Characterization of an asphalt binder and photoproducts by Fourier transform ion cyclotron resonance mass spectrometry reveals abundant water-soluble hydrocarbons

The effects of solar irradiation on an asphalt binder were investigated. Upon irradiation in a photooxidation microcosm, thin films of the asphalt binder produced abundant oil- and water-soluble oxygenated hydrocarbons, which are hypothesized to leached from roads and highways through photooxidation reactions. Ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) enabled extensive compositional characterization of the virgin asphalt binder, irradiated asphalt binder, and the water-soluble photoproducts. The results revealed the production of water-soluble species that resemble the molecular composition of petroleum-derived dissolved organic matter, including abundant hydrocarbons and S-containing species with up to 18 oxygen atoms. The results also confirmed photo-induced oxidation, fragmentation, and potentially polymerization as active processes involved in the production of water-soluble organic pollutants from asphalt.