The Individuality of Humic Substances in Diverse Environments

Abstract

Measured differences among different humic components (e.g. humic acid, fulvic acid, and humin) isolated from the same environment are often diminished to some degree by contamination of the humic samples with nonhumic materials. Characteristic differences among samples of a given humic component (e.g. humic acid) from environment to environment are frequently obscured for this same reason. Careful isolation of humic materials and separation from the nonhumic components by XAD-8 resin techniques eliminates these problems, and allows the individuality of various humic isolates to be recognized. Data are presented to show that each humic component in each environment possess an individuality that distinguishes it from other components in the same environment, and from the “same” component in different environments. The data presented in this chapter supporting these conclusions consist of amino acid and sugar contents, and 13C nuclear magnetic resonance spectra. Additional data from 1H nuclear magnetic resonance spectroscopy, carbon isotopic measurements (δ13C and 14C), and pyrolysis/mass spectrometry, in referenced literature support these conclusions. Environments investigated for this chapter are soil, stream water, and ocean water, humic components investigated are humic acid, fulvic acid, and humin. In the case of soil, fulvic acid extracted from the bulk or solid soil, as well as fulvic acid isolated from the interstitial soil water are included in the study. It is concluded that each humic component in each environment is unique and possesses an individuality that is characteristic of the particular component of the particular environment.