Quantification on the source/receptor relationship of primary pollutants and secondary aerosols by a Gaussian plume trajectory model: Part II. Case study

This study applies a newly developed model, the Gaussian trajectory transfer-coefficient model (GTx) (Part I, Atmos. Environ., this issue), to Taichung City. Two fossil-fueled power plants are situated in the vicinity of Taichung City. The model was calibrated in the winter of 1997 and verified throughout the entire following year of 1998. The results indicate that the correlation coefficients (r2) for the daily concentrations of various pollutants were in the range of 0.49–0.83 during the calibrated period and in the range of 0.37–0.71 during the verification period. The advantage of GTx is that the source/receptor relationship of sources can be determined in a single model run. It shows that line sources contributed to 62% of CO, 65% of NOx and 21% of nitrate aerosol; point sources contributed to 46% of SO2, 57% of sulfate aerosol and 27% of PM2.5; and area sources contributed to 18% of PM2.5 and 60% of PM2.5–10 during the PM10 episodes in 1998. During the episodes TC power plant contributed to more fractions of pollutants than during non-episode days since the sea breeze blew its plume to the city. According to our analysis, if a fossil-fueled power plant is built at 1–3 days upwind of a city with NOx emitted from an effective stack height within 100–800 m, it has a higher potential to deteriorate the air quality of the city by increasing the concentration level of nitrate aerosols under unfavorable meteorological conditions.