scholarly journals Modeling nitrous acid and its impact on ozone and hydroxyl radical during the Texas Air Quality Study 2006

2012 ◽  
Vol 12 (2) ◽  
pp. 5851-5880 ◽  
Author(s):  
B. H. Czader ◽  
B. Rappenglück ◽  
P. Percell ◽  
D. W. Byun ◽  
F. Ngan ◽  
...  
Keyword(s):  
Air Quality ◽  
Hydroxyl Radical ◽  
Gas Phase ◽  
Nitrous Acid ◽  
Organic Materials ◽  
Optical Absorption Spectroscopy ◽  
Ozone Formation ◽  
Mixing Ratios ◽  
Quality Study ◽  
Mist Chamber

Abstract. Nitrous acid (HONO) mixing ratios for the Houston metropolitan area were simulated with the Community Multiscale Air Quality (CMAQ) model for an episode during the Texas Air Quality Study (TexAQS) II in August/September 2006 and compared to in-situ MC/IC (mist-chamber/ion chromatograph) and long path DOAS (Differential Optical Absorption Spectroscopy) measurements at three different altitudes. Several HONO sources were accounted for in simulations, such as gas phase formation, direct emissions, nitrogen dioxide (NO2*) hydrolysis, photo-induced formation from excited NO2* and photo-induced conversion of NO2 into HONO on surfaces covered with organic materials. Compared to the gas-phase HONO formation there was about a tenfold increase in HONO mixing ratios when additional HONO sources were taken into account, which improved the correlation between modeled and measured values. Concentrations of HONO simulated with only gas phase chemistry did not change with altitude, while measured HONO concentrations decrease with height. A trend of decreasing HONO concentration with altitude was well captured with CMAQ predicted concentrations when heterogeneous chemistry and photolytic sources of HONO were taken into account. Heterogeneous HONO production mainly accelerated morning ozone formation, albeit slightly. Also HONO formation from excited NO2 only slightly affected HONO and ozone (O3) concentrations. Photo-induced conversion of NO2 into HONO on surfaces covered with organic materials turned out to be a strong source of daytime HONO. Since HONO immediately photo-dissociates during daytime its ambient mixing ratios were only marginally altered (up to 0.5 ppbv), but significant increase in the hydroxyl radical (OH) and ozone concentration was obtained. In contrast to heterogeneous HONO formation that mainly accelerated morning ozone formation, inclusion of photo-induced surface chemistry influenced ozone throughout the day.

scholarly journals Modeling nitrous acid and its impact on ozone and hydroxyl radical during the Texas Air Quality Study 2006

2012 ◽  
Vol 12 (15) ◽  
pp. 6939-6951 ◽  
Author(s):  
B. H. Czader ◽  
B. Rappenglück ◽  
P. Percell ◽  
D. W. Byun ◽  
F. Ngan ◽  
...  
Keyword(s):  
Air Quality ◽  
Hydroxyl Radical ◽  
Gas Phase ◽  
Nitrous Acid ◽  
Organic Materials ◽  
Optical Absorption Spectroscopy ◽  
Ozone Formation ◽  
Mixing Ratios ◽  
Quality Study ◽  
Mist Chamber

