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 Substances Society (IHSS) and its products and services. IHSS was founded in Denver, Colorado, USA, on September 11, 1981 aiming to bring together scientists in the soil, water, and coal sciences with interest in humic substances (HS). HS comprise a large fraction of the naturally occurring organic substances in soils and aquatic environments which collectively are referred to as natural organic matter (NOM). IHSS encompasses a membership of about 500 scientists working in institutions spread all over the world. The Society is recognized as the world leader in fostering scientific education and research and promoting public understanding of NOM and HS. 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 (HA) and fulvic (FA) acids extracted following strict protocols from aquatic NOM, soil, leonardite, and peat. In addition, the Society distributes reference samples of HA and FA from various sources and non-fractionated aquatic NOM plus bulk soil and peat samples that are sources of standard HA and FA. The society also maintains analytical data related to its collection. The IHSS convenes a biennial international conference at which relevant scientific issues are presented and discussed, ranging from chemical properties and activity of NOM and humic fractions, and applied studies within environmental, economic, and agricultural contexts. The Society also provides funding to aid national chapters in the hosting of national meetings and provides travel and research funding for graduate students and early-career researchers.

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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…