Humic Substances as Natural Interacting Agents: Their Characteristics and Possible Fate in Environment

Abstract

In the last decades, structural complexity of humic substances and their role in natural environments have been widely discussed. Their persistence and/or susceptibility to biological decomposition, however, requires for further research. Here we present a contribution dealing in part with humic acids (HA) extracted by alkali from soils differing in metal contents, and which might represent naturally occurring organic-mineral-metal complexes. If exposed to microbial activities, and especially if easily utilizable carbon and nitrogen sources were not available, HA from soils containing elevate metal contents or from a soil site located near to a Mg-plant and heavily contaminated with this element, were found to support growth of soil microorganisms. At the same time, the structure of HA underwent several structural transformations. The FT-IR spectroscopic investigations indicated releases of metal and silicate constituents from the HA preparations.