Abstract. Nitrous acid (HONO) mixing ratios for the Houston metropolitan area were simulated with the Community Multiscale Air Quality (CMAQ) Model for an episode during the Texas Air Quality Study (TexAQS) II in August/September 2006 and compared to in-situ MC/IC (mist-chamber/ion chromatograph) and long path DOAS (Differential Optical Absorption Spectroscopy) measurements at three different altitude ranges. Several HONO sources were accounted for in simulations, such as gas phase formation, direct emissions, nitrogen dioxide (NO2) hydrolysis, photo-induced formation from excited NO2 and photo-induced conversion of NO2 into HONO on surfaces covered with organic materials. Compared to the gas-phase HONO formation there was about a tenfold increase in HONO mixing ratios when additional HONO sources were taken into account, which improved the correlation between modeled and measured values. Concentrations of HONO simulated with only gas phase chemistry did not change with altitude, while measured HONO concentrations decrease with height. A trend of decreasing HONO concentration with altitude was well captured with CMAQ predicted concentrations when heterogeneous chemistry and photolytic sources of HONO were taken into account. Heterogeneous HONO production mainly accelerated morning ozone formation, albeit slightly. Also HONO formation from excited NO2 only slightly affected HONO and ozone (O3) concentrations. Photo-induced conversion of NO2 into HONO on surfaces covered with organic materials turned out to be a strong source of daytime HONO. Since HONO immediately photo-dissociates during daytime its ambient mixing ratios were only marginally altered (up to 0.5 ppbv), but significant increase in the hydroxyl radical (OH) and ozone concentration was obtained. In contrast to heterogeneous HONO formation that mainly accelerated morning ozone formation, inclusion of photo-induced surface chemistry influenced ozone throughout the day.

scholarly journals Assessing indoor gas phase oxidation capacity through real-time measurements of HONO and NOxin Guangzhou, China

2019 ◽  
Vol 21 (8) ◽  
pp. 1393-1402 ◽  
Author(s):  
Jiangping Liu ◽  
Sheng Li ◽  
Jiafa Zeng ◽  
Majda Mekic ◽  
Zhujun Yu ◽  
...  
Keyword(s):  
Hydroxyl Radical ◽  
Real Time ◽  
Gas Phase ◽  
Nitrous Acid ◽  
Oxidation Capacity ◽  
Phase Oxidation ◽  
Gas Phase Oxidation

The photolysis of nitrous acid (HONO) is the main initiation source of hydroxyl radical (OH) which in turn is the main oxidant controlling the oxidation capacity of the indoor atmosphere.

scholarly journals Measurements of HONO during BAQS-Met

2010 ◽  
Vol 10 (24) ◽  
pp. 12285-12293 ◽  
Author(s):  
J. J. B. Wentzell ◽  
C. L. Schiller ◽  
G. W. Harris
Keyword(s):  
Gas Phase ◽  
Water Vapour ◽  
Nitrous Acid ◽  
Meteorological Parameters ◽  
Border Region ◽  
Night Time ◽  
Mixing Ratios ◽  
Oxidation Chemistry ◽  
Absorption Photometer ◽  
Shed Light

Abstract. Measurements of nitrous acid (HONO) were performed as part of the 2007 Border Air Quality and Meteorology Study (BAQS-Met) at the Harrow, Ontario, Canada supersite between 20 June and 10 July 2007. Nitrous acid is an important precursor of the hydroxyl radical and understanding its chemistry is important to understanding daytime oxidation chemistry. The HONO measurements were made using a custom built Long Path Absorption Photometer (LOPAP). The goal of this work was to shed light on sources of daytime HONO in the border region. During the course of the campaign HONO mixing ratios consistently exceeded expected daytime values by more than a factor of 6. Mean daytime mixing ratios of 61 pptv were observed. While HONO decay began at sunrise, minimum HONO values were measured during the late afternoon. There was little difference between the daytime (mean = 1.5%) and night-time (mean = 1.7%) ratios of HONO/NO2, thus there was a very strong daytime source of HONO which is consistent with other recent studies. Correlations of daytime HONO production with a variety of chemical and meteorological parameters indicate that production is dependent on UV radiation, NO2 and water vapour but is not consistent with a simple gas phase process. Apparent rate constants for the production of HONO from photolyticaly excited NO2 and water vapour vary from 2.8–7.8×10−13 cm3 molec−1 s−1, during the campaign. These results appear to be consistent with the heterogeneous conversion of NO2 enhanced by photo-excitation.

scholarly journals Considering the future of anthropogenic gas-phase organic compound emissions and the increasing influence of non-combustion sources on urban air quality

