- Atmospheric chemistry and composition
- Tropospheric oxidation reactions
- Alkene ozonolysis
- Air Pollution and Meteorology
- Numerical modeling
- Particulate Matter and Human Exposure
- GCxGC-ToF-MS Analysis
Current and Recent Research
Fundamental studies of the sources, properties and environmental behavious of exhaust nanoparticles from road vehicles (FASTER)
The aim of this project is to study, at a fundamental level, the composition and properties of semi-volatile constituents of vehicle exhaust particles, and to measure and model their behaviour in the atmosphere. This will be completed by elucidating the composition of the exhaust particles utilising GCxGC-ToF-MS and studying thier conversion to vapour. This information will then be exploited to develop models of traffic particle behavious in street canyons and the urban atmosphere.
Collaborators: Prof Roy Harrison, Prof Rob MacKenzie, Dr Xiaoming Cai, Prof Hongming Xu, Dr Irina Nikolova and Mr Christopher Stark
Sources and atmospheric processes determining airborne concentrations of polycyclic aromatic hydrocarbons (PAH) and their degradation products
Polycyclic Aromatic Hydrocarbons (PAH) are ubiquitous organic pollutants, emitted into the atmosphere through incomplete combustion of organic materials. They are present in both gaseous and associated with particulate matter and are harmful to human health. PAHs can react with other constituents in the atmosphere which can lead to the formation of products such as quinones, which may be more toxic than their parent PAH.
The aim of this project was to determine the sources and atmospheric processes of airborne concentrations of PAH and their degradation products. This was completed by sampling from various monitoring stations throughout the UK using meteorological and air pollution instrumentation collecting environmental data and PAHs / quinones, respectively. The data collected was then subjected to GC-MS analysis followed by interpretation using positive matrix factorisation.
Collaborators: Prof Roy Harrison, Dr Juana Maria Delgado-Saborit and Mr Christopher Stark
Total Radical Production and Degradation Products from Alkene Ozonolysis
Unsaturated VOCs (alkenes) are emitted to the atmosphere both anthropogenically and biogenically from natural sources. Alkenes react with ozone leading to the production of organic species such as HCHO, acetone and acetaldehyde, as well as radical species HO2, RO2 and OH. The formation of these radicals (HO2, RO2 and OH) is of significant interest, as it may influence the radical budget in the urban and rural environments; ultimately affecting the removal of pollutants and greenhouse gases, otherwise known as the oxidative capacity of the atmosphere.
The aim of this project was to directly observe the degradation products from selected alkene ozone reactions. The experiments were performed in an outdoor smog simulation chamber (EUPHORE) equipped with a range of instrumentation, including Laser Induced Fluorescence (LIF) and Chemical-Ionisation Time-Of-Flight Mass-Spectrometry (CIR-TOF-MS) to measure OH/HO2 and VOCs/OVOCs, respectively. The results were interpreted through detailed numerical modelling, drawing upon atmospheric models, namely the Master Chemical Mechanism. Reaction rate coefficients, humidity dependent radical yields and stable product yields were compared with those simulated, and implications for atmospheric oxidant levels were explored.
Collaborators: Dr William Bloss (PhD, Supervisor), Dr Andrew Rickard (Leeds), Dr Marie Camredon (Paris) and Prof Paul Monks (Leicester)
Interferences in commercial nitric oxide(s) analysers
Nitric oxide(s) (NO and NO2) are important air pollutants which drive hydrocarbon oxidation in the atmosphere. NOx abundance controls the levels of the atmospheric oxidants OH, NO3 and ozone, and also regulates the production of ozone resulting from the degradation of VOCs. Accurate measurement of nitrogen oxides in the atmosphere is therefore of major importance in understanding the atmosphere. This project was designed to quantify the interference posed by alkenes, monoterpenes and sesquiterpenes in the nitric oxide mode of detection in commercial nitric oxide(s) analysers; and was achieved by testing a range of commercially available analysers at the EUPHORE smog simulation chamber.
Collaborators: Dr William Bloss, Dr James Lee (York), Dr Monica Varquez (Valencia)