scholarly journals Secondary organic aerosol formation exceeds primary particulate matter emissions for light-duty gasoline vehicles

2013 ◽  
Vol 13 (9) ◽  
pp. 23173-23216 ◽  
Author(s):  
T. D. Gordon ◽  
A. A. Presto ◽  
A. A. May ◽  
N. T. Nguyen ◽  
E. M. Lipsky ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Secondary Organic Aerosol ◽  
Cold Start ◽  
Organic Aerosol ◽  
Smog Chamber ◽  
Aerosol Formation ◽  
Gas Emissions ◽  
Light Duty ◽  
Gasoline Vehicles ◽  
Diesel Trucks

Abstract. The effects of photochemical aging on emissions from 15 light-duty gasoline vehicles were investigated using a smog chamber to probe the critical link between the tailpipe and ambient atmosphere. The vehicles were recruited from the California in-use fleet; they represent a wide range of model years (1987 to 2011), vehicle types and emission control technologies. Each vehicle was tested on a chassis dynamometer using the unified cycle. Dilute emissions were sampled into a portable smog chamber and then photochemically aged under urban-like conditions. For every vehicle, substantial secondary organic aerosol (SOA) formation occurred during cold-start tests, with the emissions from some vehicles generating as much as 6 times the amount of SOA as primary particulate matter after three hours of oxidation inside the chamber at typical atmospheric oxidant levels. Therefore, the contribution of light duty gasoline vehicle exhaust to ambient PM levels is likely dominated by secondary PM production (SOA and nitrate). Emissions from hot-start tests formed about a factor of 3–7 less SOA than cold-start tests. Therefore, catalyst warm-up appears to be an important factor in controlling SOA precursor emissions. The mass of SOA generated by photo-oxidizing exhaust from newer (LEV1 and LEV2) vehicles was only modestly lower (38%) than that formed from exhaust emitted by older (pre-LEV) vehicles, despite much larger reductions in non-methane organic gas emissions. These data suggest that a complex and non-linear relationship exists between organic gas emissions and SOA formation, which is not surprising since SOA precursors are only one component of the exhaust. Except for the oldest (pre-LEV) vehicles, the SOA production could not be fully explained by the measured oxidation of speciated (traditional) SOA precursors. Over the time scale of these experiments, the mixture of organic vapors emitted by newer vehicles appear to be more efficient (higher yielding) in producing SOA than the emissions from older vehicles. About 30% of the non-methane organic gas emissions from the newer (LEV1 and LEV2) vehicles could not be speciated, and the majority of the SOA formed from these vehicles appears to be associated with these unspeciated organics. These results for light-duty gasoline vehicles contrast with the results from a companion study of on-road heavy-duty diesel trucks; in that study late model (2007 and later) diesel trucks equipped with catalyzed diesel particulate filters emitted very little primary PM, and the photo-oxidized emissions produced negligible amounts of SOA.

scholarly journals Secondary organic aerosol formation exceeds primary particulate matter emissions for light-duty gasoline vehicles

2014 ◽  
Vol 14 (9) ◽  
pp. 4661-4678 ◽  
Author(s):  
T. D. Gordon ◽  
A. A. Presto ◽  
A. A. May ◽  
N. T. Nguyen ◽  
E. M. Lipsky ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Secondary Organic Aerosol ◽  
Cold Start ◽  
Organic Aerosol ◽  
Smog Chamber ◽  
Aerosol Formation ◽  
Gas Emissions ◽  
Light Duty ◽  
Gasoline Vehicles ◽  
Diesel Trucks

Abstract. The effects of photochemical aging on emissions from 15 light-duty gasoline vehicles were investigated using a smog chamber to probe the critical link between the tailpipe and ambient atmosphere. The vehicles were recruited from the California in-use fleet; they represent a wide range of model years (1987 to 2011), vehicle types and emission control technologies. Each vehicle was tested on a chassis dynamometer using the unified cycle. Dilute emissions were sampled into a portable smog chamber and then photochemically aged under urban-like conditions. For every vehicle, substantial secondary organic aerosol (SOA) formation occurred during cold-start tests, with the emissions from some vehicles generating as much as 6 times the amount of SOA as primary particulate matter (PM) after 3 h of oxidation inside the chamber at typical atmospheric oxidant levels (and 5 times the amount of SOA as primary PM after 5 × 106 molecules cm−3 h of OH exposure). Therefore, the contribution of light-duty gasoline vehicle exhaust to ambient PM levels is likely dominated by secondary PM production (SOA and nitrate). Emissions from hot-start tests formed about a factor of 3–7 less SOA than cold-start tests. Therefore, catalyst warm-up appears to be an important factor in controlling SOA precursor emissions. The mass of SOA generated by photooxidizing exhaust from newer (LEV2) vehicles was a factor of 3 lower than that formed from exhaust emitted by older (pre-LEV) vehicles, despite much larger reductions (a factor of 11–15) in nonmethane organic gas emissions. These data suggest that a complex and nonlinear relationship exists between organic gas emissions and SOA formation, which is not surprising since SOA precursors are only one component of the exhaust. Except for the oldest (pre-LEV) vehicles, the SOA production could not be fully explained by the measured oxidation of speciated (traditional) SOA precursors. Over the timescale of these experiments, the mixture of organic vapors emitted by newer vehicles appears to be more efficient (higher yielding) in producing SOA than the emissions from older vehicles. About 30% of the nonmethane organic gas emissions from the newer (LEV1 and LEV2) vehicles could not be speciated, and the majority of the SOA formed from these vehicles appears to be associated with these unspeciated organics. By comparing this study with a companion study of diesel trucks, we conclude that both primary PM emissions and SOA production for light-duty gasoline vehicles are much greater than for late-model (2007 and later) on-road heavy-duty diesel trucks.

