU  - Hartikainen, A.*
AU  - Virkkula, A.*
AU  - Yli-Pirilä, P.*
AU  - Kortelainen, M.*
AU  - Suhonen, H.*
AU  - Kilpeläinen, L.*
AU  - Ihalainen, M.*
AU  - Väätäinen, S.*
AU  - Louhisalmi, J.*
AU  - Somero, M.*
AU  - Tissari, J.*
AU  - Jakobi, G.
AU  - Zimmermann, R.
AU  - Kilpeläinen, A.*
AU  - Sippula, O.*
C1  - 70322
C2  - 55513
CY  - Bahnhofsallee 1e, Gottingen, 37081, Germany
SP  - 3197-3215
TI  - Contribution of brown carbon to light absorption in emissions of European residential biomass combustion appliances.
JO  - Atmos. Chem. Phys.
VL  - 24
IS  - 5
PB  - Copernicus Gesellschaft Mbh
PY  - 2024
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - We investigated the distribution of polycyclic aromatic hydrocarbons (PAHs) on individual ambient aerosol particles at the Swedish western coast in a pristine environment for 10 d in October 2019. The measurements were carried out using new technology with single-particle mass spectrometry (SPMS) that reveals both the inorganic particle composition as well as the particle-bound PAHs (Schade et al., 2019). More than 290 000 particles were characterized; 4412 of them reveal PAH signatures. Most of the PAH-containing particles were internal mixtures of carbonaceous material, secondary nitrate and metals from distant sources in central and eastern Europe. We characterize the aerosol with respect to the inorganic composition, comparable to conventional SPMS, before we discuss the distribution of PAHs within this particle ensemble. Vice versa, we analyze the single-particle PAH spectra for characteristic patterns and discuss the inorganic composition, origin and atmospheric processing of the respective particles. The study period comprised different meteorological situations: clean air conditions with winds from the North Sea/Kattegat and little terrestrial air pollution, long-range transport from eastern Europe and southern Sweden, and transport of aerosols from central Europe over the sea. For all meteorological conditions, PAHs were detected in particles whose inorganic content indicates traffic emissions, such as combinations of soot, iron and calcium as well as in particles with biomass-burning signatures. However, there were variations in their amounts, dependent on the geographic origin. Because of strong mixing, rapid degradation and speciation limits, e.g., for PAHs of the same nominal mass, the application of diagnostic ratios for source apportionment is limited under the conditions of our study. Nevertheless, the combination with the inorganic content and meteorological data provides unique insights into the particles' origin, aging and mixing state. We exemplarily show how the observation of PAH profiles and inorganic secondary components on a single-particle level can open a new door to investigate aerosol aging processes. To our best knowledge, we herewith present the first comprehensive study on the single-particle distribution of PAHs in ambient air as well as the first set of combined data on PAHs and inorganic composition on a single-particle level.
AU  - Passig, J.
AU  - Schade, J.*
AU  - Irsig, R.*
AU  - Kröger-Badge, T.*
AU  - Czech, H.
AU  - Adam, T.
AU  - Fallgren, H.*
AU  - Moldanova, J.*
AU  - Sklorz, M.
AU  - Streibel, T.
AU  - Zimmermann, R.
C1  - 64294
C2  - 51884
CY  - Bahnhofsallee 1e, Gottingen, 37081, Germany
SP  - 1495-1514
TI  - Single-particle characterization of polycyclic aromatic hydrocarbons in background air in northern Europe.
JO  - Atmos. Chem. Phys.
VL  - 22
IS  - 2
PB  - Copernicus Gesellschaft Mbh
PY  - 2022
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - It is being suggested that particle-bound or particle-induced reactive oxygen species (ROS), which significantly contribute to the oxidative potential (OP) of aerosol particles, are a promising metric linking aerosol compositions to toxicity and adverse health effects. However, accurate ROS quantification remains challenging due to the reactive and short-lived nature of many ROS components and the lack of appropriate analytical methods for a reliable quantification. Consequently, it remains difficult to gauge their impact on human health, especially to identify how aerosol particle sources and atmospheric processes drive particle-bound ROS formation in a real-world urban environment. In this study, using a novel online particle-bound ROS instrument (OPROSI), we comprehensively characterized and compared the formation of ROS in secondary organic aerosols (SOAs) generated from organic compounds that represent anthropogenic (naphthalene, SOANAP) and biogenic (β-pinene, SOAβPIN) precursors. The SOA mass was condensed onto soot particles (SP) under varied atmospherically relevant conditions (photochemical aging and humidity) to mimic the SOA formation from a mixing of traffic-related carbonaceous primary aerosols and volatile organic compounds (VOCs). We systematically analyzed the ability of the aqueous extracts of the two aerosol types (SOANAP-SP and SOAβPIN-SP) to induce ROS production and OP. We further investigated cytotoxicity and cellular ROS production after exposing human lung epithelial cell cultures (A549) to extracts of the two aerosols. A significant finding of this study is that more than 90% of all ROS components in both SOA types have a short lifetime, highlighting the need to develop online instruments for a meaningful quantification of ROS. Our results also show that photochemical aging promotes particle-bound ROS production and enhances the OP of the aerosols. Compared to SOAβPIN-SP, SOANAP-SP elicited a higher acellular and cellular ROS production, a higher OP, and a lower cell viability. These consistent results between chemical-based and biological-based analyses indicate that particle-bound ROS quantification could be a feasible metric to predict aerosol particle toxicity and adverse human effects. Moreover, the cellular ROS production caused by SOA exposure not only depends on aerosol type but is also affected by exposure dose, highlighting a need to mimic the process of particle deposition onto lung cells and their interactions as realistically as possible to avoid unknown biases.
AU  - Zhang, Z.H.*
AU  - Hartner, E.
AU  - Utinger, B.*
AU  - Gfeller, B.*
AU  - Paul, A.*
AU  - Sklorz, M.
AU  - Czech, H.
AU  - Yang, B.X.*
AU  - Su, X.Y.*
AU  - Jakobi, G.
AU  - Orasche, J.
AU  - Schnelle-Kreis, J.
AU  - Jeong, S.
AU  - Gröger, T.M.
AU  - Pardo, M.*
AU  - Hohaus, T.*
AU  - Adam, T.*
AU  - Kiendler-Scharr, A.*
AU  - Rudich, Y.*
AU  - Zimmermann, R.
AU  - Kalberer, M.*
C1  - 64383
C2  - 51885
CY  - Bahnhofsallee 1e, Gottingen, 37081, Germany
SP  - 1793-1809
TI  - Are reactive oxygen species (ROS) a suitable metric to predict toxicity of carbonaceous aerosol particles?
JO  - Atmos. Chem. Phys.
VL  - 22
IS  - 3
PB  - Copernicus Gesellschaft Mbh
PY  - 2022
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - We investigated concentrations of organic carbon (OC), elemental carbon (EC), and a wide range of particlebound organic compounds in daily sampled PM2:5 at the remote Pha Din (PDI) Global Atmosphere Watch (GAW) monitoring station in northwestern Vietnam during an intense 3-week sampling campaign from 23 March to 12 April 2015. The site is known to receive trans-regional air masses during large-scale biomass burning (BB) episodes. BB is a globally widespread phenomenon and BB emission characterization is of high scientific and societal relevance. Emissions composition is influenced by multiple factors (e.g., fuel and thereby vegetation type, fuel moisture, fire temperature, available oxygen). Due to regional variations in these parameters, studies in different world regions are needed. OC composition provides valuable information regarding the healthand climate-relevant properties of PM2.5 Yet, OC composition studies from PDI are missing in the scientific literature to date. Therefore, we quantified 51 organic compounds simultaneously by in situ derivatization thermal desorption gas chromatography and time-of-flight mass spectrometry (IDTD-GC-TOFMS). Anhydrosugars, methoxyphenols, nalkanes, fatty acids, polycyclic aromatic hydrocarbons, oxygenated polycyclic aromatic hydrocarbons, nitrophenols, and OC were used in a hierarchical cluster analysis highlighting distinctive patterns for periods under low, medium, and high BB influence. The highest particle phase concentration of the typical primary organic aerosol (POA) and possible secondary organic aerosol (SOA) constituents, especially nitrophenols, were found on 5 and 6 April. We linked the trace gas mixing ratios of methane (CH4), carbon dioxide (CO2), carbon monoxide (CO), and ozone (O3) to the statistical classification of BB events based on OA composition and found increased CO and O3 levels during medium and high BB influence. Likewise, a backward trajectory analysis indicates different source regions for the identified periods based on the OA clusters, with cleaner air masses arriving from the northeast, i.e., mainland China and the Yellow Sea. The more polluted periods are characterized by trajectories from the southwest, with more continental recirculation of the medium cluster and more westerly advection for the high cluster. These findings highlight that BB activities in northern Southeast Asia significantly enhance the regional organic aerosol loading and also affect the carbonaceous PM2.5 constituents and the trace gases in northwestern Vietnam. The presented analysis adds valuable data on the carbonaceous and chemical composition of PM2.5, in particular of OC, in a region of scarce data availability, and thus offers a reference dataset from Southeast Asian large-scale BB for future studies. Such a reference dataset may be useful for the evaluation of atmospheric transport simulation models, or for comparison with other world regions and BB types, such as Australian bush fires, African savannah fires, or tropical peatland fires.
