Thermodesorbates 350ΠC and pyrolyzates 750ΠC of anthropogenic Ε½ . and natural humic organic matter HOM were identified and quantified by Ε½ . microcolumn gas chromatographyαmass spectrometry GCr MS and gas chro-Ε½ . matography-atomic emission detection GCr AED . After thermal treatment, HOM Ε½ . leaves a highly carbonaceous residue )90 wt % C with about one-third the mass of the total HOM. As a first approximation, this value applies for various humic and fulvic acids independent of their origin. Only 30α40% of the volatilized carbon w Ε½ .x 10α13% of the total organic carbon OC carries structural information. The Ε½ . residual volatile carbon is assigned to light gases CO, CO , CH . Moreover, the 2 4
aromatic compounds in the pyrolyzate may be misleading: they can be derived from aromatic building blocks of the HOM network or can be formed from nonaromatic precursors by thermal reactions. Nevertheless, even the relatively small fraction of OC in pyrolysis products with diagnostic value can be used to characterize HOM from different sources. Heterocyclic compounds and benzenediols are important markers of anthropogenic HOM. Thermochemolysis using tetramethyl ammonium Ε½ . hydroxide TMAH makes it possible to reveal the pattern of fatty acids and dicarboxylic acids but does not dramatically enhance the yield of the GC-detectable pyrolyzate.