scholarly journals Seasonal Analysis of Reduced and Oxidized Nitrogen-Containing Organic Compounds at a Coastal Site

2021 ◽  
Author(s):  
Jenna C. Ditto ◽  
Jo Machesky ◽  
Drew R. Gentner
Keyword(s):  
Liquid Chromatography ◽  
Gas Phase ◽  
Functional Groups ◽  
Organic Compounds ◽  
High Resolution Mass Spectrometry ◽  
Analytical Techniques ◽  
Chemical Transformations ◽  
Particle Phase ◽  
Coastal Site ◽  
Reduced Nitrogen

Abstract. Nitrogen-containing organic compounds, which may be directly emitted to the atmosphere or may form via reactions with prevalent reactive nitrogen species (e.g. NH3, NOx, NO3), have important but uncertain effects on climate and human health. Using gas and liquid chromatography with soft ionization and high-resolution mass spectrometry, we performed a molecular-level speciation of functionalized organic compounds at a coastal site on the Long Island Sound in summer (during the LISTOS 2018 campaign) and winter. This region often experiences poor air quality due to the emissions of reactive anthropogenic, biogenic, and marine-derived compounds and their chemical transformation products. Indeed, we observed a range of functionalized compounds containing oxygen, nitrogen, and/or sulfur atoms resulting from a mix of direct emissions and chemical transformations, including photochemical processing in summer and aqueous-phase processing in winter. In both summer and winter, nitrogen-containing organic aerosols dominated the observed distribution of functionalized particle-phase species ionized by our analytical techniques, with 85 % and 68 % of measured compound abundance containing a nitrogen atom, respectively. Nitrogen-containing particles included reduced nitrogen functional groups (e.g. amines, imines, azoles) and common NOz contributors (e.g. organonitrates). The prevalence of reduced nitrogen functional groups observed in the particle-phase, while frequently paired with oxygen-containing groups elsewhere on the molecule, often rivaled that of oxidized nitrogen groups detected by our methods. Supplemental gas-phase measurements, collected on adsorptive samplers and analyzed with a novel liquid chromatography-based method, suggest that gas-phase reduced nitrogen compounds are possible contributing precursors to the observed nitrogen-containing particles. Altogether, this work highlights the prevalence of reduced nitrogen-containing compounds in the less-studied Northeastern U.S., and potentially in other regions with similar anthropogenic, biogenic, and marine source signatures.

scholarly journals Coupling of organic and inorganic aerosol systems and the effect on gas–particle partitioning in the southeastern US

2018 ◽  
Vol 18 (1) ◽  
pp. 357-370 ◽  
Author(s):  
Havala O. T. Pye ◽  
Andreas Zuend ◽  
Juliane L. Fry ◽  
Gabriel Isaacman-VanWertz ◽  
Shannon L. Capps ◽  
...  
Keyword(s):  
Gas Phase ◽  
Organic Compounds ◽  
Thermodynamic Model ◽  
Ambient Air ◽  
Particle Phase ◽  
Organic System ◽  
Pure Species ◽  
Southeastern Us ◽  
Model Predictions ◽  
Total Ammonia

