Humic substances interaction products

FIGURE 6 Potential interactive pathways and processes of humic substances emanating from decomposition products of higher plant tissues with extracellular and surface-bound enzymes and photolytic reactions, particularly with UV irradiance. Humic acid-enzyme complexes can be stable for long periods (weeks and months) and subsequently reactivated upon exposure to weak UV light. Further photolysis can cleave simple compounds from the macromolecules for subsequent utilization by microbes. 

Piccolo, A., G. Celano, and C. DeSimone (1992). Interactions of atrazine with humic substances of different origins and their hydrolysed products. Sci. Total Environ., 117/118 403 -12. 

Humic substance has a complex structure, comprising a hydrophobic core carrying functional radicals, mainly carboxyls and hydroxyls. Thus, humic substances can react with different products of various chemical functions, and so they interact ecologically with all classes of toxic products such as heavy metals, pesticides, etc. 

A study of the bulk properties of seawater humic substances was carried out by Kerr and Quinn (1975), while a detailed structural analysis was undertaken by Stuermer (1975) and Stuermer jmd Harvey (1978). Stuermer discussed the structural features in terms of origin, chemical and physical properties, interaction in the sea and eventual fate. As an example of the formation of a humic substance in seawater, we will discuss Stuermer s proposed structure of seawater fulvic material (Gagosian and Stuermer, 1977), the precursor compounds to its formation, and the condensation and polymerization reactions responsible for its synthesis. Although the material isolated by Stuermer represents only a small portion of the total hiunic material, it serves as an example of a possible condensation product. 

A. Buondoimo, M.L. Ambrosino, E. Coppola, D. Felleca, F. Palmieri, P. Piazzolla and A. De Stradis, Models of organo-mineral aggregates with polyphenols. 2. Stability of bentonite-Ca-gallotannin interaction products. In N. Senesi e T.M. Miano (eds.). Humic substances in the global environment and implications on human health, Elsevier, Amsterdam, 1994, p. 1101. 

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