Modelling of aerosol processes in plumes

A modelling platform for studying photochemical gaseous and aerosol phase p rocesses from localized (e.g., point) sources has been presented. The curre nt approach employs a reactive plume model which extends the regulatory mod el RPM-IV by incorporating aerosol processes and heterogeneous chemistry. T he physics and chemistry of elemental carbon, organic carbon, sulfate, nitr ate, ammonium material of aerosols are treated and attributed to the PM siz e distribution. A modified version of the carbon bond IV chemical mechanism is included to model the formation of organic aerosol. Aerosol dynamics mo deled include mechanisms of nucleation, condensation, dry deposition and ga s/particle partitioning of organic matter. The model is first applied to a number of case studies involving emissions from point sources and sulfate p article formation in plumes. Model calculations show that homogeneous nucle ation is an efficient process for new particle formation in plumes, in agre ement with previous field studies and theoretical predictions. In addition, the model is compared with field data from power plant plumes with satisfa ctory predictions against gaseous species and total sulphate mass measureme nts. Finally, the plume model is applied to study secondary organic matter formation due to various emission categories such as vehicles and the oil p roduction sector.