Sources of fine organic aerosol. 3. Road dust, tire debris, and organometallic brake lining dust: roads as sources and sinks

Abstract

Particulate matter emitted to the atmosphere due to motor
\nvehicles arises from several sources in addition to tailpipe
\nexhaust. In this study, the organic constituents present
\nin fine particulate (d_p ≤ 2.0 µm) road dust, brake lining
\nwear particles, and tire tread debris (not size segregated)
\nare analyzed using gas chromatography/mass spectrometry.
\nThe objective is to characterize such traffic-related
\nsources on an organic compound basis and to search for
\nmolecular markers that will assist the identification of
\ntraffic-associated dusts in the urban atmosphere. More
\nthan 100 organic compounds are quantified in these
\nsamples, including n-alkanes, n-alkanoic acids, n-alkenoic
\nacids, n-alkanals, n-alkanols, benzoic acids, benzaldehydes,
\npolyalkylene glycol ethers, PAH, oxy-PAH, steranes,
\nhopanes, natural resins and other compound classes.
\nPaved road dust acts as a repository for vehicle-related
\nparticles, which can then be resuspended by the passing
\ntraffic. To evaluate the contributions from major urban
\nsources to the road dust complex, source profiles representing different types of vehicle exhaust, brake dust, tire debris, and vegetative detritus are compared, and their fractional contributions are estimated using several groups of organic tracer compounds. Likewise, the close relationship between airborne fine particulate organic constituents and road dust organic matter is discussed.