scholarly journals Gasoline aromatic: a critical determinant of urban secondary organic aerosol formation

2017 ◽  
Author(s):  
Jianfei Peng ◽  
Min Hu ◽  
Zhuofei Du ◽  
Yinhui Wang ◽  
Jing Zheng ◽  
...  
Keyword(s):  
Urban Areas ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Urban Atmosphere ◽  
Aerosol Formation ◽  
Vehicle Exhaust ◽  
Critical Determinant ◽  
Aromatic Content ◽  
Depth Study ◽  
The Impact

Abstract. Gasoline vehicle exhaust is an important contributor to secondary organic aerosol (SOA) formation in urban atmosphere. Fuel composition has considerable potential impact on gasoline SOA production, but this impact is still taken little account in the emission regulations due to the poor understanding of the link between fuel components and SOA production. Here, we present an in-depth study to investigate the impact of gasoline aromatic content on SOA production through chamber approach. A significant amplification factor of 3–6 for SOA productions from gasoline exhausts was observed as gasoline aromatic content rose from 29 % to 37 %. Considerably higher emissions of aromatic volatile organic compounds performed an essential role in the SOA production enhancement. Our findings indicate that gasoline aromatics have significant influence on ambient PM2.5 concentration in megacities and highlight that more stringent regulation on gasoline aromatic content will achieve unexpected benefit on air quality in urban areas.

scholarly journals Gasoline aromatics: a critical determinant of urban secondary organic aerosol formation

2017 ◽  
Vol 17 (17) ◽  
pp. 10743-10752 ◽  
Author(s):  
Jianfei Peng ◽  
Min Hu ◽  
Zhuofei Du ◽  
Yinhui Wang ◽  
Jing Zheng ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Urban Areas ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Urban Atmosphere ◽  
Aerosol Formation ◽  
Vehicle Exhaust ◽  
Aromatic Content ◽  
Volatile Organic

Abstract. Gasoline vehicle exhaust is an important contributor to secondary organic aerosol (SOA) formation in urban atmosphere. Fuel composition has a potentially considerable impact on gasoline SOA production, but the link between fuel components and SOA production is still poorly understood. Here, we present chamber experiments to investigate the impacts of gasoline aromatic content on SOA production through chamber oxidation approach. A significant amplification factor of 3–6 for SOA productions from gasoline exhausts is observed as gasoline aromatic content rose from 29 to 37 %. Considerably higher emission of aromatic volatile organic compounds (VOCs) using high-aromatic fuel plays an essential role in the enhancement of SOA production, while semi-volatile organic compounds (e.g., gas-phase PAHs) may also contribute to the higher SOA production. Our findings indicate that gasoline aromatics significantly influence ambient PM2. 5 concentration in urban areas and emphasize that more stringent regulation of gasoline aromatic content will lead to considerable benefits for urban air quality.

scholarly journals Reducing secondary organic aerosol formation from gasoline vehicle exhaust

2017 ◽  
Vol 114 (27) ◽  
pp. 6984-6989 ◽  
Author(s):  
Yunliang Zhao ◽  
Rawad Saleh ◽  
Georges Saliba ◽  
Albert A. Presto ◽  
Timothy D. Gordon ◽  
...  
Keyword(s):  
Los Angeles ◽  
Atmospheric Chemistry ◽  
Urban Areas ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Peroxy Radicals ◽  
Oxides Of Nitrogen ◽  
Aerosol Formation ◽  
Vehicle Exhaust ◽  
Gasoline Vehicles

On-road gasoline vehicles are a major source of secondary organic aerosol (SOA) in urban areas. We investigated SOA formation by oxidizing dilute, ambient-level exhaust concentrations from a fleet of on-road gasoline vehicles in a smog chamber. We measured less SOA formation from newer vehicles meeting more stringent emissions standards. This suggests that the natural replacement of older vehicles with newer ones that meet more stringent emissions standards should reduce SOA levels in urban environments. However, SOA production depends on both precursor concentrations (emissions) and atmospheric chemistry (SOA yields). We found a strongly nonlinear relationship between SOA formation and the ratio of nonmethane organic gas to oxides of nitrogen (NOx) (NMOG:NOx), which affects the fate of peroxy radicals. For example, changing the NMOG:NOxfrom 4 to 10 ppbC/ppbNOxincreased the SOA yield from dilute gasoline vehicle exhaust by a factor of 8. We investigated the implications of this relationship for the Los Angeles area. Although organic gas emissions from gasoline vehicles in Los Angeles are expected to fall by almost 80% over the next two decades, we predict no reduction in SOA production from these emissions due to the effects of rising NMOG:NOxon SOA yields. This highlights the importance of integrated emission control policies for NOxand organic gases.

