While more than 70 percent of the Earth's surface is water, most of it is seawater.Seawater is salt water and cannot be used directly,while freshwater resources only account for 2% of the global water body.With the development of science and technology.With the progress of the times,with the rapid growth of population, the environment for human survival and development has been polluted and the ecological environment has been destroyed.On this basis, the ecosystem will also be destroyed.Water pollution problems range from regional to global.Humanity must pay attention to and solve global environmental problems.
Effects of water pollution on human health:
1.Water-borne infectious diseases
Animal feces and other biological pollutants can pollute water bodies, such as typhoid fever, dysentery, enteritis, cholera, etc.; poliovirus, coxsackie virus, infectious hepatitis virus and other common intestinal viruses can cause infection through water bodies. In 1989, a hepatitis A incident occurred in Shanghai due to water pollution. Dysentery kills about 60 million people in developing countries each year, most of them children.
2.Acute and chronic poisoning
After water is contaminated with toxic and harmful chemicals, it can cause poisoning through drinking water or the food chain. The famous paddy field disease. The pain is caused by water pollution.
3.Indirect influence
After water pollution,it often leads to the deterioration of water quality characteristics. For example, some pollutants at a certain concentration, although there is no direct harm to human health,will cause the water to produce peculiar smell.Different color, foam,oil film,etc.affect the normal use of water.At a certain concentration,copper,zinc,nickel and other substances can inhibit the growth and reproduction of microorganisms,affect the decomposition and biological oxidation of organic matter in water,reduce the self-purification ability of water,and affect the health of water.
4.Carcinogenic effects
Arsenic Some carcinogenic chemicals,such as arsenic, chromium,nickel,beryllium,aniline and (a) pyrene and other polycyclic aromatic hydrocarbons.After halocarbons pollute water bodies, they can be adsorbed by suspended solids and sediments, or accumulated in aquatic organisms. Long-term drinking of water containing these substances or eating organisms (such as fish) that store these substances can cause cancer in the body.
Main water pollutants:
Mercury is very harmful to the human body, mainly damages the kidneys and the central nervous system.
Carbon tetrachloride (organic compound): has a wide range of effects on human health, is carcinogenic, and has a large impact on liver and kidney function.
Lead: Harmful to the kidneys, nervous system, highly toxic to children, and has been shown to be carcinogenic.
Trihalomethanes: Chloroform has the greatest impact on human health, and the most common carcinogenicity is bladder cancer.
Cadmium:acute damage to renal tissue.
Selenium:High concentrations can damage the muscles and nervous system.
Arsenic:Harmful substances that have carcinogenic effects on the skin and nervous system.
Nitrite:Causes cardiovascular disease,has the greatest impact on infants (blue baby disease),and is carcinogenic.
Trichloroethylene(organic):Excessive inhalation will reduce the central nervous system.Heart function,long-term exposure is harmful to the liver.
