scholarly journals Particulate organic nitrates observed in an oil and natural gas production region during wintertime

2015 ◽  
Vol 15 (16) ◽  
pp. 9313-9325 ◽  
Author(s):  
L. Lee ◽  
P. J. Wooldridge ◽  
J. deGouw ◽  
S. S. Brown ◽  
T. S. Bates ◽  
...  
Keyword(s):  
Field Measurements ◽  
Atomic Ratio ◽  
Gas Production ◽  
Heterogeneous Reactions ◽  
Organic Nitrate ◽  
Organic Nitrates ◽  
Production Region ◽  
Aerosol Mass ◽  
Oil And Natural Gas ◽  
Aerosol Volume

Abstract. Organic nitrates in both gas and condensed (aerosol) phases were measured during the Uintah Basin Winter Ozone Study from January to February in 2012. A high degree of correlation between total aerosol volume at diameters less than 500 nm and the particulate organic nitrate concentration indicates that organic nitrates are a consistent, if not dominant, fraction of fine aerosol mass. In contrast, a similar correlation with sub-2.5 μm aerosol volume is weaker. The C : N atomic ratio inferred from field measurements of PM2.5 and particulate organic nitrate is 34 : 1. Calculations constrained by the observations indicate that both condensation of gas-phase nitrates and heterogeneous reactions of NO3 / N2O5 are responsible for introducing organic nitrate functionality into the aerosol and that the source molecules are alkanes. Extrapolating the results to urban aerosol suggests organic nitrate production from alkanes may be a major secondary organic aerosol source.

scholarly journals Particulate organic nitrates observed in an oil and natural gas production region during wintertime

2015 ◽  
Vol 15 (7) ◽  
pp. 10677-10708 ◽  
Author(s):  
L. Lee ◽  
P. J. Wooldridge ◽  
J. deGouw ◽  
S. S. Brown ◽  
T. S. Bates ◽  
...  
Keyword(s):  
Field Measurements ◽  
Atomic Ratio ◽  
Gas Production ◽  
Heterogeneous Reactions ◽  
Organic Nitrate ◽  
Organic Nitrates ◽  
Production Region ◽  
Aerosol Mass ◽  
Oil And Natural Gas ◽  
Aerosol Volume

Abstract. Organic nitrates in both gas and condensed (aerosol) phases were measured during the Uintah Basin Winter Ozone Study from January to February in 2012. A high degree of correlation between total aerosol volume at diameters less than 500 nm and the particulate organic nitrate concentration indicates that organic nitrates are a consistent, if not dominant, fraction of fine aerosol mass. In contrast, a similar correlation with sub 2.5 μm aerosol volume is weaker. The C : N atomic ratio inferred from field measurements of PM2.5 and particulate organic nitrate is 34 : 1. Calculations constrained by the observations indicate that both condensation of gas phase nitrates and heterogeneous reactions of NO3 / N2O5 are responsible for introducing organic nitrate functionality into the aerosol and that the source molecules are alkanes. Extrapolating the results to urban aerosol suggests organic nitrate production from alkanes may be a major secondary organic aerosol source.

scholarly journals A Systematic Re-evaluation of Methods for Quantification of Bulk Particle-phase Organic Nitrates Using Real-time Aerosol Mass Spectrometry

2021 ◽  
Author(s):  
Douglas A. Day ◽  
Pedro Campuzano-Jost ◽  
Benjamin A. Nault ◽  
Brett B. Palm ◽  
Weiwei Hu ◽  
...  
Keyword(s):  
Phase Particle ◽  
Laboratory Data ◽  
Field Measurements ◽  
Organic Nitrate ◽  
Organic Nitrates ◽  
Particle Phase ◽  
Aerosol Formation ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Aerosol Mass Spectrometry

