Since the 1960s, it has been common to use the quality of the environment to indicate the degree of pollution suffered by the environment, natural disasters, resource utilization, waste discharge, and the size of the population and the state of the culture can change or affect the quality of the environment in a region. Environmental problems are diverse, and can be divided into two main categories when considering the root causes of environmental problems: one is the primary environmental problems caused by natural evolution and natural disasters, also called the first environmental problems, mainly: earthquakes, tsunamis, floods, droughts, typhoons, landslides, mudslides and other natural disasters. One category is secondary environmental problems caused by human activities, also called secondary environmental problems. Secondary environmental problems are generally subdivided into two categories: environmental pollution and ecological damage. Usually, it is difficult to separate the two categories of environmental problems, primary and secondary, and they often influence and interact with each other. Since entering the new century, national environmental security has become a hot topic of concern, some international politicians believe that the threat to national security is not only the invasion of foreign enemies, but also serious environmental pollution and ecological damage, the invasion of exotic species, environmental intrusion caused by the competition for resources also directly affect national security. During the "Tenth Five-Year Plan" period, China, from the perspective of ensuring national environmental security, has made water and air pollution the focus of its control efforts, so that the environmental quality of large and medium-sized cities can be significantly improved. In order to ensure the safety of water quality in the South-to-North Water Diversion Scheme and the Three Gorges Reservoir area, important ecological function reserves were established at the headwaters of the Yangtze River, the Yellow River and other large rivers, and a number of high-quality nature reserves were constructed in species-rich areas. However, China's environmental security still has many hidden dangers, mainly manifested in: shortage of water resources and serious pollution, 50% of the drinking water sources in cities and towns come from lakes (reservoirs), and the vast majority of these lakes are in a serious state of eutrophication, and the pollution of groundwater by harmful substances directly affects people's lives and economic development; regional acid rain pollution and serious urban air pollution and harmful organic pollution directly jeopardizes people's health; regional acid rain pollution and serious urban air pollution and harmful organic pollution directly jeopardizes people's health. Regional acid rain pollution and serious urban air pollution and harmful organic pollution directly jeopardize the health of the people; still deteriorating ecological environment threatens the survival and reproduction of the Chinese nation; biodiversity has been sharply reduced, the invasion of foreign species, jeopardizing the future development.
One, China's environmental pollution
Environmental pollution is due to man-made factors, so that the composition or state of the environment has changed, compared with the original situation, the deterioration of the quality of the environment, disturbing and destroying the ecosystem and the people's normal production and life, when the pollution is serious, the occurrence of "public nuisance" events. Pollution is a common but insensitive phenomenon faced by modern human society. From industrial production to agricultural production, from the consumption of daily necessities to the consumption of various products for food, drink and entertainment, from telecommunications and information technology to weapons of war, all of them cause pollution to the environment and human society. For example, chemical products, automobile exhaust, industrial wastewater, toxic metals, crude oil spills, solid waste, pesticides, herbicides, all kinds of drugs, stain removers, laundry detergents, refrigerants, preservatives, water pollution, acid rain, greenhouse effect, depleted uranium shells and even noise pollution from military and ships in the ocean ......
The 2002 National Environmental Bulletin shows that our country is still facing very serious pollution from surface sources. For example, the seven major water systems in order of pollution from heavy to light: the Haihe River, Liaohe River, Yellow River, Huaihe River, Songhua River, Pearl River, Yangtze River. The main lakes are heavily polluted with nitrogen and phosphorus, resulting in a heavily eutrophic Dianchi Caohai, and a mildly eutrophic Taihu and Chaohu.