Abstract. Several models were used to describe the partitioning of ammonia, water, and organic compounds between the gas and particle phases for conditions in the southeastern US during summer 2013. Existing equilibrium models and frameworks were found to be sufficient, although additional improvements in terms of estimating pure-species vapor pressures are needed. Thermodynamic model predictions were consistent, to first order, with a molar ratio of ammonium to sulfate of approximately 1.6 to 1.8 (ratio of ammonium to 2  ×  sulfate, RN∕2S  ≈  0.8 to 0.9) with approximately 70 % of total ammonia and ammonium (NHx) in the particle. Southeastern Aerosol Research and Characterization Network (SEARCH) gas and aerosol and Southern Oxidant and Aerosol Study (SOAS) Monitor for AeRosols and Gases in Ambient air (MARGA) aerosol measurements were consistent with these conditions. CMAQv5.2 regional chemical transport model predictions did not reflect these conditions due to a factor of 3 overestimate of the nonvolatile cations. In addition, gas-phase ammonia was overestimated in the CMAQ model leading to an even lower fraction of total ammonia in the particle. Chemical Speciation Network (CSN) and aerosol mass spectrometer (AMS) measurements indicated less ammonium per sulfate than SEARCH and MARGA measurements and were inconsistent with thermodynamic model predictions. Organic compounds were predicted to be present to some extent in the same phase as inorganic constituents, modifying their activity and resulting in a decrease in [H+]air (H+ in µg m−3 air), increase in ammonia partitioning to the gas phase, and increase in pH compared to complete organic vs. inorganic liquid–liquid phase separation. In addition, accounting for nonideal mixing modified the pH such that a fully interactive inorganic–organic system had a pH roughly 0.7 units higher than predicted using traditional methods (pH  =  1.5 vs. 0.7). Particle-phase interactions of organic and inorganic compounds were found to increase partitioning towards the particle phase (vs. gas phase) for highly oxygenated (O : C  ≥  0.6) compounds including several isoprene-derived tracers as well as levoglucosan but decrease particle-phase partitioning for low O : C, monoterpene-derived species.

scholarly journals Coupling of organic and inorganic aerosol systems and the effect on gas-particle partitioning in the southeastern United States

2017 ◽  
Author(s):  
Havala O. T. Pye ◽  
Andreas Zuend ◽  
Juliane L. Fry ◽  
Gabriel Isaacman-VanWertz ◽  
Shannon L. Capps ◽  
...  
Keyword(s):  
United States ◽  
Gas Phase ◽  
Organic Compounds ◽  
Thermodynamic Model ◽  
Southeastern United States ◽  
Particle Phase ◽  
Organic System ◽  
Pure Species ◽  
Model Predictions ◽  
Total Ammonia

Abstract. Several models were used to describe the partitioning of ammonia, water, and organic compounds between the gas and particle phase for conditions in the southeastern United States during summer 2013. Existing equilibrium models and frameworks were found to be sufficient although additional improvements in terms of estimating pure-species vapor pressures are needed. Thermodynamic model predictions were consistent, to first order, with a molar ratio of ammonium to sulfate of approximately 1.6 to 1.8 (Ratio of ammonium to 2 × sulfate, RN/2S ≈ 0.8 to 0.9) with approximately 70 % of total ammonia and ammonium (NHx) in the particle. Southeastern Aerosol Research and Characterization (SEARCH) network gas and aerosol and Southern Oxidant and Aerosol Study (SOAS) Monitor for Aerosols and Gases in Air (MARGA) aerosol measurements were consistent with these conditions. CMAQv5.2 regional chemical transport model predictions did not reflect these conditions due to biases in the nonvolatile cations that resulted from either overestimated emissions and/or underestimated mixing. In addition, gas-phase ammonia was overestimated in the CMAQ model leading to an even lower fraction of total ammonia in the particle. Chemical Speciation Network (CSN) and Aerosol Mass Spectrometer (AMS) measurements indicated less ammonium per sulfate than SEARCH and MARGA measurements and were inconsistent with thermodynamic model predictions. Organic compounds were predicted to be present to some extent in the same phase as inorganic constituents, modifying their activity and resulting in a decrease in [H+]air (H+ in μg m−3 air), increase in ammonia partitioning to the gas phase, and increase in pH compared to complete organic vs. inorganic liquid-liquid phase separation. In addition, accounting for non-ideal mixing modified the pH such that a fully interactive inorganic-organic system had a pH roughly 0.7 units higher than predicted by traditional methods (pH = 1.5 vs. 0.7). Particle-phase interactions of organic and inorganic compounds were found to increase partitioning towards the particle phase (vs. gas phase) for highly oxygenated (O : C ≥ 0.6) compounds including several isoprene-derived tracers as well as levoglucosan, but decrease particle-phase partitioning for low O : C, monoterpene-derived species.

