Spectroscopic characterization of humic-like substances in airborne particulate matter

In a standard reference air dust (NIST 1648 - urban particulate matter) as well as in airborne particulate matter collected in German urban and rural areas (Dortmund, Sauerland) 10% and more of the organic carbon can be attributed to macromolecular substances like humic and fulvic acids (HA, FA). Indirect evidence for the presence of humin was also obtained. HA and FA extracted from NIST 1648 and other urban and rural atmospheric particles using 0.1 m NaOH and isolated by ion-exchangers were characterized by their molecular-size distribution applying multistage ultrafiltration, their carbon content and their UV/VIS, Fourier-transformed infrared (FTIR) and nuclear magnetic resonance ((1)H-NMR) spectra. Summarizing, the structural studies exhibit that these humic-like substances (HULIS) contained in air dust samples are small in their molecular size and rich in aliphatic and carbohydrate substructures compared to HA and FA from soils and aquatic systems.