scholarly journals Synergetic formation of secondary inorganic and organic aerosol: Influence of SO<sub>2</sub> and/or NH<sub>3</sub> in the heterogeneous process

2016 ◽  
Author(s):  
Biwu Chu ◽  
Xiao Zhang ◽  
Yongchun Liu ◽  
Hong He ◽  
Yele Sun ◽  
...  
Keyword(s):  
Secondary Organic Aerosol ◽  
Synergistic Effects ◽  
Particle Growth ◽  
Organic Aerosol ◽  
Interactive Effects ◽  
Aerosol Formation ◽  
Secondary Aerosol ◽  
Heterogeneous Process ◽  
So2 Concentration ◽  
Inorganic And Organic

Abstract. The effects of SO2 and NH3 on secondary organic aerosol formation have rarely been investigated together, while the interactive effects between inorganic and organic species under highly complex pollution conditions remain uncertain. Here we studied the effects of SO2 and NH3 on secondary aerosol formation in the photooxidation system of toluene/NOx in the presence or absence of Al2O3 seed aerosols in a 2 m3 smog chamber. The presence of SO2 increased new particle formation and particle growth significantly, regardless of whether NH3 was present or not. Sulfate, organic aerosol, nitrate and ammonium were all found to increase linearly with increasing SO2 concentrations. The increases in these four species were more obvious under NH3-rich conditions, and the generation of nitrate, ammonium and organic aerosol increased more significantly than sulfate with respect to SO2 concentration, while sulfate was the most sensitive species under NH3-poor conditions. The synergistic effects between SO2 and NH3 in the heterogeneous process contributed greatly to secondary aerosol formation. Specifically, the generation of NH4NO3 was found to be highly dependent on the surface area concentration of suspended particles, and increased most significantly among the four species with respect to SO2 concentration under ammonia-rich conditions. Meanwhile, the absorbed NH3 might provide a liquid surface layer for the absorption and subsequent reaction of SO2 and organic products, and therefore, enhance sulfate and secondary organic aerosol (SOA) formation. This effect mainly occurred in the heterogeneous process and resulted in a significantly higher growth rate of seed aerosols compared to that without NH3. By applying positive matrix factorization (PMF) analysis to the AMS data, two factors were identified for the generated SOA. One factor, assigned to less-oxidized organic aerosol and some oligomers, increased with increasing SO2 under NH3-poor conditions, mainly due to the well-known acid catalytic effect of the acid products on SOA formation in the heterogeneous process. The other factor, assigned to the highly oxidized organic component and some nitrogen-containing organics (NOC), increased with SO2 under a NH3-rich environment, with NOC (organonitrates and NOC with reduced N) contributing most of the increase.

scholarly journals Synergetic formation of secondary inorganic and organic aerosol: effect of SO<sub>2</sub> and NH<sub>3</sub> on particle formation and growth

2016 ◽  
Vol 16 (22) ◽  
pp. 14219-14230 ◽  
Author(s):  
Biwu Chu ◽  
Xiao Zhang ◽  
Yongchun Liu ◽  
Hong He ◽  
Yele Sun ◽  
...  
Keyword(s):  
Secondary Organic Aerosol ◽  
Synergistic Effects ◽  
Organic Aerosol ◽  
Particle Formation ◽  
Interactive Effects ◽  
Aerosol Formation ◽  
Secondary Aerosol ◽  
Heterogeneous Process ◽  
So2 Concentration ◽  
Inorganic And Organic

Abstract. The effects of SO2 and NH3 on secondary organic aerosol formation have rarely been investigated together, while the interactive effects between inorganic and organic species under highly complex pollution conditions remain uncertain. Here we studied the effects of SO2 and NH3 on secondary aerosol formation in the photooxidation system of toluene∕NOx in the presence or absence of Al2O3 seed aerosols in a 2 m3 smog chamber. The presence of SO2 increased new particle formation and particle growth significantly, regardless of whether NH3 was present. Sulfate, organic aerosol, nitrate, and ammonium were all found to increase linearly with increasing SO2 concentrations. The increases in these four species were more obvious under NH3-rich conditions, and the generation of nitrate, ammonium, and organic aerosol increased more significantly than sulfate with respect to SO2 concentration, while sulfate was the most sensitive species under NH3-poor conditions. The synergistic effects between SO2 and NH3 in the heterogeneous process contributed greatly to secondary aerosol formation. Specifically, the generation of NH4NO3 was found to be highly dependent on the surface area concentration of suspended particles, and increased most significantly with SO2 concentration among the four species under NH3-rich conditions. Meanwhile, the absorbed NH3 might provide a liquid surface layer for the absorption and subsequent reaction of SO2 and organic products and, therefore, enhance sulfate and secondary organic aerosol (SOA) formation. This effect mainly occurred in the heterogeneous process and resulted in a significantly higher growth rate of seed aerosols compared to without NH3. By applying positive matrix factorisation (PMF) analysis to the AMS data, two factors were identified for the generated SOA. One factor, assigned to less-oxidised organic aerosol and some oligomers, increased with increasing SO2 under NH3-poor conditions, mainly due to the well-known acid catalytic effect of the acid products on SOA formation in the heterogeneous process. The other factor, assigned to the highly oxidised organic component and some nitrogen-containing organics (NOC), increased with SO2 under a NH3-rich environment, with NOC (organonitrates and NOC with reduced N) contributing most of the increase.