2018 ◽  
Vol 18 (8) ◽  
pp. 5391-5413 ◽  
Author(s):  
Peeyush Khare ◽  
Drew R. Gentner
Keyword(s):  
Air Quality ◽  
Chemical Composition ◽  
Volatile Organic Compounds ◽  
Gas Phase ◽  
Organic Compounds ◽  
Motor Vehicles ◽  
Ozone Formation ◽  
Life Cycle Approach ◽  
Volatile Organic ◽  
Emissions Inventories

Abstract. Decades of policy in developed regions has successfully reduced total anthropogenic emissions of gas-phase organic compounds, especially volatile organic compounds (VOCs), with an intentional, sustained focus on motor vehicles and other combustion-related sources. We examine potential secondary organic aerosol (SOA) and ozone formation in our case study megacity (Los Angeles) and demonstrate that non-combustion-related sources now contribute a major fraction of SOA and ozone precursors. Thus, they warrant greater attention beyond indoor environments to resolve large uncertainties in their emissions, oxidation chemistry, and outdoor air quality impacts in cities worldwide. We constrain the magnitude and chemical composition of emissions via several bottom-up approaches using chemical analyses of products, emissions inventory assessments, theoretical calculations of emission timescales, and a survey of consumer product material safety datasheets. We demonstrate that the chemical composition of emissions from consumer products as well as commercial and industrial products, processes, and materials is diverse across and within source subcategories. This leads to wide ranges of SOA and ozone formation potentials that rival other prominent sources, such as motor vehicles. With emission timescales from minutes to years, emission rates and source profiles need to be included, updated, and/or validated in emissions inventories with expected regional and national variability. In particular, intermediate-volatility and semi-volatile organic compounds (IVOCs and SVOCs) are key precursors to SOA, but are excluded or poorly represented in emissions inventories and exempt from emissions targets. We present an expanded framework for classifying VOC, IVOC, and SVOC emissions from this diverse array of sources that emphasizes a life cycle approach over longer timescales and three emission pathways that extend beyond the short-term evaporation of VOCs: (1) solvent evaporation, (2) solute off-gassing, and (3) volatilization of degradation by-products. Furthermore, we find that ambient SOA formed from these non-combustion-related emissions could be misattributed to fossil fuel combustion due to the isotopic signature of their petroleum-based feedstocks.

Corrigendum to: Atmospheric variation of nitrous acid at different sites in Europe

2007 ◽  
Vol 4 (5) ◽  
pp. 364 ◽  
Author(s):  
Karin Acker ◽  
Detlev Möller
Keyword(s):  
Hydroxyl Radical ◽  
Nitrous Acid ◽  
Field Experiments ◽  
Early Morning ◽  
Mixing Ratio ◽  
Gas Phase Reactions ◽  
Sources And Sinks ◽  
Mixing Ratios ◽  
Secondary Pollutants ◽  
Rural Sites

Environmental context. Nitrous acid (HNO2) is an important source of the hydroxyl radical (OH.), the most important daytime oxidising species that contributes to the formation of ozone as well as of other secondary pollutants in the troposphere. Understanding the sources and sinks of HNO2 is of crucial interest for accurately modelling the chemical composition of the troposphere and predicting future trace gas concentrations. Abstract. Nitrous acid and several other atmospheric components and variables were continuously measured during complex field experiments at seven different suburban and rural sites in Europe. HNO2 is mainly formed by heterogeneous processes and is often accumulated in the nighttime boundary layer. Our results confirm that the photolysis of HNO2 is an important source of the hydroxyl radical, not only in the early morning hours but also throughout the entire day, and is often comparable with the contribution of ozone and formaldehyde photolysis. At all research sites unexpectedly high HNO2 mixing ratios were observed during the daytime (up to several hundred ppt, or pmol mol-1). Moreover, surprisingly, the HNO2 mixing ratio at the three mountain sites often showed a broad maximum or several distinct peaks at midday and lower mixing ratios during the night. Assuming a quickly established photo-equilibrium between the known significant gas phase reactions, only a few ppt HNO2 should be present around noon. The ratio of known sources to sinks indicates a missing daytime HNO2 source of 160-2600 ppt h-1 to make up the balance. Based on these values and on production mechanisms proposed in the literature we hypothesise that the daytime mixing ratio levels may only be explained by a fast electron transfer onto adsorbed NO2.