AU  - Nguyen, D.-L.
AU  - Czech, H.
AU  - Pieber, S.M.*
AU  - Schnelle-Kreis, J.
AU  - Steinbacher, M.*
AU  - Orasche, J.
AU  - Henne, S.*
AU  - Popovicheva, O.B.*
AU  - Abbaszade, G.
AU  - Engling, G.*
AU  - Bukowiecki, N.*
AU  - Nguyen, N.A.*
AU  - Nguyen, X.A.*
AU  - Zimmermann, R.
C1  - 62174
C2  - 50677
CY  - Bahnhofsallee 1e, Gottingen, 37081, Germany
SP  - 8293-8312
TI  - Carbonaceous aerosol composition in air masses influenced by large-scale biomass burning: A case study in northwestern Vietnam.
JO  - Atmos. Chem. Phys.
VL  - 21
IS  - 10
PB  - Copernicus Gesellschaft Mbh
PY  - 2021
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - Residential wood combustion (RWC) emits large amounts of gaseous and particulate organic aerosol (OA). In the atmosphere, the emission is transformed via oxidative reactions, which are under daylight conditions driven mainly by hydroxyl radicals (OH). This continuing oxidative ageing produces secondary OA and may change the health- and climate-related properties of the emission. However, it is not well known how the composition of RWC-originated OA changes as the function of OH exposure. In this work, emissions from two modern residential logwood combustion appliances were photochemically aged in an oxidation flow reactor (OFR) with various OH exposure levels, reaching up to 6 x 10(11) s cm(-3) (equivalent to 1 week in the atmosphere). Gaseous organic compounds were analysed by proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS), while particulate OA was analysed online by a high-resolution soot particle aerosol mass spectrometer (SP-HR-ToF-AMS) and offline by in situ derivatization thermal desorptiongas chromatography-time-of-flight mass spectrometry (IDTD-GC-ToF-MS). Photochemical reactions increased the mass of particulate organic carbon by a factor of 1.3-3.9. The increase in mass took place during the first atmospheric equivalent day of ageing, after which the enhancement was independent of the extent of photo-chemical exposure. However, ageing increased the oxidation state of the particulate OA linearly throughout the assessed range, with Delta H : C/Delta O : C slopes between -0.17 and -0.49 in van Krevelen space. Ageing led to an increase in acidic fragmentation products in both phases, as measured by the IDTD-GC-ToF-MS for the particulate and PTR-ToF-MS for the gaseous phase. For the gaseous organic compounds, the formation of small carbonylic compounds combined with the rapid degradation of primary volatile organic compounds such as aromatic compounds led to a continuous increase in both the O : C and H : C ratios. Overall, the share of polycyclic aromatic compounds (PACs) in particles degraded rapidly during ageing, although some oxygen-substituted PACs, most notably naphthaldehydic acid, increased, in particular during relatively short exposures. Similarly, the concentrations of particulate nitrophenols rose extensively during the first atmospheric equivalent day. During continuous photochemical ageing, the dominant transformation mechanisms shifted from the initial gasphase function-alization/condensation to the transformation of the particulate OA by further oxidation reactions and fragmentation. The observed continuous transformation of OA composition throughout a broad range of OH exposures indicates that the entire atmospheric lifetime of the emission needs to be explored to fully assess the potential climate and health effects of RWC emissions.
AU  - Hartikainen, A.*
AU  - Tiitta, P.*
AU  - Ihalainen, M.*
AU  - Yli-Pirilä, P.*
AU  - Orasche, J.
AU  - Czech, H.
AU  - Kortelainen, M.*
AU  - Lamberg, H.*
AU  - Suhonen, H.*
AU  - Koponen, H.*
AU  - Hao, L.*
AU  - Zimmermann, R.
AU  - Jokiniemi, J.*
AU  - Tissari, J.*
AU  - Sippula, O.*
C1  - 59335
C2  - 48783
CY  - Bahnhofsallee 1e, Gottingen, 37081, Germany
SP  - 6357-6378
TI  - Photochemical transformation of residential wood combustion emissions: Dependence of organic aerosol composition on OH exposure.
JO  - Atmos. Chem. Phys.
VL  - 20
IS  - 11
PB  - Copernicus Gesellschaft Mbh
PY  - 2020
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - We describe resonance effects in laser desorption-ionization (LDI) of particles that substantially increase the sensitivity and selectivity to metals in single-particle mass spectrometry (SPMS). Within the proposed scenario, resonant light absorption by ablated metal atoms increases their ionization rate within a single laser pulse. By choosing the appropriate laser wavelength, the key micronutrients Fe, Zn and Mn can be detected on individual aerosol particles with considerably improved efficiency. These ionization enhancements for metals apply to natural dust and anthropogenic aerosols, both important sources of bioavailable metals to marine environments. Transferring the results into applications, we show that the spectrum of our KrF-excimer laser is in resonance with a major absorption line of iron atoms. To estimate the impact of resonant LDI on the metal detection efficiency in SPMS applications, we performed a field experiment on ambient air with two alternately firing excimer lasers of different wavelengths. Herein, resonant LDI with the KrF-excimer laser (248.3 nm) revealed iron signatures for many more particles of the same aerosol ensemble compared to the more common ArF-excimer laser line of 193.3 nm (nonresonant LDI of iron). Many of the particles that showed iron contents upon resonant LDI were mixtures of sea salt and organic carbon. For nonresonant ionization, iron was exclusively detected in particles with a soot contribution. This suggests that resonant LDI allows a more universal and secure metal detection in SPMS. Moreover, our field study indicates relevant atmospheric iron transport by mixed organic particles, a pathway that might be underestimated in SPMS measurements based on nonresonant LDI. Our findings show a way to improve the detection and source attribution capabilities of SPMS for particle-bound metals, a health-relevant aerosol component and an important source of micronutrients to the surface oceans affecting marine primary productivity.
AU  - Passig, J.
AU  - Schade, J.*
AU  - Iva Rosewig, E.*
AU  - Irsig, R.*
AU  - Kröger-Badge, T.*
AU  - Czech, H.
AU  - Sklorz, M.
AU  - Streibel, T.
AU  - Li, L.*
AU  - Li, X.*
AU  - Zhou, Z.*
AU  - Fallgren, H.*
AU  - Moldanova, J.*
AU  - Zimmermann, R.
C1  - 59609
C2  - 48895
CY  - Bahnhofsallee 1e, Gottingen, 37081, Germany
SP  - 7139-7152
TI  - Resonance-enhanced detection of metals in aerosols using single-particle mass spectrometry.
JO  - Atmos. Chem. Phys.
VL  - 20
IS  - 12
PB  - Copernicus Gesellschaft Mbh
PY  - 2020
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - Anthropogenic emissions are dominant contributors to air pollution. Consequently, mitigation policies have been attempted since the 1990s in Europe to reduce pollution by anthropogenic emissions. To evaluate the effectiveness of these mitigation policies, the German Ultrafine Aerosol Network (GUAN) was established in 2008, focusing on black carbon (BC) and sub-micrometre aerosol particles. In this study, long-term trends of atmospheric particle number concentrations (PNCs) and equivalent BC (eBC) mass concentration over a 10-year period (2009-2018) were determined for 16 GUAN sites ranging from roadside to high Alpine environments. Overall, statistically significant decreasing trends are found for most of these parameters and environments in Germany. The annual relative slope of eBC mass concentration varies between -13.1 % and -1.7 % per year. The slopes of the PNCs vary from -17.2 % to -1.7 %, -7.8 % to -1.1 %, and -11.1 % to -1.2 % per year for 10-30, 30-200, and 200-800 nm size ranges, respectively. The reductions in various anthropogenic emissions are found to be the dominant factors responsible for the decreasing trends of eBC mass concentration and PNCs. The diurnal and seasonal variations in the trends clearly show the effects of the mitigation policies for road transport and residential emissions. The influences of other factors such as air masses, precipitation, and temperature were also examined and found to be less important or negligible. This study proves that a combination of emission mitigation policies can effectively improve the air quality on large spatial scales. It also suggests that a long-term aerosol measurement network at multi-type sites is an efficient and necessary tool for evaluating emission mitigation policies.
AU  - Sun, J.*
AU  - Birmili, W.*
AU  - Hermann, M.*
AU  - Tuch, T.*
AU  - Weinhold, K.*
AU  - Merkel, M.*
AU  - Rasch, F.*
AU  - Mueller, T.*
AU  - Schladitz, A.*
AU  - Bastian, S.*
AU  - Loeschau, G.*
AU  - Cyrys, J.
AU  - Gu, J.
AU  - Flentje, H.*
AU  - Briel, B.*
AU  - Asbach, C.*
AU  - Kaminski, H.*
AU  - Ries, L.*
AU  - Sohmer, R.*
AU  - Gerwig, H.*
AU  - Wirtz, K.*
AU  - Meinhardt, F.*
AU  - Schwerin, A.*
AU  - Bath, O.*
AU  - Ma, N.*
AU  - Wiedensohler, A.*
C1  - 59626
C2  - 48891
CY  - Bahnhofsallee 1e, Gottingen, 37081, Germany
SP  - 7049-7068
TI  - Decreasing trends of particle number and black carbon mass concentrations at 16 observational sites in Germany from 2009 to 2018.
