Humus is a complex organic matter formed by the long-term physical, chemical and biological effects of plants and animals.
It is a large molecular polymer with complex chemical structure, with carboxyl, phenol, ketone and other active groups, whose molecular weight is from 102 to 106. The composition of humus is different from that of the humus, which can be divided into two types: humic acid (HA), fulvic acid (FA), and black substance. The organic matter in natural drinking water is mainly HA, and its concentration range is from 20 g/ L of groundwater to 30 mg/ L of surface water. The higher the content, the worse the sanitation of water quality. The content of humic acid in general water sources is about 10 mg/ L, accounting for 50% ~ 90% of the total organic matter in water. The presence of humic acid in natural drinking water has a series of effects on human and animal and plant life:
It is a complex agent for trace metal elements. The presence of humic acid, on the one hand, can make the content of metal ions and trace elements in water drop, lower salinity, undermining the body for some elements such as Ca, Mg, Mn, Mo, V, SO2-4, such as adsorption, and balance; On the other hand, it can affect the toxicity and bioavailability of metal ions.
The humic acid in the water body is an important precursor of halogenated by-products. Humus is very easy to form disinfection by-product DBPs and trihalomethane carcinogenic substance THMs in the process of chlorination of water plants. It is reported that almost all aquatic natural organisms may be chlorinated in the process of disinfection, in which humic acid, which accounts for about half of dissolved aquatic organisms, is the most important precursor to THMs. Research shows that dissolved humic acid class is generated in the natural water body MX (a kind of disinfection byproducts with strong respectively) of the main precursors, some of the phenol, aldehyde, aromatic acid compounds may play an important role in the formation of MX.
It is one of the main environmental factors that lead to the disease. The drinking water of the residents in the disease area is usually dark and moist, and there is no sufficient sunlight. The humic acid in the water is low in photolysis, so the content is high.
The acidification of water causes the change of humus (HS) characteristics, which can affect the environment. With the continuous deterioration of human living environment, the formation of acid rain and the decrease of pH in natural water bodies such as lakes. Organic nitrogen content of the HS water increases, its material hydrophobic and hydrophilic material proportion reduced, the content of carbon and carboxylic acid is reduced, the content of oxygen and phenolic aldehyde acid increased, leading to fish toxicity and primary production of phytoplankton increase and make some major zooplankton species disappear, giant plants reduce, epiphytes of dealing with the basin increased.