Thermodynamic characterization of Mexico City aerosol during MILAGRO 2006

Fountoukis, C.; Nenes, Athanasios; Sullivan, A.; Weber, R. J.; Reken, T. Van; Fischer, M. L.; Matías, E.; Moya, M.; Farmer, Delphine K.; Cohen, R. C.

doi:10.5194/acp-9-2141-2009

Cited by 134 publications

(177 citation statements)

References 41 publications

(47 reference statements)

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“…Evaporation also plays an important role as airmasses are advected away from Mexico City with the nitrate/ CO ratio dropping by about a factor of 4 . HNO 3 also reacts with dust to form supermicron nitrates, which contribute about a third of the total nitrate during dry periods (Querol et al, 2008;Fountoukis et al, 2009;McNaughton et al, 2009), consistent with a recent 3-D modeling study using MCMA-2003 data . The suppression of dust (and thus of this HNO 3 sink) by precipitation during the latter part of MILAGRO led to an increase of NH 4 NO 3 concentrations by over 50% after March 23 rd ).…”

Section: Secondary Inorganic Aerosols (Sia)supporting

confidence: 59%

“…The suppression of dust (and thus of this HNO 3 sink) by precipitation during the latter part of MILAGRO led to an increase of NH 4 NO 3 concentrations by over 50% after March 23 rd ). Model-predicted submicron nitrate levels inside Mexico City are often sensitive to the aerosol physical state (solid vs. liquid) assumption during periods with ambient RH less than 50% (Fountoukis et al, 2009;Karydis et al, 2010).…”

Section: Secondary Inorganic Aerosols (Sia)mentioning

confidence: 99%

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An overview of the MILAGRO 2006 Campaign: Mexico City emissions and their transport and transformation

et al. 2010

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Abstract. MILAGRO (Megacity Initiative: Local And Global Research Observations) is an international collaborative project to examine the behavior and the export of atmospheric emissions from a megacity. The Mexico City Metropolitan Area (MCMA) -one of the world's largest megacities and North America's most populous city -was selected as the case study to characterize the sources, concentrations, transport, and transformation processes of the gases and fine particles emitted to the MCMA atmosphere and to evaluate the regional and global impacts of these emissions. The findings of this study are relevant to the evolution and impacts of pollution from many other megacities.The measurement phase consisted of a month-long series of carefully coordinated observations of the chemistry and physics of the atmosphere in and near Mexico City duringCorrespondence to: L. T. Molina (ltmolina@mit.edu) March 2006, using a wide range of instruments at ground sites, on aircraft and satellites, and enlisting over 450 scientists from 150 institutions in 30 countries. Three ground supersites were set up to examine the evolution of the primary emitted gases and fine particles. Additional platforms in or near Mexico City included mobile vans containing scientific laboratories and mobile and stationary upward-looking lidars. Seven instrumented research aircraft provided information about the atmosphere over a large region and at various altitudes. Satellite-based instruments peered down into the atmosphere, providing even larger geographical coverage. The overall campaign was complemented by meteorological forecasting and numerical simulations, satellite observations and surface networks. Together, these research observations have provided the most comprehensive characterization of the MCMA's urban and regional atmospheric composition and chemistry that will take years to analyze and evaluate fully.Published by Copernicus Publications on behalf of the European Geosciences Union. L. T. Molina et al.: Mexico City emissions and their transport and transformationIn this paper we review over 120 papers resulting from the MILAGRO/INTEX-B Campaign that have been published or submitted, as well as relevant papers from the earlier MCMA-2003 Campaign, with the aim of providing a road map for the scientific community interested in understanding the emissions from a megacity such as the MCMA and their impacts on air quality and climate. This paper describes the measurements performed during MILAGRO and the results obtained on MCMA's atmospheric meteorology and dynamics, emissions of gases and fine particles, sources and concentrations of volatile organic compounds, urban and regional photochemistry, ambient particulate matter, aerosol radiative properties, urban plume characterization, and health studies. A summary of key findings from the field study is presented.

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Section: Secondary Inorganic Aerosols (Sia)supporting

confidence: 59%

Section: Secondary Inorganic Aerosols (Sia)mentioning

confidence: 99%

An overview of the MILAGRO 2006 Campaign: Mexico City emissions and their transport and transformation

et al. 2010

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“…The four oven channels are alternately sampled in two detection cells (P∼1.5 Torr 200 Pa) pumped in series by a single laser. Comparison of the HNO 3 (gas + aerosol) channel of this instrument to a particle-intoliquid sampler (PILS) HNO 3 measurement in the presence of high NH 3 shows strong agreement (Fountoukis et al, 2007).…”