scholarly journals Exploration of oxidative chemistry and secondary organic aerosol formation in the Amazon during the wet season: explicit modeling of the Manaus urban plume with GECKO-A

2020 ◽  
Vol 20 (10) ◽  
pp. 5995-6014 ◽  
Author(s):  
Camille Mouchel-Vallon ◽  
Julia Lee-Taylor ◽  
Alma Hodzic ◽  
Paulo Artaxo ◽  
Bernard Aumont ◽  
...  
Keyword(s):  
Secondary Organic Aerosol ◽  
Background Level ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Box Model ◽  
Basis Set ◽  
Aerosol Formation ◽  
Wet Season ◽  
Urban Plume ◽  
The Impact

Abstract. The GoAmazon 2014/5 field campaign took place in Manaus, Brazil, and allowed the investigation of the interaction between background-level biogenic air masses and anthropogenic plumes. We present in this work a box model built to simulate the impact of urban chemistry on biogenic secondary organic aerosol (SOA) formation and composition. An organic chemistry mechanism is generated with the Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A) to simulate the explicit oxidation of biogenic and anthropogenic compounds. A parameterization is also included to account for the reactive uptake of isoprene oxidation products on aqueous particles. The biogenic emissions estimated from existing emission inventories had to be reduced to match measurements. The model is able to reproduce ozone and NOx for clean and polluted situations. The explicit model is able to reproduce background case SOA mass concentrations but does not capture the enhancement observed in the urban plume. The oxidation of biogenic compounds is the major contributor to SOA mass. A volatility basis set (VBS) parameterization applied to the same cases obtains better results than GECKO-A for predicting SOA mass in the box model. The explicit mechanism may be missing SOA-formation processes related to the oxidation of monoterpenes that could be implicitly accounted for in the VBS parameterization.

scholarly journals Impact of molecular structure on secondary organic aerosol formation from aromatic hydrocarbon photooxidation under low NO<sub><i>x</i></sub> conditions

2016 ◽  
Author(s):  
L. Li ◽  
P. Tang ◽  
S. Nakao ◽  
D. R. Cocker III
Keyword(s):  
Molecular Structure ◽  
Chemical Composition ◽  
Aromatic Hydrocarbon ◽  
Chain Length ◽  
Aromatic Hydrocarbons ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Ortho Position ◽  
Aerosol Formation ◽  
The Impact

Abstract. The molecular structure of volatile organic compounds (VOC) determines their oxidation pathway, directly impacting secondary organic aerosol (SOA) formation. This study comprehensively investigates the impact of molecular structure on SOA formation from the photooxidation of twelve different eight to nine carbon aromatic hydrocarbons under low NOx conditions. The effects of the alkyl substitute number, location, carbon chain length and branching structure on the photooxidation of aromatic hydrocarbons are demonstrated by analyzing SOA yield, chemical composition and physical properties. Aromatic hydrocarbons, categorized into five groups, show a yield order of ortho (o-xylene and o-ethyltoluene) > one substitute (ethylbenzene, propylbenzene and isopropylbenzene) > meta (m-xylene and m-ethyltoluene) > three substitute (trimethylbenzenes) > para (p-xylene and p-ethyltoluene). SOA yields of aromatic hydrocarbon photooxidation do not monotonically decrease when increasing alkyl substitute number. The ortho position promotes SOA formation while the para position suppresses aromatic oxidation and SOA formation. Observed SOA chemical composition and volatility confirm that higher yield is associated with further oxidation. SOA chemical composition also suggests that aromatic oxidation increases with increasing alkyl substitute chain length and branching structure. Further, carbon dilution theory developed by Li et al. (2015a) is extended in this study to serve as a standard method to determine the extent of oxidation of an alkyl substituted aromatic hydrocarbon.