In 2002, the total amount of wastewater discharged nationwide was 43.95 billion tons, an increase of 1.5% over the previous year. The total amount of sulfur dioxide discharged in the national waste gas was 19.266 million tons, the total amount of soot discharged was 10.127 million tons, and the total amount of industrial dust discharged was 9.41 million tons. Nearly two-thirds of the cities' air quality did not meet the secondary standard. Urban road traffic noise is seriously polluted in 4.9% of cities, moderately polluted in 17.2%, and lightly polluted in 64.3%. The regional environmental noise situation was that 3.4%, 44.2%, 48.6% and 3.8% of the cities were severely polluted, moderately polluted, mildly polluted and had better acoustic environment quality respectively. The amount of industrial solid waste generated nationwide was 950 million tons, an increase of 6.5% over the previous year.
1. Air Pollution
The important pollutants (sources) in the atmosphere are respirable particulate matter, ozone (O3), nitrogen oxides (NOx), carbon monoxide (CO), and sulfur dioxide (SO2). In addition to air pollution caused by these sources, there is also photochemical smog formed by secondary pollution, which can also cause serious air pollution. Photochemical smog is produced due to secondary pollution. Nitrogen oxides emitted by car exhaust and factory emissions of hydrocarbons in the sunlight, in the wavelength of 4000 × 10-5m below the ultraviolet region - a series of chemical reactions, generating ozone O3 and peroxynitrite peroxidation products such as peroxyl nitrate and a variety of free radicals, aldehydes, ketones and other components, the formation of a toxic blue smoke floating in the air, called "photochemical smog", "Photochemical smog".
According to the function of human social activities, air pollution sources can be divided into industrial pollution sources, agricultural pollution sources, transportation pollution sources and living pollution sources.
Industrial pollution sources refers to the thermal power generation, iron and steel, chemical and silicate industrial and mining enterprises in the production process, the emission of soot, dust and harmful compounds and other sources of pollution. Such sources of pollution due to different industrial and mining enterprises of the nature of production and process technology, the emission of pollutants and the number of different types, but there is a *** with the same characteristics is that the emission source is concentrated, high concentration, high local pollution intensity. Is the culprit of urban air pollution.
Agricultural pollution sources are mainly improper application of pesticides, fertilizers, organic manure and other harmful substances generated by the process of volatile diffusion, as well as the application of late NOX, CH4, volatile pesticide components from the soil to escape into the atmosphere, such as the formation of sources of pollution.
Transportation sources of pollution refers to the exhaust emitted into the atmosphere by automobiles, airplanes, trains and ships and other means of transportation. This type of pollution source is a mobile source of pollution, the main pollutants are soot, hydrocarbons, NOX, metal dust, etc., is one of the main reasons for the deterioration of the urban atmospheric environment.
Living sources of pollution refers to the residents of daily cooking, heating, bathing and other activities, the burning of fossil fuels and emissions to the atmosphere of soot, SO2, NOX and other pollutants. This type of pollution source is a fixed source, has a wide distribution, large discharge, low pollution height and other characteristics, is some of the urban air pollution can not be ignored source of pollution.
China's environmental conditions
Since the 1960s, it has been common to use the quality of the environment to indicate the degree of pollution suffered by the environment, natural disasters, resource utilization, waste emissions, as well as the size of the population and the state of the culture will change or affect the quality of the environment in a region. Environmental problems are diverse, and can be divided into two main categories when considering the root causes of environmental problems: one is the primary environmental problems caused by natural evolution and natural disasters, also called the first environmental problems, mainly: earthquakes, tsunamis, floods, droughts, typhoons, landslides, mudslides and other natural disasters. One category is secondary environmental problems caused by human activities, also called secondary environmental problems. Secondary environmental problems are generally subdivided into two categories: environmental pollution and ecological damage. Usually, it is difficult to separate the two categories of environmental problems, primary and secondary, and they often influence and interact with each other. Since entering the new century, national environmental security has become a hot topic of concern, some international politicians believe that the threat to national security is not only the invasion of foreign enemies, but also serious environmental pollution and ecological damage, the invasion of exotic species, environmental intrusion caused by the competition for resources also directly affect national security. During the "Tenth Five-Year Plan" period, China, from the perspective of ensuring national environmental security, has made water and air pollution the focus of its control efforts, so that the environmental quality of large and medium-sized cities can be significantly improved. In order to ensure the safety of water quality in the South-to-North Water Diversion Scheme and the Three Gorges Reservoir area, important ecological function reserves were established at the headwaters of the Yangtze River, the Yellow River and other large rivers, and a number of high-quality nature reserves were constructed in species-rich areas. However, China's environmental security still has many hidden dangers, mainly manifested in: shortage of water resources and serious pollution, 50% of the drinking water sources in cities and towns come from lakes (reservoirs), and the vast majority of these lakes are in a serious state of eutrophication, and the pollution of groundwater by harmful substances directly affects people's lives and economic development; regional acid rain pollution and serious urban air pollution and harmful organic pollution directly jeopardizes people's health; regional acid rain pollution and serious urban air pollution and harmful organic pollution directly jeopardizes people's health. Regional acid rain pollution and serious urban air pollution and harmful organic pollution directly jeopardize the health of the people; still deteriorating ecological environment threatens the survival and reproduction of the Chinese nation; biodiversity has been sharply reduced, the invasion of foreign species, jeopardizing the future development.
