What harm will water pollution bring?

(1) Harm of water eutrophication Under normal circumstances, oxygen has certain solubility in water. Dissolved oxygen is not only the survival condition of aquatic organisms, but also participates in various redox reactions in water, promoting the transformation and degradation of pollutants, which is an important reason why natural water bodies have self-purification ability. The discharge of domestic sewage containing a large amount of nitrogen, phosphorus and potassium leads to the degradation of a large number of organic substances and the release of nutrients in the water, which promotes the excessive growth of algae and plants in the water, makes the water body poorly ventilated, reduces dissolved oxygen and even appears anaerobic layer. A large number of aquatic plants die, the water surface turns black, and the water stinks to form a "dead lake", "dead river" and "dead sea", which in turn becomes a swamp. This phenomenon is called water eutrophication. Eutrophicated water has an unpleasant smell, dark color and many bacteria. This kind of water is of poor quality and can't be used directly, which prevents the fish from dying. ?

(2) Water pollution is harmful to industrial and agricultural production, and industrial water must be treated with more expenses, resulting in a waste of resources and energy. The food industry has stricter requirements for water. If the water quality is unqualified, it will stop production. This is also a factor of low efficiency and poor quality of industrial enterprises. The use of sewage in agriculture will reduce crop yield and quality, even harm people and animals, pollute large areas of farmland and reduce soil quality. The consequences of marine pollution are also very serious, such as oil pollution, which causes the death of seabirds and marine life. ?

(3) After water pollution harms human health, pollutants enter the human body through drinking water or food chain, causing acute or chronic poisoning. Arsenic, chromium, ammonium, benzopyrene, etc. It can also induce cancer. Water polluted by parasites, viruses or other pathogenic bacteria will cause many infectious diseases and parasitic diseases. Water polluted by heavy metals is harmful to human health. Water and food polluted by cadmium will cause kidney and bone diseases after people eat it. Ingestion of 20 mg of cadmium sulfate will lead to death. Lead poisoning can lead to anemia and insanity. Hexavalent chromium is very toxic, which can cause skin ulcers and cause cancer. Drinking arsenic-containing water can cause acute or chronic poisoning. Arsenic inhibits or deactivates many enzymes, leading to metabolic disorders, skin keratinization and skin cancer. Organophosphorus pesticides can cause neurotoxicity, while organochlorine pesticides can accumulate in fat, which is harmful to endocrine, immune and reproductive functions of human beings and animals. Most polycyclic aromatic hydrocarbons are carcinogenic. Cyanide is also a highly toxic substance. After entering the blood, it combines with the pigment oxidase of cells, which interrupts breathing and causes respiratory failure, suffocation and death. We know that 80% of the diseases in the world are related to water. Typhoid fever, cholera, gastroenteritis, dysentery and infectious liver disease are the five major diseases of human beings, all of which are caused by unclean water. ?

Acids, alkalis and oxidants in sewage, as well as compounds such as copper, cadmium, mercury and arsenic, and organic poisons such as benzene, phenol, dichloroethane and ethylene glycol will poison aquatic organisms and affect drinking water sources and scenic spots. When the organic matter in sewage is decomposed by microorganisms, it consumes dissolved oxygen in the water and affects the life of aquatic organisms such as fish. After the dissolved oxygen in the water is exhausted, the organic matter is decomposed anaerobically, producing unpleasant gases such as hydrogen sulfide and mercaptan, which further deteriorates the water quality. Oil will also float on the water surface, affecting the life of aquatic organisms and causing fires.