A5004957874- Atmospheric chemistry and aerosols
- Atmospheric Ozone and Climate
- Air Quality and Health Impacts
- Air Quality Monitoring and Forecasting
- Atmospheric and Environmental Gas Dynamics
- Spectroscopy and Laser Applications
- Vehicle emissions and performance
- Catalytic Processes in Materials Science
- Atmospheric aerosols and clouds
- Advanced Chemical Sensor Technologies
- Analytical Chemistry and Chromatography
- Toxic Organic Pollutants Impact
- Indoor Air Quality and Microbial Exposure
- Chemical Reactions and Mechanisms
- Catalysis and Oxidation Reactions
- Free Radicals and Antioxidants
- Marine and coastal ecosystems
- Radical Photochemical Reactions
- Water Quality Monitoring and Analysis
- Scientific Computing and Data Management
- Advanced Chemical Physics Studies
- Fire effects on ecosystems
- Molecular Spectroscopy and Structure
- Radioactive contamination and transfer
- Analytical Chemistry and Sensors
National Centre for Atmospheric Science
2014-2024
University of York
2014-2024
Foundation for Research and Technology Hellas
2023
Guangzhou Institute of Geochemistry
2021
Chinese Academy of Sciences
2021
University of Leeds
2006-2015
European Centre for Medium-Range Weather Forecasts
2014
University of Birmingham
2012
University of Leicester
2002-2006
London Borough of Camden
2002
Abstract. The chemistry of isoprene degradation in the Master Chemical Mechanism (MCM) has been systematically refined and updated to reflect recent advances understanding, with these updates appearing latest version, MCM v3.3.1. complete mechanism v3.3.1 consists 1926 reactions 602 closed shell free radical species, which treat initiated by reaction OH radicals, NO3 radicals ozone (O3). A detailed overview is provided, within context reported kinetic mechanistic information. revisions...
Abstract. The oxidation capacity of the highly polluted urban area Santiago, Chile has been evaluated during a summer measurement campaign carried out from 8–20 March 2005. hydroxyl (OH) radical budget was employing simple quasi-photostationary-state model (PSS) constrained with simultaneous measurements HONO, HCHO, O3, NO, NO2, j(O1D), j(NO2), 13 alkenes and meteorological parameters. In addition, zero dimensional photochemical box based on Master Chemical Mechanism (MCMv3.1) used to...
Abstract. Renewal of ultrafine aerosols in the marine boundary layer may lead to repopulation distribution and ultimately determine concentration cloud condensation nuclei (CCN). Thus formation nanometre-scale particles can enhanced scattering incoming radiation a net cooling atmosphere. The recent demonstration chamber new from photolytic production condensable iodine-containing compounds diiodomethane (CH2I2), (O'Dowd et al., 2002; Kolb, Jimenez 2003a; Burkholder Ravishankara, 2003),...
Abstract. A degradation mechanism for β-caryophyllene has recently been released as part of version 3.2 the Master Chemical Mechanism (MCM v3.2), describing gas phase oxidation initiated by reaction with ozone, OH radicals and NO3 radicals. detailed overview construction methodology is given, within context reported experimental theoretical mechanistic appraisals. The performance evaluated in chamber simulations which chemistry was coupled to a representation gas-to-aerosol partitioning 280...
Abstract. Isoprene is the most abundant non-methane biogenic volatile organic compound (BVOC), but processes governing secondary aerosol (SOA) formation from isoprene oxidation are only beginning to become understood and selective quantification of atmospheric particulate burden remains difficult. Organic above a tropical rainforest located in Danum Valley, Borneo, Malaysia, high emission region, was studied during Summer 2008 using Aerosol Mass Spectrometry offline detailed characterisation...
Abstract. Organic peroxy radicals (RO2), formed from the degradation of hydrocarbons and other volatile organic compounds (VOCs), play a key role in tropospheric oxidation mechanisms. Several competing reactions may be available for given RO2 radical, relative rates which depend on both structure ambient conditions. Published kinetics branching ratio data are reviewed bimolecular with NO, NO2, NO3, OH HO2; their self-reactions cross-reactions radicals. This information is used to define...
Abstract. Secondary Organic Aerosol (SOA) affects atmospheric composition, air quality and radiative transfer, however major difficulties are encountered in the development of reliable models for SOA formation. Constraints on processes involved formation can be obtained by interpreting speciation evolution organics gaseous condensed phase simultaneously. In this study we investigate from dark α-pinene ozonolysis with particular emphasis upon mass distribution particulate organic species. A...
Abstract. The Atmospheric Pollution and Human Health in a Chinese Megacity (APHH-Beijing) programme is an international collaborative project focusing on understanding the sources, processes health effects of air pollution Beijing megacity. APHH-Beijing brings together leading China UK research groups, state-of-the-art infrastructure quality models to work four themes: (1) sources emissions pollutants; (2) atmospheric affecting urban pollution; (3) exposure impacts; (4) interventions...
The removal of SO<sub>2</sub>in the presence of<italic>cis</italic>-but-2-ene and ozone exhibits a strong dependence on water vapour concentration.
Abstract. Reaction with the hydroxyl (OH) radical is dominant removal process for volatile organic compounds (VOCs) in atmosphere. Rate coefficients reactions of OH VOCs are therefore essential parameters chemical mechanisms used chemistry transport models, and required more generally impact assessments involving estimation atmospheric lifetimes or oxidation rates VOCs. Updated extended structure–activity relationship (SAR) methods presented aliphatic compounds, aromatic considered a...
