Diurnal and seasonal trends in the apparent density of ambient fine and coarse particles in Los Angeles

作者：Hasheminassab Sina; Pakbin Payam; Delfino Ralph J; Schauer James J; Sioutas Constantinos^*

来源：Environmental Pollution, 2014, 187: 1-9.

DOI：10.1016/j.envpol.2013.12.015

• Particulate matter (PM)
• Apparent density
• Material density
• Chemical composition
• Morphology

Diurnal and seasonal variations in the apparent density of ambient fine and coarse particulate matter (PM2.5 and CPM [PM2.5-10], respectively) were investigated in a location near downtown Los Angeles. The apparent densities, determined by particle mass-to-volume ratios, showed strong diurnal and seasonal variations, with higher values during the warm phase (June to August 2013) compared to cold phase (November 2012 to February 2013). PM2.5 apparent density showed minima during the morning and afternoon rush hours of the cold phase (1.20 g cm(-3)), mainly due to the increased contribution of traffic-emitted soot particles, and highest values were found during the midday in the warm phase (2.38 g cm(-3)). The lowest CPM apparent density was observed during the morning rush hours of the cold phase (1.41 g cm(-3)), while highest in early afternoon during the warm phase (2.91 g cm(-3)), most likely due to the increased wind-induced resuspension of road dust.

• 出版日期2014-4