Water is an indispensable basic substance for all life on earth and a precious natural resource for the survival and development of human society. Since the beginning of this century, due to the rapid development of industry and agriculture in the world, the urban population has increased sharply, and the water consumption for production and life has also increased sharply. At the same time, a large amount of production and domestic sewage is discharged into rivers, lakes and underground, which pollutes many water sources and causes serious water shortage in many countries, including China. Therefore, water pollution prevention and water environmental protection has become a worldwide problem, and it is also a top priority for environmental protection in China.
water pollution
Water pollution refers to the phenomenon that the water quality, physical and chemical properties of sediments or the composition of aquatic organisms change after harmful substances are directly or indirectly discharged into the water body due to human factors or natural factors, thus reducing the use value and function of water.
Water pollution can be divided into three types: chemical pollution, physical contamination and biological pollution. Chemical pollution refers to water pollution caused by the discharge of acid, alkali, organic and inorganic pollutants in water. Physical contamination refers to the pollution of water bodies by sediments, suspended solid substances, colored substances, radioactive substances and water above normal temperature discharged into water bodies; Biological pollution refers to water pollution caused by pathogenic microorganisms discharged into water with sewage.
(B) the hazards of water pollution
After the polluted water body, the water quality deteriorates, which not only reduces or even loses the use function, but also aggravates the shortage of water resources, and also causes a series of hazards to human health and ecological environment.
First, endanger human health
The polluted water contains pesticides, polychlorinated biphenyls, polycyclic aromatic hydrocarbons, phenol, mercury, chromium, lead, cadmium, arsenic, cyanide, radioactive elements, pathogenic bacteria and other harmful substances, which are highly toxic and some are carcinogenic. These substances can enter the human body through drinking water and food chain and accumulate in the human body, causing harm.
B, causing eutrophication of water body
When domestic sewage and farmland drainage containing a large amount of plant nutrients such as nitrogen and phosphorus are continuously discharged into the slow flowing water in lakes, reservoirs and rivers, there will be excess nutrients in the water, which will lead to the proliferation of algae, which will reduce the transparency of the water body and lose its ornamental value. At the same time, because algae multiply quickly and have a short growth cycle, they die constantly and are decomposed by aerobic microorganisms, consuming dissolved oxygen in water; It can also be decomposed by anaerobic microorganisms to produce harmful substances such as hydrogen sulfide. From the above two aspects, the water quality deteriorated and a large number of aquatic organisms such as fish died.
C, destroy the ecological balance of water environment
In a good water body, all kinds of aquatic organisms and their living environment maintain a close relationship of interdependence and mutual restriction, and are in a good ecological balance. When the water body is polluted and the water environment conditions change, different aquatic organisms have different requirements and adaptability to the environment, which will lead to the change of population and destroy the ecological balance of the water environment.
(3) methods to prevent water pollution
The prevention and control of water pollution should proceed from the whole and take the road of comprehensive prevention and control. Comprehensive prevention and control is to take a water area, water system or urban water environment as the object of pollution prevention and control, and use various measures such as administrative management, legal system, economy and engineering technology to prevent and control, restore and maintain good water quality and normal use value.
I. Implementing cleaner production
By adjusting the industrial structure, improving the industrial layout, improving the utilization rate of resources and production efficiency, and reducing the emission of pollution sources, not only the economic benefits are improved, but also the purpose of environmental governance is achieved more effectively.
B, recycling useful substances
C. Developing water-saving industries
Second, air pollution and its prevention and control
In physical geography, the atmosphere is a mixture of gases in the troposphere, stratosphere, middle layer and outer layer, which rotates with the earth due to its gravity. It consists of three parts: constant, variable and indefinite.
(1) air pollution
Various pollutants discharged into the atmosphere by human production and living activities or nature exceed the carrying capacity of the environment, which deteriorates the air quality and adversely affects and destroys people's work, life, health, equipment and property and ecological environment. This phenomenon is called air pollution.
Pollution sources can be divided into natural pollution sources and man-made pollution sources. Natural pollution sources refer to places or areas where nature discharges pollutants into the atmosphere, such as active volcanoes that discharge pollutants such as dust, sulfur dioxide and hydrogen sulfide, escaping natural gas, and places where natural disasters such as forest fires and earthquakes occur. Man-made pollution sources can be classified in different ways: according to their spatial distribution, they can be divided into point pollution sources, non-point pollution sources and regional pollution sources; According to people's social activities, it can be divided into domestic pollution sources, industrial pollution sources and traffic pollution sources. According to the existing forms of pollution sources, they can be divided into fixed pollution sources and mobile pollution sources.
(2) Hazards of air pollution
First, the harm of air pollution to human health
Air pollution can easily affect human health, and its harm to human health is often multifaceted and comprehensive. Among them, chemical pollutants such as sulfur dioxide, nitrogen dioxide, carbon monoxide, heavy metal dust, fluoride and hydrocarbons are the most common respiratory hazards. This is because respiratory mucosa is particularly sensitive to pollutants and has great absorption capacity. In addition, air pollution often irritates and harms eyes and skin, and can induce cardiovascular and nervous system diseases.
