The chemical composition of secondary organic aerosols regulates transcriptomic and metabolomic signaling in an epithelial-endothelial in vitro coculture.

Background: The formation of secondary organic aerosols (SOA) by atmospheric oxidation reactions substantially contributes to the burden of fine particulate matter (PM), which has been associated with adverse health effects (e.g., cardiovascular diseases).

Observational evidence reveals the significance of nocturnal chemistry in seasonal secondary organic aerosol formation.

Oxidized Organic Aerosol (OOA), a major component of fine atmospheric particles, impacts climate and human health. Previous experiments and atmospheric models emphasize the importance of nocturnal OOA formation from NO· oxidation of biogenic VOCs. This seasonal study extends the understanding by showing that nocturnal oxidation of biomass-burning emissions can account for up to half of total OOA production in fall and winter.

Exposure to naphthalene and β-pinene-derived secondary organic aerosol induced divergent changes in transcript levels of BEAS-2B cells.

The health effects of exposure to secondary organic aerosols (SOAs) are still limited. Here, we investigated and compared the toxicities of soot particles (SP) coated with β-pinene SOA (SOA-SP) and SP coated with naphthalene SOA (SOA-SP) in a human bronchial epithelial cell line (BEAS-2B) residing at the air-liquid interface. SOA-SP mostly contained oxygenated aliphatic compounds from β-pinene photooxidation, whereas SOA-SP contained a significant fraction of oxygenated aromatic products under similar conditions.

Effect of Atmospheric Aging on Soot Particle Toxicity in Lung Cell Models at the Air-Liquid Interface: Differential Toxicological Impacts of Biogenic and Anthropogenic Secondary Organic Aerosols (SOAs).

Background: Secondary organic aerosols (SOAs) formed from anthropogenic or biogenic gaseous precursors in the atmosphere substantially contribute to the ambient fine particulate matter [PM in aerodynamic diameter ()] burden, which has been associated with adverse human health effects. However, there is only limited evidence on their differential toxicological impact.

Objectives: We aimed to discriminate toxicological effects of aerosols generated by atmospheric aging on combustion soot particles (SPs) of gaseous biogenic () or anthropogenic (naphthalene) precursors in two different lung cell models exposed at the air-liquid interface (ALI).

Highly Oxygenated Organic Nitrates Formed from NO Radical-Initiated Oxidation of β-Pinene.

The reactions of biogenic volatile organic compounds (BVOC) with the nitrate radicals (NO) are major night-time sources of organic nitrates and secondary organic aerosols (SOA) in regions influenced by BVOC and anthropogenic emissions. In this study, the formation of gas-phase highly oxygenated organic molecules-organic nitrates (HOM-ON) from NO-initiated oxidation of a representative monoterpene, β-pinene, was investigated in the SAPHIR chamber (Simulation of Atmosphere PHotochemistry In a large Reaction chamber). Six monomer (C = 7-10, N = 1-2, O = 6-16) and five accretion product (C = 17-20, N = 2-4, O = 9-22) families were identified and further classified into first- or second-generation products based on their temporal behavior.

Gas-Particle Partitioning and SOA Yields of Organonitrate Products from NO-Initiated Oxidation of Isoprene under Varied Chemical Regimes.

Alkyl nitrate (AN) and secondary organic aerosol (SOA) from the reaction of nitrate radicals (NO) with isoprene were observed in the Simulation of Atmospheric PHotochemistry In a large Reaction (SAPHIR) chamber during the NOIsop campaign in August 2018. Based on 15 day-long experiments under various reaction conditions, we conclude that the reaction has a nominally unity molar AN yield (observed range 90 ± 40%) and an SOA mass yield of OA + organic nitrate aerosol of 13-15% (with ∼50 μg m inorganic seed aerosol and 2-5 μg m total organic aerosol). Isoprene (5-25 ppb) and oxidant (typically ∼100 ppb O and 5-25 ppb NO) concentrations and aerosol composition (inorganic and organic coating) were varied while remaining close to ambient conditions, producing similar AN and SOA yields under all regimes.

Wintertime NO uptake coefficients over the North China Plain.

The heterogeneous hydrolysis of dinitrogen pentoxide (NO) plays an important role in regulating NO. The NO uptake coefficient, γ(NO), was determined using an iterative box model that was constrained to observational data obtained in suburban Beijing from February to March 2016. The box model determined 2289 individual γ(NO) values that varied from <0.

No Evidence for a Significant Impact of Heterogeneous Chemistry on Radical Concentrations in the North China Plain in Summer 2014.

The oxidation of nitric oxide to nitrogen dioxide by hydroperoxy (HO) and organic peroxy radicals (RO) is responsible for the chemical net ozone production in the troposphere and for the regeneration of hydroxyl radicals, the most important oxidant in the atmosphere. In Summer 2014, a field campaign was conducted in the North China Plain, where increasingly severe ozone pollution has been experienced in the last years. Chemical conditions in the campaign were representative for this area.

