Organic Nitrates Chemistry: sources, sinks and impact on the long-range transport of reactive nitrogen – ONCEM

The photooxidant pollution is responsible of the air quality degradation by producing photo-oxidants such as ozone, potentially irritants secondary oxidized compounds or through production of secondary organic particles. The development of such phenomena involves complex interactions between the solar irradiation, volatile organic compounds and nitrogen oxides.

The intensities of the sources and precursors are extremely variable in space and time. The long distance development of this type of pollution depends directly on the transport of reservoir species, namely, some species that preserve their precursors of being degraded in the atmosphere before allowing their release far from their sources.

The organic nitrates are the main nitrogen oxides reservoirs species. They are formed in NOx rich air by the degradation of hydrocarbons initiated by OH (daytime) and NO3 (nighttime) radicals. Since they have lifetimes of several days or weeks, they behave as reservoirs for reactive nitrogen by undergoing long-range transport in the free troposphere before decomposing to release NOx in remote regions.. The chemical transport models, therefore, integrate elements of the organic nitrates chemistry.

However, the knowledge on the organic nitrates sources (NOx sequestration) and sinks (NOx release) are quantitatively and qualitatively extremely limited. The chemical mechanisms, the products formation or degradation yields and the kinetic constants are crucial elements that affect the confidence level when estimating the spatial-temporal distribution of photooxidants.

The current project gathers a consortium that is focused on fulfill the gaps on the mechanisms and the kinetics of the formation and degradation of organic nitrates. It involves laboratory, simulation chambers and theoretical calculation studies, which are then implemented to evaluate the impact on the pollution at large-scale by the integration of the new results within a 0D model and finally within a chemical transport model.