scholarly journals Model for acid-base chemistry in nanoparticle growth (MABNAG)

2013 ◽  
Vol 13 (3) ◽  
pp. 7175-7222 ◽  
Author(s):  
T. Yli-Juuti ◽  
K. Barsanti ◽  
L. Hildebrandt Ruiz ◽  
A.-J. Kieloaho ◽  
U. Makkonen ◽  
...  
Keyword(s):  
Particle Size ◽  
Sulfuric Acid ◽  
Gas Phase ◽  
Organic Compounds ◽  
Particle Growth ◽  
Particle Phase ◽  
Vapor Pressures ◽  
Salt Formation ◽  
Acid Base ◽  
Nanoparticle Growth

Abstract. Climatic effects of newly-formed atmospheric secondary aerosol particles are to a large extent determined by their condensational growth rates. However, all the vapors condensing on atmospheric nanoparticles and growing them to climatically relevant sizes are not identified yet and the effects of particle phase processes on particle growth rates are poorly known. Besides sulfuric acid, organic compounds are known to contribute significantly to atmospheric nanoparticle growth. In this study a particle growth model MABNAG (Model for Acid-Base chemistry in NAnoparticle Growth) was developed to study the effect of salt formation on nanoparticle growth, which has been proposed as a potential mechanism lowering the equilibrium vapor pressures of organic compounds through dissociation in the particle phase and thus preventing their evaporation. MABNAG is a model for monodisperse aqueous particles and it couples dynamics of condensation to particle phase chemistry. Non-zero equilibrium vapor pressures, with both size and composition dependence, are considered for condensation. The model was applied for atmospherically relevant systems with sulfuric acid, one organic acid, ammonia, one amine and water in the gas phase allowed to condense on 3–20 nm particles. The effect of dissociation of the organic acid was found to be small under ambient conditions typical for a boreal forest site, but considerable for base-rich environments (gas phase concentrations of about 1010 cm−3 for the sum of the bases). The contribution of the bases to particle mass decreased as particle size increased, except at very high gas phase concentrations of the bases. The relative importance of amine versus ammonia did not change significantly as a function of particle size. While our results give a reasonable first estimate on the maximum contribution of salt formation to nanoparticle growth, further studies on, e.g. the thermodynamic properties of the atmospheric organics, concentrations of low-volatility organic acids and amines, along with studies investigating the applicability of thermodynamics for the smallest nanoparticles are needed to truly understand the acid-base chemistry of atmospheric nanoparticles.

scholarly journals Coupling a gas chromatograph simultaneously to a flame ionization detector and chemical ionization mass spectrometer for isomer-resolved measurements of particle-phase organic compounds

2020 ◽  
Author(s):  
Chenyang Bi ◽  
Jordan E. Krechmer ◽  
Graham O. Frazier ◽  
Wen Xu ◽  
Andrew T. Lambe ◽  
...  
Keyword(s):  
Functional Groups ◽  
Organic Compounds ◽  
Mass Spectrometer ◽  
Chemical Ionization ◽  
Measurement Techniques ◽  
Oxidation Products ◽  
Ionization Mass ◽  
Particle Phase ◽  
Gas Chromatograph ◽  
New Instrument