Abstract. Organic nitrate (RONO2) formation in the atmosphere represents a sink of NOx (NOx = NO + NO2) and termination of the NOx/HOx (HOx = HO2 + OH) ozone formation and radical propagation cycles, can act as a NOx reservoir transporting reactive nitrogen, and contributes to secondary organic aerosol formation. While some fraction of RONO2 is thought to reside in the particle phase, particle-phase organic nitrates (pRONO2) are infrequently measured and thus poorly understood. There is an increasing prevalence of aerosol mass spectrometer (AMS) instruments, which have shown promise for determining quantitative total organic nitrate functional group contribution to aerosols. A simple approach that relies on the relative intensities of NO+ and NO2+ ions in the AMS spectrum, the calibrated NOx+ ratio for NH4NO3, and the inferred ratio for pRONO2 has been proposed as a way to apportion the total nitrate signal to NH4NO3 and pRONO2. This method is increasingly being applied to field and laboratory data. However, the methods applied have been largely inconsistent and poorly characterized, and therefore, a detailed evaluation is timely. Here, we compile an extensive survey of NOx+ ratios measured for various pRONO2 compounds and mixtures from multiple AMS instruments, groups, and laboratory and field measurements. We show that, in the absence of pRONO2 standards, the pRONO2 NOx+ ratio can be estimated using a ratio referenced to the calibrated NH4NO3 ratio, a so-called Ratio-of-Ratios method (RoR = 2.75 ± 0.41). We systematically explore the basis for quantifying pRONO2 (and NH4NO3) with the RoR method using ground and aircraft field measurements conducted over a large range of conditions. The method is compared to another AMS method (positive matrix factorization, PMF) and other pRONO2 and related (e.g., total gas + particle RONO2) measurements, generally showing good agreement/correlation. A broad survey of ground and aircraft AMS measurements shows a pervasive trend of higher fractional contribution of pRONO2 to total nitrate with lower total nitrate concentrations, which generally corresponds to shifts from urban-influenced to rural/remote regions. Compared to ground campaigns, observations from all aircraft campaigns showed substantially lower pRONO2 contributions at mid ranges of total nitrate (0.01–0.1 up to 2–5 μg m−3), suggesting that the balance of effects controlling NH4NO3 and pRONO2 formation and lifetimes — such as higher humidity, lower temperatures, greater dilution, different sources, higher particle acidity, and pRONO2 hydrolysis (possibly accelerated by particle acidity) — favors lower pRONO2 contributions for those environments and altitudes sampled.

scholarly journals Secondary formation of nitrated phenols: insights from observations during the Uintah Basin Winter Ozone Study (UBWOS) 2014

2015 ◽  
Vol 15 (20) ◽  
pp. 28659-28697 ◽  
Author(s):  
B. Yuan ◽  
J. Liggio ◽  
J. Wentzell ◽  
S.-M. Li ◽  
H. Stark ◽  
...  
Keyword(s):  
Gas Phase ◽  
Oil And Gas ◽  
Gas Production ◽  
Heterogeneous Reactions ◽  
Box Model ◽  
Ionization Mass ◽  
Oil And Gas Production ◽  
Production Region ◽  
Secondary Formation ◽  
Online Measurements

Abstract. We describe the results from online measurements of nitrated phenols using a time of flight chemical ionization mass spectrometer (ToF-CIMS) with acetate as reagent ion in an oil and gas production region in January and February of 2014. Strong diurnal profiles were observed for nitrated phenols, with concentration maxima at night. Based on known markers (CH4, NOx, CO2), primary emissions of nitrated phenols were not important in this study. A box model was used to simulate secondary formation of phenol, nitrophenol (NP) and dinitrophenols (DNP). The box model results indicate that oxidation of aromatics in the gas phase can explain the observed concentrations of NP and DNP in this study. Photolysis was the most efficient loss pathway for NP in the gas phase. We show that aqueous-phase reactions and heterogeneous reactions were minor sources of nitrated phenols in our study. This study demonstrates that the emergence of new ToF-CIMS (including PTR-TOF) techniques allows for the measurement of intermediate oxygenates at low levels and these measurements improve our understanding of the evolution of primary VOCs in the atmosphere.

scholarly journals Characterization of nighttime formation of particulate organic nitrates based on high-resolution aerosol mass spectrometry in an urban atmosphere in China

