In recent years, with the rapid development of human society, the water sources in many areas have been polluted to varying degrees, but at the same time, people pay more and more attention to the problem of water pollution. So what are the causes of water pollution? What harm will water pollution bring? This article brings you a detailed introduction. Let's have a look.
Introduction to water pollution
Water pollution is caused by harmful chemicals that reduce or lose the use value of water and pollute the environment. Acids, alkalis and oxidants in sewage, compounds such as copper, cadmium, mercury and arsenic, and organic poisons such as benzene, dichloroethane and ethylene glycol will poison dead aquatic organisms and affect drinking water sources and scenic spots.
When the organic matter in the sewage is decomposed by microorganisms, it consumes oxygen in the water and affects the life of aquatic organisms. After the dissolved oxygen in the water is exhausted, the organic matter undergoes anaerobic decomposition to produce unpleasant gases such as hydrogen sulfide and mercaptan, which further worsens the water quality.
Causes of water pollution
Water pollution is mainly caused by pollutants produced by human activities, including industrial pollution sources, agricultural pollution sources and domestic pollution sources.
1、 Industrial pollution
Industrial wastewater is an important pollution source of water area, which has the characteristics of large quantity, wide area, complex composition, high toxicity, difficult purification and treatment.
According to the data of China water resources bulletin in 1998, the total discharge of wastewater in China was 53.9 billion tons, including 40.9 billion tons of industrial wastewater, accounting for 75.88%. In fact, the amount of sewage discharge far exceeds this number, because it is difficult to count the industrial sewage discharge of many township enterprises.
2、 Agricultural pollution
Agricultural pollution sources include livestock manure, pesticides, chemical fertilizers, etc. In pesticide wastewater, one is the high content of organic matter, plant nutrients and pathogenic microorganisms, and the other is the high content of pesticides and chemical fertilizers.
China has not carried out agricultural monitoring. According to relevant data, 1104900 tons of pesticides are used every year on 100 million hectares of cultivated land and 2.2 million hectares of grassland.
China is one of the countries with the most serious soil erosion in the world. The annual loss of topsoil is about 5 billion tons, resulting in a large number of pesticides and chemical fertilizers flowing into rivers, rivers, lakes and reservoirs with the topsoil, and the subsequent loss of nitrogen, phosphorus and potassium nutrients, endangering two-thirds of the lakes by varying degrees of eutrophication pollution, resulting in abnormal reproduction of algae and other organisms, Cause changes in water transparency and dissolved oxygen, resulting in deterioration of water quality.
3、 Domestic pollution
Domestic pollution sources are mainly various detergents, sewage, garbage and feces used in urban life, mostly non-toxic inorganic salts. Domestic sewage contains more nitrogen, phosphorus and sulfur, and more pathogenic bacteria. According to the survey, China's domestic sewage discharge in 1998 was 18.4 billion tons.
About one-third of China's industrial wastewater and more than 90% of domestic sewage are discharged into water areas without treatment every year. Of the more than 1200 rivers monitored in China, more than 850 are polluted and more than 90% of urban water areas are also polluted, resulting in the disappearance of fish and shrimp in many river sections. Only 32.2% of the rivers that meet the national first and second-class water quality standards.
Pollution is developing from shallow to deep, groundwater and sea water near the sea are also being polluted, and the water we can drink and use is unconsciously decreasing.
Hazards caused by water pollution
The increasing water pollution has posed a major threat to human survival and safety, and has become a major obstacle to human health, economic and social sustainable development.
According to the survey of world authorities, in developing countries, 80% of all kinds of diseases are transmitted by drinking unsanitary water. Drinking unsanitary water causes at least 20 million deaths worldwide every year. Therefore, water pollution is known as the world's number one killer.
Water pollution affects industrial production, increases equipment corrosion, affects product quality, and even makes production impossible. Water pollution affects people's life, destroys ecology, directly endangers people's health and causes great damage.