Photochemistry of mineral dust surface as a potential atmospheric renoxification process

Ndour, Marième; Conchon, Pierre; D’Anna, Barbara; Ka, Oumar; George, Christian

doi:10.1029/2008gl036662

Cited by 101 publications

(164 citation statements)

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“…The difference between the values observed by and by Underwood et al (2001) might be due to saturation effects at the higher pressures noted by . The same likely applies to the study of Li et al (2010) on CaCO 3 performed at NO 2 pressures in the 0.1 mbar range. We therefore recommend the parameterisation obtained by Ndour et al (2009) for Saharan dust, with a large uncertainty .…”

Section: Comments On Preferred Valuesmentioning

confidence: 91%

“…The same likely applies to the study of Li et al (2010) on CaCO 3 performed at NO 2 pressures in the 0.1 mbar range. We therefore recommend the parameterisation obtained by Ndour et al (2009) for Saharan dust, with a large uncertainty . Distinctly different mechanisms are suggested for the different substrates and especially in the presence and absence of water.…”

Section: Comments On Preferred Valuesmentioning

confidence: 91%

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Evaluated kinetic and photochemical data for atmospheric chemistry: Volume V – heterogeneous reactions on solid substrates

et al. 2010

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Abstract. This article, the fifth in the ACP journal series, presents data evaluated by the IUPAC Subcommittee on Gas Kinetic Data Evaluation for Atmospheric Chemistry. It covers the heterogeneous processes on surfaces of solid particles present in the atmosphere, for which uptake coefficients and adsorption parameters have been presented on the IUPAC website in 2010. The article consists of an introduction and guide to the evaluation, giving a unifying framework for parameterisation of atmospheric heterogeneous processes. We provide summary sheets containing the recommended uptake parameters for the evaluated processes. Four substantial appendices contain detailed data sheets for each process considered for ice, mineral dust, sulfuric acid hydrate and nitric acid hydrate surfaces, which provide information upon which the recommendations are made.

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Section: Comments On Preferred Valuesmentioning

confidence: 91%

Section: Comments On Preferred Valuesmentioning

confidence: 91%

Evaluated kinetic and photochemical data for atmospheric chemistry: Volume V – heterogeneous reactions on solid substrates

et al. 2010

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“…Ndour et al (2009a) have shown that nitrate ions adsorbed onto mixed TiO 2 /SiO 2 and pure TiO 2 can be converted into gaseous NO and NO 2 under UV irradiation. Moreover, it was shown that the interaction of NO 2 with TiO 2 (Monge et al, 2010) and commercial self-cleaning TiO 2 -containing window glass (Langridge et al, 2009) results in the formation of nitrous acid (HONO) in the gas phase, that may have a negative environmental impact (Monge et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

“…However, the antipolluting nature of the TiO 2 -containing materials was recently questioned (Langridge et al, 2009;Monge et al, 2010;Ndour et al, 2009a). Ndour et al (2009a) have shown that nitrate ions adsorbed onto mixed TiO 2 /SiO 2 and pure TiO 2 can be converted into gaseous NO and NO 2 under UV irradiation.…”

Section: Introductionmentioning

confidence: 99%

Interaction of NO<sub>2</sub> with TiO<sub>2</sub> surface under UV irradiation: measurements of the uptake coefficient

Zein

Bedjanian

2012

Atmos. Chem. Phys.

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Abstract. The interaction of NO 2 with TiO 2 solid films was studied under UV irradiation using a low pressure flow reactor (1-10 Torr) combined with a modulated molecular beam mass spectrometer for monitoring of the gaseous species involved. The NO 2 to TiO 2 reactive uptake coefficient was measured from the kinetics of NO 2 loss on TiO 2 coated Pyrex rods as a function of NO 2 concentration, irradiance intensity (J NO 2 = 0.002-0.012 s −1 ), relative humidity (RH = 0.06-69 %), temperature (T = 275-320 K) and partial pressure of oxygen (0.001-3 Torr). TiO 2 surface deactivation upon exposure to NO 2 was observed. The initial uptake coefficient of NO 2 on illuminated TiO 2 surface (with 90 ppb of NO 2 and J NO 2 ∼ =0.006 s −1 ) was found to be γ 0 = (1.2±0.4) ×10 −4 (calculated using BET surface area) under dry conditions at T = 300 K. The steady state uptake, γ , was several tens of times lower than the initial one, independent of relative humidity, and was found to decrease in the presence of molecular oxygen. In addition, it was shown that γ is not linearly dependent on the photon flux and seems to level off under atmospheric conditions. Finally, the following expression for γ was derived, γ = 2.3×10 −3 exp(-1910/T)/(1 + P 0.36 ) (where P is O 2 pressure in Torr), and recommended for atmospheric applications (for any RH, near 90 ppb of NO 2 and J NO 2 = 0.006 s −1 ).