2019 ◽  
Vol 19 (7) ◽  
pp. 5235-5249 ◽  
Author(s):  
Kuangyou Yu ◽  
Qiao Zhu ◽  
Ke Du ◽  
Xiao-Feng Huang
Keyword(s):  
High Resolution ◽  
Organic Aerosol ◽  
The United States ◽  
Ozone Production ◽  
Urban Site ◽  
Organic Nitrate ◽  
High Time Resolution ◽  
Organic Nitrates ◽  
Aerosol Mass

Abstract. Organic nitrates are important atmospheric species that significantly affect the cycling of NOx and ozone production. However, characterization of particulate organic nitrates and their sources in polluted atmosphere is a big challenge and has not been comprehensively studied in Asia. In this study, an aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) was deployed at an urban site in China from 2015 to 2016 to characterize particulate organic nitrates in total nitrates with a high time resolution. Based on the cross-validation of two different data processing methods, organic nitrates were effectively quantified to contribute a notable fraction of organic aerosol (OA), namely 9 %–21 % in spring, 11 %–25 % in summer, and 9 %–20 % in autumn, while contributing a very small fraction in winter. The good correlation between organic nitrates and fresh secondary organic aerosol (SOA) at night, as well as the diurnal trend of size distribution of organic nitrates, indicated a key role of nighttime local secondary formation of organic nitrates. Furthermore, theoretical calculations of nighttime SOA production of NO3 reactions with volatile organic compounds (VOCs) measured during the spring campaign were performed, resulting in three biogenic VOCs (α-pinene, limonene, and camphene) and one anthropogenic VOC (styrene) identified as the possible key VOC precursors to particulate organic nitrates. The comparison with similar studies in the literature implied that nighttime particulate organic nitrate formation is highly relevant to NOx levels. This study proposes that unlike the documented cases in the United States and Europe, modeling nighttime particulate organic nitrate formation in China should incorporate not only biogenic VOCs but also anthropogenic VOCs for urban air pollution, which needs the support of relevant smog chamber studies in the future.

scholarly journals SOA from limonene: role of NO<sub>3</sub> in its generation and degradation

2011 ◽  
Vol 11 (8) ◽  
pp. 3879-3894 ◽  
Author(s):  
J. L. Fry ◽  
A. Kiendler-Scharr ◽  
A. W. Rollins ◽  
T. Brauers ◽  
S. S. Brown ◽  
...  
Keyword(s):  
Organic Aerosol ◽  
Organic Nitrate ◽  
Organic Nitrates ◽  
Vapor Pressures ◽  
Aerosol Composition ◽  
Aerosol Mass ◽  
Mechanistic Insight ◽  
Seed Aerosol ◽  
Atmosphere Simulation Chamber

Abstract. The formation of organic nitrates and secondary organic aerosol (SOA) were monitored during the NO3 + limonene reaction in the atmosphere simulation chamber SAPHIR at Research Center Jülich. The 24-h run began in a purged, dry, particle-free chamber and comprised two injections of limonene and oxidants, such that the first experiment measured SOA yield in the absence of seed aerosol, and the second experiment yields in the presence of 10 μg m−3 seed organic aerosol. After each injection, two separate increases in aerosol mass were observed, corresponding to sequential oxidation of the two limonene double bonds. Analysis of the measured NO3, limonene, product nitrate concentrations, and aerosol properties provides mechanistic insight and constrains rate constants, branching ratios and vapor pressures of the products. The organic nitrate yield from NO3 + limonene is ≈30%. The SOA mass yield was observed to be 25–40%. The first injection is reproduced by a kinetic model. PMF analysis of the aerosol composition suggests that much of the aerosol mass results from combined oxidation by both O3 and NO3, e.g., oxidation of NO3 + limonene products by O3. Further, later aerosol nitrate mass seems to derive from heterogeneous uptake of NO3 onto unreacted aerosol alkene.

scholarly journals The Production and Hydrolysis of Organic Nitrates from OH Radical Oxidation of β-Ocimene

