Rapid deposition of oxidized biogenic compounds to a temperate forest

Nguyen, Tran B.; Crounse, J. D.; Teng, Alexander P.; Clair, Jason M. St.; Paulot, Fabien; Wolfe, G. M.; Wennberg, P. O.

doi:10.1073/pnas.1418702112

Cited by 242 publications

(469 citation statements)

References 106 publications

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“…Based on back-trajectories, the most probable transport time from the city to the measurement site was between 4 h and 5 h. By comparison, (4, 3)-ISOPOOH, isoprene, (1, 2)-ISOPOOH, MACR, and MVK have characteristic lifetimes to OH loss of ∼2 h, 3 h, 4 h, 10 h, and 14 h, respectively, for a reference OH concentration of 10 6 cm −3 typical of many environments. Deposition and entrainment can also be important loss mechanisms (26,27). Background air, meaning the Amazon basin in the nominal absence of the pollution plume of Manaus, had significant variability associated with it, especially with respect to effective photochemical age.…”

Section: Significancementioning

confidence: 99%

Isoprene photochemistry over the Amazon rainforest

Liu

Brito

Dorris

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

103

165

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Isoprene photooxidation is a major driver of atmospheric chemistry over forested regions. Isoprene reacts with hydroxyl radicals (OH) and molecular oxygen to produce isoprene peroxy radicals (ISOPOO). These radicals can react with hydroperoxyl radicals (HO 2 ) to dominantly produce hydroxyhydroperoxides (ISOPOOH). They can also react with nitric oxide (NO) to largely produce methyl vinyl ketone (MVK) and methacrolein (MACR). Unimolecular isomerization and bimolecular reactions with organic peroxy radicals are also possible. There is uncertainty about the relative importance of each of these pathways in the atmosphere and possible changes because of anthropogenic pollution. Herein, measurements of ISOPOOH and MVK + MACR concentrations are reported over the central region of the Amazon basin during the wet season. The research site, downwind of an urban region, intercepted both background and polluted air masses during the GoAmazon2014/5 Experiment. Under background conditions, the confidence interval for the ratio of the ISOPOOH concentration to that of MVK + MACR spanned 0.4-0.6. This result implies a ratio of the reaction rate of ISOPOO with HO 2 to that with NO of approximately unity. A value of unity is significantly smaller than simulated at present by global chemical transport models for this important, nominally low-NO, forested region of Earth. Under polluted conditions, when the concentrations of reactive nitrogen compounds were high (>1 ppb), ISOPOOH concentrations dropped below the instrumental detection limit (<60 ppt). This abrupt shift in isoprene photooxidation, sparked by human activities, speaks to ongoing and possible future changes in the photochemistry active over the Amazon rainforest.isoprene photochemistry | Amazon | organic hydroperoxides

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Section: Significancementioning

confidence: 99%

Isoprene photochemistry over the Amazon rainforest

Liu

Brito

Dorris

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

103

165

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“…It has been reported that the heterogeneous reaction is the most important sink for H 2 O 2 in urban (Liang et al, 2013b) and suburban areas (Guo et al, 2014). In contrast, OH-initiated reaction and dry deposition were regarded as the major removal pathways of organic peroxides in rural and forests areas (Nguyen et al, 2015). Here, heterogeneous uptake by aerosols turned out to be the predominant sink for atmospheric peroxides in the NCP, accounting for more than 60 % of the total loss, while dry deposition became the marginal removal pathway that contributed ∼ 10 % to the destruction of H 2 O 2 , MHP and PAA.…”

Section: Heterogeneous Uptake Of Peroxides By Aerosolmentioning

confidence: 96%

“…and 1.0 × 10 −5 s −1 , respectively at the PBL height of 1 km (Zhang et al, 2003;Emmerson et al, 2007;Lu et al, 2012;Guo et al, 2014;Liu et al, 2015;Nguyen et al, 2015). The PBL height over Wangdu during this campaign was derived from the hybrid single-particle lagrangian integrated trajectory (HYSPLIT) model (Draxler and Rolph, 2012), which varied between about 300 m at midnight and over 3000 m at noon.…”

Section: Model Descriptionmentioning

confidence: 99%

“…Zhao et al, 2013). The typical removal pathways of peroxides in the atmosphere are photolysis (Reactions R5, R6), reaction with OH radicals (Reactions R7, R8) and physical deposition (Atkinson et al, 2006;Sander et al, 2011;Nguyen et al, 2015). Heterogeneous uptake by atmospheric aerosols is recognized as another significant sink for peroxides in the troposphere, especially in dusty and polluted urban areas (Y.…”

Section: Introductionmentioning

confidence: 99%

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Observation of atmospheric peroxides during Wangdu Campaign 2014 at a rural site in the North China Plain

Wang

Chen

et al. 2016

Atmos. Chem. Phys.