Section: Atmosphere Simulation Chamber Saphirmentioning

confidence: 98%

Organic nitrate and secondary organic aerosol yield from NO<sub>3</sub> oxidation of β-pinene evaluated using a gas-phase kinetics/aerosol partitioning model

et al. 2009

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Abstract. The yields of organic nitrates and of secondary organic aerosol (SOA) particle formation were measured for the reaction NO 3 +β-pinene under dry and humid conditions in the atmosphere simulation chamber SAPHIR at Research Center Jülich. These experiments were conducted at low concentrations of NO 3 (NO 3 +N 2 O 5 <10 ppb) and β-pinene (peak∼15 ppb), with no seed aerosol. SOA formation was observed to be prompt and substantial (∼50% mass yield under both dry conditions and at 60% RH), and highly correlated with organic nitrate formation. The observed gas/aerosol partitioning of organic nitrates can be simulated using an absorptive partitioning model to derive an estimated vapor pressure of the condensing nitrate species of p vap ∼5×10 −6 Torr (6.67×10 −4 Pa), which constrains speculation about the oxidation mechanism and chemical identity of the organic nitrate. Once formed the SOA in this system continues to evolve, resulting in measurable aerosol volume decrease with time. The observations of high aerosol yield from NO x -dependent oxidation of monoterpenes provide an example of a significant anthropogenic source of SOA from biogenic hydrocarbon precursors. Estimates of the NO 3 +β-pinene SOA source strength for California and the globe indicate that NO 3 reactions with monoterpenes are likely an important source (0.5-8% of the global total) of organic aerosol on regional and global scales.

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“…First, gas and particle phases are assumed to be equilibrated. This seems reasonable given that we 30 use hourly measurement data and that the equilibration timescale for semi-volatile species between gas and submicron particles is estimated to be 15-30 min (Fountoukis et al, 2009). Second, the aerosol curvature effect on equilibrium partial pressures of semi-volatile species (also known as the Kelvin effect) is ignored.…”

Section: Assumptions and Limitations Of Thermodynamic Modelingmentioning

confidence: 99%

Fine particle pH for Beijing winter haze as inferred from different thermodynamic equilibrium models

Song¹,

Gao²,

Xu³

et al. 2018

Preprint

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Abstract. pH is an important property of aerosol particles but is difficult to measure directly. Several studies have estimated the pH values for fine particles in North China winter haze using thermodynamic models (i.e., E-AIM and ISORROPIA) and ambient measurements. The reported pH values differ widely, ranging from close to 0 (highly acidic) to as high as 7 (neutral).In order to understand the reason for this discrepancy, we calculated pH values using these models with different assumptions 25 with regard to model inputs and particle phase states. We find that the large discrepancy is due primarily to differences in the model assumptions adopted in previous studies. Calculations using only aerosol phase composition as inputs (i.e., reverse mode) are sensitive to the measurement errors of ionic species and inferred pH values exhibit a bimodal distribution with peaks between −2 and 2 and between 7 and 10. Calculations using total (gas plus aerosol phase) measurements as inputs (i.e., forward mode) are affected much less by the measurement errors, and results are thus superior to those obtained from the reverse mode 30 calculations. Forward mode calculations in this and previous studies collectively indicate a moderately acidic condition (pH from about 4 to about 5) for fine particles in North China winter haze, indicating further that ammonia plays an important role in determining this property. The differences in pH predicted by the forward mode E-AIM and ISORROPIA calculations may be attributed mainly to differences in estimates of activity coefficients for hydrogen ions. The phase state assumed, which can be either stable (solid plus liquid) or metastable (only liquid), does not significantly impact pH predictions of ISORROPIA. 35Atmos. Chem. Phys. Discuss., https://doi

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Thermodynamic characterization of Mexico City aerosol during MILAGRO 2006

Cited by 134 publications

References 41 publications

An overview of the MILAGRO 2006 Campaign: Mexico City emissions and their transport and transformation

An overview of the MILAGRO 2006 Campaign: Mexico City emissions and their transport and transformation

Organic nitrate and secondary organic aerosol yield from NO<sub>3</sub> oxidation of β-pinene evaluated using a gas-phase kinetics/aerosol partitioning model

Fine particle pH for Beijing winter haze as inferred from different thermodynamic equilibrium models

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Thermodynamic characterization of Mexico City aerosol during MILAGRO 2006

Cited by 134 publications

References 41 publications

An overview of the MILAGRO 2006 Campaign: Mexico City emissions and their transport and transformation

An overview of the MILAGRO 2006 Campaign: Mexico City emissions and their transport and transformation

Organic nitrate and secondary organic aerosol yield from NO&lt;sub&gt;3&lt;/sub&gt; oxidation of β-pinene evaluated using a gas-phase kinetics/aerosol partitioning model

Fine particle pH for Beijing winter haze as inferred from different thermodynamic equilibrium models

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Organic nitrate and secondary organic aerosol yield from NO<sub>3</sub> oxidation of β-pinene evaluated using a gas-phase kinetics/aerosol partitioning model