2020 ◽  
Author(s):  
Ana Cristina Morales ◽  
Thilina Jayarathne ◽  
Jonathan H. Slade ◽  
Alexander Laskin ◽  
Paul B. Shepson
Keyword(s):  
Rate Constants ◽  
Carbon Number ◽  
Agricultural Landscapes ◽  
Water Soluble ◽  
Hydrolysis Rate ◽  
Organic Nitrate ◽  
Organic Nitrates ◽  
Oh Radical ◽  
Radical Oxidation ◽  
Aerosol Mass

Abstract. Biogenic volatile organic compounds (BVOCs) emitted by plants represent the largest source of non-methane hydrocarbon emissions on Earth. Photochemical oxidation of BVOCs represents a significant pathway in the production of secondary organic aerosol (SOA), affecting Earth’s radiative balance. Organic nitrates (RONO2), formed from the oxidation of BVOCs in the presence of NOx, represent important aerosol precursors, and affect the oxidative capacity of the atmosphere, in part by sequestering NOx. In the aerosol phase, RONO2 hydrolyze to form nitric acid and numerous water-soluble products, thus contributing to an increase in aerosol mass. However, only a small number of studies have investigated the production of RONO2 from •OH oxidation of terpenes, among those, few have studied their hydrolysis. Here, we report a laboratory study of OH radical-initiated oxidation of β-ocimene, an acyclic, triolefinic monoterpene released during the daytime from vegetation, including forests, agricultural landscapes, and grasslands. We conducted studies of the OH radical oxidation of β-ocimene in the presence of NOx using a 5.5 m3 all-Teflon photochemical reaction chamber, during which we quantified the total (gas- and particle-phase) RONO2 yield and the SOA yields. We sampled the organic nitrates produced and measured their hydrolysis rate constants at different solution pH. The total organic nitrate yield was determined to be 33(±7) %, consistent with the available literature regarding the dependence of organic nitrate production (from RO2 + NO) on carbon number. We found the hydrolysis rate constants to be highly pH-dependent, with a hydrolysis lifetime of 51(±13) min at pH = 4, and 24(±3) min at pH = 2.5, a typical pH for deliquesced aerosols. We also employed high-resolution mass spectrometry for product identification, which is used to infer key mechanisms of gas–particle partitioning. The results indicate that the ocimene SOA yield under relevant aerosol mass loadings in the atmosphere is significantly lower (

scholarly journals The production and hydrolysis of organic nitrates from OH radical oxidation of <i>β</i>-ocimene

2021 ◽  
Vol 21 (1) ◽  
pp. 129-145
Author(s):  
Ana C. Morales ◽  
Thilina Jayarathne ◽  
Jonathan H. Slade ◽  
Alexander Laskin ◽  
Paul B. Shepson
Keyword(s):  
Mass Spectrometry ◽  
Rate Constants ◽  
Agricultural Landscapes ◽  
Water Soluble ◽  
Hydrolysis Rate ◽  
Organic Nitrate ◽  
Organic Nitrates ◽  
Ionization Mass ◽  
Particle Phase ◽  
Aerosol Mass