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Abstract. Measurements of atmospheric peroxides were made during Wangdu Campaign 2014 at Wangdu, a rural site in the North China Plain (NCP) in summer 2014. The predominant peroxides were detected to be hydrogen peroxide (H 2 O 2 ), methyl hydroperoxide (MHP) and peroxyacetic acid (PAA). The observed H 2 O 2 reached up to 11.3 ppbv, which was the highest value compared with previous observations in China at summer time. A box model simulation based on the Master Chemical Mechanism and constrained by the simultaneous observations of physical parameters and chemical species was performed to explore the chemical budget of atmospheric peroxides. Photochemical oxidation of alkenes was found to be the major secondary formation pathway of atmospheric peroxides, while contributions from alkanes and aromatics were of minor importance. The comparison of modeled and measured peroxide concentrations revealed an underestimation during biomass burning events and an overestimation on haze days, which were ascribed to the direct production of peroxides from biomass burning and the heterogeneous uptake of peroxides by aerosols, respectively. The strengths of the primary emissions from biomass burning were on the same order of the known secondary production rates of atmospheric peroxides during the biomass burning events. The heterogeneous process on aerosol particles was suggested to be the predominant sink for atmospheric peroxides. The atmospheric lifetime of peroxides on haze days in summer in the NCP was about 2-3 h, which is in good agreement with the laboratory studies. Further comprehensive investigations are necessary to better understand the impact of biomass burning and heterogeneous uptake on the concentration of peroxides in the atmosphere.

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“…As these dummy 15 species will not participate in any further chemical reaction, their precursors are effectively removed from the model chemical scheme. The deposition velocities of peroxides, formic and nitric acid are based on (Nguyen et al, 2015) while those for PINAL and PAN are based on (Evans et al, 2000) using the average of the deposition rates for water, forest and grass. The model scheme is included in the supplementary of this manuscript.…”

Section: The Caaba/mecca Modelmentioning

confidence: 99%

Oxidation processes in the Eastern Mediterranean atmosphere: Evidence from the Modelling of HO<sub>x</sub> Measurements over Cyprus

Mallik¹,

Tomsche²,

Bourtsoukidis³

et al. 2018

Preprint

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Abstract. The Mediterranean is a climatically sensitive region located at the crossroads of air masses from three continents: 15Europe, Africa and Asia. The chemical processing of air masses over this region has implications not only for the air quality, but also for the long-range transport of air pollution. To obtain a comprehensive understanding of oxidation processes over the Mediterranean, atmospheric concentrations of the hydroxyl radical (OH) and the hydroperoxyl radical (HO2) were measured during an intensive field campaign (CYprus PHotochemistry EXperiment, CYPHEX-2014) in the north-west of Cyprus in the summer of 2014. Very low local anthropogenic and biogenic emissions around the measurement location 20 provided a vantage point to study the contrasts in atmospheric oxidation pathways under highly processed marine air masses and those influenced by relatively fresh emissions from mainland Europe.The CYPHEX measurements were used to evaluate OH and HO2 simulations using a photochemical box model (CAABA/MECCA) constrained with CYPHEX observations of O3, CO, NOx, hydrocarbons, peroxides and other major HOx (OH + HO2) sources and sinks in a low NOx environment (<100 pptv NO). The model simulations for OH showed very good 25 agreement with in-situ OH observations. Model simulations for HO2 also agreed fairly well with in-situ observations except when pinene levels exceeded 80 pptv. Different schemes to improve the agreement between observed and modelled HO2, including changing the rate coefficients for the reactions of terpene generated peroxy radicals (RO2) with NO and HO2 as well as the autoxidation of terpene generated RO2 species, are explored in this work. The main source of OH in Cyprus was its primary production from O3 photolysis during the day and HONO photolysis during early morning. Recycling contributed 30 about one-third of the total OH production, and the maximum recycling efficiency was about 70 %. CO, which was the largest OH sink was also the largest HO2 source. Lowest HOx production and losses occurred when the air masses had higher residence time over the oceans.Atmos. Chem. Phys. Discuss., https://doi.org/10. 5194/acp-2018-25 Manuscript under review for journal Atmos. Chem. Phys. Air pollution and HOx chemistryThe chemical and photochemical processing of air pollutants, in conjunction with local emissions, meteorology and atmospheric transport, strongly influences the air quality over a region. The regional air quality impacts human health, agriculture, the overall condition of the biosphere and subsequently the climate. Studies attribute 2-4 million premature 5 deaths globally to outdoor air pollution (Silva et al., 2013;Lelieveld et al., 2015). Oxidants in the Earth's atmosphere prevent the pollutants released into it from building up to toxic levels. These oxidants not only convert many toxic pollutants into less toxic forms (e.g. CO to CO2) but also help in their removal (e.g. NOx and SO2 are converted into soluble HNO3 and H2SO4 respectively), although some toxic chemicals may s...

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Rapid deposition of oxidized biogenic compounds to a temperate forest

Cited by 242 publications

References 106 publications

Isoprene photochemistry over the Amazon rainforest

Isoprene photochemistry over the Amazon rainforest

Observation of atmospheric peroxides during Wangdu Campaign 2014 at a rural site in the North China Plain

Oxidation processes in the Eastern Mediterranean atmosphere: Evidence from the Modelling of HO<sub>x</sub> Measurements over Cyprus

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Rapid deposition of oxidized biogenic compounds to a temperate forest

Cited by 242 publications

References 106 publications

Isoprene photochemistry over the Amazon rainforest

Isoprene photochemistry over the Amazon rainforest

Observation of atmospheric peroxides during Wangdu Campaign 2014 at a rural site in the North China Plain

Oxidation processes in the Eastern Mediterranean atmosphere: Evidence from the Modelling of HO&lt;sub&gt;x&lt;/sub&gt; Measurements over Cyprus

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Oxidation processes in the Eastern Mediterranean atmosphere: Evidence from the Modelling of HO<sub>x</sub> Measurements over Cyprus