Observations of biogenic volatile organic compounds over a mixed temperate forest during the summer to autumn transition

Atmospheric chemistry and physics, Journal Year: 2023, Volume and Issue: 23(7), P. 4123 - 4148

Published: April 5, 2023

Abstract. The exchange of trace gases between the biosphere and atmosphere is an important process that controls both chemical physical properties with implications for air quality climate change. terrestrial a major source reactive biogenic volatile organic compounds (BVOCs) govern atmospheric concentrations hydroxy radical (OH) ozone (O3) control formation growth secondary aerosol (SOA). Common simulations BVOC surface–atmosphere in transport models use parameterizations derived from growing season do not consider potential changes emissions during seasonal transitions. Here, we observations BVOCs over mixed temperate forest northern Wisconsin broadleaf senescence to better understand effects canopy conditions (e.g., temperature, sunlight, leaf area, stage) on net exchange. investigated here include terpenoids isoprene (C5H8), monoterpenes (MTs; C10H16), monoterpene oxide (C10H16O), sesquiterpenes (SQTs; C15H24), as well subset other oxides dimethyl sulfide (DMS). During this period, MTs were primarily composed α-pinene, β-pinene, camphene, α-pinene camphene dominant first half September β-pinene thereafter. We observed enhanced MT following onset suggest has be significant late-season ecosystem. show common cannot reproduce fluxes MT, C10H16O, SQT continuation but can correctly simulate flux. also describe impact emission enhancement form highly oxygenated molecules (HOMs). calculated production rates HOMs H2SO4, constrained by terpene DMS concentrations, region should dominated organics rather than sulfate. Further, using parameterized likely underestimate HOM production, thus formation, early autumn region. Further measurements forest–atmosphere transitions regions are needed effectively predict carbon cycling production.

Language: Английский

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Sources of Wintertime Atmospheric Organic Pollutants in a Large Canadian City: Insights from Particle and Gas Phase Measurements

ACS ES&T Air, Journal Year: 2024, Volume and Issue: 1(7), P. 690 - 703

Published: May 3, 2024

Although atmospheric organic pollutants have been extensively studied to elucidate summertime urban photochemical air pollution, uncertainties remain concerning the quality of wintertime in large northern North American cities. Here, we used online mass spectrometric measurements volatile compounds (VOCs) and aerosol (OA), combined with positive matrix factorization (PMF), identify sources downtown Toronto, Canada during February–March 2023. In some cases, comparable PMF factors were identified for both VOCs OA, such as from traffic, cooking, background oxygenated sources. However, VOC yielded additional information, a factor associated human-related emissions VOCs. Additionally, yields two traffic factors: one likely related gasoline diesel use. Despite cold relatively dark conditions, OA grow intensity daytime, indicative activity, whereas cooking enhanced morning late evening due timing vehicle use, boundary layer effects. This study illustrates benefits that arise parallel source–receptor analyses gases particles.

Language: Английский

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Measurement report: Molecular composition and volatility of gaseous organic compounds in a boreal forest – from volatile organic compounds to highly oxygenated organic molecules

Atmospheric chemistry and physics, Journal Year: 2021, Volume and Issue: 21(11), P. 8961 - 8977

Published: June 14, 2021

Abstract. The molecular composition and volatility of gaseous organic compounds were investigated during April–July 2019 at the Station for Measuring Ecosystem – Atmosphere Relations (SMEAR) II situated in a boreal forest Hyytiälä, southern Finland. In order to obtain more complete picture full understanding ambient (from volatile compounds, VOCs, highly oxygenated molecules, HOMs), two different instruments used. A Vocus proton-transfer-reaction time-of-flight mass spectrometer (Vocus PTR-ToF; hereafter Vocus) was deployed measure VOCs less (i.e., OVOCs). addition, multi-scheme chemical ionization inlet coupled an atmospheric pressure interface (MION API-ToF) used detect (using Br− as reagent ion; MION-Br) (including HOMs; using NO3- MION-NO3). comparison among measurement techniques revealed that highest elemental oxygen-to-carbon ratios (O : C) observed by MION-NO3 (0.9 ± 0.1, average 1 standard deviation), followed MION-Br (0.8 0.1); lowest O C (0.2 0.1). Diurnal patterns measured found vary techniques, even with same formula, suggesting contributions isomers detected and/or fragmentation from parent inside instruments. Based on complementary information obtained Vocus, MION-Br, MION-NO3, bulk all this obtained. As expected, VOC class most abundant (about 53.2 %), intermediate-volatility (IVOCs, about 45.9 %). Although condensable (low-volatility LVOCs; extremely low ELVOCs; ultralow-volatility ULVOCs) only comprised 0.2 % total they play important role new particle formation shown previous studies forest. Our study shows characterization advantages combining MION API-ToF measuring oxidation extents HOMs). results therefore provide comprehensive well insights into interpreting measurements or testing/improving parameterizations transport climate models.