One, China's environmental pollution
Environmental pollution is due to man-made factors, so that the composition or state of the environment has changed, compared with the original situation, the deterioration of the quality of the environment, disturbing and destroying the ecosystem and the people's normal production and life, when the pollution is serious, the occurrence of "public nuisance" events. Pollution is a common but insensitive phenomenon faced by modern human society. From industrial production to agricultural production, from the consumption of daily necessities to the consumption of various products for food, drink and entertainment, from telecommunications and information technology to weapons of war, all of them cause pollution to the environment and human society. For example, chemical products, automobile exhaust, industrial wastewater, toxic metals, crude oil spills, solid waste, pesticides, herbicides, all kinds of drugs, stain removers, laundry detergents, refrigerants, preservatives, water pollution, acid rain, greenhouse effect, depleted uranium shells and even noise pollution from military and ships in the ocean ......
The 2002 National Environmental Bulletin shows that our country is still facing very serious pollution from surface sources. For example, the seven major water systems in order of pollution from heavy to light: Haihe, Liaohe, Yellow River, Huaihe, Songhua River, Pearl River, Yangtze River. The main lakes are heavily polluted with nitrogen and phosphorus, resulting in a heavily eutrophic Dianchi Caohai, and a mildly eutrophic Taihu and Chaohu.
In 2002, the total amount of wastewater discharged nationwide was 43.95 billion tons, an increase of 1.5% over the previous year. The total amount of sulfur dioxide discharged in the national waste gas was 19.266 million tons, the total amount of soot discharged was 10.127 million tons, and the total amount of industrial dust discharged was 9.41 million tons. Nearly two-thirds of the cities' air quality did not meet the secondary standard. Urban road traffic noise is seriously polluted in 4.9% of cities, moderately polluted in 17.2%, and lightly polluted in 64.3%. The regional environmental noise situation was that 3.4%, 44.2%, 48.6% and 3.8% of the cities were severely polluted, moderately polluted, mildly polluted and had better acoustic environment quality respectively. The amount of industrial solid waste generated nationwide was 950 million tons, an increase of 6.5% over the previous year.
1. Air Pollution
The important pollutants (sources) in the atmosphere are respirable particulate matter, ozone (O3), nitrogen oxides (NOx), carbon monoxide (CO), and sulfur dioxide (SO2). In addition to air pollution caused by these sources, there is also photochemical smog formed by secondary pollution, which can also cause serious air pollution. Photochemical smog is produced due to secondary pollution. Nitrogen oxides emitted by car exhaust and factory emissions of hydrocarbons in the sunlight, in the wavelength of 4000 × 10-5m below the ultraviolet region - a series of chemical reactions, generating ozone O3 and peroxynitrite peroxidation products such as peroxyl nitrate and a variety of free radicals, aldehydes, ketones and other components, the formation of a toxic blue smoke floating in the air, called "photochemical smog", "Photochemical smog".
