Formation of Volatile Organic Compounds in the Heterogeneous Oxidation of Condensed-Phase Organic Films by Gas-Phase OH

Abstract. In this study we modeled secondary organic aerosol (SOA) mass loadings from the oxidation (by O3, OH and NO3) of five representative biogenic volatile organic compounds (BVOCs): isoprene, endocyclic bond-containing monoterpenes (α-pinene and limonene), exocyclic double-bond compound (β-pinene) and a sesquiterpene (β-caryophyllene). The simulations were designed to replicate an idealized smog chamber and oxidative flow reactors (OFRs). The Master Chemical Mechanism (MCM) together with the peroxy radical autoxidation mechanism (PRAM) were used to simulate the gas-phase chemistry. The aim of this study was to compare the potency of MCM and MCM + PRAM in predicting SOA formation. SOA yields were in good agreement with experimental values for chamber simulations when MCM + PRAM was applied, while a stand-alone MCM underpredicted the SOA yields. Compared to experimental yields, the OFR simulations using MCM + PRAM yields were in good agreement for BVOCs oxidized by both O3 and OH. On the other hand, a stand-alone MCM underpredicted the SOA mass yields. SOA yields increased with decreasing temperatures and NO concentrations and vice versa. This highlights the limitations posed when using fixed SOA yields in a majority of global and regional models. Few compounds that play a crucial role (>95 % of mass load) in contributing to SOA mass increase (using MCM + PRAM) are identified. The results further emphasized that incorporating PRAM in conjunction with MCM does improve SOA mass yield estimation.

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Importance of biogenic volatile organic compounds to acyl peroxy nitrates (APN) production in the southeastern US during SOAS 2013

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-1867-2019 ◽

2019 ◽

Vol 19 (3) ◽

pp. 1867-1880 ◽

Cited By ~ 3

Author(s):

Shino Toma ◽

Steve Bertman ◽

Christopher Groff ◽

Fulizi Xiong ◽

Paul B. Shepson ◽

...

Keyword(s):

Volatile Organic Compounds ◽

Gas Phase ◽

Organic Compounds ◽

Model Simulation ◽

Statistical Correlation ◽

Organic Nitrates ◽

Biogenic Volatile Organic Compounds ◽

The North ◽

Southeastern Us ◽

Volatile Organic

Abstract. Gas-phase atmospheric concentrations of peroxyacetyl nitrate (PAN), peroxypropionyl nitrate (PPN), and peroxymethacryloyl nitrate (MPAN) were measured on the ground using a gas chromatograph electron capture detector (GC-ECD) during the Southern Oxidants and Aerosols Study (SOAS) 2013 campaign (1 June to 15 July 2013) in Centreville, Alabama, in order to study biosphere–atmosphere interactions. Average levels of PAN, PPN, and MPAN were 169, 5, and 9 pptv, respectively, and the sum accounts for an average of 16 % of NOy during the daytime (10:00 to 16:00 local time). Higher concentrations were seen on average in air that came to the site from the urban NOx sources to the north. PAN levels were the lowest observed in ground measurements over the past two decades in the southeastern US. A multiple regression analysis indicates that biogenic volatile organic compounds (VOCs) account for 66 % of PAN formation during this study. Comparison of this value with a 0-D model simulation of peroxyacetyl radical production indicates that at least 50 % of PAN formation is due to isoprene oxidation. MPAN has a statistical correlation with isoprene hydroxynitrates (IN). Organic aerosol mass increases with gas-phase MPAN and IN concentrations, but the mass of organic nitrates in particles is largely unrelated to MPAN.

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Modelling gas-phase recovery of volatile organic compounds during in situ thermal treatment

Journal of Contaminant Hydrology ◽

10.1016/j.jconhyd.2020.103698 ◽

2020 ◽

Vol 234 ◽

pp. 103698

Author(s):

Qianli Xie ◽

Kevin G. Mumford ◽

Bernard H. Kueper

Keyword(s):

Volatile Organic Compounds ◽

Thermal Treatment ◽

Gas Phase ◽

Organic Compounds ◽

Phase Recovery ◽

Volatile Organic

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Physicochemical uptake and release of volatile organic compounds by soil in coated-wall flow tube experiments with ambient air

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-2209-2019 ◽

2019 ◽

Vol 19 (4) ◽

pp. 2209-2232 ◽

Cited By ~ 3

Author(s):

Guo Li ◽

Yafang Cheng ◽

Uwe Kuhn ◽

Rongjuan Xu ◽

Yudong Yang ◽

...

Keyword(s):

Volatile Organic Compounds ◽

Organic Compounds ◽

Atmospheric Chemistry ◽

Soil Surface ◽

Ambient Air ◽

Flow Tube ◽

Heterogeneous Oxidation ◽

Volatile Organic ◽

Wall Flow

Abstract. Volatile organic compounds (VOCs) play a key role in atmospheric chemistry. Emission and deposition on soil have been suggested as important sources and sinks of atmospheric trace gases. The exchange characteristics and heterogeneous chemistry of VOCs on soil, however, are not well understood. We used a newly designed differential coated-wall flow tube system to investigate the long-term variability of bidirectional air–soil exchange of 13 VOCs under ambient air conditions of an urban background site in Beijing. Sterilized soil was investigated to address physicochemical processes and heterogeneous/multiphase reactions independently from biological activity. Most VOCs revealed net deposition with average uptake coefficients (γ) in the range of 10−7–10−6 (referring to the geometric soil surface area), corresponding to deposition velocities (Vd) of 0.0013–0.01 cm s−1 and soil surface resistances (Rc) of 98–745 s cm−1, respectively. Formic acid, however, was emitted at a long-term average rate of ∼6×10-3 nmol m−2 s−1, suggesting that it was formed and released upon heterogeneous oxidation of other VOCs. The soil–atmosphere exchange of one individual VOC species can be affected by both its surface degradation/depletion caused by surface reactions and by competitive uptake or heterogeneous formation/accommodation of other VOC species. Overall, the results show that physicochemical processing and heterogeneous oxidation on soil and soil-derived dust can act as a sink or as a source of atmospheric VOCs, depending on molecular properties and environmental conditions.

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Temporally resolved thermal desorption of volatile organics from nanoporous silica preconcentrator

The Analyst ◽

10.1039/d0an01822h ◽

2021 ◽

Vol 146 (1) ◽

pp. 109-117

Author(s):

William Winter ◽

Coco Day ◽

Joshua Prestage ◽

Tanya Hutter

Keyword(s):

Volatile Organic Compounds ◽

Gas Phase ◽

Organic Compounds ◽

Thermal Desorption ◽

Nanoporous Silica ◽

Volatile Organics ◽

Desorption Temperature ◽

Volatile Organic

Gas-phase volatile organic compounds (VOCs) are collected in a nanoporous silica preconcentrator, then released slowly by heating onto a detector. Desorption temperature depends on VOC properties, allowing potential discrimination.

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