Аннотация:Humic substances (HS) are the most abundant refractory organic compounds in the environment. Synthesis of HS is not deterministic, but a stochastic process that selects for kinetically stable molecular entities. As a result, HS represent a molecular ensemble that cannot be ascribed a single structural formula. Consequently, current definition and classifications of HS are based on isolation procedures rather than on specific structural formulas. HS require a structural description that is consistent with their stochastic origins. This research has formulated and demonstrated classifying capabilities of a deterministic approach that numerically describes structure of HS in terms of the macroscopic parameters of elemental, fragmental and molecular weight composition provided by elemental analysis, 13C NMR spectroscopy, and size exclusion chromatography, respectively. A stochastic approach is proposed here, whereby the probability density functions of microscopic parameters are derived from the data of high-resolution analytical techniques (e.g., FTICR-MS).