Abstract. Wet deposition is the dominant mechanism for removing black carbon (BC) from atmosphere and key in determining its atmospheric lifetime, vertical gradient global transport. Despite importance of BC climate system, especially terms ability to modulate radiative energy budget, there are few quantitative case studies wet removal ambient environments. We present a study by examining aerosol size distributions coating properties sampled three Canadian boreal biomass burning plumes, one...
Abstract. The Indian megacity of Delhi suffers from some the poorest air quality in world. While ambient NO2 and particulate matter (PM) concentrations have received considerable attention city, high ground-level ozone (O3) are an often overlooked component pollution. O3 can lead to significant ecosystem damage agricultural crop losses, adversely affect human health. During October 2018, speciated non-methane hydrocarbon volatile organic compounds (C2–C13), oxygenated (o-VOCs), NO, NO2,...
Abstract. Aromatic volatile organic compounds (VOCs) are key anthropogenic pollutants emitted to the atmosphere and important for both ozone secondary aerosol (SOA) formation in urban areas. Recent studies have indicated that aromatic hydrocarbons may follow previously unknown oxidation chemistry pathways, including autoxidation can lead of highly oxidised products. In this study we evaluate gas- particle-phase ions measured by online mass spectrometry during hydroxyl radical substituted...
Formic acid (HCOOH), one of the most important and ubiquitous organic acids in Earth's atmosphere, contributes substantially to atmospheric acidity affects pH-dependent reactions aqueous phase. However, based on current mechanistic understanding, even advanced chemical models significantly underestimate HCOOH concentrations when compared ambient observations at both ground-level high altitude, thus underrating its impact. Here we reveal new pathways formation from O3 OH with ketene-enols,...
Abstract. The impact of emissions volatile organic compounds (VOCs) to the atmosphere on production secondary pollutants, such as ozone and aerosol (SOA), is mediated by concentration nitric oxide (NO). Polluted urban atmospheres are typically considered be “high-NO” environments, while remote regions rainforests, with minimal anthropogenic influences, “low NO”. However, our observations from central Beijing show that this simplistic separation regimes flawed. Despite being in one largest...
Abstract. Twenty-nine different fuel types used in residential dwellings northern India were collected from across Delhi (76 samples total). Emission factors of a wide range non-methane volatile organic compounds (NMVOCs) (192 total) measured during controlled burning experiments using dual-channel gas chromatography with flame ionisation detection (DC-GC-FID), two-dimensional (GC × GC-FID), proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS) and solid-phase extraction...
Abstract. Biomass burning emits significant quantities of intermediate-volatility and semi-volatile organic compounds (I/SVOCs) in a complex mixture, probably containing many thousands chemical species. These components are significantly more toxic have poorly understood chemistry compared to volatile routinely quantified ambient air; however, analysis I/SVOCs presents difficult analytical challenge. The gases particles emitted during the test combustion range domestic solid fuels collected...
We report a new general method for trapping short-lived radicals, based on homolytic substitution reaction SH2′. This departure from conventional radical by addition or radical–radical cross-coupling results in high sensitivity, detailed structural information, and applicability of the approach. The traps this are terminal alkenes possessing nitroxide leaving group (e.g., allyl-TEMPO derivatives). process thus yields stable products which can be stored subsequently analyzed mass spectrometry...
Hydroxyl radical yields are reported for the gas-phase ozonolyses of a range alkenes. 1,3,5-Trimethylbenzene was employed as an OH tracer, and diminution in its concentration used to calculate by both simple analytical kinetic expression numerically integrated model. The following were obtained, relative alkene consumed: ethene (0.14), propene (0.32), 2-methylpropene (0.60), 2,3-dimethyl-2-butene (0.89), isoprene (0.44), β-pinene (0.24), α-pinene (0.83). A structure activity relationship...
The impact of iodine oxide chemistry upon OH and HO 2 concentrations in the coastal marine boundary layer has been evaluated using data from NAMBLEX (North Atlantic Marine Boundary Layer Experiment) campaign, conducted at Mace Head, Ireland during summer 2002. Observationally constrained calculations show that under low NO x conditions experienced (NO ≤ 50 pptv), reaction IO + → HOI O accounted for up to 40% total radical sink, subsequent photolysis form I comprised 15% midday production...
Abstract. A series of photooxidation experiments were conducted in an atmospheric simulation chamber order to investigate the oxidation mechanism and secondary organic aerosol (SOA) formation potential model anthropogenic gas phase precursor, 1,3,5-trimethylbenzene. Alongside specific measurements, comprehensive primarily by Chemical Ionisation Reaction Time-of-Flight Mass Spectrometry (CIR-TOF-MS), carried out provide detailed insight into composition behaviour components matrix during SOA...
Abstract. Forests are the dominant source of volatile organic compounds into atmosphere, with isoprene being most significant species. The oxidation chemistry these is a driver local, regional and global atmospheric composition. Observations made over Borneo during OP3 project in 2008, together an observationally constrained box model used to assess our understanding this chemistry. In line previous work tropical forests, we find that standard based on MCM significantly underestimates...
The gas-phase reactions of ozone with alkenes can be significant sources free radicals (OH, HO(2) and RO(2)) in the Earth's atmosphere. In this study total radical production degradation products from ethene ozonolysis have been measured, under conditions relevant to troposphere, during a series detailed simulation chamber experiments. Experiments were carried out European photoreactor EUPHORE (Valencia, Spain), utilising various instrumentation including chemical-ionisation-reaction...