JO  - Atmos. Chem. Phys.
VL  - 20
IS  - 11
PB  - Copernicus Gesellschaft Mbh
PY  - 2020
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - Following wood pyrolysis, tar ball aerosols were laboratory generated from wood tar separated into polar and nonpolar phases. Chemical information of fresh tar balls was obtained from a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and single-particle laser desorption/resonance enhanced multiphoton ionization mass spectrometry (SP-LD-REMPI-MS). Their continuous refractive index (RI) between 365 and 425 rim was retrieved using a broadband cavity enhanced spectroscopy (BBCES). Dynamic changes in the optical and chemical properties for the nonpolar tar ball aerosols in NOx-dependent photo-chemical process were investigated in an oxidation flow reactor (OFR). Distinct differences in the chemical composition of the fresh polar and nonpolar tar aerosols were identified. Nonpolar tar aerosols contain predominantly high-molecular weight unsubstituted and alkyl-substituted polycylic aromatic hydrocarbons (PAHs), while polar tar aerosols consist of a high number of oxidized aromatic substances (e.g., methoxy-phenols, benzenediol) with higher O : C ratios and carbon oxidation states. Fresh tar balls have light absorption characteristics similar to atmospheric brown carbon (BrC) aerosol with higher absorption efficiency towards the UV wavelengths. The average retrieved RI is 1.661 + 0.020i and 1.635 + 0.003i for the nonpolar and polar tar aerosols, respectively, with an absorption Angstrom exponent (AAE) between 5.7 and 7.8 in the detected wavelength range. The RI fits a volume mixing rule for internally mixed nonpolar/polar tar balls. The RI of the tar ball aerosols decreased with increasing wavelength under photochemical oxidation. Photolysis by UV light (254 nm), without strong oxidants in the system, slightly decreased the RI and increased the oxidation state of the tar balls. Oxidation under varying OH exposure levels and in the absence of NOx diminished the absorption (bleaching) and increased the O : C ratio of the tar balls. The photobleaching via OH radical initiated oxidation is mainly attributed to decomposition of chromophoric aromatics, nitrogen-containing organics, and high-molecular weight components in the aged particles. Photolysis of nitrous oxide (N2O) was used to simulate NOx-dependent photochemical aging of tar balls in the OFR. Under high-NOx conditions with similar OH exposure, photochemical aging led to the formation of organic nitrates, and increased both oxidation degree and light absorption for the aged tar ball aerosols. These observations suggest that secondary organic nitrate formation counteracts the bleaching by OH radical photooxidation to eventually regain some absorption of the aged tar ball aerosols. The atmospheric implication and climate effects from tar balls upon various oxidation processes are briefly discussed.
AU  - Li, C.*
AU  - He, Q.*
AU  - Schade, J.*
AU  - Passig, J.
AU  - Zimmermann, R.
AU  - Meidan, D.*
AU  - Laskin, A.*
AU  - Rudich, Y.*
C1  - 55121
C2  - 46283
CY  - Bahnhofsallee 1e, Gottingen, 37081, Germany
SP  - 139-163
TI  - Dynamic changes in optical and chemical properties of tar ball aerosols by atmospheric photochemical aging.
JO  - Atmos. Chem. Phys.
VL  - 19
IS  - 1
PB  - Copernicus Gesellschaft Mbh
PY  - 2019
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - The paper presents the first modelling experiment of the European-scale olive pollen dispersion, analyses the quality of the predictions, and outlines the research needs. A 6-model strong ensemble of Copernicus Atmospheric Monitoring Service (CAMS) was run throughout the olive season of 2014, computing the olive pollen distribution. The simulations have been compared with observations in eight countries, which are members of the European Aeroallergen Network (EAN). Analysis was performed for individual models, the ensemble mean and median, and for a dynamically optimised combination of the ensemble members obtained via fusion of the model predictions with observations. The models, generally reproducing the olive season of 2014, showed noticeable deviations from both observations and each other. In particular, the season was reported to start too early by 8 days, but for some models the error mounted to almost 2 weeks. For the end of the season, the disagreement between the models and the observations varied from a nearly perfect match up to 2 weeks too late. A series of sensitivity studies carried out to understand the origin of the disagreements revealed the crucial role of ambient temperature and consistency of its representation by the meteorological models and heat-sum-based phenological model. In particular, a simple correction to the heat-sum threshold eliminated the shift of the start of the season but its validity in other years remains to be checked. The short-term features of the concentration time series were reproduced better, suggesting that the precipitation events and cold/warm spells, as well as the large-scale transport, were represented rather well. Ensemble averaging led to more robust results. The best skill scores were obtained with data fusion, which used the previous days' observations to identify the optimal weighting coefficients of the individual model forecasts. Such combinations were tested for the forecasting period up to 4 days and shown to remain nearly optimal throughout the whole period.
AU  - Sofiev, M.*
AU  - Ritenberga, O.*
AU  - Albertini, R.*
AU  - Arteta, J.*
AU  - Belmonte, J.*
AU  - Bernstein, C.G.*
AU  - Bonini, M.*
AU  - Celenk, S.*
AU  - Damialis, A.
AU  - Douros, J.*
AU  - Elbern, H.*
AU  - Friese, E.*
AU  - Galan, C.*
AU  - Oliver, G.*
AU  - Hrga, I.*
AU  - Kouznetsov, R.*
AU  - Krajsek, K.*
AU  - Magyar, D.*
AU  - Parmentier, J.*
AU  - Plu, M.*
AU  - Prank, M.*
AU  - Robertson, L.*
AU  - Steensen, B.M.*
AU  - Thibaudon, M.*
AU  - Segers, A.*
AU  - Stepanovich, B.*
AU  - Valdebenito, A.M.*
AU  - Vira, J.*
AU  - Vokou, D.*
C1  - 52252
C2  - 43836
CY  - Gottingen
SP  - 12341-12360
TI  - Multi-model ensemble simulations of olive pollen distribution in Europe in 2014: Current status and outlook.
JO  - Atmos. Chem. Phys.
VL  - 17
IS  - 20
PB  - Copernicus Gesellschaft Mbh
PY  - 2017
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - Trees can significantly impact the urban air chemistry by the uptake and emission of reactive biogenic volatile organic compounds (BVOCs), which are involved in ozone and particle formation. Here we present the emission potentials of "constitutive" (cBVOCs) and "stress-induced" BVOCs (sBVOCs) from the dominant broadleaf woody plant species in the megacity of Beijing. Based on the municipal tree census and cuvette BVOC measurements on leaf level, we built an inventory of BVOC emissions, and assessed the potential impact of BVOCs on secondary organic aerosol (SOA) formation in 2005 and 2010, i.e., before and after realizing the large tree-planting program for the 2008 Olympic Games. We found that sBVOCs, such as fatty acid derivatives, benzenoids, and sesquiterpenes, constituted a significant fraction (∼40) of the total annual BVOC emissions, and we estimated that the overall annual BVOC budget may have doubled from ∼4.8 × 109Cg-1 in 2005 to ∼10.3×109gC year-1 in 2010 due to the increase in urban greening, while at the same time the emission of anthropogenic VOCs (AVOCs) decreased by 24%. Based on the BVOC emission assessment, we estimated the biological impact on SOA mass formation potential in Beijing. Constitutive and stress-induced BVOCs might produce similar amounts of secondary aerosol in Beijing. However, the main contributors of SOA-mass formations originated from anthropogenic sources (>90%). This study demonstrates the general importance to include sBVOCs when studying BVOC emissions. Although the main problems regarding air quality in Beijing still originate from anthropogenic activities, the present survey suggests that in urban plantation programs, the selection of low-emitting plant species has some potential beneficial effects on urban air quality.
AU  - Ghirardo, A.
AU  - Xie, J.*
AU  - Zheng, X.*
AU  - Wang, Y.*
AU  - Grote, R.*
AU  - Block, K.
AU  - Wildt, J.*
AU  - Mentel, T.*
AU  - Kiendler-Scharr, A.*
AU  - Hallquist, M.*
AU  - Butterbach-Bahl, K.*
AU  - Schnitzler, J.-P.
C1  - 48154
C2  - 39990
CY  - Gottingen
SP  - 2901-2920
TI  - Urban stress-induced biogenic VOC emissions and SOA-forming potentials in Beijing.
JO  - Atmos. Chem. Phys.
