A continuous dichotomous beta gauge monitor was used to characterize the hourly content of PM2.5, PM10-2.5, and Black Carbon （BC） over a 12-month period in an urban street canyon of Hong Kong. Hourly vehicle counts ...A continuous dichotomous beta gauge monitor was used to characterize the hourly content of PM2.5, PM10-2.5, and Black Carbon （BC） over a 12-month period in an urban street canyon of Hong Kong. Hourly vehicle counts for nine vehicle classes and meteorological data were also recorded. The average weekly cycles of PM2.5, PM10-2.5, and BC suggested that all species are related to traffic, with high concentrations on workdays and low concentrations over the weekends. PM2.s exhibited two comparable concentrations at 10：00-11：00 （63.4 μg/m3） and 17：00-18：00 （65.0 p.g/m3 ） local time （LT） during workdays, correspond- ing to the hours when the numbers of diesel-fueled and gasoline-fueled vehicles were at their maximum levels： 3179 and 2907 h-1, respectively. BC is emitted mainly by diesel-fueled vehicles and this showed the highest concentration （31.2μg/m3） during the midday period （10：00-11：00 LT） on workdays. A poor correlation was found between PM2.s concentration and wind speed （R= 0.51, P-value 〉 0.001 ）. In contrast, the concentration of PM10-2.s was found to depend upon wind speed and it increased with obvious statistical significance as wind speed increased （R = 0,98, P-value 〈 0.0001 ）.展开更多
基金supported by the Hong Kong Polytechnic University(G-YX3L)National Science Foundation of China(NSFC21107084)State Key Laboratory of Loess & Quaternary Geology(SKLLQG0804)
文摘A continuous dichotomous beta gauge monitor was used to characterize the hourly content of PM2.5, PM10-2.5, and Black Carbon （BC） over a 12-month period in an urban street canyon of Hong Kong. Hourly vehicle counts for nine vehicle classes and meteorological data were also recorded. The average weekly cycles of PM2.5, PM10-2.5, and BC suggested that all species are related to traffic, with high concentrations on workdays and low concentrations over the weekends. PM2.s exhibited two comparable concentrations at 10：00-11：00 （63.4 μg/m3） and 17：00-18：00 （65.0 p.g/m3 ） local time （LT） during workdays, correspond- ing to the hours when the numbers of diesel-fueled and gasoline-fueled vehicles were at their maximum levels： 3179 and 2907 h-1, respectively. BC is emitted mainly by diesel-fueled vehicles and this showed the highest concentration （31.2μg/m3） during the midday period （10：00-11：00 LT） on workdays. A poor correlation was found between PM2.s concentration and wind speed （R= 0.51, P-value 〉 0.001 ）. In contrast, the concentration of PM10-2.s was found to depend upon wind speed and it increased with obvious statistical significance as wind speed increased （R = 0,98, P-value 〈 0.0001 ）.