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 Assessing the impact of anthropogenic pollution on isoprene-derived secondary organic aerosol formation in PM<sub>2.5</sub> collected from the Birmingham, Alabama ground site during the 2013 Southern Oxidant and Aerosol Study

2016 ◽  
Author(s):  
W. Rattanavaraha ◽  
K. Chu ◽  
S. H. Budisulistiorini ◽  
M. Riva ◽  
Y.-H. Lin ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Secondary Organic Aerosol ◽  
Anthropogenic Pollution ◽  
Organic Aerosol ◽  
Limiting Factor ◽  
Ionization Mass ◽  
Aerosol Formation ◽  
Anthropogenic Pollutants ◽  
Aerosol Acidity ◽  
The Impact

Abstract. In the southeastern U.S., substantial emissions of isoprene from deciduous trees undergo atmospheric oxidation to form secondary organic aerosol (SOA) that contributes to fine particulate matter (PM2.5). Laboratory studies have revealed that anthropogenic pollutants, such as sulfur dioxide (SO2), oxides of nitrogen (NOx), and aerosol acidity, can enhance SOA formation from the hydroxyl radical (OH)-initiated oxidation of isoprene; however, the mechanisms by which specific pollutants enhance isoprene SOA in ambient PM2.5 remain unclear. As one aspect of an investigation to examine how anthropogenic pollutants influence isoprene-derived SOA formation, high-volume PM2.5 filter samples were collected at the Birmingham, Alabama (BHM) ground site during the 2013 Southern Oxidant and Aerosol Study (SOAS). Sample extracts were analyzed by gas chromatography/electron ionization-mass spectrometry (GC/EI-MS) with prior trimethylsilylation and ultra performance liquid chromatography coupled to an electrospray ionization high-resolution quadrupole time-of-flight mass spectrometry (UPLC/ESI-HR QTOFMS) to identify known isoprene SOA tracers. Tracers quantified using both surrogate and authentic standards were compared with collocated gas- and particle-phase data as well as meteorological data provided by the Southeastern Aerosol Research and Characterization (SEARCH) network to assess the impact of anthropogenic pollution on isoprene-derived SOA formation. Results of this study reveal that isoprene-derived SOA tracers contribute a substantial mass fraction of organic matter (OM) (~7 to ~20%). Isoprene-derived SOA tracers correlated with sulfate (SO42-) (r2 = 0.34, n = 117), but not with NOx. Moderate correlation between methacrylic acid epoxide and hydroxymethyl-methyl-α-lactone (MAE/HMML)-derived SOA tracers and nitrate radical production (P[NO3]) (r2 = 0.57, n = 40) were observed during nighttime, suggesting a potential role of NO3 radical in forming this SOA type. However, the nighttime correlation of these tracers with nitrogen dioxide (NO2) (r2 = 0.26, n = 40) was weaker. Ozone (O3) correlated strongly with MAE/HMML-derived tracers (r2 = 0.72, n = 30) and moderately with 2-methyltetrols (r2 = 0.34, n = 15) during daytime only, suggesting that a fraction of SOA formation could occur from isoprene ozonolysis in urban areas. No correlation was observed between aerosol pH and isoprene-derived SOA. Lack of correlation between aerosol acidity and isoprene-derived SOA indicates that acidity is not a limiting factor for isoprene SOA formation at the BHM site as aerosols were acidic enough to promote multiphase chemistry of isoprene-derived epoxides throughout the duration of the study. All in all, these results confirm the reports that anthropogenic pollutants enhance isoprene-derived SOA formation.

scholarly journals Secondary organic aerosol formation from isoprene photooxidation during cloud condensation–evaporation cycles

2016 ◽  
Vol 16 (3) ◽  
pp. 1747-1760 ◽  
Author(s):  
L. Brégonzio-Rozier ◽  
C. Giorio ◽  
F. Siekmann ◽  
E. Pangui ◽  
S. B. Morales ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Mass Concentration ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Water Soluble ◽  
Aerosol Formation ◽  
Multiphase Systems ◽  
Dry Conditions ◽  
Water Cloud ◽  
The Impact