VL  - 16
IS  - 5
PB  - Copernicus Gesellschaft Mbh
PY  - 2016
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - Organic aerosols (OA) derived from small-scale wood combustion emissions are not well represented by current emissions inventories and models, although they contribute substantially to the atmospheric particulate matter (PM) levels. In this work, a 29 m3 smog chamber in the ILMARI facility of the University of Eastern Finland was utilized to investigate the formation of secondary organic aerosol (SOA) from a small-scale modern masonry heater commonly used in northern Europe. Emissions were oxidatively aged in the smog chamber for a variety of dark (i.e., O3 and NO3) and UV (i.e., OH) conditions, with OH concentration levels of (0.5–5)  ×  106 molecules cm−3, achieving equivalent atmospheric aging of up to 18 h. An aerosol mass spectrometer characterized the direct OA emissions and the SOA formed from the combustion of three wood species (birch, beech and spruce) using two ignition processes (fast ignition with a VOC-to-NOx ratio of 3 and slow ignition with a ratio of 5). Dark and UV aging increased the SOA mass fraction with average SOA productions 2.0 times the initial OA mass loadings. SOA enhancement was found to be higher for the slow ignition compared with fast ignition conditions. Positive matrix factorization (PMF) was used to separate SOA, primary organic aerosol (POA) and their subgroups from the total OA mass spectra. PMF analysis identified two POA and three SOA factors that correlated with the three major oxidizers: ozone, the nitrate radical and the OH radical. Organonitrates (ONs) were observed to be emitted directly from the wood combustion and additionally formed during oxidation via NO3 radicals (dark aging), suggesting small-scale wood combustion may be a significant ON source. POA was oxidized after the ozone addition, forming aged POA, and after 7 h of aging more than 75 % of the original POA was transformed. This process may involve evaporation and homogeneous gas-phase oxidation as well as heterogeneous oxidation of particulate organic matter. The results generally prove that logwood burning emissions are the subject of intensive chemical processing in the atmosphere, and the timescale for these transformations is relatively short, i.e., hours.
AU  - Tiitta, P.*
AU  - Leskinen, A.*
AU  - Hao, L.*
AU  - Yli-Pirilä, P.*
AU  - Kortelainen, M.*
AU  - Grigonyte, J.*
AU  - Tissari, J.*
AU  - Lamberg, H.*
AU  - Hartikainen, A.L.*
AU  - Kuuspalo, K.*
AU  - Kortelainen, A.*
AU  - Virtanen, A.*
AU  - Lehtinen, K.E.J.*
AU  - Komppula, M.*
AU  - Pieber, S.M.*
AU  - Prevot, A.S.H.*
AU  - Onasch, T.B.*
AU  - Worsnop, D.R.*
AU  - Czech, H.*
AU  - Zimmermann, R.
AU  - Jokiniemi, J.*
AU  - Sippula, O.*
C1  - 50041
C2  - 42050
CY  - Gottingen
SP  - 13251-13269
TI  - Transformation of logwood combustion emissions in a smog chamber: Formation of secondary organic aerosol and changes in the primary organic aerosol upon daytime and nighttime aging.
JO  - Atmos. Chem. Phys.
VL  - 16
IS  - 20
PB  - Copernicus Gesellschaft Mbh
PY  - 2016
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - In early spring the Baltic region is frequently affected by high-pollution events due to biomass burning in that area. Here we present a comprehensive study to investigate the impact of biomass/grass burning (BB) on the evolution and composition of aerosol in Preila, Lithuania, during springtime open fires. Non-refractory submicron particulate matter (NR-PM1) was measured by an Aerodyne aerosol chemical speciation monitor (ACSM) and a source apportionment with the multilinear engine (ME-2) running the positive matrix factorization (PMF) model was applied to the organic aerosol fraction to investigate the impact of biomass/grass burning. Satellite observations over regions of biomass burning activity supported the results and identification of air mass transport to the area of investigation. Sharp increases in biomass burning tracers, such as levoglucosan up to 683 ng m-3 and black carbon (BC) up to 17μgm-3 were observed during this period. A further separation between fossil and non-fossil primary and secondary contributions was obtained by coupling ACSM PMF results and radiocarbon (14C) measurements of the elemental (EC) and organic (OC) carbon fractions. Non-fossil organic carbon (OCnf) was the dominant fraction of PM1, with the primary (POCnf) and secondary (SOCnf) fractions contributing 26-44% and 13-23% to the total carbon (TC), respectively. 5-8% of the TC had a primary fossil origin (POCf), whereas the contribution of fossil secondary organic carbon (SOCnf) was 4-13%. Non-fossil EC (ECnf) and fossil EC (ECf) ranged from 13-24 and 7-13%, respectively. Isotope ratios of stable carbon and nitrogen isotopes were used to distinguish aerosol particles associated with solid and liquid fossil fuel burning.
AU  - Ulevicius, V.*
AU  - Byčenkiene, S.*
AU  - Bozzetti, C.*
AU  - Vlachou, A.*
AU  - Plauškaite, K.*
AU  - Mordas, G.*
AU  - Dudoitis, V.*
AU  - Abbaszade, G.
AU  - Remeikis, V.*
AU  - Garbaras, A.*
AU  - Masalaite, A.*
AU  - Blees, J.*
AU  - Fröhlich, R.*
AU  - Dällenbach, K.R.*
AU  - Canonaco, F.*
AU  - Slowik, J.G.*
AU  - Dommen, J.*
AU  - Zimmermann, R.
AU  - Schnelle-Kreis, J.
AU  - Salazar, G.A.*
AU  - Agrios, K.*
AU  - Szidat, S.*
AU  - El Haddad, I.*
AU  - Prevot, A.S.H.*
C1  - 48728
C2  - 41308
CY  - Gottingen
SP  - 5513-5529
TI  - Fossil and non-fossil source contributions to atmospheric carbonaceous aerosols during extreme spring grassland fires in Eastern Europe.
JO  - Atmos. Chem. Phys.
VL  - 16
IS  - 9
PB  - Copernicus Gesellschaft Mbh
PY  - 2016
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - Residential wood burning contributes to the total atmospheric aerosol burden; however, large uncertainties remain in the magnitude and characteristics of wood burning products. Primary emissions are influenced by a variety of parameters, including appliance type, burner wood load and wood type. In addition to directly emitted particles, previous laboratory studies have shown that oxidation of gas-phase emissions produces compounds with sufficiently low volatility to readily partition to the particles, forming considerable quantities of secondary organic aerosol (SOA). However, relatively little is known about wood burning SOA, and the effects of burn parameters on SOA formation and composition are yet to be determined. There is clearly a need for further study of primary and secondary wood combustion aerosols to advance our knowledge of atmospheric aerosols and their impacts on health, air quality and climate. For the first time, smog chamber experiments were conducted to investigate the effects of wood loading on both primary and secondary wood combustion products. Products were characterized using a range of particle- and gas-phase instrumentation, including an aerosol mass spectrometer (AMS). A novel approach for polycyclic aromatic hydrocarbon (PAH) quantification from AMS data was developed and results were compared to those from GC-MS analysis of filter samples. Similar total particle mass emission factors were observed under high and average wood loadings; however, high fuel loadings were found to generate significantly higher contributions of PAHs to the total organic aerosol (OA) mass compared to average loadings. PAHs contributed 15 ± 4% (mean ±2 sample standard deviations) to the total OA mass in high-load experiments, compared to 4 ± 1% in average-load experiments. With aging, total OA concentrations increased by a factor of 3 ± 1 for high load experiments compared to 1.6 ± 0.4 for average-load experiments. In the AMS, an increase in PAH and aromatic signature ions at lower m/z values, likely fragments from larger functionalized PAHs, was observed with aging. Filter samples also showed an increase in functionalized PAHs in the particles with aging, particularly oxidized naphthalene species. As PAHs and their oxidation products are known to have deleterious effects on health, this is a noteworthy finding to aid in the mitigation of negative wood burning impacts by improving burner operation protocols.
AU  - Bruns, E.A.*
AU  - Krapf, M.*
AU  - Orasche, J.
AU  - Huang, Y.
AU  - Zimmermann, R.
AU  - Drinovec, L.*
AU  - Močnik, G.*
AU  - El Haddad, I.*
AU  - Slowik, J.G.*
AU  - Dommen, J.*
AU  - Baltensperger, U.R.S.*
AU  - Prevot, A.S.H.*
C1  - 43870
C2  - 36752
CY  - Gottingen
SP  - 2825-2841
TI  - Characterization of primary and secondary wood combustion products generated under different burner loads.
JO  - Atmos. Chem. Phys.
VL  - 15
IS  - 5
PB  - Copernicus Gesellschaft Mbh
PY  - 2015
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - From the rural Global Atmosphere Watch (GAW) site Hohenpeissenberg in the pre-alpine area of southern Germany, a data set of 24 C2-C8 non-methane hydrocarbons over a period of 7 years was analyzed. Receptor modeling was performed by positive matrix factorization (PMF) and the resulting factors were interpreted with respect to source profiles and photochemical aging. Differing from other studies, no direct source attribution was intended because, due to chemistry along transport, mass conservation from source to receptor is not given. However, at remote sites such as Hohenpeissenberg, the observed patterns of non-methane hydrocarbons can be derived from combinations of factors determined by PMF. A six-factor solution showed high stability and the most plausible results. In addition to a biogenic and a background factor of very stable compounds, four additional anthropogenic factors were resolved that could be divided into two short-and two long-lived patterns from evaporative sources/natural gas leakage and incomplete combustion processes. The volume or mass contribution at the site over the entire period was, in decreasing order, from the following factor categories: background, gas leakage and long-lived evaporative, residential heating and long-lived combustion, short-lived evaporative, short-lived combustion, and biogenic. The importance with respect to reactivity contribution was generally in reverse order, with the biogenic and the short-lived combustion factors contributing most. The seasonality of the factors was analyzed and compared to results of a simple box model using constant emissions and the photochemical decay calculated from the measured annual cycles of OH radicals and ozone. Two of the factors, short-lived combustion and gas leakage/long-lived evaporative, showed winter/summer ratios of about 9 and 7, respectively, as expected from constant source estimations. Contrarily, the short-lived evaporative emissions were about 3 times higher in summer than in winter, while residential heating/long-lived combustion emissions were about 2 times higher in winter than in summer.
