What are Humic Substances?

What are Humic Substances? Humic substances (HS) are complex and heterogeneous mixtures of polydispersed materials formed in soils, sediments, and natural waters by biochemical and chemical reactions during the decay and transformation of plant and microbial remains (a process called humification). Plant lignin and its transformation products, polysaccharides, melanin, cutin, proteins, lipids, nucleic acids, fine char particles, etc., are important components taking part in this process. Humic substances are involved in many processes in soils and natural waters: e.g., soil weathering, plant nutrition, pH buffering, trace metal mobility and toxicity, bioavailability, degradation and transport of hydrophobic organic chemicals, formation of disinfection by-products during water treatment, and heterotrophic production in blackwater ecosystems. Accordingly, humic substances have received attention from scientists in a wide variety of disciplines. More information about humic substances…

Introduction to the International Humic Substances Society (IHSS). This website provides information on the International Humic Substance Society (IHSS), its products and services. IHSS was founded in Denver, Colorado, USA, on September 11, 1981 to bring together scientists in the coal, soil, and water sciences with interests in humic substances. IHSS has a membership of nearly 500 scientists. The Society is recognized as a world leader in fostering scientific education and research, and promoting public understanding of humic substances. The motto of the IHSS is: “To Advance the Knowledge and Research of Natural Organic Matter in Soil and Water”. The aims of the Society include the establishment and maintenance of a collection of standard samples of humic and fulvic acids from lignite, fresh water, a mineral soil, and an organic soil, and the assembling of characterization data. In addition, the Society has added reference samples that are a source of humic materials for research. The IHSS convenes biennial international conferences, which bring together scientists from the soil, coal, freshwater, and marine sciences. These conferences are convened by leading scientists in collaboration with the IHSS Board.


The 22nd meeting of the IHSS new-01

“The role of NOM and HS in achieving Sustainable Development Goals”
Rimini, Italy, August 25-30, 2024

The NL63 is now online new-01

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IHSS flyer

IHSS flyer is now available. Click here to download it!

The third batch of Suwannee River Humic and Fulvic Acids is now available

IHSS has recently completed the processing new batches of Suwannee River Humic and Fulvic acid. A 13-minute video about the sampling and processing of the HA and FA  is available on YouTube. For more information about sampling and processes…

NOM from the Upper Mississippi River is available

Since January 2015, IHSS sells a reference sample of NOM collected from the Mississippi River in Minneapolis, Minnesota, USA. The collection of the NOM is documented in a 10 minute video available on YouTube. The collection of the NOM involved the innovative use of reverse osmosis combined with electrodialysis to separate the NOM from a hardwater, high in calcium and magnesium. Researchers will now have access to a low mineral content NOM (8% ash) from a major river that supplies drinking water to a major city. For more information about collection of the NOM…