scholarly journals Secondary organic aerosol formation from photochemical aging of light-duty gasoline vehicle exhausts in a smog chamber

2015 ◽  
Vol 15 (15) ◽  
pp. 9049-9062 ◽  
Author(s):  
T. Liu ◽  
X. Wang ◽  
W. Deng ◽  
Q. Hu ◽  
X. Ding ◽  
...  
Keyword(s):  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Smog Chamber ◽  
Atmospheric Conditions ◽  
Aerosol Formation ◽  
Vehicle Exhaust ◽  
Molar Ratios ◽  
Passenger Vehicles ◽  
Light Duty ◽  
Oxidation Chemistry

Abstract. In China, a rapid increase in passenger vehicles has led to the growing concern of vehicle exhaust as an important source of anthropogenic secondary organic aerosol (SOA) in megacities hard hit by haze. In this study, the SOA formation of emissions from two idling light-duty gasoline vehicles (LDGVs) (Euro 1 and Euro 4) operated in China was investigated in a 30 m3 smog chamber. Five photo-oxidation experiments were carried out at 25 °C with relative humidity at around 50 %. After aging at an OH exposure of 5 × 106 molecules cm−3 h, the formed SOA was 12–259 times as high as primary organic aerosol (POA). The SOA production factors (PF) were 0.001–0.044 g kg−1 fuel, comparable with those from the previous studies at comparable OH exposure. This quite lower OH exposure than that in typical atmospheric conditions might however lead to the underestimation of the SOA formation potential from LDGVs. Effective SOA yields in this study were well fit by a one-product gas-particle partitioning model but quite lower than those of a previous study investigating SOA formation from three idling passenger vehicles (Euro 2–4). Traditional single-ring aromatic precursors and naphthalene could explain 51–90 % of the formed SOA. Unspeciated species such as branched and cyclic alkanes might be the possible precursors for the unexplained SOA. A high-resolution time-of-flight aerosol mass spectrometer was used to characterize the chemical composition of SOA. The relationship between f43 (ratio of m/z 43, mostly C2H3O+, to the total signal in mass spectrum) and f44 (mostly CO2+) of the gasoline vehicle exhaust SOA is similar to the ambient semi-volatile oxygenated organic aerosol (SV-OOA). We plot the O : C and H : C molar ratios of SOA in a Van Krevelen diagram. The slopes of ΔH : C / ΔO : C ranged from −0.59 to −0.36, suggesting that the oxidation chemistry in these experiments was a combination of carboxylic acid and alcohol/peroxide formation.

scholarly journals Secondary organic aerosol formation from idling gasoline passenger vehicle emissions investigated in a smog chamber

2013 ◽  
Vol 13 (12) ◽  
pp. 6101-6116 ◽  
Author(s):  
E. Z. Nordin ◽  
A. C. Eriksson ◽  
P. Roldin ◽  
P. T. Nilsson ◽  
J. E. Carlsson ◽  
...  
Keyword(s):  
Mass Spectrum ◽  
Mass Spectrometer ◽  
Urban Areas ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Smog Chamber ◽  
Aerosol Formation ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Gasoline Vehicles