Language: Английский

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Marine gas-phase sulfur emissions during an induced phytoplankton bloom

Atmospheric chemistry and physics, Journal Year: 2022, Volume and Issue: 22(2), P. 1601 - 1613

Published: Feb. 1, 2022

Abstract. The oxidation of dimethyl sulfide (DMS; CH3SCH3), emitted from the surface ocean, contributes to formation Aitken mode particles and their growth cloud condensation nuclei (CCN) sizes in remote marine environments. It is not clear whether other less commonly measured marine-derived, sulfur-containing gases share similar dynamics DMS contribute secondary aerosol formation. Here, we present measurements gas-phase volatile organosulfur molecules taken with a Vocus proton-transfer-reaction high-resolution time-of-flight mass spectrometer during mesocosm phytoplankton bloom experiment using coastal seawater. We show that DMS, methanethiol (MeSH; CH3SH), benzothiazole (C7H5NS) account for on average over 90 % total sulfur emissions, non-DMS sources representing 36.8 ± 7.7 emissions first 9 d pre-bloom phase prior major biological growth, before declining 14.5 6.0 latter half when dominates decay phases. molar ratio MeSH (DMS : = 4.60 0.93) was consistent range previously calculated ambient DMS-to-MeSH sea-to-air flux ratios. As progressed, emission increased significantly, reaching 31.8 18.7 decay. Measurements dimethylsulfoniopropionate (DMSP), heterotrophic bacteria, enzyme activity seawater suggest sensitive indicator bacterial demand composition magnitude available evolving new precursor gas, benzothiazole, have important implications sulfate pathways

Language: Английский

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Fragmentation inside proton-transfer-reaction-based mass spectrometers limits the detection of ROOR and ROOH peroxides

Atmospheric measurement techniques, Journal Year: 2022, Volume and Issue: 15(6), P. 1811 - 1827

Published: March 25, 2022

Abstract. Proton transfer reaction (PTR) is a commonly applied ionization technique for mass spectrometers, in which hydronium ions (H3O+) proton to analytes with higher affinities than the water molecule. This method has most been used quantify volatile hydrocarbons, but later-generation PTR instruments have designed better throughput of less species, allowing detection more functionalized molecules as well. For example, recently developed Vocus time-of-flight spectrometer (PTR-TOF) shown agree well an iodide-adduct-based chemical (CIMS) products 3–5 O atoms from oxidation monoterpenes (C10H16). However, while several different types CIMS (including those using iodide) detect abundant signals also at “dimeric” believed be primarily ROOR peroxides, no such observed even though these compounds fulfil condition having affinity water. More traditional limited inlets not transmission easily condensable species. Some newer instruments, like PTR, overcome this limitation are still able full range products, suggesting that other limitations need considered. One limitation, well-documented literature, tendency protonation lead fragmentation some analytes. In work, we evaluate potential dimers and oxygenated crucial forming atmospheric aerosol particles. We studied PTR-TOF laboratory experiments, through quantum calculations. Only noisy were during experiments on ozonolysis monoterpene α-pinene, few small dimeric detected cyclohexene. During latter tested varying pressures electric fields region PTR-TOF, finding only improvements possible relative dimer contributions. Calculations model ROOH systems showed peroxides should fragment partially following protonation. With inclusion additional energy ion–molecule collisions driven by source, computational results suggest substantial or nearly complete dimers. Our study thus suggests improved versions PTR-based spectrometers very powerful tools measuring hydrocarbons their moderately oxidized likely suitable

Language: Английский

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Recent advances in mass spectrometry techniques for atmospheric chemistry research on molecular‐level

Mass Spectrometry Reviews, Journal Year: 2023, Volume and Issue: 43(5), P. 1091 - 1134

Published: July 13, 2023

Abstract The Earth's atmosphere is composed of an enormous variety chemical species associated with trace gases and aerosol particles whose composition chemistry have critical impacts on the climate, air quality, human health. Mass spectrometry analysis as a powerful popular analytical technique has been widely developed applied in atmospheric for decades. allows effective detection, identification, quantification broad range organic inorganic high sensitivity resolution. In this review, we summarize recently mass techniques, methods, applications research past several years molecular‐level. Specifically, new developments ion‐molecule reactors, various soft ionization unique coupling separation techniques are highlighted. laboratory studies field measurements focused improving detection limits traditional emerging volatile compounds, characterizing multiphase highly oxygenated molecules, monitoring particle bulk surface compositions.