Abstract. Atmospheric oxidation products of volatile organic compounds consist of thousands of unique chemicals that have distinctly different physical and chemical properties depending on their detailed structures and functional groups. Measurement techniques that can achieve molecular characterizations with details down to functional groups (i.e., isomer-resolved resolution) are consequently necessary to provide understandings of differences of fate and transport within isomers produced in the oxidation process. We demonstrate a new instrument coupling the thermal desorption aerosol gas chromatograph (TAG), which enables the separation of isomers, with the high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS), which has the capability of classifying unknown compounds by their molecular formulas, and the flame ion detector (FID), which provide a near-universal response to organic compounds. The TAG-CIMS/FID is used to provide isomer-resolved measurements of samples from liquid standard injections and particle-phase organics generated in oxidation flow reactors. By coupling a TAG to a CIMS, the CIMS is enhanced with an additional dimension of information (resolution of individual molecules) at the cost of time resolution (i.e., one sample per hour instead of per minute). We found that isomers are prevalent in sample matrix with an average number of three to five isomers per formula depending on the precursors in the oxidation experiments. Additionally, a multi-reagent ionization mode is investigated in which both zero air and iodide are introduced as reagent ions, to examine the feasibility of extending the use of an individual CIMS to a broader range of analytes with still selective reagent ions. While this approach reduces iodide-adduct ions by a factor of two, [M−H]− and [M+O2]− ions produced from lower-polarity compounds increase by a factor of five to ten, improving their detection by CIMS. The method expands the range of detected chemical species by using two chemical ionization reagents simultaneously, enabled by the pre-separation of analyte molecules before ionization.

scholarly journals Model for acid-base chemistry in nanoparticle growth (MABNAG)

2013 ◽  
Vol 13 (24) ◽  
pp. 12507-12524 ◽  
Author(s):  
T. Yli-Juuti ◽  
K. Barsanti ◽  
L. Hildebrandt Ruiz ◽  
A.-J. Kieloaho ◽  
U. Makkonen ◽  
...  
Keyword(s):  
Particle Size ◽  
Sulfuric Acid ◽  
Gas Phase ◽  
Organic Compounds ◽  
Growth Rates ◽  
Particle Growth ◽  
Particle Phase ◽  
Salt Formation ◽  
Acid Base ◽  
Nanoparticle Growth

Abstract. Climatic effects of newly-formed atmospheric secondary aerosol particles are to a large extent determined by their condensational growth rates. However, all the vapours condensing on atmospheric nanoparticles and growing them to climatically relevant sizes are not identified yet and the effects of particle phase processes on particle growth rates are poorly known. Besides sulfuric acid, organic compounds are known to contribute significantly to atmospheric nanoparticle growth. In this study a particle growth model MABNAG (Model for Acid-Base chemistry in NAnoparticle Growth) was developed to study the effect of salt formation on nanoparticle growth, which has been proposed as a potential mechanism lowering the equilibrium vapour pressures of organic compounds through dissociation in the particle phase and thus preventing their evaporation. MABNAG is a model for monodisperse aqueous particles and it couples dynamics of condensation to particle phase chemistry. Non-zero equilibrium vapour pressures, with both size and composition dependence, are considered for condensation. The model was applied for atmospherically relevant systems with sulfuric acid, one organic acid, ammonia, one amine and water in the gas phase allowed to condense on 3–20 nm particles. The effect of dissociation of the organic acid was found to be small under ambient conditions typical for a boreal forest site, but considerable for base-rich environments (gas phase concentrations of about 1010 cm−3 for the sum of the bases). The contribution of the bases to particle mass decreased as particle size increased, except at very high gas phase concentrations of the bases. The relative importance of amine versus ammonia did not change significantly as a function of particle size. While our results give a reasonable first estimate on the maximum contribution of salt formation to nanoparticle growth, further studies on, e.g. the thermodynamic properties of the atmospheric organics, concentrations of low-volatility organics and amines, along with studies investigating the applicability of thermodynamics for the smallest nanoparticles are needed to truly understand the acid-base chemistry of atmospheric nanoparticles.

scholarly journals Atmospheric oxidation of 1,3-butadiene: characterization of gas and aerosol reaction products and implications for PM<sub>2.5</sub>

2014 ◽  
Vol 14 (24) ◽  
pp. 13681-13704 ◽  
Author(s):  
M. Jaoui ◽  
M. Lewandowski ◽  
K. Docherty ◽  
J. H. Offenberg ◽  
T. E. Kleindienst
Keyword(s):  
Gas Phase ◽  
Organic Compounds ◽  
The United States ◽  
Gas Chromatography Mass Spectrometry ◽  
Glyceric Acid ◽  
Particle Phase ◽  
Sampling System ◽  
A Value ◽  
Field Samples ◽  
Threonic Acid