According to the function of human social activities, air pollution sources can be divided into industrial pollution sources, agricultural pollution sources, transportation pollution sources and living pollution sources.
Industrial pollution sources refers to the thermal power generation, iron and steel, chemical and silicate industrial and mining enterprises in the production process, the emission of soot, dust and harmful compounds and other sources of pollution. Such sources of pollution due to different industrial and mining enterprises of the nature of production and process technology, the emission of pollutants and the number of different types, but there is a *** with the same characteristics is that the emission source is concentrated, high concentration, high local pollution intensity. Is the culprit of urban air pollution.
Agricultural pollution sources are mainly improper application of pesticides, fertilizers, organic manure and other harmful substances generated by the process of volatile diffusion, as well as the application of late NOX, CH4, volatile pesticide components from the soil to escape into the atmosphere, such as the formation of sources of pollution.
Transportation sources of pollution refers to the exhaust emitted into the atmosphere by automobiles, airplanes, trains and ships and other means of transportation. This type of pollution source is a mobile source of pollution, the main pollutants are soot, hydrocarbons, NOX, metal dust, etc., is one of the main reasons for the deterioration of the urban atmospheric environment.
Living sources of pollution refers to the residents of daily cooking, heating, bathing and other activities, the burning of fossil fuels and emissions to the atmosphere of soot, SO2, NOX and other pollutants. This type of pollution source is a fixed source, has a wide distribution, large discharge, low pollution height and other characteristics, is a number of urban air pollution can not be ignored source of pollution.
Wind erosion refers to the lack of vegetation cover on the surface, soil paper loose and dry, wind-powered soil particles scattered caused by soil erosion phenomenon. In recent years, China's frequent occurrence of dust storms and forest destruction, indiscriminate cultivation of grasslands, overgrazing and other triggers of soil wind erosion is closely related. High evaporation rate of surface water can lead to salinization of soil surface in arid areas. In rocky desertification areas, surface soil is lost and rocks are exposed, with no vegetation or only a small amount of vegetation growing in slightly soiled rock crevices.
China's potential area for desertification is about 3.317 million square kilometers, accounting for 34.6% of the national territory, of which 2.62 million square kilometers are desertified, accounting for 27.3% of the national territory, which is more than twice as much as the total area of arable land in the country, and it is expanding at the rate of more than 2,460 square kilometers per year, and the population living in the desert areas and being affected by desertification is nearly 400 million, with direct economic losses caused by desertification every year. The direct economic losses caused by desertification amount to 54 billion yuan each year, with an average daily loss of nearly 150 million yuan, and food losses amounting to more than 3 billion kilograms each year. In Inner Mongolia, in the past 10 years, 220 million mu of pasture have been damaged to different degrees by digging hairy vegetables, of which 60 million mu have been reduced to desert, and the rest are also in the process of desertification, which causes direct economic losses of 3 billion yuan per year to the pastoral industry, and the loss of ecological damage is even more incalculable. China's average annual rocky desertification area of about 2,500 square kilometers.
The savage exploitation of nature by human beings has led to the spread of desertification, and the expansion of desertification has caused the ravages of sandstorms and dust storms. Dust storms have become a symbol of increasing desertification. According to historical records, dust storms have occurred 70 times in China*** over the past hundred years. every two years in the 60s and 70s, and every year in the 90s, with 12 occurrences in 2000 alone. the dust storm of January 1, 2001 affected most of the northern part of China, and there were sandstorms in Beijing. in the spring of 2001, the northern part of China*** there were 18 sand and dust weather processes, of which strong sandstorm process amounted to 41 days.
