A Reactivity Based Emission Inventory for the South Pars and Its Implication for Ozone Pollution Control

The South Pars zone in Iran encompasses the largest gas refineries and petrochemical complexes in the world. In the South Pars zone, elevated concentrations of reactive hydrocarbons co-emitted with nitrogen oxides from industrial facilities lead to substantial ozone production downwind. To understand the role of these emissions on the ozone formation and, to formulate appropriate control strategies in this zone, emissions of precursors of ozone were quantified, and compounds that deserve relatively more attention were determined. To do this, first, a fully- speciated ozone precursors emission inventory was prepared to provide necessary input data for air quality simulation models. Then, the emission inventory was weighted by emitted mass and incremental reactivity scales to determine which compounds deserve relatively more detailed representation in the modeling. Afterward, a photochemical model was applied to determine the ozone sensitivity to its precursors. Finally, source apportionment was done for the most important compounds. Additionally, the reactivity-based inventory was compared with other regions. Results show that nitrogen oxides -sensitive chemistry is dominant in the zone thus the most effective control strategy is the mitigation of the nitrogen oxides emissions. Gas refinery plants have a larger share than petrochemical plants in the nitrogen oxides emission and, the gas turbines are the main sources of nitrogen oxides emission in this region. Emitted volatile organic compounds contain more highly reactive species in comparison with the ambient air composition of typical urban areas and areas with gas production industries. Propylene and ethylene have the most contribution to the ozone formation in comparison with other volatile organic compounds. The major sources of their emissions are the olefin processes and polymer production plants.