Humic substance

Major component of natural organic matter

Humic substances (HS) are coloured recalcitrant organic compounds naturally formed during long-term decomposition and transformation of biomass residues. The colour of humic substances varies from yellow to brown to black. The term comes from humus, which in turn comes from the Latin word humus, meaning "soil, earth". Humic substances represent the major part of organic matter in soil, peat, coal, and sediments, and are important components of dissolved natural organic matter (NOM) in lakes, rivers, and sea water.

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