Sand and dust storms bring human casualties and health damage. There have been incidents in Beijing and Shanxi where outdoor workers have died due to sandstorm attacks. The number of respiratory and ophthalmologic patients admitted to hospitals increases exponentially whenever a sandstorm hits. Sandstorms are a serious threat to transportation and bring great inconvenience to our lives. More than 3,000 kilometers of railroads, 30,000 kilometers of highways and 50,000 kilometers of roads in China are endangered by sandstorms all year round. Sand and dust storms have reduced China's already limited land resources and degraded their quality. More than 50,000 villages across the country are constantly being victimized by sand and wind, and thousands of farmers and herdsmen have become "ecological refugees".
Soil pollution is a byproduct of industrialization. It can be said that all sources of pollution come from industrial production. Soil pollution, including sewage irrigation pollution, acid rain pollution, heavy metal pollution, pesticide and organic pollution, radioactive pollution, pathogenic bacterial pollution and a variety of pollution caused by cross-compound pollution. It has been reported that at present, China's arable land contaminated by cadmium, arsenic, chromium and other heavy metals covers an area of nearly 300 million mu, of which 150 million mu are contaminated by "three wastes", and the area of farmland occupied and destroyed by solid waste dumping amounts to more than 2 million mu; arable land contaminated by air pollution amounts to more than 80 million mu; and the area of sewage-irrigated farmland accounts for 7.3% of the total irrigated area of the country. 7.3% of the total irrigated area; pesticide contamination of farmland area of 140 million mu, an average of about 14 kilograms of pesticides per hectare, twice as much as in developed countries, while the effective rate of only 30%, a large number of pesticide loss into the atmosphere, water, soil and agricultural products, the amount of pesticide residues in the soil increases year by year.
In addition to this, the excessive input of chemical fertilizers in the soil nitrate accumulation, threatening the quality and safety of groundwater and agricultural by-products; the use of film residues in the soil over the years is difficult to degrade; even in the past that beneficial organic fertilizers have undergone qualitative changes, due to the large number of livestock feed added to copper, iron, zinc, manganese, cobalt, selenium, iodine, and other trace elements, antibiotics, growth hormones, when these things are discharged with livestock manure, as organic fertilizer into the soil, it will pollute the environment.
Soil pollution can bring serious economic losses. China's annual grain production loss due to soil heavy metal pollution alone amounts to more than 10 million tons, and as much as 12 million tons of grain is contaminated by heavy metals every year, **** about RMB 20 billion. Soil pollution has led to a steady decline in the quality of agricultural by-products, and in many places the heavy metal content of food such as grain, vegetables and fruits exceeds the standard or is close to the critical value. Some contaminated arable land has produced "cadmium rice", and some vegetables from contaminated irrigation areas have unpleasant odors. Soil pollution through the food chain to enrich the human and animal body, health hazards, triggering disease. According to the survey, a mining area in Guangxi due to sewage irrigation so that the concentration of cadmium in rice seriously exceeded the standard, the local residents of long-term consumption of this "cadmium rice" has reached the "pain through the disease" of the third stage. Some areas due to long-term drinking water, many people suffer from various diseases.
Polluted soil topsoil will enter the atmosphere and water under the action of wind or water, leading to atmospheric, surface water, groundwater pollution, bringing other secondary ecological and environmental problems. For example, if the urban population density is high, the pollutants in the topsoil can enter the human body through the respiratory system with the dust, affecting health. In addition, pollutants in the soil can be gradually transferred to the groundwater through precipitation, etc., causing groundwater pollution. Heavy metals such as fluorine, mercury, cadmium and arsenic have been detected in the groundwater of the Chuansha Dirty Irrigation Area in Shanghai. Some rural wells on the outskirts of Chengdu have also exceeded standards for mercury, chromium, phenol, cyanide and other pollutants in well water due to soil pollution.
Soil pollution is different from the atmosphere, water or waste pollution as intuitive, can be felt or found through the senses. Soil pollution is like an invisible killer, hidden and lagging. It needs to analyze soil samples through laboratory tests, crop residue testing to determine, this hidden nature of its impact on human or livestock health is often a long time after the occurrence of pollution can be found. Soil pollution is cumulative. It does not migrate, spread or dilute as easily as pollutants in the atmosphere or water. Once a pollutant enters the soil, it will continue to accumulate until it exceeds the limit. Therefore, soil pollution is irreversible and very difficult to manage, even if the source of pollution is cut off, it is difficult to achieve recovery by dilution or self-purification.