Particulate matter emissions over the oil sands regions in Alberta, Canada

2017 ◽  
Vol 25 (4) ◽  
pp. 432-443 ◽  
Author(s):  
Zhenyu Xing ◽  
Ke Du
Keyword(s):  
Particulate Matter ◽  
Oil Sands ◽  
Secondary Organic Aerosol ◽  
Ambient Air ◽  
Organic Aerosol ◽  
Open Pit ◽  
Open Pit Mining ◽  
Formation Mechanisms ◽  
Aerosol Formation ◽  
Secondary Aerosol

Particulate matter (PM) emissions from the expanded oil sands development in Alberta are becoming a focus among the aerosol science community because of its significant negative impact on the regional air quality and climate change. Open-pit mining, petroleum coke (petcoke) dust, and the transportation of oil sands and waste materials by heavy-duty trucks on unpaved roads could release PM into the air. Incomplete combustion of fossil fuels by engines and stationary boilers leads to the formation of carbonaceous aerosols. In addition, wildfire and biogenic emissions surrounding the oil sands regions also have the potential to contribute primary PM to the ambient air. Secondary organic aerosol formation has been revealed as an important source of PM over nearby and distant areas from the oil sands regions. This review summarizes the primary PM sources and some secondary aerosol formation mechanisms that are linked to oil sands development. It also reviews the approaches that can be applied in aerosol source apportionment. Meteorological condition is an important factor that may influence the primary PM emission and secondary aerosol formation in Alberta’s oil sands regions. Current concern should not be limited to the primary emission of atmospheric PM. Secondary formation of aerosols, especially secondary organic aerosol originating from photochemical reaction, should also be taken into consideration. To obtain a more comprehensive understanding of the sources and amount of PM emissions based on the bottom-up emission inventory approach, investigations on how to reduce the uncertainty in determination of real-world PM emission factors for the variable sources are needed. Long-range transport trajectories of fine PM from Alberta’s oil sands regions remain unknown.

scholarly journals A secondary organic aerosol formation model considering successive oxidation aging and kinetic condensation of organic compounds: global scale implications

2011 ◽  
Vol 11 (3) ◽  
pp. 1083-1099 ◽  
Author(s):  
F. Yu
Keyword(s):  
Boundary Layer ◽  
Secondary Organic Aerosol ◽  
Large Fraction ◽  
Lower Boundary ◽  
Particle Growth ◽  
Organic Aerosol ◽  
Forest Site ◽  
Aerosol Formation ◽  
Formation Model ◽  
Condensation Nuclei

Abstract. The widely used two-product secondary organic aerosol (SOA) formation model has been extended in this study to consider the volatility changes of secondary organic gases (SOG) arising from the aging process as well as the kinetic condensation of low volatile SOG (LV-SOG). In addition to semi-volatile SOG (SV-SOG) with saturation vapor pressure at 290 K (C*290) in the range of ~3 ppt–3 ppb and medium-volatile SOG (MV-SOG) with C*290 in the range of ~0.3–300 ppb, we add a third component representing LV-SOG with C*290 below ~3 ppt and design a scheme to transfer MV-SOG to SV-SOG and SV-SOG to LV-SOG associated with oxidation aging. This extended SOA formation model has been implemented in a global aerosol model (GEOS-Chem) and the co-condensation of H2SO4 and LV-SOG on pre-existing particles is explicitly simulated. We show that, over many parts of the continents, LV-SOG concentrations are generally a factor of ~2–20 higher than those of H2SO4 and the kinetic condensation of LV-SOG significantly enhances particle growth rates. Comparisons of the simulated and observed evolution of particle size distributions at a boreal forest site (Hyytiälä, Finland) clearly show that LV-SOG condensation is critical in order to bring the simulations closer to the observations. With the new SOA formation scheme, annual mean SOA mass increases by a factor of 2–10 in many parts of the boundary layer and reaches above 0.5 μg m−3 in most parts of the main continents, improving the agreement with aerosol mass spectrometer (AMS) SOA measurements. While the new scheme generally decreases the concentration of condensation nuclei larger than 10 nm by 3–30% in the lower boundary layer as a result of enhanced surface area and reduced nucleation rates, it substantially increases the concentration of cloud condensation nuclei at a water supersaturation ratio of 0.2%, ranging from ~5–20% over a large fraction of oceans and high latitude continents to more than 50% over some parts of South America, Australia, and Indonesia. Our study highlights the importance for global aerosol models to explicitly account for the oxidation aging of SOGs and their contribution to particle growth.