Abstract. Gasoline vehicles have recently been pointed out as potentially the main source of anthropogenic secondary organic aerosol (SOA) in megacities. However, there is a lack of laboratory studies to systematically investigate SOA formation in real-world exhaust. In this study, SOA formation from pure aromatic precursors, idling and cold start gasoline exhaust from three passenger vehicles (EURO2–EURO4) were investigated with photo-oxidation experiments in a 6 m3 smog chamber. The experiments were carried out down to atmospherically relevant organic aerosol mass concentrations. The characterization instruments included a high-resolution aerosol mass spectrometer and a proton transfer mass spectrometer. It was found that gasoline exhaust readily forms SOA with a signature aerosol mass spectrum similar to the oxidized organic aerosol that commonly dominates the organic aerosol mass spectra downwind of urban areas. After a cumulative OH exposure of ~5 × 106 cm−3 h, the formed SOA was 1–2 orders of magnitude higher than the primary OA emissions. The SOA mass spectrum from a relevant mixture of traditional light aromatic precursors gave f43 (mass fraction at m/z = 43), approximately two times higher than to the gasoline SOA. However O : C and H : C ratios were similar for the two cases. Classical C6–C9 light aromatic precursors were responsible for up to 60% of the formed SOA, which is significantly higher than for diesel exhaust. Important candidates for additional precursors are higher-order aromatic compounds such as C10 and C11 light aromatics, naphthalene and methyl-naphthalenes. We conclude that approaches using only light aromatic precursors give an incomplete picture of the magnitude of SOA formation and the SOA composition from gasoline exhaust.

scholarly journals Impact of aftertreatment devices on primary emissions and secondary organic aerosol formation potential from in-use diesel vehicles: results from smog chamber experiments

2010 ◽  
Vol 10 (6) ◽  
pp. 16055-16109 ◽  
Author(s):  
R. Chirico ◽  
P. F. DeCarlo ◽  
M. F. Heringa ◽  
T. Tritscher ◽  
R. Richter ◽  
...  
Keyword(s):  
Urban Areas ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Oxidation Catalyst ◽  
Particulate Filter ◽  
Exhaust Aftertreatment ◽  
Smog Chamber ◽  
Aerosol Formation ◽  
Diesel Particulate ◽  
Diesel Vehicles

Abstract. Diesel particulate matter (DPM) is a significant source of aerosol in urban areas and has been linked to adverse health effects. Although newer European directives have introduced increasingly stringent standards for primary PM emissions, gaseous organics emitted from diesel cars can still lead to large amounts of secondary organic aerosol (SOA) in the atmosphere. Here we present results from smog chamber investigations characterizing the primary organic aerosol (POA) and the corresponding SOA formation at atmospherically relevant concentrations for three in-use diesel vehicles with different exhaust aftertreatment systems. One vehicle lacked exhaust aftertreatment devices, one vehicle was equipped with a diesel oxidation catalyst (DOC) and the final vehicle used both a DOC and diesel particulate filter (DPF). The experiments presented here were obtained from the vehicles at conditions representative of idle mode, and for one car in addition at a speed of 60 km/h. An Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) was used to measure the organic aerosol (OA) concentration and to obtain information on the chemical composition. For the conditions explored in this paper, primary aerosols from vehicles without a particulate filter consisted mainly of black carbon (BC) with a low fraction of organic matter (OM, OM/BC<0.5), while the subsequent aging by photooxidation resulted in a consistent production of SOA only for the vehicles without a DOC and with a deactivated DOC. After 5 h of aging ~80% of the total organic aerosol was on average secondary and the estimated "emission factor" for SOA was 0.23–0.56 g/kg fuel burned. In presence of both a DOC and a DPF, primary particles with a mobility diameter above 5 nm were 300±19 cm−3, and only 0.01 g SOA per kg fuel burned was produced within 5 h after lights on. The mass spectra indicate that POA was mostly a non-oxidized OA with an oxygen to carbon atomic ratio (O/C) ranging from 0.097 to 0.190. Five hours of oxidation led to a more oxidized OA with an O/C range of 0.208 to 0.369.

scholarly journals Secondary organic aerosol formation from smoldering and flaming combustion of biomass: a box model parametrization based on volatility basis set

2019 ◽  
Author(s):  
Giulia Stefenelli ◽  
Jianhui Jiang ◽  
Amelie Bertrand ◽  
Emily A. Bruns ◽  
Simone M. Pieber ◽  
...  
Keyword(s):  
Mass Spectrometer ◽  
Secondary Organic Aerosol ◽  
Time Of Flight ◽  
Organic Aerosol ◽  
Box Model ◽  
Basis Set ◽  
Model Parameters ◽  
Oh Radicals ◽  
Smog Chamber ◽  
Aerosol Formation