Language: Английский

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Tracing the Formation of Secondary Aerosols Influenced by Solar Radiation and Relative Humidity in Suburban Environment

Journal of Geophysical Research Atmospheres, Journal Year: 2022, Volume and Issue: 127(17)

Published: Sept. 1, 2022

Abstract Secondary particulate matter exerts adverse effects on air quality and human health. The production or reaction rate of secondary aerosols in polluted environments remains uncertain is complicated by diverse emissions meteorological conditions. By concurrently measuring the mass spectra compounds both (using an aerosol spectrometer) gas phases proton‐transfer‐reaction spectrometry) suburban Beijing, we linked organic (OA) volatile (VOCs) to photochemical age ( t ) obtained their rates. Factorization analysis OA 108 VOC species resolved three oxygenated OAs (OOA) factors at different oxidation levels. Primary VOCs from traffic sources were determined be important for formation. At high pollution levels under conditions weaker solar radiation higher relative humidity, moderately (O/C = 0.61) inorganics coproduced combination with rapid consumption all VOCs. lower levels, intense caused substantial OOA 0.81) intermediate (both a state) 15.0% h −1 14.0% , respectively. These results highlight feedback between moisture terms altering formation mechanism aerosols. In particular, highly airborne products strong should considered regard environmental impact.

Language: Английский

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Characterization of organic vapors by a Vocus proton-transfer-reaction mass spectrometry at a mountain site in southeastern China

The Science of The Total Environment, Journal Year: 2024, Volume and Issue: 919, P. 170633 - 170633

Published: Feb. 9, 2024

Language: Английский

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Deployment and evaluation of an NH₄⁺∕ H₃O⁺ reagent ion switching chemical ionization mass spectrometer for the detection of reduced and oxygenated gas-phase organic compounds

Atmospheric measurement techniques, Journal Year: 2025, Volume and Issue: 18(1), P. 17 - 35

Published: Jan. 6, 2025

Abstract. Reactive organic carbon (ROC) is diverse in its speciation, functionalization, and volatility, with varying implications for ozone production secondary aerosol formation growth. Chemical ionization mass spectrometry (CIMS) approaches can provide situ ROC observations, the CIMS reagent ion controls detectable species. To expand range of ROC, we describe a method switching between ions NH4+ H3O+ Vocus chemical time-of-flight spectrometer (Vocus-CI-ToFMS). We optimization ion–molecule reactor conditions both ions, at same temperature, compare ability to detect variety volatile compounds (VOCs) semi-volatile intermediate-volatility (SVOCs IVOCs), including oxygenates sulfur compounds. Sensitivities are comparable other similar instruments (up ∼5 counts s−1 pptv-1), detection limits on order 1–10 s pptv (1 integration time). report characterizing filtering periods hysteresis following each switch use persistent ambient deuterated internal standard diagnosing this hysteresis. deploy NH4+/H3O+ rural pine forest central Colorado, US, our measurements capabilities instrument, without interferences from variation instrument inlet designs. find that optimally detects reduced species high while improves functionalized compounds, nitrates oxygenated SVOCs IVOCs readily fragmented by H3O+.

Language: Английский

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Detailed Speciation of Non-Methane Volatile Organic Compounds in Exhaust Emissions from Diesel and Gasoline Euro 5 Vehicles Using Online and Offline Measurements

Toxics, Journal Year: 2022, Volume and Issue: 10(4), P. 184 - 184

Published: April 8, 2022

The characterization of vehicle exhaust emissions volatile organic compounds (VOCs) is essential to estimate their impact on the formation secondary aerosol (SOA) and, more generally, air quality. This paper revises and updates non-methane (NMVOCs) tailpipe three Euro 5 vehicles during Artemis cold urban (CU) motorway (MW) cycles. Positive matrix factorization (PMF) analysis carried out for first time proton transfer reaction time-of-flight mass spectrometer (PTR-ToF-MS) datasets vehicular emission. Statistical helped associate emitted VOCs specific driving conditions, such as start vehicles, activation catalysts, or engine combustion regimes. Merged PTR-ToF-MS automated thermal desorption gas chromatography (ATD-GC-MS) provided an exhaustive description NMVOC emission factors (EFs) thus helping identify quantify up 147 individual compounds. In general, CU cycle exceed those MW cycle. gasoline direct injection (GDI) exhibits highest EF both cycles (252 15 mg/km), followed by port-fuel (PFI) (24 0.4 finally diesel (15 3 mg/km). For all are dominated unburnt fuel incomplete products. Diesel mostly represented oxygenated (65%) aliphatic hydrocarbons (23%) C22, while GDI PFI composed monoaromatics (68%) alkanes (15%). Intermediate volatility (IVOCs) range from 2.7 13% emissions, comprising essentially linear vehicle, naphthalene accounts 42% IVOC fraction vehicles. work demonstrates that PMF GC-MS provide a revised deep enrich current inventories.

Language: Английский

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