AU  - Leuchner, M.*
AU  - Gubo, S.*
AU  - Schunk, C.*
AU  - Wastl, C.*
AU  - Kirchner, M.
AU  - Menzel, A.*
AU  - Plaß-Dülmer, C.*
C1  - 43445
C2  - 36627
CY  - Gottingen
SP  - 1221-1236
TI  - Can positive matrix factorization help to understand patterns of organic trace gases at the continental Global Atmosphere Watch site Hohenpeissenberg?
JO  - Atmos. Chem. Phys.
VL  - 15
IS  - 3
PB  - Copernicus Gesellschaft Mbh
PY  - 2015
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - 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 I1/4m) 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.
AU  - Zhang, Y.*
AU  - Huang, R.J.*
AU  - El Haddad, I.*
AU  - Ho, K.F.*
AU  - Cao, J.*
AU  - Han, Y.*
AU  - Zotter, P.*
AU  - Bozzetti, C.*
AU  - Daellenbach, K.R.*
AU  - Canonaco, F.*
AU  - Slowik, J.G.*
AU  - Salazar, G.A.*
AU  - Schwikowski, M.*
AU  - Schnelle-Kreis, J.
AU  - Abbaszade, G.
AU  - Zimmermann, R.
AU  - Baltensperger, U.R.S.*
AU  - Prevot, A.S.H.*
AU  - Szidat, S.*
C1  - 43378
C2  - 36623
CY  - Gottingen
SP  - 1299-1312
TI  - Fossil vs. non-fossil sources of fine carbonaceous aerosols in four Chinese cities during the extreme winter haze episode of 2013.
JO  - Atmos. Chem. Phys.
VL  - 15
IS  - 3
PB  - Copernicus Gesellschaft Mbh
PY  - 2015
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - The effect of a post-industrial megacity on local and regional air quality was assessed via a month-long field measurement campaign in the Paris metropolitan area during winter 2010. Here we present source apportionment results from three aerosol mass spectrometers and two aethalometers deployed at three measurement stations within the Paris region. Submicron aerosol composition is dominated by the organic fraction (30-36%) and nitrate (28-29%), with lower contributions from sulfate (14-16%), ammonium (12-14%) and black carbon (7-13%). Organic source apportionment was performed using positive matrix factorization, resulting in a set of organic factors corresponding both to primary emission sources and secondary production. The dominant primary sources are traffic (11-15% of organic mass), biomass burning (13-15%) and cooking (up to 35% during meal hours). Secondary organic aerosol contributes more than 50% to the total organic mass and includes a highly oxidized factor from indeterminate and/or diverse sources and a less oxidized factor related to wood burning emissions. Black carbon was apportioned to traffic and wood burning sources using a model based on wavelength-dependent light absorption of these two combustion sources. The time series of organic and black carbon factors from related sources were strongly correlated. The similarities in aerosol composition, total mass and temporal variation between the three sites suggest that particulate pollution in Paris is dominated by regional factors, and that the emissions from Paris itself have a relatively low impact on its surroundings.
AU  - Crippa, M.*
AU  - DeCarlo, P.F.*
AU  - Slowik, J.G.*
AU  - Mohr, C.*
AU  - Heringa, M.F.*
AU  - Chirico, R.*
AU  - Poulain, L.*
AU  - Freutel, F.*
AU  - Sciare, J.*
AU  - Cozic, J.*
AU  - di Marco, C.F.*
AU  - Elsasser, M.
AU  - Nicolas, J.B.*
AU  - Marchand, N.*
AU  - Abidi, E.*
AU  - Wiedensohler, A.*
AU  - Drewnick, F.*
AU  - Schneider, J.*
AU  - Borrmann, S.*
AU  - Nemitz, E.*
AU  - Zimmermann, R.
AU  - Jaffrezo, J.-L.*
AU  - Prevot, A.S.H.*
AU  - Baltensperger, U.*
C1  - 23541
C2  - 31216
SP  - 961-981
TI  - Wintertime aerosol chemical composition and source apportionment of the organic fraction in the metropolitan area of Paris.
JO  - Atmos. Chem. Phys.
VL  - 13
IS  - 2
PB  - Copernicus Gesellschaft Mbh
PY  - 2013
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - The impact of wood combustion on ambient aerosols was investigated in Augsburg, Germany during a winter measurement campaign of a six-week period. Special attention was paid to the high time resolution observations of wood combustion with different mass spectrometric methods. Here we present and compare the results from an Aerodyne aerosol mass spectrometer (AMS) and gas chromatographic – mass spectrometric (GC-MS) analysed PM1 filters on an hourly basis. This includes source apportionment of the AMS derived organic matter (OM) using positive matrix factorisation (PMF) and analysis of levoglucosan as wood combustion marker, respectively. During the measurement period nitrate and OM mass are the main contributors to the defined submicron particle mass of AMS and Aethalometer with 28% and 35 %, respectively. Wood combustion organic aerosol (WCOA) contributes to OM with 23% on average and 27% in the evening and night time. Conclusively, wood combustion has a strong influence on the organic matter and overall aerosol composition. Levoglucosan accounts for 14% of WCOA mass with a higher percentage in comparison to other studies. The ratio between the mass of levoglucosan and organic carbon amounts to 0.06. This study is unique in that it provides a one-hour time resolution comparison between the wood combustion results of the AMS and the GC-MS analysed filter method at a PM1 particle size range. The comparison of the concentration variation with time of the PMF WCOA factor, levoglucosan estimated by the AMS data and the levoglucosan measured by GC-MS is highly correlated (R2 = 0.84), and a detailed discussion on the contributors to the wood combustion marker ion at mass-to-charge ratio 60 is given. At the end, both estimations, the WCOA factor and the levoglucosan concentration estimated by AMS data, allow to observe the variation with time of wood combustion emissions (gradient correlation with GC-MS levoglucosan of R2 = 0.84). In the case of WCOA, it provides the estimated magnitude of wood combustion emission. Quantitative estimation of the levoglucosan concentration from the AMS data is problematic due to its overestimation in comparison to the levoglucosan measured by the GC-MS.
AU  - Elsasser, M.
AU  - Crippa, M.*
AU  - Orasche, J.
AU  - DeCarlo, P.F.*
AU  - Oster, M.
AU  - Pitz, M.
AU  - Cyrys, J.
AU  - Gustafson, T.L.*
AU  - Pettersson, J.B.C.*
AU  - Schnelle-Kreis, J.
AU  - Prevot, A.S.H.*
AU  - Zimmermann, R.
C1  - 8339
C2  - 29276
SP  - 6113-6128
TI  - Organic molecular markers and signature from wood combustion particles in winter ambient aerosols: Aerosol Mass Spectrometer (AMS) and high time-resolved GC-MS measurements in Augsburg, Germany.
JO  - Atmos. Chem. Phys.
VL  - 12
IS  - 14
PB  - Copernicus Gesellschaft mbH
PY  - 2012
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - Stress-induced volatile organic compound (VOC) emissions from transgenic Grey poplar modified in isoprene emission potential were used for the investigation of photochemical secondary organic aerosol (SOA) formation. In poplar, acute ozone stress induces the emission of a wide array of VOCs dominated by sesquiterpenes and aromatic VOCs. Constitutive light-dependent emission of isoprene ranged between 66 nmol m(-2) s(-1) in non-transgenic controls (wild type WT) and nearly zero (<0.5 nmol m(-2) s(-1)) in isoprene emission-repressed plants (line RA22), respectively. Nucleation rates of up to 3600 cm(-3) s(-1) were observed in our experiments. In the presence of isoprene new particle formation was suppressed compared to non-isoprene containing VOC mixtures. Compared to isoprene/monoterpene systems emitted from other plants the suppression of nucleation by isoprene was less effective for the VOC mixture emitted from stressed poplar. This is explained by the observed high efficiency of new particle formation for emissions from stressed poplar. Direct measurements of OH in the reaction chamber revealed that the steady state concentration of OH is lower in the presence of isoprene than in the absence of isoprene, supporting the hypothesis that isoprenes' suppressing effect on nucleation is related to radical chemistry. In order to test whether isoprene contributes to SOA mass formation, fully deuterated isoprene (C5D8) was added to the stress-induced emission profile of an isoprene free poplar mutant. Mass spectral analysis showed that, despite the isoprene-induced suppression of particle formation, fractions of deuterated isoprene were incorporated into the SOA. A fractional mass yield of 2.3% of isoprene was observed. Future emission changes due to land use and climate change may therefore affect both gas phase oxidation capacity and new particle number formation.