scholarly journals An extended secondary organic aerosol formation model: effect of oxidation aging and implications

2010 ◽  
Vol 10 (8) ◽  
pp. 19811-19844 ◽  
Author(s):  
F. Yu
Keyword(s):  
Boundary Layer ◽  
Secondary Organic Aerosol ◽  
Large Fraction ◽  
Lower Boundary ◽  
Particle Growth ◽  
Organic Aerosol ◽  
Forest Site ◽  
Aerosol Formation ◽  
Formation Model ◽  
Condensation Nuclei

Abstract. The widely used 2-product secondary organic aerosol (SOA) formation model has been extended in this study to consider the volatility changes of secondary organic gases (SOGs) arising from the aging process. In addition to semi-volatile SOG (SV-SOG) and medium-volatile SOG (MV-SOG), we add a third component representing low-volatile SOG (LV-SOG) and design a scheme to transfer MV-SOG to SV-SOG and SV-SOG to LV-SOG associated with oxidation aging. This extended SOA formation model has been implemented in a global aerosol model (GEOS-Chem) and the co-condensation of H2SO4 and LV-SOG on pre-existing particles is explicitly simulated. We show that, over many parts of the continents, LV-SOG concentrations are generally a factor of ~2–20 higher than those of H2SO4 and LV-SOG condensation significantly enhances particle growth rates. Comparisons of the simulated and observed evolution of particle size distributions in a boreal forest site (Hyytiälä, Finland) clearly show that LV-SOG condensation is critical in order to bring the simulations closer to the observations. With the new SOA formation scheme, annual mean SOA mass increases by a fact of 2–10 in many parts of the boundary layer and reaches above 1 μg m−3 in most parts of the main continents. As a result of enhanced surface area and reduced nucleation rates, the new scheme generally decreases the concentration of condensation nuclei larger than 10 nm (CN10) by 3–30% in the lower boundary layer, which slightly improves agreement between simulated annual mean CN10 values and those observed in 21 surface sites around the globe. SOG oxidation aging and LV-SOG condensation substantially increases the concentration of cloud condensation nuclei at a water supersaturation ratio of 0.2%, ranging from ~3–10% over a large fraction of oceans to ~10–100% over major continents. Our study highlights the importance for global aerosol models to explicitly account for the oxidation aging of SOGs and their contribution of particle growth.

scholarly journals Secondary organic aerosol formation from biomass burning emissions

2019 ◽  
Author(s):  
Christopher Y. Lim ◽  
David H. Hagan ◽  
Matthew M. Coggon ◽  
Abigail R. Koss ◽  
Kanako Sekimoto ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Secondary Organic Aerosol ◽  
Total Concentration ◽  
Organic Aerosol ◽  
Oh Radicals ◽  
Aerosol Formation ◽  
Atmospheric Aging ◽  
Aerosol Mass ◽  
Photochemical Aging ◽  
Organic Gases

Abstract. Biomass burning is an important source of aerosol and trace gases to the atmosphere, but how these emissions change chemically during their lifetimes is not fully understood. As part of the Fire Influence on Regional and Global Environments Experiment (FIREX 2016), we investigated the effect of photochemical aging on biomass burning organic aerosol (BBOA), with a focus on fuels from the western United States. Emissions were sampled into a small (150 L) environmental chamber and photochemically aged via the addition of ozone and irradiation by 254 nm light. While some fraction of species undergoes photolysis, the vast majority of aging occurs via reaction with OH radicals, with total OH exposures corresponding to the equivalent of up to 10 days of atmospheric oxidation. For all fuels burned, large and rapid changes are seen in the ensemble chemical composition of BBOA, as measured by an aerosol mass spectrometer (AMS). Secondary organic aerosol (SOA) formation is seen for all aging experiments and continues to grow with increasing OH exposure, but the magnitude of the SOA formation is highly variable between experiments. This variability can be explained well by a combination of experiment-to-experiment differences in OH exposure and the total concentration of non-methane organic gases (NMOGs) in the chamber before oxidation, measured by PTR-ToF-MS (r2 values from 0.64 to 0.83). From this relationship, we calculate the fraction of carbon from biomass burning NMOGs that is converted to SOA as a function of equivalent atmospheric aging time, with carbon yields ranging from 24 ± 4 % after 6 hours to 56 ± 9 % after 4 days.

Secondary organic aerosol formation from untreated exhaust of gasoline four-stroke motorcycles

Urban Climate ◽  
2021 ◽  
Vol 36 ◽  
pp. 100778
Author(s):  
Sepideh Esmaeilirad ◽  
Ari Setyan ◽  
Jing Wang ◽  
Vahid Hosseini
Keyword(s):  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Aerosol Formation ◽  
Secondary Organic Aerosol Formation
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