INERIS (France), the French National Institute for Industrial Environment and Risks offers a
Air quality; Atmospheric chemistry; Aerosol; Sources; Secondary organic aerosol (SOA); molecular “tracers”.
Context and objectives
Impact of particulate matter (PM) (aerosols) on air quality, and so on health, is now well recognized. However, due to their wide emission sources and to the complexity of their (trans)-formation processes in the atmosphere, the implementation of actions, in order to decrease the ambient air PM concentration levels, is dependent of a better knowledge about the origin and the behaviour of the pollutants emitted by human activities. If aerosols are formed of a complex mixture, organic matter (organic aerosol, OA) represents a large fraction of the total mass of the fine particles in the atmosphere (from 20 to 90 % in the low troposphere). OA sources, formation processes and chemical composition still remain quite unrecognized. Carbonaceous species are commonly separated according to their introduction mode in the particulate phase. Organic compounds directly emitted in particulate phase in ambient air are defined as primary organic aerosol (POA). Particulate organic species from oxidation reactions in gaseous phase of volatile or semi-volatile organic compounds (VOCs, SVOCs) and transfer mass processes of the by-products into the aerosol form the secondary organic aerosol (SOA). The knowledge of SOA is essential on a climatic or sanitary point of view because it could constitute about 80 to 90 % of total OA in some locations. If primary emission could be controlled, secondary sources, influenced by biogenic emissions (and also anthropogenic) and by the photochemistry, are difficult to regulate. In this context, the discrimination of POA and SOA sources is fundamental.
The main objective of this PhD work is to get an extensive description and evaluation of the OA sources (POA and SOA) using the combination of “off-line” aerosol chemical speciation (POA and SOA molecular “tracers”, major and trace inorganic species) and real time aerosol chemical characterization by “on-line” instrumentation (Tof-ACSM, SMPS, multi-wavelengths Aethalometer...) on a long term basis (>1 year). The synergism of both aerosol characterization methodologies will be obtained through the statistical data analysis using a composite positive matrix factorization (PMF, receptor model): PMF² OO (« off-line », « on-line ») and will bring a comprehensive source apportionment of the entire fine aerosol fraction and insights onto secondary formation processes.
Another originality of the work is the accuracy evaluation of recently proposed and newly identified SOA molecular “tracers” from photo-oxidation processes of PAHs (polycyclic aromatic hydrocarbons) and biomass burning intermediates.
This will be done by combining complementary off-line/on-line approaches during experiments in controlled conditions performed in laboratory and/or at quasi actual size; laboratory reactivity experiments and field studies. The work will particularly focus on the biomass burning source (residential heating) as it is an increasing renewable energy source used in Europe. Moreover, the SOA formation from this source is still largely unknown.
- Master Environmental chemistry, atmospheric chemistry, and/or analytical chemistry.
- Lab and field work interest.
- Knowledge in atmospheric physico-chemistry.
- Knowledge in analytical –chemistry (HPLC-Fluorescence/UV, GC-MS, TD-GC-MS, LC-MS/MS).
- Computer knowledge and data analysis (Igor, PMF).
- Autonomy, adaptability, communication and writing abilities.
- Good English level
Place of PhD work: INERIS (Verneuil-en-Halatte, France)= 60 % ; EPOC-LPTC/University Bordeaux 1 (Talence, France)= 20 % ; LSCE (Saclay, France) = 20 %
PhD start: September-October 2014
To apply: Send CV + letter of motivation before 30/04/2014.