Role of the NO&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt; radicals in oxidation processes in the eastern Mediterranean troposphere during the MINOS campaign

Vrekoussis, Mihalis; Kanakidou, Maria; Mihalopoulos, Nikos; Crutzen, Paul J.; Lelieveld, J.; Perner, D.; Berresheim, H.; Baboukas, E.

doi:10.5194/acp-4-169-2004

Cited by 111 publications

(106 citation statements)

References 33 publications

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“…55,56 This result may well support our speculation that on the atmospheric particles, N 2 O 5 would ionize in the adsorbed water, leading to a sink of NO 3 and the generation of NO 2 + . As a result, the low ratio of [NO 3 (g)]/ [NO 2 + (aq)] on the particle surface would make the heterogeneous reaction of PAHs significantly different from that in the gas phase, causing different nitro-PAHs isomers to be produced.…”

Section: ■ Atmospheric Implicationssupporting

confidence: 82%

Effects of Humidity and [NO₃]/[N₂O₅] Ratio on the Heterogeneous Reaction of Fluoranthene and Pyrene with N₂O₅/NO₃/NO₂

Zhang

Sun

et al. 2014

Environ. Sci. Technol.

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Atmospheric 2-nitrofluoranthene (2-NFL) and 2-nitropyrene (2-NPY) were two important nitro-polycyclic aromatic hydrocarbons (NPAHs). Especially, 2-NFL was recognized to be the most abundant particle-associated NPAH . In previous studies, these two products were observed in the gas-phase reaction between N 2 O 5 /NO 3 /NO 2 and their parent polycyclic aromatic hydrocarbons (PAHs), while the heterogeneous reaction generated other nitro-PAH isomers (1, 3, 7, 8-NFL and 1-NPY) (Atkinson et al. 1990). To clarify the possible reasons for this difference, the heterogeneous reactions of suspended fluoranthene (FL) and pyrene (PY) particles under different relative humidity (RH; 0.5%−43%) and [NO 3 + (aq)] in the particle surface has an influence on the product distribution of FL and PY in the atmosphere. The experimental results provide evidence for the heterogeneous formations of particle-bound 2-NFL and 2-NPY. However, relative to the gas-phase formation, they will be negligible in the real atmosphere. 2-NFL and 2-NPY observed in the ambient particles should mainly derive from deposition of gas-phase reactions. Additionally, this study also clarifies the reason for different nitro-PAHs isomers observed between gas and particulate reactions. ■ INTRODUCTIONThe atmospheric chemistry between polycyclic aromatic hydrocarbons (PAHs) and gas-phase oxidants (O 3 , OH, NO 3 , and NO 2 ) is the most important source of toxic and mutagenic PAH derivatives (nitro-PAHs and oxy-PAHs) in the atmosphere. 1−6 Nitro-PAHs (NPAHs) have mutagenic potencies up to 100 000 times greater than PAHs 7−10 and constitute 10% of the total mutagenicity of inhalable particles in the ambient atmosphere. 11,12 Additionally, these nitrated species especially have strong narrow band adsorption bands in the UV−visible range, which may enhance the radiative forcing in the atmosphere and therefore contribute to significant climate effects. 13,14 Both 2-nitrofluoranthene (2-NFL) and 2-nitropyrene (2-NPY) are two ubiquitous nitro-PAH pollutants and ambient 2-NFL/2-NPY ratio is generally used to assess the contribution of the NO 3 radical chemistry for NPAHs formation. 15−18 Considering that neither 2-NFL nor 2-NPY have been directly observed from combustion emissions, 19−21 most research has focused on the contribution of the atmospheric reactions of FL and PY with gas-phase oxidants (OH or NO 3 radicals in the presence of NO 2 ). Some studies have suggested that these two nitro-PAHs were formed exclusively via atmospheric gas-phase reactions of FL and PY. 22,23 The production of 2-NFL involves the gas-phase reaction between FL and either OH or NO 3 radicals in the presence of NO 2 , whereas the production of 2-NPY mainly involves the gas-phase reaction of PY initiated by OH radical. 24−27 The formation of both 2-NFL and 2-NPY in the gas phase is a multistep addition−elimination reaction initiated by OH or NO 3 radical species. This radical-initiated reaction is postulated to proceed by an initiated-addition of OH radical (present during the day...

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Section: ■ Atmospheric Implicationssupporting

confidence: 82%

Effects of Humidity and [NO₃]/[N₂O₅] Ratio on the Heterogeneous Reaction of Fluoranthene and Pyrene with N₂O₅/NO₃/NO₂

Zhang

Sun

et al. 2014

Environ. Sci. Technol.

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“…Hua dust samples mainly originated from Gobi plants. NO (Formenti et al, 2011;Jöckel et al, 2003;Seinfeld and Pandis, 1998), but the NO − 3 formation is about 10 times faster than that of SO 2− 4 (Rodhe et al, 1981;Vrekoussis et al, 2004Vrekoussis et al, , 2007. Field observation showed that ground surface levels of NO 2 and SO 2 are similar in inland China.…”

