The reasons and the harm of water pollution
Causes of water pollution: three pollution
Water pollution is mainly caused by the pollutants generated by human activities, which includes industrial pollution, agricultural pollution source and domestic pollution source of three parts.
Industrial wastewater is the important water sources, has the characteristics of large amount, wide area, complex composition, toxicity, easy purification, intractable and so. According to the 1998 Chinese water resources bulletin data show: this year, the national total of 539 tons of wastewater emissions (excluding fire direct current cooling water), of which, industrial wastewater emissions 409 tons, accounting for 69%. In fact, the sewage water, far more than this number, because many industrial wastewater of township enterprises to statistics.
Agricultural pollution sources include livestock manure, chemical fertilizer, pesticide. Pesticides in the water, one is organic matter, plant nutrients and high content of pathogenic microorganism, pesticide, fertilizer is high content of two. Chinese currently not on monitoring the agricultural aspect, according to statistics, in 100000000 hectares of arable land and 2200000 hectares of grasslands, the annual use of 1104900 tons of pesticides. China is one of the most serious soil erosion in the country the world, about 50 tonnes of annual soil erosion amount, resulting in a large number of pesticides, fertilizer with surface into river, river, lake, reservoir, then the loss of nitrogen, phosphorus, potassium nutrition elements, make the 2/3 lakes are different degree of harm caused by eutrophication, algae and other biological abnormal reproduction, cause the change of dissolved oxygen and water transparency, which leads to the deterioration of water quality.
Domestic pollution source is mainly used in the city life detergent and sewage, garbage, feces, much as non-toxic inorganic salt, nitrogen, phosphorus, sulfur containing sewage, pathogenic bacteria. According to the survey, in 1998 the domestic sewage discharge volume of 184 tons Chinese.
China every year there are about 1/3 of industrial waste water and more than 90% of untreated sewage is discharged into the water, the country has more than 1200 river monitoring, at present more than 850 pollution, more than 90% of the city water have been contaminated, resulting in many river fish, accord with national level one and level two of the river water quality standard accounted for only 32.2%. Pollution from shallow to deep development, and groundwater near the sea water is polluted, we can use the water for drinking and is imperceptibly reduced.
The harm of water pollution
The increasing water pollution, has posed a great threat to the survival of human security, become a major obstacle to human health, economic and social sustainable development. According to the world authoritative organization investigation, in developing countries, 80% of all diseases because of drinking unsafe water and spread each year from drinking unsafe water, at least 20000000 people worldwide die, therefore, water pollution was known as "the world's number one killer".
The impact of water pollution of industrial production, increased equipment corrosion, affecting product quality, production can not even make go. Water pollution, and affects people's lives, the destruction of the ecological, directly endanger people's health, great damage.
(1) water pollution does harm to people's health, through drinking water or food chain, pollutants enter the body, make the person of acute or chronic poisoning. Arsenic, chromium, ammonium, B benzo (a) pyrene, still can cause cancer. The parasites, viruses or other pathogens in contaminated water, can cause a variety of infectious and parasitic diseases. Heavy metal pollution of water, on human health are harmful. Be cadmium contaminated water and food, the people after eating, can cause kidney, bone lesions, intake of cadmium sulfate 20 mg, will result in death. Lead poisoning, causing anemia, take leave of one's senses. Six chromium is highly toxic, causing skin ulcer, and carcinogenesis. Drinking water containing arsenic, causes acute or chronic poisoning. Arsenic in many enzyme is inhibited or lose activity, cause metabolism disorder, the horny skin, cause skin cancer. Organic phosphorus pesticide poisoning can cause nerve, organochlorine pesticides will accumulate in the fat, endocrine, immune function and reproductive function of human and animal are harmful. Polycyclic aromatic hydrocarbons in the majority of the carcinogenic. Cyanide is highly toxic substances into the blood, combined with cytochrome oxidase cells, make the apnea, respiratory failure caused by asphyxia death. We know that 80% of the world's disease associated with water. Typhoid, cholera, dysentery, infectious gastroenteritis, liver is the five big disease, which are caused by water is not clean.
(2) the harm of water pollution to the industrial and agricultural production, industrial water treatment must be input costs more, resulting in waste of resources and energy, water for food industry requirements more stringent, water quality is not qualified, will make the production to a standstill. This is the industrial enterprise benefit is not high, not good quality factors. Agricultural use of sewage, the crop yield and quality decrease, even make the human and animal victims, large tracts of farmland pollution, decrease of soil quality. Marine pollution is also very serious consequences, such as oil pollution, cause of seabirds and marine biological death.
(3) the water eutrophication hazards under normal conditions, oxygen solubility in water. Dissolved oxygen is not only to survive the conditions of aquatic organisms, various oxidation - reduction reaction and oxygen in the water, and promote the transformation of pollutants degradation, is an important cause of natural water has self purification ability. Containing a large amount of nitrogen, phosphorus and potassium of sewage discharge, large quantities of organic matter released nutrient elements in the water degradation, promoting algae tufted, vegetative, make water poor aeration, dissolved oxygen decreased, and even the emergence of anaerobic layer. So that a large number of aquatic plants death, water is black, smelly water form the "lake of death", "dead", "Dead Sea", and become a swamp. This phenomenon is known as the water eutrophication. Eutrophication of water foul smell, color depth, bacteria, the water quality of this water is poor, can not directly use, the water off a large number of dead fish.