Fast Photochemistry in Wintertime Haze: Consequences for Pollution Mitigation Strategies.

In contrast to summer smog, the contribution of photochemistry to the formation of winter haze in northern mid-to-high latitude is generally assumed to be minor due to reduced solar UV and water vapor concentrations. Our comprehensive observations of atmospheric radicals and relevant parameters during several haze events in winter 2016 Beijing, however, reveal surprisingly high hydroxyl radical oxidation rates up to 15 ppbv/h, which is comparable to the high values reported in summer photochemical smog and is two to three times larger than those determined in previous observations during winter in Birmingham (Heard et al. 2004, 31, (18)), Tokyo (Kanaya et al.

Secondary organic aerosol reduced by mixture of atmospheric vapours.

Secondary organic aerosol contributes to the atmospheric particle burden with implications for air quality and climate. Biogenic volatile organic compounds such as terpenoids emitted from plants are important secondary organic aerosol precursors with isoprene dominating the emissions of biogenic volatile organic compounds globally. However, the particle mass from isoprene oxidation is generally modest compared to that of other terpenoids.

New application of direct analysis in real time high-resolution mass spectrometry for the untargeted analysis of fresh and aged secondary organic aerosols generated from monoterpenes.

Rationale: Secondary organic aerosols (SOAs) represent a significant portion of total atmospheric aerosols. They are generated by the oxidation of volatile organic compounds (VOCs), and particularly biogenic VOCs (BVOCs). The analysis of such samples is usually performed by targeted methods that often require time-consuming preparation steps that can induce loss of compounds and/or sample contaminations.

Corrigendum: Collocated observations of cloud condensation nuclei, particle size distributions, and chemical composition.

This corrects the article DOI: 10.1038/sdata.2017.

Collocated observations of cloud condensation nuclei, particle size distributions, and chemical composition.

Cloud condensation nuclei (CCN) number concentrations alongside with submicrometer particle number size distributions and particle chemical composition have been measured at atmospheric observatories of the Aerosols, Clouds, and Trace gases Research InfraStructure (ACTRIS) as well as other international sites over multiple years. Here, harmonized data records from 11 observatories are summarized, spanning 98,677 instrument hours for CCN data, 157,880 for particle number size distributions, and 70,817 for chemical composition data. The observatories represent nine different environments, e.

Nitrate radicals and biogenic volatile organic compounds: oxidation, mechanisms, and organic aerosol.

Oxidation of biogenic volatile organic compounds (BVOC) by the nitrate radical (NO) represents one of the important interactions between anthropogenic emissions related to combustion and natural emissions from the biosphere. This interaction has been recognized for more than 3 decades, during which time a large body of research has emerged from laboratory, field, and modeling studies. NO-BVOC reactions influence air quality, climate and visibility through regional and global budgets for reactive nitrogen (particularly organic nitrates), ozone, and organic aerosol.

Enhanced Volatile Organic Compounds emissions and organic aerosol mass increase the oligomer content of atmospheric aerosols.

Secondary organic aerosol (SOA) accounts for a dominant fraction of the submicron atmospheric particle mass, but knowledge of the formation, composition and climate effects of SOA is incomplete and limits our understanding of overall aerosol effects in the atmosphere. Organic oligomers were discovered as dominant components in SOA over a decade ago in laboratory experiments and have since been proposed to play a dominant role in many aerosol processes. However, it remains unclear whether oligomers are relevant under ambient atmospheric conditions because they are often not clearly observed in field samples.

Twenty years of ambient observations of nitrogen oxides and specified hydrocarbons in air masses dominated by traffic emissions in Germany.

The analysis of the individual composition of hydrocarbon (VOC) mixtures enables us to transform observed VOC-concentrations into their respective total VOC-reactivity versus OH radicals (RVOC = Σ(kOH+VOCi × [VOCi])). This is particularly useful because local ozone production essentially depends on this single parameter rather than on the details of the underlying hydrocarbon mixture (Klemp et al., Schriften des Forschungszentrums Jülich, Energy & Environment, 2012, 21).

ATMOSPHERIC SCIENCE. Response to Comment on "Missing gas-phase source of HONO inferred from Zeppelin measurements in the troposphere".

Ye et al. have determined a maximum nitrous acid (HONO) yield of 3% for the reaction HO2·H2O + NO2, which is much lower than the yield used in our work. This finding, however, does not affect our main result that HONO in the investigated Po Valley region is mainly from a gas-phase source that consumes nitrogen oxides.

Experimental determination of the partitioning coefficient of β-pinene oxidation products in SOAs.

The composition of secondary organic aerosols (SOAs) formed by β-pinene ozonolysis was experimentally investigated in the Juelich aerosol chamber. Partitioning of oxidation products between gas and particles was measured through concurrent concentration measurements in both phases. Partitioning coefficients (Kp) of 2.