Atmospheric variation of nitrous acid at different sites in Europe

2007 ◽  
Vol 4 (4) ◽  
pp. 242 ◽  
Author(s):  
Karin Acker ◽  
Detlev Möller
Keyword(s):  
Hydroxyl Radical ◽  
Nitrous Acid ◽  
Field Experiments ◽  
Early Morning ◽  
Mixing Ratio ◽  
Gas Phase Reactions ◽  
Sources And Sinks ◽  
Mixing Ratios ◽  
Secondary Pollutants ◽  
Rural Sites

Environmental context. Nitrous acid (HNO2) is an important source of the hydroxyl radical (OH•), the most important daytime oxidising species that contributes to the formation of ozone as well as of other secondary pollutants in the troposphere. Understanding the sources and sinks of HNO2 is of crucial interest for accurately modelling the chemical composition of the troposphere and predicting future trace gas concentrations. Abstract. Nitrous acid and several other atmospheric components and variables were continuously measured during complex field experiments at seven different suburban and rural sites in Europe. HNO2 is mainly formed by heterogeneous processes and is often accumulated in the nighttime boundary layer. Our results confirm that the photolysis of HNO2 is an important source of the hydroxyl radical, not only in the early morning hours but also throughout the entire day, and is often comparable with the contribution of ozone and formaldehyde photolysis. At all research sites unexpectedly high HNO2 mixing ratios were observed during the daytime (up to several hundred ppt, or pmol mol–1). Moreover, surprisingly, the HNO2 mixing ratio at the three mountain sites often showed a broad maximum or several distinct peaks at midday and lower mixing ratios during the night. Assuming a quickly established photo-equilibrium between the known significant gas phase reactions, only a few ppt HNO2 should be present around noon. The ratio of known sources to sinks indicates a missing daytime HNO2 source of 160–2600 ppt h–1 to make up the balance. Based on these values and on production mechanisms proposed in the literature we hypothesise that the daytime mixing ratio levels may only be explained by a fast electron transfer onto adsorbed NO2.

scholarly journals Abundance of NO3 Derived Organo-Nitrates and Their Importance in the Atmosphere

Atmosphere ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1381
Author(s):  
Amy Foulds ◽  
M. Anwar H. Khan ◽  
Thomas J. Bannan ◽  
Carl J. Percival ◽  
Mark H. Lowenberg ◽  
...  
Keyword(s):  
Air Quality ◽  
Significant Contribution ◽  
Transport Model ◽  
Temporal Analysis ◽  
Ozone Formation ◽  
Nitrate Radical ◽  
Night Time ◽  
Mixing Ratios ◽  
Model Measurement ◽  
Good Agreement

The chemistry of the nitrate radical and its contribution to organo-nitrate formation in the troposphere has been investigated using a mesoscale 3-D chemistry and transport model, WRF-Chem-CRI. The model-measurement comparisons of NO2, ozone and night-time N2O5 mixing ratios show good agreement supporting the model’s ability to represent nitrate (NO3) chemistry reasonably. Thirty-nine organo-nitrates in the model are formed exclusively either from the reaction of RO2 with NO or by the reaction of NO3 with alkenes. Temporal analysis highlighted a significant contribution of NO3-derived organo-nitrates, even during daylight hours. Night-time NO3-derived organo-nitrates were found to be 3-fold higher than that in the daytime. The reactivity of daytime NO3 could be more competitive than previously thought, with losses due to reaction with VOCs (and subsequent organo-nitrate formation) likely to be just as important as photolysis. This has highlighted the significance of NO3 in daytime organo-nitrate formation, with potential implications for air quality, climate and human health. Estimated atmospheric lifetimes of organo-nitrates showed that the organo-nitrates act as NOx reservoirs, with particularly short-lived species impacting on air quality as contributors to downwind ozone formation.

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