AU  - Kiendler-Scharr, A.*
AU  - Andres, S.*
AU  - Bachner, M.*
AU  - Behnke, K.*
AU  - Broch, S.*
AU  - Hofzumahaus, A.*
AU  - Holland, F.*
AU  - Kleist, E.*
AU  - Mentel, T. F.*
AU  - Rubach, F.*
AU  - Springer, M.*
AU  - Steitz, B.*
AU  - Tillmann, R.*
AU  - Wahner, A.*
AU  - Schnitzler, J.-P.
AU  - Wildt, J.*
C1  - 11057
C2  - 30483
SP  - 1021-1030
TI  - Isoprene in poplar emissions: Effects on new particle formation and OH concentrations.
JO  - Atmos. Chem. Phys.
VL  - 12
IS  - 2
PB  - Copernicus Gesellschaft mbH
PY  - 2012
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - PM1 (particulate matter with an aerodynamic diameter <1 mu m) non-refractory components and black carbon were measured continuously together with additional air quality and atmospheric parameters at an urban background site in Barcelona, Spain, during March 2009 (campaign DAURE, Determination of the sources of atmospheric Aerosols in Urban and Rural Environments in the western Mediterranean). Positive matrix factorization (PMF) was conducted on the organic aerosol (OA) data matrix measured by an aerosol mass spectrometer, on both unit mass (UMR) and high resolution (HR) data. Five factors or sources could be identified: LV-OOA (low-volatility oxygenated OA), related to regional, aged secondary OA; SV-OOA (semi-volatile oxygenated OA), a fresher oxygenated OA; HOA (hydrocarbon-like OA, related to traffic emissions); BBOA (biomass burning OA) from domestic heating or agricultural biomass burning activities; and COA (cooking OA). LV-OOA contributed 28% to OA, SV-OOA 27%, COA 17%, HOA 16%, and BBOA 11%. The COA HR spectrum contained substantial signal from oxygenated ions (O:C: 0.21) whereas the HR HOA spectrum had almost exclusively contributions from chemically reduced ions (O: C: 0.03). If we assume that the carbon in HOA is fossil while that in COA and BBOA is modern, primary OA in Barcelona contains a surprisingly high fraction (59%) of non-fossil carbon.
AU  - Mohr, C.*
AU  - DeCarlo, P.F.*
AU  - Heringa, M.F.*
AU  - Chirico, R.*
AU  - Slowik, J.G.*
AU  - Richter, R.*
AU  - Reche, C.*
AU  - Alastuey, A.*
AU  - Querol, X.*
AU  - Seco, R.*
AU  - Penuelas, J.*
AU  - Jimenez, J.L.*
AU  - Crippa, M.*
AU  - Zimmermann, R.
AU  - Baltensperger, U.*
AU  - Prevot, A.S.H.*
C1  - 7411
C2  - 29707
SP  - 1649-1665
TI  - Identification and quantification of organic aerosol from cooking and other sources in Barcelona using aerosol mass spectrometer data.
JO  - Atmos. Chem. Phys.
VL  - 12
IS  - 4
PB  - Copernicus Gesellschaft mbH
PY  - 2012
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - Reactive halogen species (RHS), such as X·, X2 and HOX containing X = chlorine and/or bromine, are released by various sources like photo-activated sea-salt aerosol or from salt pans, and salt lakes. Despite many studies of RHS reactions, the potential of RHS reacting with secondary organic aerosol (SOA) and organic aerosol derived from biomass-burning (BBOA) has been neglected. Such reactions can constitute sources of gaseous organohalogen compounds or halogenated organic matter in the tropospheric boundary layer and can influence physicochemical properties of atmospheric aerosols. Model SOA from α-pinene, catechol, and guaiacol was used to study heterogeneous interactions with RHS. Particles were exposed to molecular chlorine and bromine in an aerosol smog-chamber in the presence of UV/VIS irradiation and to RHS, released from simulated natural halogen sources like salt pans. Subsequently, the aerosol was characterized in detail using a variety of physicochemical and spectroscopic methods. Fundamental features were correlated with heterogeneous halogenation, which results in new functional groups (FTIR spectroscopy), changes UV/VIS absorption, chemical composition (ultrahigh resolution mass spectroscopy (ICR-FT/MS)), or aerosol size distribution. However, the halogen release mechanisms were also found to be affected by the presence of organic aerosol. Those interaction processes, changing chemical and physical properties of the aerosol are likely to influence e.g. the ability of the aerosol to act as cloud condensation nuclei, its potential to adsorb other gases with low-volatility, or its contribution to radiative forcing and ultimately the Earth's radiation balance.
AU  - Ofner, J.*
AU  - Balzer, N.*
AU  - Buxmann, J.*
AU  - Grothe, H.*
AU  - Schmitt-Kopplin, P.
AU  - Platt, U.*
AU  - Zetzsch, C.*
C1  - 8207
C2  - 30047
SP  - 5787-5806
TI  - Halogenation processes of secondary organic aerosol and implications on halogen release mechanisms.
JO  - Atmos. Chem. Phys.
VL  - 12
IS  - 13
PB  - Copernicus Gesellschaft mbH
PY  - 2012
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - Secondary organic aerosol (SOA) was produced from the aromatic precursors catechol and guaiacol by reaction with ozone in the presence and absence of simulated sunlight and humidity and investigated for its properties as a proxy for HUmic-LIke Substances (HULIS). Beside a small particle size, a relatively low molecular weight and typical optical features in the UV/VIS spectral range, HULIS contain a typical aromatic and/or olefinic chemical structure and highly oxidized functional groups within a high chemical diversity. Various methods were used to characterize the secondary organic aerosols obtained: Fourier transform infrared spectroscopy (FTIR) demonstrated the formation of several carbonyl containing functional groups as well as structural and functional differences between aerosols formed at different environmental conditions. UV/VIS spectroscopy of filter samples showed that the particulate matter absorbs far into the visible range up to more than 500 nm. Ultrahigh resolved mass spectroscopy (ICR-FT/MS) determined O/C-ratios between 0.3 and 1 and observed m/z ratios between 200 and 450 to be most abundant. Temperature-programmed-pyrolysis mass spectroscopy (TPP-MS) identified carboxylic acids and lactones/esters as major functional groups. Particle sizing using a condensation-nucleus-counter and differential-mobility-particle-sizer (CNC/DMPS) monitored the formation of small particles during the SOA formation process. Particle imaging, using field-emission-gun scanning electron microscopy (FEG-SEM), showed spherical particles, forming clusters and chains. We conclude that catechol and guaiacol are appropriate precursors for studies of the processing of aromatic SOA with atmospheric HULIS properties on the laboratory scale.
AU  - Ofner, J.*
AU  - Krüger, H.-U.*
AU  - Grothe, H.*
AU  - Schmitt-Kopplin, P.
AU  - Whitmore, K.*
AU  - Zetzsch, C.*
C1  - 6093
C2  - 27837
SP  - 1-15
TI  - Physico-chemical characterization of SOA derived from catechol and guaiacol - a model substance for the aromatic fraction of atmospheric HULIS.
JO  - Atmos. Chem. Phys.
VL  - 11
IS  - 1
PB  - Copernicus Gesellschaft mbh
PY  - 2011
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - An in-situ derivatization thermal desorption method followed by gas chromatography and time-of-flight mass spectrometry (IDTD-GC-TOFMS) was developed for determination of polar organic compounds together with non-polar compounds in one measurement. Hydroxyl and carboxyl groups of compounds such as anhydrous sugars, alcohols and phenols, fatty acids and resin acids are targets of the derivatization procedure. Derivatization is based on silylation with N-Methyl-N-trimethylsilyl-trifluoroacetamide (MSTFA) during the step of thermal desorption. The high temperature of 300 °C during desorption is utilized for the in-situ derivatization on the collection substrate (quartz fibre filters) accelerating the reaction rate. Thereby, the analysis time is as short as without derivatization. At first the filter surface is dampened with derivatization reagent before insertion of the sample into the thermal desorption unit. To ensure ongoing derivatization during thermal desorption the carrier gas is enriched with MSTFA until the desorption procedure is finished. The precisions of all studied analytes were below 17 % within a calibration range from 22 pg (abietic acid) up to 342 ng (levoglucosan). Limits of quantification (LOQ) for polycyclic aromatic hydrocarbons (PAH) were between 1 pg (fluoranthene) and 8 pg (indeno[1,2,3-cd]pyrene), for resin acids 37–102 pg and for studied phenols 4–144 pg. LOQ for levoglucosan was 17 pg.
AU  - Orasche, J.
AU  - Schnelle-Kreis, J.
AU  - Abbaszade, G.
AU  - Zimmermann, R.
C1  - 5612
C2  - 28890
SP  - 8977-8993
TI  - Technical Note: In-situ derivatization thermal desorption GC-TOFMS for direct analysis of particle-bound non-polar and polar organic species.
JO  - Atmos. Chem. Phys.