Abstract. Biogenic volatile organic compounds (BVOCs) emitted by plants represent the largest source of non-methane hydrocarbon emissions on Earth. Photochemical oxidation of BVOCs represents a significant pathway in the production of secondary organic aerosol (SOA), affecting Earth's radiative balance. Organic nitrates (RONO2), formed from the oxidation of BVOCs in the presence of NOx, represent important aerosol precursors and affect the oxidative capacity of the atmosphere, in part by sequestering NOx. In the aerosol phase, RONO2 hydrolyze to form nitric acid and numerous water-soluble products, thus contributing to an increase in aerosol mass. However, only a small number of studies have investigated the production of RONO2 from OH oxidation of terpenes, and among those, few have studied their hydrolysis. Here, we report a laboratory study of OH-initiated oxidation of β-ocimene, an acyclic, tri-olefinic monoterpene released during the daytime from vegetation, including forests, agricultural landscapes, and grasslands. We conducted studies of the OH oxidation of β-ocimene in the presence of NOx using a 5.5 m3 all-Teflon photochemical reaction chamber, during which we quantified the total (gas- and particle-phase) RONO2 yield and the SOA yields. We sampled the organic nitrates produced and measured their hydrolysis rate constants across a range of atmospherically relevant pH. The total organic nitrate yield was determined to be 38(±9) %, consistent with the available literature regarding the dependence of organic nitrate production (from RO2 + NO) on carbon number. We found the hydrolysis rate constants to be highly pH dependent, with a hydrolysis lifetime of 51(±13) min at pH = 4 and 24(±3) min at pH = 2.5, a typical pH for deliquesced aerosols. We also employed high-resolution mass spectrometry for preliminary product identification. The results indicate that the ocimene SOA yield (< 1 %) under relevant aerosol mass loadings in the atmosphere is significantly lower than reported yields from cyclic terpenes, such as α-pinene, likely due to alkoxy radical decomposition and formation of smaller, higher-volatility products. This is also consistent with the observed lower particle-phase organic nitrate yields of β-ocimene – i.e., 1.5(±0.5) % – under dry conditions. We observed the expected hydroxy nitrates by chemical ionization mass spectrometry (CIMS) and some secondary production of the dihydroxy dinitrates, likely produced by oxidation of the first-generation hydroxy nitrates. Lower RONO2 yields were observed under high relative humidity (RH) conditions, indicating the importance of aerosol-phase RONO2 hydrolysis under ambient RH. This study provides insight into the formation and fate of organic nitrates, β-ocimene SOA yields, and NOx cycling in forested environments from daytime monoterpenes not currently included in atmospheric models.

scholarly journals SOA from limonene: role of NO<sub>3</sub> in its generation and degradation

2010 ◽  
Vol 10 (12) ◽  
pp. 31083-31121
Author(s):  
J. L. Fry ◽  
A. Kiendler-Scharr ◽  
A. W. Rollins ◽  
T. Brauers ◽  
S. S. Brown ◽  
...  
Keyword(s):  
Organic Aerosol ◽  
Organic Nitrate ◽  
Organic Nitrates ◽  
Vapor Pressures ◽  
Aerosol Composition ◽  
Aerosol Mass ◽  
Mechanistic Insight ◽  
Seed Aerosol ◽  
Atmosphere Simulation Chamber

Abstract. The formation of organic nitrates and secondary organic aerosol (SOA) were monitored during the NO3 + limonene reaction in the atmosphere simulation chamber SAPHIR at Research Center Jülich. The 24-h run began in a purged, dry, particle-free chamber and comprised two injections of limonene and oxidants, such that the first experiment measured SOA yield in the absence of seed aerosol, and the second experiment yields in the presence of 10 μg m−3 seed organic aerosol. After each injection, two separate increases in aerosol mass were observed, corresponding to sequential oxidation of the two limonene double bonds. Analysis of the measured NO3, limonene, product nitrate concentrations, and aerosol properties provides mechanistic insight and constrains rate constants, branching ratios and vapor pressures of the products. The organic nitrate yield from NO3 + limonene is ≈30%. The SOA mass yield was observed to be 25–40%. The first injection is reproduced by a kinetic model. PMF analysis of the aerosol composition suggests that much of the aerosol mass results from combined oxidation by both O3 and NO3, e.g., oxidation of NO3 + limonene products by O3. Further, later aerosol nitrate mass seems to derive from heterogeneous uptake of NO3 onto unreacted aerosol alkene.

scholarly journals A comparative and experimental study of the reactivity with nitrate radical of two terpenes: <i>α</i>-terpinene and <i>γ</i>-terpinene