Abstract. Secondary organic aerosol (SOA) was generated by irradiating 1,3-butadiene (13BD) in the presence of H2O2 or NOx. Experiments were conducted in a smog chamber operated in either flow or batch mode. A filter/denuder sampling system was used for simultaneously collecting gas- and particle-phase products. The chemical composition of the gas phase and SOA was analyzed using derivative-based methods (BSTFA, BSTFA + PFBHA, or DNPH) followed by gas chromatography–mass spectrometry (GC–MS) or high-performance liquid chromatography (HPLC) analysis of the derivative compounds. The analysis showed the occurrence of more than 60 oxygenated organic compounds in the gas and particle phases, of which 31 organic monomers were tentatively identified. The major identified products include glyceric acid, d-threitol, erythritol, d-threonic acid, meso-threonic acid, erythrose, malic acid, tartaric acid, and carbonyls including glycolaldehyde, glyoxal, acrolein, malonaldehyde, glyceraldehyde, and peroxyacryloyl nitrate (APAN). Some of these were detected in ambient PM2.5 samples, and could potentially serve as organic markers of 13BD. Furthermore, a series of oligoesters were detected and found to be produced through chemical reactions occurring in the aerosol phase between compounds bearing alcoholic groups and compounds bearing acidic groups. SOA was analyzed for organic mass to organic carbon (OM /OC) ratio, effective enthalpy of vaporization (Δ Hvapeff), and aerosol yield. The average OM /OC ratio and SOA density were 2.7 ± 0.09 and 1.2 ± 0.05, respectively. The average Δ Hvapeff was −26.08 ± 1.46 kJ mol−1, a value lower than that of isoprene SOA. The average laboratory SOA yield measured in this study at aerosol mass concentrations between 22.5 and 140.2 μg m−3 was 0.025 ± 0.011, a value consistent with the literature (0.021–0.178). While the focus of this study has been examination of the particle-phase measurements, the gas-phase photooxidation products have also been examined. The contribution of SOA products from 13BD oxidation to ambient PM2.5 was investigated by analyzing a series of ambient PM2.5 samples collected in several locations around the United States. In addition to the occurrence of several organic compounds in field and laboratory samples, glyceric acid, d-threitol, erythritol, erythrose, and threonic acid were found to originate only from the oxidation of 13BD based on our previous experiments involving chamber oxidation of a series of hydrocarbons. Initial attempts have been made to quantify the concentrations of these compounds. The average concentrations of these compounds in ambient PM2.5 samples from the California Research at the Nexus of Air Quality and Climate Change (CalNex) study ranged from 0 to approximately 14.1 ng m−3. The occurrence of several other compounds in both laboratory and field samples suggests that SOA originating from 13BD oxidation could contribute to the ambient aerosol mainly in areas with high 13BD emission rates.

scholarly journals Emissions of intermediate-volatility and semi-volatile organic compounds from domestic fuels used in Delhi, India

2021 ◽  
Vol 21 (4) ◽  
pp. 2407-2426 ◽  
Author(s):  
Gareth J. Stewart ◽  
Beth S. Nelson ◽  
W. Joe F. Acton ◽  
Adam R. Vaughan ◽  
Naomi J. Farren ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Municipal Solid Waste ◽  
Solid Waste ◽  
Gas Phase ◽  
Organic Compounds ◽  
Ambient Air ◽  
Emission Factors ◽  
Cow Dung ◽  
Particle Phase ◽  
Volatile Organic