B, the harm of air pollution to plants
The harm of air pollution to plants varies with the nature, concentration, emission and contact time of pollutants, plant varieties, growth period and meteorological conditions. Gas pollutants usually enter plants through the stomata on the back of leaves, and then gradually spread to sponge tissue and grid tissue, destroying chlorophyll and making tissues dehydrated and necrotic; Interfere with the action of enzymes, hinder various metabolic functions and inhibit plant growth. Particulate pollutants can scratch leaves, block sunlight, affect photosynthesis and hinder the normal growth of plants. Harmful elements such as heavy metals on particulate matter will also enter plant cells, causing further damage and causing plants to wither or even die.
C, other hazards
Air pollution can also cause global disasters through dry deposition and wet deposition (such as acid rain); Make the global climate gradually warm and endanger the ecological environment; Harm the ozone layer, destroy the protective barrier of people, animals and plants to ultraviolet rays, and so on.
(3) Prevention and control of air pollution
Adjust the energy strategy and adopt clean energy. China's disposable energy consumption is mainly coal in fossil fuels. The emission of greenhouse gases such as carbon dioxide not only warms the global climate, but also forms acid rain, which poses a great threat to the global ecological environment. Therefore, adjusting energy strategy and gradually changing energy structure are important ways to prevent and control air pollution.
First, vigorously develop and utilize hydropower.
B. Progressive development of nuclear energy
C. actively develop and utilize bioenergy.
D. Use other clean energy sources
Pollution and prevention of other environmental factors and substances
(1) soil pollution and its prevention and control
I. Soil pollutants
Generally, it refers to substances that enter the soil and affect its characteristics, which are divided into organic substances; Heavy metal pollutants; Radioactive substances; Pathogenic microorganisms.
B, the prevention and control of soil pollution
When formulating measures to prevent and control soil pollution, we must consider practical methods according to local conditions to control and eliminate the discharge of industrial "three wastes"; Strengthen the monitoring and management of soil pollution areas; Rational use of chemical fertilizers and pesticides.
(2) Pollution and prevention of solid waste
I. Pollution by solid waste
Solid waste usually refers to solid and muddy substances discarded by human beings in production and life activities, including solid particles separated from waste water and waste gas.
There are many ways to classify solid waste, which can be classified according to its nature, state and source. For example, according to chemical properties, it can be divided into organic waste and inorganic waste. According to its dangerous state, it can be divided into hazardous waste and general waste. Many countries, such as Europe and America, divide them into five categories according to their sources: industrial solid waste, mining solid waste, urban solid waste, agricultural solid waste and radioactive solid waste.
B, the harm of solid waste
Occupy land;
Soil and groundwater pollution;
Polluted water bodies;
Pollution to the atmosphere;
Harm to human health.
C, prevention and control of solid waste
The main way to control environmental pollution and harm to human health by solid waste is to recycle, harmless and reduce solid waste.
Resource recovery
The recycling of solid waste is to recover energy and resources. The recovery of industrial solid waste must be based on the production characteristics of specific industries, and attention should also be paid to factors such as feasible technology, competitive products and economic benefits.
Harmless treatment
Harmless disposal of solid waste means that after proper treatment or disposal, solid waste or its harmful components will not cause harm to the environment, or will be transformed into substances harmless to the environment. Commonly used methods are: land landfill; Incineration; Composting method.
(3) Noise pollution and its prevention and control
First, noise pollution
From the perspective of environmental protection, all sounds that interfere with people's normal rest, study and work are collectively called noise. Such as the roar of machines, the sounds of motors and horns of various vehicles, human noise and all kinds of sudden sounds, are all called noise.
Noise pollution is a kind of sensory pollution, which is related to people's subjective will and their living conditions, so it has different characteristics from other public hazards.
B, noise control
Noise pollution consists of three parts: sound source, sound propagation path and receiver. Noise pollution can be controlled from these two aspects: reducing sound source noise; Control the noise in the propagation path.
(4) radioactive, electromagnetic and thermal pollution
First, the concept and source of radioactive pollution
The concept of radioactive pollution
Radioactive pollution refers to the environmental pollution and harm to human body caused by radioactive pollutants discharged from human activities. Natural radiation released from the natural environment can be regarded as the background value of the environment.
Radioactive pollution source: nuclear industry; Nuclear power plant; Nuclear fuel reprocessing plant; Nuclear tests, etc.
Electromagnetic pollution and its sources
Electromagnetic pollution refers to natural and man-made electromagnetic interference and electromagnetic radiation harmful to human body. In environmental protection work, it is mainly to study the destructive effect of electromagnetic field intensity on human function when it reaches a certain limit.
Man-made electromagnetic pollution comes from:
① pulse discharge;
② Power frequency alternating electromagnetic field;
③ Radio frequency electromagnetic radiation. The harm of electromagnetic radiation pollution increases with the increase of frequency. The harm of medium and short frequency electromagnetic fields to the body is mainly caused by neurasthenia syndrome and autonomic nerve disorder, such as headache, dizziness, general malaise, fatigue, insomnia and dreaminess, memory loss, chest tightness, palpitation and menstrual cycle disorder in women.
C, thermal pollution
Human social and economic activities warm the local environment or the global environment, and may cause direct or indirect, immediate and potential harm to human beings and ecosystems, which is called thermal pollution or environmental thermal pollution.
Thermal pollution can change the state of the surface and cause disasters; Forming a heat island effect; Affect fishery production.
(5) Pollution of living environment
Indoor pollution mainly has the following ways: CO2 is emitted by human body's own breathing; Smoking pollutes the air; Kitchen pollution; Pollution of household chemicals; Indoor decoration pollution.