Diurnal variation of PM10 concentrations and its spatial distribution in the South East Queensland airshed

摘要

The aim of this work was quantification of the diurnal variation of PM10 concentrations and the variation in its spatial distribution in the South East Queensland (SEQ) airshed with a specific focus on vehicle emissions as a contributing factor. The PM10 levels recorded at half-hourly intervals at six monitoring stations over a four-year period were used. Levels below 30 g m-3 recorded at wind speeds less than 2.5 ms-1 and during times of clear visibility were selected for the analysis to lower the probability of interference from non-vehicular sources. The levels recorded between 2:00 and 5:00 am were considered to be the urban baseline and subtracted from the daytime readings to obtain a mean difference in concentration between daytime and night time. For a four-year period this mean difference in PM10 levels estimated for all the monitoring stations varied in the range between 3.8 and 6.9 g m-3. In addition to the diurnal variation in the depth of the boundary layer (which was not quantified), vehicle emissions were concluded to be the major contributor to this variation. The method used in this study for quantification of the diurnal variation and spatial distribution of PM10 provides useful information on the influence of motor vehicle emissions on air quality, particularly in relation to human exposure. It provides information not directly available using source emission inventories, which yield data on the total emissions to the air, and cannot be directly translated into concentrations in the different areas of the airshed.