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“…Daytime HONO formation pathways on aerosol and ground surfaces include the photo-enhanced heterogeneous conversion of NO 2 to HONO on TiO 2 (Bedjanian and El Zein, 2012;Langridge et al, 2009;Ndour et al, 2008Ndour et al, , 2009, soot (Ammann et al, 1998;Aubin and Abbatt, 2007;Gerecke et al, 1998;Khalizov et al, 2010;Monge et al, 2010), humic acid (BartelsRausch et al, 2010;Stemmler et al, 2006Stemmler et al, , 2007, and organic films (Brigante et al, 2008;George et al, 2005;Gutzwiller et al, 2002). While we know little about the detailed mechanism, Stemmler et al (2006) proposed that the formation of HONO from NO 2 to HONO conversion on surface-adsorbed humic acid is first order in NO 2 at low NO 2 mixing ratios and linearly dependent on irradiance.…”

Section: Introductionmentioning

confidence: 99%

Nitrous acid formation in a snow-free wintertime polluted rural area

et al. 2018

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Abstract. Nitrous acid (HONO) photolysis is an important source of hydroxyl radicals (OH) in the lower atmosphere, in particular in winter when other OH sources are less efficient. The nighttime formation of HONO and its photolysis in the early morning have long been recognized as an important contributor to the OH budget in polluted environments. Over the past few decades it has become clear that the formation of HONO during the day is an even larger contributor to the OH budget and additionally provides a pathway to recycle NO x . Despite the recognition of this unidentified HONO daytime source, the precise chemical mechanism remains elusive. A number of mechanisms have been proposed, including gas-phase, aerosol, and ground surface processes, to explain the elevated levels of daytime HONO. To identify the likely HONO formation mechanisms in a wintertime polluted rural environment we present LP-DOAS observations of HONO, NO 2 , and O 3 on three absorption paths that cover altitude intervals from 2 to 31, 45, and 68 m above ground level (a.g.l.) during the UBWOS 2012 experiment in the Uintah Basin, Utah, USA. Daytime HONO mixing ratios in the 2-31 m height interval were, on average, 78 ppt, which is lower than HONO levels measured in most polluted urban environments with similar NO 2 mixing ratios of 1-2 ppb. HONO surface fluxes at 19 m a.g.l., calculated using the HONO gradients from the LP-DOAS and measured eddy diffusivity coefficient, show clear upward fluxes. The hourly average vertical HONO flux during sunny days followed solar irradiance, with a maximum of (4.9 ± 0.2) × 10 10 molec. cm −2 s −1 at noontime. A photostationary state analysis of the HONO budget shows that the surface flux closes the HONO budget, accounting for 63 ± 32 % of the unidentified HONO daytime source throughout the day and 90 ± 30 % near noontime. This is also supported by 1-D chemistry and transport model calculations that include the measured surface flux, thus clearly identifying chemistry at the ground as the missing daytime HONO source in this environment. Comparison between HONO surface flux, solar radiation, NO 2 and HNO 3 mixing ratios, and results from 1-D model runs suggest that, under high NO x conditions, HONO formation mechanisms related to solar radiation and NO 2 mixing ratios, such as photo-enhanced conversion of NO 2 on the ground, are most likely the source of daytime HONO. Under moderate to low NO 2 conditions, photolysis of HNO 3 on the ground seems to be the main source of HONO.

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Photochemistry of mineral dust surface as a potential atmospheric renoxification process

Cited by 101 publications

References 12 publications

Evaluated kinetic and photochemical data for atmospheric chemistry: Volume V – heterogeneous reactions on solid substrates

Evaluated kinetic and photochemical data for atmospheric chemistry: Volume V – heterogeneous reactions on solid substrates

Interaction of NO<sub>2</sub> with TiO<sub>2</sub> surface under UV irradiation: measurements of the uptake coefficient

Nitrous acid formation in a snow-free wintertime polluted rural area

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Photochemistry of mineral dust surface as a potential atmospheric renoxification process

Cited by 101 publications

References 12 publications

Evaluated kinetic and photochemical data for atmospheric chemistry: Volume V – heterogeneous reactions on solid substrates

Evaluated kinetic and photochemical data for atmospheric chemistry: Volume V – heterogeneous reactions on solid substrates

Interaction of NO&lt;sub&gt;2&lt;/sub&gt; with TiO&lt;sub&gt;2&lt;/sub&gt; surface under UV irradiation: measurements of the uptake coefficient

Nitrous acid formation in a snow-free wintertime polluted rural area

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Interaction of NO<sub>2</sub> with TiO<sub>2</sub> surface under UV irradiation: measurements of the uptake coefficient