Section: Difference In Chemical Composition Between Xi'an and Mt Huamentioning

confidence: 88%

Impact of Gobi desert dust on aerosol chemistry of Xi'an, inland China during spring 2009: differences in composition and size distribution between the urban ground surface and the mountain atmosphere

et al. 2013

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Abstract. Composition and size distribution of atmospheric aerosols from Xi'an city (∼ 400 m, altitude) in inland China during the spring of 2009 including a massive dust event on 24 April were measured and compared with a parallel measurement at the summit (2060 m, altitude) of Mt. Hua, an alpine site nearby Xi'an. EC (elemental carbon), OC (organic carbon) and major ions in the city were 2-22 times higher than those on the mountaintop during the whole sampling period. Compared to that in the non-dust period a sharp increase in OC was observed at both sites during the dust period, which was mainly caused by an input of biogenic organics from the Gobi desert. However, adsorption/heterogeneous reaction of gaseous organics with dust was another important source of OC in the urban, contributing 22 % of OC in the dust event. In contrast to the mountain atmosphere where fine particles were less acidic when dust was present, the urban fine particles became more acidic in the dust event than in the non-dust event, mainly due to enhanced heterogeneous formation of nitrate and diluted NH 3 . Cl − and NO − 3 in the urban air during the dust event significantly shifted toward coarse particles. Such redistributions were further pronounced on the mountaintop when dust was present, resulting in both ions almost entirely staying in coarse particles. On the contrary, no significant spatial difference in size distribution of SO 2− 4 was found between the urban ground surface and the mountain atmosphere, which dominated in the fine mode (< 2.1 µm) during the nonevent and comparably distributed in the fine (< 2.1 µm) and coarse (> 2.1 µm) modes during the dust event.

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“…Higher relative humidity during dew nights relative to nondew nights (Fig. 1) is likely to have a limiting influence on oxidation of GEM by NO 3 due to enhanced depletion of the radical (Geyer et al, 2001;Vrekoussis et al, 2004);Peleg et al (2015) noted a significant anti-correlation between relative humidity and NO 3 , as well as between relative humidity and GOM. They also highlighted possible evidence of GEM oxidation by O 3 , albeit only at levels above 47 ppb, higher than the nocturnal concentrations observed here.…”

Section: Nocturnal Atmospheric Mercury Depletion Eventsmentioning

confidence: 99%

Mercury fluxes over an Australian alpine grassland and observation of nocturnal atmospheric mercury depletion events

Howard

Edwards

2018

Atmos. Chem. Phys.

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Abstract. Aerodynamic gradient measurements of the airsurface exchange of gaseous elemental mercury (GEM) were undertaken over a 40 ha alpine grassland in Australia's Snowy Mountains region across a 3-week period during the late austral summer. Bi-directional GEM fluxes were observed throughout the study, with overall mean value of 0.2 ± 14.5 ng m −2 h −1 and mean nocturnal fluxes of −1.5 ± 7.8 ng m −2 h −1 compared to diurnal fluxes of 1.8 ± 18.6 ng m −2 h −1 . Deposition velocities ranged from −2.2 to 2.9 cm s −1 , whilst ambient GEM concentrations throughout the study were 0.59 ± 0.10 ng m −3 . Cumulative GEM fluxes correlated well with 24 h running mean soil temperatures, and one precipitation event was shown to have a positive impact on diurnal emission fluxes. The underlying vegetation had largely senesced and showed little stomatal control on fluxes. Nocturnal atmospheric mercury depletion events (NAMDEs) were observed concomitant with O 3 depletion and dew formation under shallow, stable nocturnal boundary layers. A mass balance box model was able to reproduce ambient GEM concentration patterns during NAMDE and non-NAMDE nights without invoking chemical oxidation of GEM throughout the column, indicating a significant role of surface processes controlling deposition in these events. Surface deposition was enhanced under NAMDE nights, though uptake to dew likely represents less than one-fifth of this enhanced deposition. Instead, enhancement of the surface GEM gradient as a result of oxidation at the surface in the presence of dew is hypothesised to be responsible for a large portion of GEM depletion during these particular events. GEM emission pulses following nights with significant deposition provide evidence for the prompt recycling of 17 % of deposited mercury, with the remaining portion retained in surface sinks. The long-term impacts of any sinks are however likely to be minimal, as cumulative GEM flux across the study period was close to zero.

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Role of the NO<sub>3</sub> radicals in oxidation processes in the eastern Mediterranean troposphere during the MINOS campaign

Cited by 111 publications

References 33 publications

Effects of Humidity and [NO₃]/[N₂O₅] Ratio on the Heterogeneous Reaction of Fluoranthene and Pyrene with N₂O₅/NO₃/NO₂

Effects of Humidity and [NO₃]/[N₂O₅] Ratio on the Heterogeneous Reaction of Fluoranthene and Pyrene with N₂O₅/NO₃/NO₂

Impact of Gobi desert dust on aerosol chemistry of Xi'an, inland China during spring 2009: differences in composition and size distribution between the urban ground surface and the mountain atmosphere

Mercury fluxes over an Australian alpine grassland and observation of nocturnal atmospheric mercury depletion events

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Role of the NO&lt;sub&gt;3&lt;/sub&gt; radicals in oxidation processes in the eastern Mediterranean troposphere during the MINOS campaign

Cited by 111 publications

References 33 publications

Effects of Humidity and [NO3]/[N2O5] Ratio on the Heterogeneous Reaction of Fluoranthene and Pyrene with N2O5/NO3/NO2

Effects of Humidity and [NO3]/[N2O5] Ratio on the Heterogeneous Reaction of Fluoranthene and Pyrene with N2O5/NO3/NO2

Impact of Gobi desert dust on aerosol chemistry of Xi'an, inland China during spring 2009: differences in composition and size distribution between the urban ground surface and the mountain atmosphere

Mercury fluxes over an Australian alpine grassland and observation of nocturnal atmospheric mercury depletion events

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Product

Resources

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Role of the NO<sub>3</sub> radicals in oxidation processes in the eastern Mediterranean troposphere during the MINOS campaign

Effects of Humidity and [NO₃]/[N₂O₅] Ratio on the Heterogeneous Reaction of Fluoranthene and Pyrene with N₂O₅/NO₃/NO₂

Effects of Humidity and [NO₃]/[N₂O₅] Ratio on the Heterogeneous Reaction of Fluoranthene and Pyrene with N₂O₅/NO₃/NO₂