Environmental impact of Humic acid

Humus is a complex organic matter formed by long-term physical, chemical and biological actions of animals and plants. Humus is contained in water, sediment, soil, etc. Humus is a macromolecular polymer with complex chemical structure, which contains carboxyl, phenolic, ketone and other active groups, and its molecular weight ranges from 102 to 106. The composition of Humus varies with different sources. Humus can be divided into: Humic acid, also known as humic acid (HA), fulvic acid (FA) and humic acid according to its solubility in acid and alkali. The organic matter in natural drinking water, mainly HA, has a concentration range of 20% in groundwater μ The higher the content from g/L to 30 mg/L of surface water, the poorer the water quality and hygiene status. The content of Humic acid in general water sources is about 10 mg/L, accounting for 50%~90% of the total organic matter in the water. The presence of Humic acid in natural drinking water sources has brought a series of impacts on human beings, animals and plants:
(1) HA is a complexing agent for trace metal elements. The presence of Humic acid, on the one hand, will reduce the content of metal ions and trace elements in the water, and reduce the degree of mineralization, thus destroying the human body's adsorption and balance of certain elements such as Ca, Mg, Mn, V, Mo, SO24-, etc; On the other hand, it can affect the toxicity and bioavailability of metal ions.
⑵ Humic acid in water is an important precursor of halogenation by-products. Humus is very easy to form disinfection by-products DBPs and Trihalomethane Carcinogen THMs during chlorination in water plants. It is reported that almost all the natural aquatic organics may be chlorinated during disinfection, and Humic acid, which accounts for about half of dissolved aquatic organics, is the most important precursor for THMs production. The research shows that dissolved humic acids are the main precursors for the formation of MX (a disinfection by-product with strong mutagenicity) in natural water. Some phenols, aldehydes and aromatic acids may play an important role in the formation of MX.
⑶ Humic acid is one of the main environmental factors leading to Kashin Beck disease. The drinking water of residents in Kashin Beck disease endemic areas is often dark and humid cellar water, which cannot get sufficient sunlight, and Humic acid in the water is less photolysis, so the content is high.
⑷ The acidification of water body causes the change of Humus (HS) characteristics, thus affecting the environment. With the continuous deterioration of human living environment, the formation of acid rain, the decline of pH in natural water bodies such as lakes, the increase of organic nitrogen content, the reduction of the proportion of hydrophobic and hydrophilic substances, the reduction of carbon content and carboxyl acidity, the increase of oxygen content and the acidity of phenols and aldehydes, which further led to the increase of fish toxicity and the Primary production of Phytoplankton, the disappearance of some major Zooplankton species, and the reduction of megaplants, Increase in epiphytic plants in the treatment basin.