4. Solid Waste Pollution
Human society produces a variety of solid waste, such as urban residents of living garbage, construction waste, cleaning garbage and hazardous waste (used batteries, lamps and other kinds of chemical and biological hazards, including radioactive waste) and so on has become a real-life non-trivial social problems. Such as known as "white pollution" disposable fast food containers, plastic bags and other waste, its degradation cycle to hundreds of years, incineration will produce toxic gases. China's solid waste has three main sources.
One is industrial solid waste. Mainly industrial production and processing discharged into the environment of a variety of slag, sludge, dust, etc., which is dominated by slag. Its quantity, variety, complex composition, processing difficulties. 1996, China's industrial solid waste generation (excluding township and village enterprises) 660 million tons. Industrial solid waste has become one of the prominent environmental problems recognized worldwide, and the most fundamental way to effectively prevent the environmental pollution it causes is to comprehensively utilize these wastes through recovery, processing and recycling. With the increasingly acute environmental problems, the growing shortage of resources, the comprehensive utilization of industrial solid waste is increasingly being paid attention to.
The second is waste materials. China's waste materials recycling utilization rate is only equivalent to the world's advanced level of 1/4 ~ l/3, a large number of renewable resources have not yet been recycled, the loss of serious, resulting in pollution. According to statistics, China's annual millions of tons of scrap iron and steel, more than 6 million tons of waste paper, 2 million tons of glass is not recycled, the annual loss of renewable resources due to the loss of economic losses amounted to 25-30 billion yuan.
Third is the urban waste. China's urban garbage production is growing fast, with an annual growth rate of 8 to 10%, while the current urban garbage disposal rate is low, only 55.4%, nearly half of the garbage is not processed randomly piled up, resulting in two-thirds of the city appeared garbage around the city phenomenon.
China's traditional garbage destruction and dumping is a "pollutant transfer" method. The number and scale of the existing garbage disposal site is far from being able to adapt to the requirements of the growth of urban garbage, most of the garbage is still open and centralized piles of the state, the immediate and potential harm to the environment is very large, pollution accidents are frequent, the problem is becoming more and more serious.
Encroachment of a large amount of land, serious damage to farmland. The garbage piled up in the outskirts of the city encroaches on a large amount of agricultural land. Untreated or not strictly treated household garbage is used directly on farmland, or only after simple treatment by farmers for farmland, the consequences are serious. Because of this garbage fertilizer particles, and contains a large number of glass, metal, broken bricks and tiles and other impurities, destroying the soil's granular structure and physicochemical properties, resulting in soil water retention, fertilizer retention capacity reduced.
Pollution of air. In a large number of open dumping site, the stench of the sky, rats, mosquitoes and flies, a large number of ammonia, sulfide and other pollutants released into the atmosphere. Only organic volatile gases are up to more than 100 kinds, which contains many carcinogenic and teratogenic substances.
Pollution of water bodies. Garbage not only contains pathogenic microorganisms, in the pile of corruption process will produce a large number of acidic and alkaline pollutants, and will dissolve the heavy metals in the garbage. These ingredients seep into the soil through rain, which can cause serious pollution of surface water or groundwater.
Trash explosions continue to occur. With the increase in organic matter content in the city garbage and by the open scattered pile into a centralized storage, only a simple cover to produce methane gas. Garbage generates methane gas hazards are increasingly prominent, accidents continue, resulting in significant losses. For example, Beijing Changping District garbage dump in 1995, three consecutive garbage explosion accident.
