Characterisation of Road Dust Organic Matter as a Function of Particle Size: A PARAFAC Approach

Road dust organic matter plays a vital role in mobilization of contaminants. This study investigated and characterized organic matter (OM) presents in road dust particles of various sizes. Road dust samples were collected from an industrialized city of Ulsan, Republic of Korea and fractionated into four groups: <75, 75-180, 180-850, and 850-2000 mu m. OM extracted from the four fractions was characterized by excitation-emission matrix fluorescence and analyzed by parallel factor analysis (PARAFAC). The PARAFAC identified four major fluorophore components (C1-C4). These components were related to microbial humic-like, anthropogenic organic, fulvic-like, and low molecular weight OM contributed by anthropogenic activity, respectively. There were subtle changes in specific OM composition with change in particle size. The finest fraction contained more microbial humic-like substances whereas the coarse fraction was enriched with fulvic acid. The OM in two fractions (75-180 and 180-800 mu m) showed dual characteristics. Our findings demonstrated that PARAFAC approach can assist to assess the accumulation of pollutants in road dust.