Quantification on the source/receptor relationship of primary pollutants and secondary aerosols by a Gaussian plume trajectory model: Part I—theory

This study develops a theory for the Gaussian plume equation to account for the formation of secondary sulfate aerosol and nitrate aerosol from the oxidations of gaseous SO2 and NOx emissions. In addition, the mechanisms of scavenging, dry deposition, background pollutant transport and subsidence from the top planetary boundary layer are also considered. A Gaussian trajectory transfer-coefficient model (GTx) has been developed. Wind vector, stability class and mixing height among each time interval along a trajectory are allowed to change. Quantification on the source/receptor relationship of primary pollutants and the secondary aerosols from sources can be determined in a single model run. Nonetheless, it should be noted that the current formulation depends on the explicit description of the oxidation rates of gaseous SO2 and NOx. Since reactive chemistry, in general, is nonlinear, this would be the limitation of the approach. Alternatively, prior to application of the model to a site, the rates calibrated to specific time and the location of interest are suggested.