Dry batteries are one of the most widely used commodities in people's daily lives, from cameras, tape recorders, calculators, electronic dictionaries to palmtop computers, all of which are inseparable from dry batteries. Batteries contain a large number of heavy metals, acids, alkalis and other substances. During normal use, these substances are encapsulated within the casing and do not harm the environment or the human body. However, when the battery is discarded, due to long-term mechanical or corrosion and other effects, so that the internal heavy metals, acids and alkalis leak out, it will bring serious environmental pollution.
For a long time, our country has to add a toxic substance - mercury or mercury compounds - when producing dry batteries. China is the production and consumption of dry batteries in large countries, the production of 15 billion a year, ranking first in the world, consumption of 7 billion, due to the loss of no recycling of 1700 tons of copper, 37,000 tons of zinc, manganese powder 226,000 tons. China's alkaline dry batteries in the mercury content of 1 to 5%, neutral dry batteries for 0.025%, the country's annual production of dry batteries used in the production of tens of tons of mercury. Mercury is one of the most environmentally harmful elements in batteries, mercury and mercury compounds are toxic, scientists have found that mercury has obvious neurotoxicity, in addition to the endocrine system, the immune system and other adverse effects.
5. Toxic Waste Pollution and Transfer
Toxic waste pollution and transfer mainly includes persistent organic pollutants and medical waste.
Persistent organic pollutants (POPs) are generally categorized into three groups: chemicals used in agriculture (pesticides), chemicals used in industry, and by-products from industrial processes and the combustion of solid waste. These organic chemicals fill all corners of our lives and can pollute the atmosphere, soil, water and other environments in a variety of forms in all aspects of production, transportation, use and disposal.
China still produces and uses DDT, hexachlorobenzene, chlordane and mirex. In addition, there are a large number of discarded or still in use equipment containing PCBs. combustion and production and living processes produce dioxins, furans, hexachlorobenzene and polychlorinated biphenyls are also widespread. Although PCB-containing waste transformers and other equipment have been stored centrally in various parts of China since the 1970s, PCBs are still used in impregnants for power capacitors and in additives for paints. The 17 categories of substances listed in the POPs Convention as having the potential to produce dioxin-like substances are also present in processes such as power generation, steel making, cement production, chlor-alkali production, paper making, organic chemical production and waste incineration. In addition, sodium pentachlorophenate, the main drug used for schistosome control, also contains a certain concentration of impurity dioxins. Although the total amount of DDT produced and used in China is now considerably lower than in the 1970s, DDT can now be detected in the environment, crops, fruits, tea, meat, animal bodies and human tissues because it was once used in large quantities for a long period of time in China as a major pesticide.
Hospital waste refers to all discarded items generated in the hospital, including medical waste and uncontaminated various wastes that are not directly harmful to people and the environment. Among them, medical waste accounts for about 20% of hospital waste. China's various types of medical institutions produce about 1,700 tons of medical waste per day, with an annual output of 1.65 million tons. Due to the imperfect equipment, management and disposal of the legal system is not sound, China's medical waste disposal to self-incineration is the main, some areas can not afford to build incineration facilities, the medical waste will be mixed with domestic garbage in the landfill. Although some areas have implemented measures to centralize the treatment of medical waste, hospitals still pick out and sell what is saleable first, and then incinerate the rest, resulting in medical waste being used by unscrupulous traders and flowing into the community, leading to the prevalence of disease and the spread of pollution.
Transboundary movement of hazardous waste refers to the movement of hazardous waste from an area under the jurisdiction of one country to an area under the jurisdiction of another country, or through a third country to an area under the jurisdiction of another country. This type of transboundary movement began in the 1970's. In the late 1980's, developed countries were transferring hazardous wastes to developing countries on a scale of 50 million tons per year, with 9,000 transboundary movements per year in North America alone. Because the importation of waste is often accompanied by a financial gain for the importing country, vested interests on both sides of the equation often coincide. The transfer of hazardous wastes is often accompanied by an overall deterioration of the local ecological environment. In recent years, the transfer of hazardous wastes to China has occurred from time to time.