Abstract. The impact of cloud events on isoprene secondary organic aerosol (SOA) formation has been studied from an isoprene ∕ NOx ∕ light system in an atmospheric simulation chamber. It was shown that the presence of a liquid water cloud leads to a faster and higher SOA formation than under dry conditions. When a cloud is generated early in the photooxidation reaction, before any SOA formation has occurred, a fast SOA formation is observed with mass yields ranging from 0.002 to 0.004. These yields are 2 and 4 times higher than those observed under dry conditions. When the cloud is generated at a later photooxidation stage, after isoprene SOA is stabilized at its maximum mass concentration, a rapid increase (by a factor of 2 or higher) of the SOA mass concentration is observed. The SOA chemical composition is influenced by cloud generation: the additional SOA formed during cloud events is composed of both organics and nitrate containing species. This SOA formation can be linked to the dissolution of water soluble volatile organic compounds (VOCs) in the aqueous phase and to further aqueous phase reactions. Cloud-induced SOA formation is experimentally demonstrated in this study, thus highlighting the importance of aqueous multiphase systems in atmospheric SOA formation estimations.

scholarly journals Measurement report: Distinct emissions and volatility distribution of intermediate-volatility organic compounds from on-road Chinese gasoline vehicles: implication of high secondary organic aerosol formation potential

2021 ◽  
Vol 21 (4) ◽  
pp. 2569-2583
Author(s):  
Rongzhi Tang ◽  
Quanyang Lu ◽  
Song Guo ◽  
Hui Wang ◽  
Kai Song ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Urban Areas ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Aerosol Formation ◽  
Test Cycle ◽  
Yield Data ◽  
Formation Potential ◽  
Gasoline Vehicles ◽  
Light Duty Vehicle

Abstract. In the present work, we performed chassis dynamometer experiments to investigate the emissions and secondary organic aerosol (SOA) formation potential of intermediate-volatility organic compounds (IVOCs) from an on-road Chinese gasoline vehicle. High IVOC emission factors (EFs) and distinct volatility distribution were recognized. The IVOC EFs for the China V vehicle ranged from 12.1 to 226.3 mg per kilogram fuel, with a median value of 83.7 mg per kilogram fuel, which was higher than that from US vehicles. Besides, a large discrepancy in volatility distribution and chemical composition of IVOCs from Chinese gasoline vehicle exhaust was discovered, with larger contributions of B14–B16 compounds (retention time bins corresponding to C14-C16 n-alkanes) and a higher percentage of n-alkanes. Further we investigated the possible reasons that influence the IVOC EFs and volatility distribution and found that fuel type, starting mode, operating cycles and acceleration rates did have an impact on the IVOC EF. When using E10 (ethanol volume ratio of 10 %, v/v) as fuel, the IVOC EF of the tested vehicle was lower than that using commercial China standard V fuel. The average IVOC-to-THC (total hydrocarbon) ratios for gasoline-fueled and E10-fueled gasoline vehicles were 0.07±0.01 and 0.11±0.02, respectively. Cold-start operation had higher IVOC EFs than hot-start operation. The China Light-Duty Vehicle Test Cycle (CLTC) produced 70 % higher IVOCs than those from the Worldwide Harmonized Light Vehicles Test Cycle (WLTC). We found that the tested vehicle emitted more IVOCs at lower acceleration rates, which leads to high EFs under CLTC. The only factor that may influence the volatility distribution and compound composition is the engine aftertreatment system, which has compound and volatility selectivity in exhaust purification. These distinct characteristics in EFs and volatility may result in higher SOA formation potential in China. Using published yield data and a surrogate equivalent method, we estimated SOA formation under different OA (organic aerosol) loading and NOx conditions. Results showed that under low- and high-NOx conditions at different OA loadings, IVOCs contributed more than 80 % of the predicted SOA. Furthermore, we built up a parameterization method to simply estimate the vehicular SOA based on our bottom-up measurement of VOCs (volatile organic compounds) and IVOCs, which would provide another dimension of information when considering the vehicular contribution to the ambient OA. Our results indicate that vehicular IVOCs contribute significantly to SOA, implying the importance of reducing IVOCs when making air pollution controlling policies in urban areas of China.

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