SEASONAL AND DIURNAL VARIATIONS OF PM_(1.0),PM_(2.5) AND PM_(10) IN THE ROADSIDE ENVIRONMENT OF HONG KONG

PM1.0 （fine particles, with diameter 〈 1 pm）, PM2.5 （fine particles, with diameter 〈 2.5μm） and PM10 （coarse particles, with diameter 〈 10 μm） were measured at 24-hour intervals near a high-traffic road in Hong Kong, from October 2004 to September 2005. Mass concentrations were determined for the three particle fractions, averaging for PM1.0, PM2.5 and PM10, respectively, 44.5±18.4, 55.4±25.5 and 81.3±37.7μg·m^-3, PM2.5 was 3.7 times the U.S. EPA＇s annual NAAQS of 15 μg·m^-3,. Overall, PM1.0 accounted for 44 to 69% （average 57%） of PM10, while PM2.5 accounted for 58 to 82% （average 71%） in this study. The particulate masses showed obvious seasonal patterns with high concentrations in cold seasons and low in warm seasons, especially high concentrations of PM2.5-10 during the cold seasons. Diurnal variations of mass concentrations of PM2.5 were determined during July, showing two major peaks in the morning and afternoon rush hours.

Identify the contribution of vehicle non-exhaust emissions:a single particle aerosol mass spectrometer test case at typical road environment

A single particle aerosol mass spectrometer(SPAMS)was used to accurately quantify the contribution of vehicle non-exhaust emissions to particulate matter at typical road environment.The PM_(2.5),black carbon,meteorological parameters and traffic flow were recorded during the test period.The daily trend for traffic flow and speed on TEDA Street showed obvious“M”and“W”characteristics.6.3 million particles were captured via the SPAMS,including 1.3 million particles with positive and negative spectral map information.Heavy Metal,High molecular Organic Carbon,Organic Carbon,Mixed Carbon,Elemental Carbon,Rich Potassium,Levo-rotation Glucose,Rich Na,SiO_(3) and other categories were analyzed.The particle number concentration measured by SPAMS showed a good linear correlation with the mass concentrations of PM_(2.5) and BC,which indicates that the particulate matter captured by the SPAMS reflects the pollution level of fine particulate matter.EC,ECOC,OC,HM and crustal dust components were found to show high values from 7:00–9:00 AM,showing that these chemical components are directly or indirectly related to vehicle emissions.Based on the PMF model,7 major factors are resolved.The relative contributions of each factor were determined:vehicle exhaust emission(44.8%),coal-fired source(14.5%),biomass combustion(12.2%),crustal dust(9.4%),ship emission(9.0%),tires wear(6.6%)and brake pads wear(3.5%).The results show that the contribution of vehicle non-exhaust to particulate matter at roadside environment is approximately 10.1%.Vehicle non-exhaust emissions are the focus of future research in the vehicle pollutant emission control field.