2020 ◽  
Vol 20 (23) ◽  
pp. 15167-15189
Author(s):  
Axel Fouqueau ◽  
Manuela Cirtog ◽  
Mathieu Cazaunau ◽  
Edouard Pangui ◽  
Jean-François Doussin ◽  
...  
Keyword(s):  
Main Reaction ◽  
Organic Nitrate ◽  
Organic Nitrates ◽  
Nitrate Radical ◽  
Reaction Products ◽  
Chemical Mechanisms ◽  
Chemical Structures ◽  
Aerosol Mass ◽  
Similar Chemical ◽  
Volatile Organic

Abstract. Biogenic volatile organic compounds (BVOCs) are intensely emitted by forests and crops into the atmosphere. During the night, they react very rapidly with the nitrate radical (NO3), leading to the formation of a variety of functionalized products including organic nitrates and to large amounts of secondary organic aerosols (SOAs). Organic nitrates (ONs) have been shown not only to play a key role in the transport of reactive nitrogen and consequently in the ozone budget but also to be important components of the total organic-aerosol mass, while SOAs are known to play a direct and indirect role in the climate. However, the reactivity of BVOCs with NO3 remains poorly studied. The aim of this work is to provide new kinetic and mechanistic data for two monoterpenes (C10H16), α- and γ-terpinene, through experiments in simulation chambers. These two compounds, which have very similar chemical structures, have been chosen in order not only to overcome the lack of experimental data but also to highlight the influence of the chemical structure on the reactivity. Rate constants have been measured using both relative and absolute methods. They were found to be (1.2±0.5)×10-10 and (2.9±1.1)×10-11 cm3 molecule−1 s−1 for α- and γ-terpinene respectively. Mechanistic studies have also been conducted in order to identify and quantify the main reaction products. Total organic nitrate and SOA yields have been determined. While organic nitrate formation yields appear to be similar, SOA yields exhibit large differences with γ-terpinene being a much more efficient precursor of aerosols. In order to provide explanations for this difference, chemical analysis of the gas-phase products was performed at the molecular scale. Detected products allowed for proposing chemical mechanisms and providing explanations through peroxy and alkoxy reaction pathways.

scholarly journals Organic nitrate aerosol formation via NO<sub>3</sub> + BVOC in the Southeastern US

2015 ◽  
Vol 15 (12) ◽  
pp. 16235-16272 ◽  
Author(s):  
B. R. Ayres ◽  
H. M. Allen ◽  
D. C. Draper ◽  
S. S. Brown ◽  
R. J. Wild ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Thermal Dissociation ◽  
Organic Nitrate ◽  
Organic Nitrates ◽  
Ionization Mass ◽  
Aerosol Formation ◽  
Phase Measurements ◽  
Aerosol Mass ◽  
Southeastern Us ◽  
Nitrate Aerosol

Abstract. Gas- and aerosol-phase measurements of oxidants, biogenic volatile organic compounds (BVOC) and organic nitrates made during the Southern Oxidant and Aerosol Study (SOAS campaign, Summer 2013) in central Alabama show that nitrate radical (NO3) reaction with monoterpenes leads to significant secondary aerosol formation. Cumulative losses of NO3 to terpenes are calculated and correlated to gas and aerosol organic nitrate concentrations made during the campaign. Correlation of NO3 radical consumption to organic nitrate aerosol as measured by Aerosol Mass Spectrometry (AMS) and Thermal Dissociation – Laser Induced Fluorescence (TD-LIF) suggests a range of molar yield of aerosol phase monoterpene nitrates of 23–44 %. Compounds observed via chemical ionization mass spectrometry (CIMS) are correlated to predicted nitrate loss to terpenes and show C10H17NO5, likely a hydroperoxy nitrate, is a major nitrate oxidized terpene product being incorporated into aerosols. The comparable isoprene product C5H9NO5 was observed to contribute less than 0.5 % of the total organic nitrate in the aerosol-phase and correlations show that it is principally a gas-phase product from nitrate oxidation of isoprene. Organic nitrates comprise between 30 and 45 % of the NOy budget during SOAS. Inorganic nitrates were also monitored and showed that during incidents of increased coarse-mode mineral dust, HNO3 uptake produced nitrate aerosol mass loading comparable to that of organic nitrate produced via NO3 + BVOC.

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