VL  - 11
IS  - 17
PB  - Copernicus Gesellschaft mbH
PY  - 2011
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - During the time period of the Eyjafjallajokull volcano eruption in 2010 increased mass concentration of PM(10) (particulate matter, diameter < 10 mu m) were observed at ground level in Augsburg, Germany. In particular on 19 and 20 April 2010 the daily PM10 limit value of 50 mu g m(-3) was exceeded. Because ambient particles are in general a complex mixture originating from different sources, a source apportionment method (positive matrix factorization (PMF)) was applied to particle size distribution data in the size range from 3 nm to 10 mu m to identify and estimate the volcanic ash contribution to the overall PM10 load in the ambient air in Augsburg. A PMF factor with relevant particle mass concentration in the size range between 1 and 4 mu m (maximum at 2 mu m) was associated with long range transported dust. This factor increased from background concentration to high levels simultaneously with the arrival of the volcanic ash plume in the planetary boundary layer. Hence, we assume that this factor could be used as an indicator for the impact of the Eyjafjallajokull ash plume on ground level in Augsburg. From 17 to 22 April 2010 long range transported dust factor contributed on average 30% (12 mu g m(-3)) to PM10. On 19 April 2010 at 20:00 UTC+1 the maximum percentage of the long range transported dust factor accounted for around 65% (35 mu g m(-3)) to PM10 and three hours later the maximum absolute value with around 48 mu g m(-3) (61 %) was observed. Additional PMF analyses for a Saharan dust event occurred in May and June 2008 suggest, that the long range transported dust factor could also be used as an indicator for Saharan dust events.
AU  - Pitz, M.
AU  - Gu, J.W.
AU  - Soentgen, J.*
AU  - Peters, A.
AU  - Cyrys, J.
C1  - 6675
C2  - 29227
SP  - 9367-9374
TI  - Particle size distribution factor as an indicator for the impact of the Eyjafjallajökull ash plume at ground level in Augsburg, Germany.
JO  - Atmos. Chem. Phys.
VL  - 11
IS  - 17
PB  - Copernicus Gesellschaft mbH
PY  - 2011
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - A series of major eruptions of the Eyjafjallaj ¨ okull volcano in Iceland started on 14 April 2010 and continued until the end of May 2010. The volcanic emissions moved over nearly the whole of Europe and were observed first on 16 April 2010 in Southern 5 Germany with different remote sensing systems from the ground and space. Enhanced PM10 and SO2 concentrations were detected on 17 April at mountain stations (Zugspitze/Schneefernerhaus and Schauinsland) as well as in Innsbruck by insitu measurement devices. On 19 April intensive vertical mixing and advection along with clear sky-conditions facilitated the entrainment of volcanic material down to the 10 ground. The subsequent formation of a stably stratified lower atmosphere with limited mixing near the ground during the evening of 19 April led to an additional enhancement of near-surface particle concentrations. Consequently, on 19 April and 20 April exceedances of the daily threshold value for particulate matter (PM10) were reported at nearly all monitoring stations of the North Alpine foothills as well as at mountain and 15 valley stations in the northern Alps. The chemical analyses of ambient PM10 at monitoring stations of the North Alpine foothills yielded elevated Titanium concentrations on 19/20 April which prove the presence of volcanic plume material. Following this result the PM10 threshold exceedances are also associated with the volcanic plume. The entrainment of the volcanic plume material mainly affected the concentrations of coarse 20 particles (>1 μm) –- interpreted as volcanic ash - and ultrafine particles (<100 nm), while the concentrations of accumulation mode aerosol (0.1–1 μm) were not changed significantly. With regard to the occurrence of ultrafine particles, it is concluded that their formation was triggered by high sulphuric acid concentrations which are necessarily generated by the photochemical processes in a plume rich in sulphur dioxide under 25 high solar irradiance. It became evident that during the course of several days, the Eyjafjallaj ¨ okull volcanic emissions influenced the near-surface atmosphere and thus the ambient air quality. Following knowledge about health effects of air pollutants and volcanic plume compounds, it is assumed that the volcanic plume contributed to the overall exposure of the population and therefore may have had minor effects on the exacerbation of respiratory and cardiovascular symptoms.
AU  - Schäfer, K.*
AU  - Thomas, W.*
AU  - Peters, A.
AU  - Ries, L.*
AU  - Obleitner, F.*
AU  - Schnelle-Kreis, J.
AU  - Birmili, W.*
AU  - Diemer, J.*
AU  - Fricke, W.*
AU  - Junkermann, W.*
AU  - Pitz, M.
AU  - Emeis, S.*
AU  - Forkel, R.*
AU  - Suppan, P.*
AU  - Flentje, H.*
AU  - Gilge, S.*
AU  - Wichmann, H.-E.
AU  - Meinhardt, F.*
AU  - Zimmermann, R.
AU  - Weinhold, K.*
AU  - Soentgen, J.*
AU  - Munkel, C.*
AU  - Freuer, C.*
AU  - Cyrys, J.*
C1  - 5566
C2  - 28801
CY  - Gottingen
SP  - 9083-9132
TI  - Influences of the 2010 Eyjafjallajökull volcanic plume on air quality in the northern Alpine region.
JO  - Atmos. Chem. Phys.
VL  - 11
IS  - 16
PB  - Copernicus Gesellschaft mbH
PY  - 2011
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - Aerosol particle number size distributions (size range 0.003-10 μm) with and without using a thermodenuder are measured continuously in the city of Augsburg, Germany. Here, the data between 2004 and 2006 are examined with respect to the governing anthropogenic sources and meteorological factors. The two-year average particle number concentration in Augsburg was found to be 12 200 cm−3, similar to previous observations in other European cities. A seasonal analysis yielded twice the total particle number concentrations in winter as compared to summer, a consequence of more frequent inversion situations and particulate emissions in winter. The diurnal variation of the size distribution is shaped by a remarkable increase in the morning along with the peak traffic hours. After a mid-day decrease along with the onset of vertical mixing, an evening increase in concentration could frequently be observed, suggesting a re-stratification of the urban atmosphere. The mixed layer height turned out to be the most influential meteorological parameter on particle size distribution. Its influence was greater than that of the geographical origin of the synoptic-scale air masses.
AU  - Birmili, W.*
AU  - Heinke, K.*
AU  - Pitz, M.
AU  - Matschullat, J.*
AU  - Wiedensohler, A.*
AU  - Cyrys, J.
AU  - Wichmann, H.-E.
AU  - Peters, A.
C1  - 2227
C2  - 27121
SP  - 4643-4660
TI  - Particle number size distributions in urban air before and after volatilisation.
JO  - Atmos. Chem. Phys.
VL  - 10
IS  - 10
PB  - Copernicus
PY  - 2010
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - The scattering and absorption of solar radiation by atmospheric aerosols is a key element of the Earth's radiative energy balance and climate. The optical properties of aerosol particles are, however, highly variable and not well characterized, especially near newly emerging mega-cities. In this study, aerosol optical properties were measured at a rural site approximately 60 km northwest of the mega-city Guangzhou in southeast China. The measurements were part of the PRIDE-PRD2006 intensive campaign, covering the period of 1–30 July 2006. Scattering and absorption coefficients of dry aerosol particles with diameters up to 10 ?m (PM10) were determined with a three-wavelength integrating nephelometer and with a photoacoustic spectrometer, respectively.
AU  - Garland, R.M.*
AU  - Yang, H.*
AU  - Schmid, O.
AU  - Rose, D.*
AU  - Nowak, A.*
AU  - Achtert, P.*
AU  - Wiedensohler, A.*
AU  - Takegawa, N.*
AU  - Kita, K.*
AU  - Miyazaki, Y.*
AU  - Kondo, Y.*
AU  - Hu, M.*
AU  - Sha, M.*
AU  - Zeng, L.M.*
AU  - Zhang, Y.-H.*
AU  - Andreae, M.O.
AU  - Pöschl, U.*
C1  - 2979
C2  - 25581
SP  - 5161-5186
TI  - Aerosol optical properties in a rural environment near the mega-city Guangzhou, China: Implications for regional air pollution, radiative forcing and remote sensing.
JO  - Atmos. Chem. Phys.
VL  - 8
IS  - 17
PB  - EGU
PY  - 2008
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - 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. The combustion conditions were monitored with concomitant CO2 and CO measurements. The mass scattering efficiencies of 8.9±0.2 m2 g-1 and 9.3±0.3 m2 g-1 obtained for aerosol particles from the combustion of savanna grass and an African hardwood (musasa), respectively, are larger than typically reported mainly due to differences in particle size distribution. The photoacoustically measured mass absorption efficiencies of 0.51±0.02 m2 g-1 and 0.50±0.02 m2 g-1 were at the lower end of the literature values. Using the measured size distributions as well as the mass scattering and absorption efficiencies, Mie calculations provided effective refractive indices of 1.60-0.010i (savanna grass) and 1.56-0.010i (musasa) (?=0.55 ?m). The apparent discrepancy between the low imaginary part of the refractive index and the high apparent elemental carbon (ECa) fractions (8 to 15%) obtained from the thermographic analysis of impactor samples can be explained by a positive bias in the elemental carbon data due to the presence of high molecular weight organic substances. Potential artefacts in optical properties due to instrument bias, non-natural burning conditions and unrealistic dilution history of the laboratory smoke cannot be ruled out and are also discussed in this study.