Abstract. Biomass burning emits significant quantities of intermediate-volatility and semi-volatile organic compounds (I/SVOCs) in a complex mixture, probably containing many thousands of chemical species. These components are significantly more toxic and have poorly understood chemistry compared to volatile organic compounds routinely quantified in ambient air; however, analysis of I/SVOCs presents a difficult analytical challenge. The gases and particles emitted during the test combustion of a range of domestic solid fuels collected from across Delhi were sampled and analysed. Organic aerosol was collected onto Teflon (PTFE) filters, and residual low-volatility gases were adsorbed to the surface of solid-phase extraction (SPE) discs. A new method relying on accelerated solvent extraction (ASE) coupled to comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC × GC–ToF-MS) was developed. This highly sensitive and powerful analytical technique enabled over 3000 peaks from I/SVOC species with unique mass spectra to be detected. A total of 15 %–100 % of gas-phase emissions and 7 %–100 % of particle-phase emissions were characterised. The method was analysed for suitability to make quantitative measurements of I/SVOCs using SPE discs. Analysis of SPE discs indicated phenolic and furanic compounds were important for gas-phase I/SVOC emissions and levoglucosan to the aerosol phase. Gas- and particle-phase emission factors for 21 polycyclic aromatic hydrocarbons (PAHs) were derived, including 16 compounds listed by the US EPA as priority pollutants. Gas-phase emissions were dominated by smaller PAHs. The new emission factors were measured (mg kg−1) for PAHs from combustion of cow dung cake (615), municipal solid waste (1022), crop residue (747), sawdust (1236), fuelwood (247), charcoal (151) and liquefied petroleum gas (56). The results of this study indicate that cow dung cake and municipal solid waste burning are likely to be significant PAH sources, and further study is required to quantify their impact alongside emissions from fuelwood burning.

scholarly journals Emissions of intermediate-volatility and semi-volatile organic compounds from domestic fuels used in Delhi, India

2020 ◽  
Author(s):  
Gareth J. Stewart ◽  
Beth S. Nelson ◽  
W. Joe F. Acton ◽  
Adam R. Vaughan ◽  
Naomi J. Farren ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Municipal Solid Waste ◽  
Solid Waste ◽  
Gas Phase ◽  
Organic Compounds ◽  
Emission Factors ◽  
Cow Dung ◽  
Particle Phase ◽  
Fuel Wood ◽  
Volatile Organic

Abstract. Biomass burning emits significant quantities of intermediate-volatility and semi-volatile volatile organic compounds (I/SVOCs) in a complex mixture, probably containing many thousands of chemical species. These components are significantly more toxic and have poorly understood chemistry compared to volatile organic compounds routinely analysed in ambient air, however quantification of I/SVOCs presents a difficult analytical challenge. The gases and particles emitted during the test combustion of a range of domestic solid fuels collected from across New Delhi were sampled and analysed. Organic aerosol was collected onto Teflon (PTFE) filters and residual low-volatility gases were adsorbed to the surface of solid-phase extraction (SPE) disks. A new method relying on accelerated solvent extraction (ASE) coupled to comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-ToF-MS) was developed. This highly sensitive and powerful analytical technique enabled over 3000 peaks from I/SVOC species with unique mass spectra to be detected. 15–100 % of gas-phase emissions and 7–100 % of particle-phase emissions were characterised. The method was analysed for suitability to make quantitative measurements of I/SVOCs using SPE disks. Analysis of SPE disks indicated phenolic and furanic compounds were important to gas-phase I/SVOC emissions and levoglucosan to the aerosol phase. Gas- and particle-phase emission factors for 21 polycyclic aromatic hydrocarbons (PAHs) were derived, including 16 compounds listed by the US EPA as priority pollutants. Gas-phase emissions were dominated by smaller PAHs. New emission factors were measured (mg kg−1) for PAHs from combustion of cow dung cake (615), municipal solid waste (1022), crop residue (747), sawdust (1236), fuel wood (247), charcoal (151) and liquified petroleum gas (56). The results of this study indicate that cow dung cake and municipal solid waste burning are likely to be significant PAH sources and further study is required to quantify their impact, alongside emissions from fuel wood burning.

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