Industrial wastewater: direct discharge of untreated industrial wastewater is an important source of pollution of water bodies, with a large amount, a wide range of complex composition, toxicity, not easy to purify, difficult to deal with and so on. Industrial wastewater is most commonly found in the chemical industry, paper industry, food processing industry, metal products industry, iron and steel industry, leather printing and dyeing industry. Every year in China, about 1/3 of the industrial wastewater is directly discharged into the waters without treatment, and the violation of smuggling is very serious.
For example, Jiamusi City, Heilongjiang Province, only industrial and mining enterprises each year without treatment directly discharged into the river wastewater amounted to more than 100 million tons of industrial waste, domestic waste annual accumulation of more than 1.4 million tons, of which nitro compounds and phenol in the chemical residue seriously contaminated the urban area and the surrounding groundwater, pollutant content exceeded the standard by several hundred times. Among them, the city's largest water source - six water source phenol concentration exceeded the standard up to 390 times, resulting in the scrapping of the water source, direct economic losses of more than 400,000 yuan. Groundwater in the agricultural zone, mainly nitrate-type water; in the chemical and pesticide distribution areas, sulfate-type water; in the densely populated areas, mainly chloride-type water. In recent years, chlorine and nitrate have grown the fastest, followed by sulfate. Nitrate detection rate of 93?4%, exceeding the standard rate of 60?5%; nitrite detection rate of 81?0%; ammonium detection rate of 11?0%; iron 0?3-33?0 mg / liter, exceeding the standard rate of 95?4%.
December 15, 2005, the Guangdong Provincial Environmental Protection Department monitoring found that the Guangdong Beijiang Shaoguan section of the heavy metal cadmium exceeded the phenomenon, in the Beijiang Gaoqiao section, the monitoring department measured cadmium exceeded the standard of nearly 10 times, a serious threat to the downstream of the drinking water source safety. The Guangdong Provincial Environmental Protection Bureau investigation, preliminary confirmation of this pollution incident is due to the Shaoguan smelter equipment maintenance during the excessive discharge of cadmium-containing wastewater caused by the Guangdong Provincial Government announced on December 20, the serious environmental pollution accident, the Beijiang River downstream of the drinking water in Shaoguan, Qingyuan, Yingde, three cities are threatened by the contamination of the drinking water, part of the city tap water supply stopped.
Living sewage: mainly a variety of detergents and sewage, garbage, feces, etc., used in urban life, living sewage contains more nitrogen, phosphorus, sulfur, organic fibers, starch, sugars, fats, proteins, urea, disease-causing bacteria and so on. About 90% of China's annual domestic sewage is discharged directly into the waters without treatment.
According to the former Environmental Protection Administration of a survey report shows that in recent years, China's urban sewage discharged at an average annual rate of 5% incremental increase in 1998, China's domestic sewage discharged 18.4 billion tons; in 1999, urban sewage discharged for the first time more than the amount of industrial sewage, accounting for the total amount of sewage discharged in the country's 52?9%; in 2003, the national industrial wastewater and urban The total amount of industrial wastewater and urban sewage discharged in 2003 was 46 billion tons, of which 24.7?6 billion tons of urban domestic sewage discharged, accounting for 53?8% of the total.
For example, in Taiyuan City, Shanxi Province, the city's annual discharge of wastewater is 1.9 billion cubic meters, with wastewater discharged by a variety of toxic substances about 190,000 tons per year. Fen River Taiyuan section of the water phenol, cyanide, arsenic, mercury, hexavalent chromium, five toxic, phenol content exceeds the drinking standard of more than 2,000 times.
Agricultural sewage: including livestock manure, pesticides, fertilizers and so on. Agricultural sewage, one is organic matter, plant nutrients and pathogenic microorganisms in high content; the second is pesticides and fertilizers in high content. China is currently not carried out on the surface of agricultural monitoring, according to relevant information, in 100 million hectares of arable land and 2.2 million hectares of grassland, the annual use of pesticides 1.1?490 million tons. China is one of the world's most serious soil erosion, annual topsoil loss of about 5 billion tons, resulting in a large number of pesticides, fertilizers with the topsoil into the rivers, streams, lakes and reservoirs, with the loss of nitrogen, phosphorus, potassium nutrients, so that 2/3 of the lakes are subjected to varying degrees of pollution by eutrophication hazards, resulting in the abnormal reproduction of algae and other organisms, causing changes in the transparency of the water column and dissolved oxygen, thus leading to deterioration of water quality.
Mineral mining is a major source of water pollution.
Mine residue: mining residue by the rain wash and pollute rivers, soil and groundwater. Especially rare metals, heavy metals mining plant slag by the rain to make the heavy metal content in the water exceeds the standard.
Atmospheric pollutants: atmospheric pollutants can fall into the rivers, lakes and seas through the precipitation effect of rainwater to pollute water bodies.