AU  - Hungershöfer, K.*
AU  - Zeromskiene, K.*
AU  - Iinuma, Y.*
AU  - Helas, G.*
AU  - Trentmann, J.*
AU  - Trautmann, T.*
AU  - Parmar, R.S.*
AU  - Wiedensohler, A.*
AU  - Andrae, M.O.*
AU  - Schmid, O.
C1  - 2678
C2  - 25350
SP  - 3427-3439
TI  - Modelling the optical properties of fresh biomass burning aerosol produced in a smoke chamber: Results from the EFEU campaign.
JO  - Atmos. Chem. Phys.
VL  - 8
IS  - 13
PB  - EGU
PY  - 2008
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - As part of the Large Scale Biosphere-Atmosphere Experiment in Amazonia - Smoke, Aerosols, Clouds, Rainfall and Climate (LBA-SMOCC) campaign, detailed surface and airborne aerosol measurements were performed over the Amazon Basin during the dry to wet season from 16 September to 14 November 2002. Optical and physical properties of aerosols at the surface, and in the boundary layer (BL) and free troposphere (FT) during the dry season are discussed in this article. Carbon monoxide (CO) is used as a tracer for biomass burning emissions. At the surface, good correlation among the light scattering coefficient (σs at 545 nm), PM2.5, and CO indicates that biomass burning is the main source of aerosols. Accumulation of haze during some of the large-scale biomass burning events led to high PM2.5 (225 μgm-3), σs, (1435 Mm-1), aerosol optical depth at 500 nm (3.0), and CO (3000ppb). A few rainy episodes reduced the PM2.5, number concentration (CN) and CO concentration by two orders of magnitude. The correlation analysis between σs and aerosol optical thickness shows that most of the optically active aerosols are confined to a layer with a scale height of 1617m during the burning season. This is confirmed by aircraft profiles. The average mass scattering and absorption efficiencies (545 nm) for small particles (diameter Dp < 1.5 μm) at surface level are found to be 5.0 and 0.33 m2 g-1, respectively, when relating the aerosol optical properties to PM2.5 aerosols. The observed mean single scattering albedo (ω>0 at 545 nm) for submicron aerosols at the surface is 0.92±0.02. The light scattering by particles (Δσs/ΔCN) increase 2-10 times from the surface to the FT, most probably due to the combined affects of coagulation and condensation.
AU  - Chand, D.*
AU  - Guyon, P.*
AU  - Artaxo, P.*
AU  - Schmid, O.
AU  - Frank, G.P.*
AU  - Rizzo, L.V.*
AU  - Mayol-Bracero, O.L.*
AU  - Gatti, L.V.*
AU  - Andreae, M.O.*
C1  - 5002
C2  - 23715
SP  - 2911-2925
TI  - Optical and physical properties of aerosols in the boundary layer and free troposphere over the Amazon Basin during the biomass burning season.
JO  - Atmos. Chem. Phys.
VL  - 6
PY  - 2006
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - We present here the optical properties of humic-like substances (HULIS) isolated from the fine fraction of biomass-burning aerosol collected in the Amazon basin during the LBA-SMOCC (Large scale Biosphere atmosphere experiment in Amazonia - SMOke aerosols, Clouds, rainfall and Climate) experiment in September 2002. From the isolated HULIS, aerosol particles were generated and their scattering and absorption coefficients measured. The size distribution and mass of the particles were also recorded. The value of the index of refraction was derived from "closure" calculations based on particle size, scattering and absorption measurements. On average, the complex index of refraction at 532 nm of HULIS collected during day and nighttime was 1.65-0.0019i and 1.69-0.0016i, respectively. In addition, the imaginary part of the complex index of refraction was calculated using the measured absorption coefficient of the bulk HULIS. The mass absorption coefficient of the HULIS at 532 nm was found to be quite low (0.031 and 0.029 m2 g-1 for the day and night samples, respectively). However, due to the high absorption Angstrom exponent (6-7) of HULIS, the specific absorption increases substantially towards shorter wavelengths (∼2-3 m2 g -1 at 300 nm), causing a relatively high (up to 50%) contribution to the light absorption of our Amazonian aerosol at 300 nm. For the relative contribution of HULIS to light absorption in the entire solar spectrum, lower values (6.4-8.6%) are obtained, but those are still not negligible.
AU  - Hoffer, A.*
AU  - Gelencser, A.*
AU  - Kiss, G.*
AU  - Schmid, O.
AU  - Frank, G.P.*
AU  - Artaxo, P.*
AU  - Andreae, M.O.*
C1  - 4221
C2  - 23904
SP  - 3563-3570
TI  - Optical properties of humic-like substances (HULIS) in biomass-burning aerosols.
JO  - Atmos. Chem. Phys.
VL  - 6
PY  - 2006
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - Spectral aerosol light absorption is an important parameter for the assessment of the radiation budget of the atmosphere. Although on-line measurement techniques for aerosol light absorption, such as the Aethalometer and the Particle Soot Absorption Photometer (PSAP), have been available for two decades, they are limited in accuracy and spectral resolution because of the need to deposit the aerosol on a filter substrate before measurement. Recently, a 7-wavelength (λ) Aethalometer became commercially available, which covers the visible (VIS) to near-infrared (NIR) spectral range (λ=450-950 nm), and laboratory calibration studies improved the degree of confidence in these measurement techniques. However, the applicability of the laboratory calibration factors to ambient conditions has not been investigated thoroughly yet. As part of the LBA-SMOCC (Large scale Biosphere atmosphere experiment in Amazonia - SMOke aerosols, Clouds, rainfall and Climate) campaign from September to November 2002 in the Amazon basin we performed an extensive field calibration of a 1-λ. PSAP and a 7-λ, Aethalometer utilizing a photoacoustic spectrometer (PAS, 532 nm) as reference device. Especially during the dry period of the campaign, the aerosol population was dominated by pyrogenic emissions. The most pronounced artifact of integrating-plate type attenuation techniques (e.g. Aethalometer, PSAP) is due to multiple scattering effects within the filter matrix. For the PSAP, we essentially confirmed the laboratory calibration factor by Bond et al. (1999). On the other hand, for the Aethalometer we found a multiple scattering enhancement of 5.23 (or 4.55, if corrected for aerosol scattering), which is significantly larger than the factors previously reported (∼2) for laboratory calibrations. While the exact reason for this discrepancy is unknown, the available data from the present and previous studies suggest aerosol mixing (internal versus external) as a likely cause. For Amazonian aerosol, we found no absorption enhancement due to hygroscopic particle growth in the relative humidity (RH) range between 40% and 80%. However, a substantial bias in PSAP sensitivity that correlated with both RH and temperature (T) was observed for 20%
AU  - Schmid, O.
AU  - Artaxo, P.*
AU  - Arnott, W.W.*
AU  - Chand, D.*
AU  - Gatti, L.V.*
AU  - Frank, G.P.*
AU  - Hoffer, A.*
AU  - Schnaiter, M.*
AU  - Andreae, M.O.*
C1  - 4220
C2  - 23903
SP  - 3443-3462
TI  - Spectral light absorption by ambient aerosols influenced by biomass burning in the Amazon Basin. I: Comparison and field calibration of absorption measurement techniques.
JO  - Atmos. Chem. Phys.
VL  - 6
PY  - 2006
SN  - 1680-7316
ER  - 

TY  - JOUR
AB  - Combustion of elemental carbon (EC) and organic carbon (OC) contained in ambient aerosol matter was explored using scanning electron microscopy (SEM) in combination with energy dispersive X-ray analysis (EDX). To ease identification of the particles of interest and to avoid or at least reduce interaction with simultaneously sampled inorganic oxides and salts, the approach used in this work differed in two ways from commonly applied procedures. First, rather than using a mixture of particles of vastly different sizes, as in PM10 or PM2.5, aerosol matter was collected in a 5-stage impactor. Second, the water soluble fraction of the collected matter was removed prior to analysis. Diesel soot particles, which appeared in the well-known form of chain-type aggregates, constituted the major fraction of EC. In contrast, OC containing particles were observed in a variety of shapes, including a sizable amount of bioaerosol matter appearing mostly in the size range above about 1 μm. During heating in ambient air for 1 h, diesel soot particles were found to be stable up to 470°C, but complete combustion occurred in a narrow temperature interval between about 480 and 510°C. After diesel soot combustion, minute quantities of "ash" were observed in the form of aggregated tiny particles with sizes less than 10 nm. These particles could be due to elemental or oxidic contaminants of diesel soot. Combustion of OC was observed over a wide range of temperatures, from well below 200°C to at least 500°C. Incompletely burnt bioaerosol matter was still found after heating to 600°C. The results imply that the EC fraction in aerosol matter can be overestimated significantly if the contribution of OC to a thermogram is not well separated.
AU  - Wittmaack, K.
C1  - 3081
C2  - 23050
SP  - 1905-1913
TI  - Combustion characteristics of water-insoluble elemental and organic carbon in size selected ambient aerosol particles.
JO  - Atmos. Chem. Phys.
VL  - 5
PY  - 2005
SN  - 1680-7316
ER  -