Abstract. Box model simulations based on the volatility basis set (VBS) approach were used to assess secondary organic aerosol (SOA) precursors and volatility distributions from residential wood combustion. Emissions were sampled from three different residential stoves at different combustion conditions (flaming vs. smoldering-dominated), aging temperatures (−10 °C, 2 °C and 15 °C), and emission loads, then exposed to hydroxyl (OH) radicals in a smog chamber. Primary emissions of SOA precursor compounds, organic aerosol and their evolution during aging in the smog chamber were monitored by a comprehensive suite of gas and particle instrumentation, including a proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS) and a high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). SOA precursors were classified according to their chemical composition and the identification of the nature of the precursors revealed useful to better constrain model parameters, in particular SOA production rates and molecular characteristics of the condensable gases formed. The general aim of the model was the determination of the parameters describing the volatility distributions of the oxidation products from the different chemical classes considered and their temperature dependence. Novel parameterization methods based on a genetic algorithm (GA) approach allowed estimation of precursor class contributions to SOA and evaluation of the effect of emission variability on SOA yield predictions. Significant differences were observed in the gas-phase composition between smoldering and flaming emissions. Smoldering phase emissions were dominated by oxidized VOCs with less than six carbon atoms family (OVOCc 

scholarly journals Impact of chamber wall loss of gaseous organic compounds on secondary organic aerosol formation: explicit modeling of SOA formation from alkane and alkene oxidation

2016 ◽  
Vol 16 (3) ◽  
pp. 1417-1431 ◽  
Author(s):  
Y. S. La ◽  
M. Camredon ◽  
P. J. Ziemann ◽  
R. Valorso ◽  
A. Matsunaga ◽  
...  
Keyword(s):  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Chamber Wall ◽  
Smog Chamber ◽  
Aerosol Formation ◽  
Organic Vapors ◽  
Alkene Oxidation ◽  
Branched Alkanes ◽  
Wall Loss ◽  
Kinetics Of

Abstract. Recent studies have shown that low volatility gas-phase species can be lost onto the smog chamber wall surfaces. Although this loss of organic vapors to walls could be substantial during experiments, its effect on secondary organic aerosol (SOA) formation has not been well characterized and quantified yet. Here the potential impact of chamber walls on the loss of gaseous organic species and SOA formation has been explored using the Generator for Explicit Chemistry and Kinetics of the Organics in the Atmosphere (GECKO-A) modeling tool, which explicitly represents SOA formation and gas–wall partitioning. The model was compared with 41 smog chamber experiments of SOA formation under OH oxidation of alkane and alkene series (linear, cyclic and C12-branched alkanes and terminal, internal and 2-methyl alkenes with 7 to 17 carbon atoms) under high NOx conditions. Simulated trends match observed trends within and between homologous series. The loss of organic vapors to the chamber walls is found to affect SOA yields as well as the composition of the gas and the particle phases. Simulated distributions of the species in various phases suggest that nitrates, hydroxynitrates and carbonylesters could substantially be lost onto walls. The extent of this process depends on the rate of gas–wall mass transfer, the vapor pressure of the species and the duration of the experiments. This work suggests that SOA yields inferred from chamber experiments could be underestimated up a factor of 2 due to the loss of organic vapors to chamber walls.

scholarly journals Secondary organic aerosol formation from gasoline vehicle emissions in a new mobile environmental reaction chamber

2013 ◽  
Vol 13 (18) ◽  
pp. 9141-9158 ◽  
Author(s):  
S. M. Platt ◽  
I. El Haddad ◽  
A. A. Zardini ◽  
M. Clairotte ◽  
C. Astorga ◽  
...  
Keyword(s):  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Reaction Chamber ◽  
Driving Cycle ◽  
Total Power ◽  
Aerosol Formation ◽  
Ambient Aerosols ◽  
Atmospheric Aging ◽  
Gasoline Vehicles ◽  
Vehicle Test

Abstract. We present a new mobile environmental reaction chamber for the simulation of the atmospheric aging of different emission sources without limitation from the instruments or facilities available at any single site. Photochemistry is simulated using a set of 40 UV lights (total power 4 KW). Characterisation of the emission spectrum of these lights shows that atmospheric aging of emissions may be simulated over a range of temperatures (−7 to 25 °C). A photolysis rate of NO2, JNO2, of (8.0 ± 0.7) × 10−3 s−1 was determined at 25 °C. We demonstrate the utility of this new system by presenting results on the aging (OH = 12 × 106 cm−3 h) of emissions from a modern (Euro 5) gasoline car operated during a driving cycle (New European Driving Cycle, NEDC) on a chassis dynamometer in a vehicle test cell. Emissions from the entire NEDC were sampled and aged in the chamber. Total organic aerosol (OA; primary organic aerosol (POA) emission + secondary organic aerosol (SOA) formation) was (369.8–397.5)10−3 g kg−1 fuel, or (13.2–15.4) × 10−3 g km−1, after aging, with aged OA/POA in the range 9–15. A thorough investigation of the composition of the gas phase emissions suggests that the observed SOA is from previously unconsidered precursors and processes. This large enhancement in particulate matter mass from gasoline vehicle aerosol emissions due to SOA formation, if it occurs across a wider range of gasoline vehicles, would have significant implications for our understanding of the contribution of on-road gasoline vehicles to ambient aerosols.

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