Humic SubstancesOrganic matter in a state of advanced decay, after passing through the stages of COMPOST and PEAT and before becoming lignite (COAL). It is composed of a heterogenous mixture of compounds including phenolic radicals and acids that polymerize and are not easily separated nor analyzed. (E.A. Ghabbour & G. Davies, eds. Humic Substances, 2001).
A complex mixture of dark colored hetero-polymeric phenolic compounds found in HUMUS; COAL; and PEAT; resulting from the decomposition of organic matter, particularly dead plants. They are soluble in alkali and carbonates, only slightly soluble at physiological pH, and can chelate metals.
AcidsChemical compounds which yield hydrogen ions or protons when dissolved in water, whose hydrogen can be replaced by metals or basic radicals, or which react with bases to form salts and water (neutralization). An extension of the term includes substances dissolved in media other than water. (Grant & Hackh's Chemical Dictionary, 5th ed)
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