Water, like air, is necessary for human beings and all living things.
People can't live without water, and animals and plants can't live without water. Scientists have long confirmed that early primitive life originated from water.
Therefore, we can say that water is the source of life.
In nature, oceans, rivers, lakes, glaciers and groundwater constitute a water world, which scientists call hydrosphere.
Hydrosphere and atmosphere, lithosphere and biosphere are isomorphic, forming a complete world.
The ocean is the cradle of life.
Before the ocean appeared, the earth, like other planets in the solar system, was lifeless.
The warm and humid air flow in the ocean is the main factor to form clouds and rain.
Under the irradiation of sunlight, a large amount of water vapor rushed into the sky, drifted to the mainland with the airflow, and under the action of cold air, rainfall was formed, some of which returned to the poles and the ocean through rivers, and the other part infiltrated into the ground and became groundwater.
However, in the cold regions of the North and South poles and the mainland, precipitation appears in the form of snow.
Because the temperature is too low, it is difficult for a lot of snow to become hard ice, so glaciers are formed.
Glaciers in Himalayas and Kunlun Mountains in China are the main water sources in Qinghai-Tibet Plateau and Xinjiang. Even our mother rivers, the Yellow River and the Yangtze River, all originate from the ice peaks and snow lines on the Qinghai-Tibet Plateau.
Every summer, the sun shines on the ice peak, and the melted ice flows along the gully river to Yuan Ye and pasture, which becomes the main water source for local people and animals to drink water and irrigate agriculture and animal husbandry.
Abundant water resources bring vitality to everything and maintain ecological balance.
Seen from space, the earth is a blue planet, and 7 1% of its area is covered with water. However, it is hard for people to imagine that the traditional concept of "inexhaustible" water has begun to become a scarce resource, and protecting water resources has become an important issue facing the whole world.
According to scientists' estimation, the total water storage capacity of the earth is 654.38+0.37 billion cubic kilometers, of which fresh water only accounts for 2.5%.
68.7% of fresh water is sealed in permanent snow in polar glaciers and mountains. Therefore, less than 65,438+0% of available fresh water exists in aquifers, rivers, lakes, soils, swamps, plants and the atmosphere, and a large part of it is difficult to obtain.
According to the United Nations standard, a country is considered as a water-deficient country if its per capita annual water supply is less than 1000 cubic meters. China's population accounts for 22% of the world's total population, while its per capita freshwater possession accounts for only 8% of the world's total, and its per capita freshwater possession is only 1/3 of the world average. It is a well-known water-deficient country.
The most serious consequence of water shortage is the deterioration of people's health in some countries.
According to the survey of the World Health Organization, 654.38+0 billion people in developing countries can't drink fresh water, and 654.38+0 million people worldwide die of diseases caused by drinking unclean or polluted water every year.
What is even more disturbing is that in many parts of the world, there is a conflict crisis between countries for water resources.
Another aspect that can't be ignored in the water crisis is the problem of urban water shortage. The list of cities most likely to face water shortage listed by the United Nations includes Beijing and Shanghai in China, as well as Cairo, Mumbai, Jakarta, Mexico and other megacities.
China is a mountainous and watery country, with more than 1500 rivers, and the basin area exceeds 1000 square kilometers.
However, China has a large population and relatively poor water resources.
As far as the whole world is concerned, the high development of industry not only uses more and more fresh water, but also pollutes rivers, lakes and oceans day by day, leading to marine red tides, the extinction of fish and shrimp in rivers, and some even become smelly rivers and dead rivers.
Protecting water resources and preventing water pollution have become the top priority of environmental protection.
■ The water of the whole earth is about 14× 10 17 cubic meters, of which more than 97% is seawater that human beings can't drink, and the rest is fresh water, but 77.2% of fresh water exists in glacier snow-capped mountains, 22.4% is soil water and groundwater, and the rest is surface water.
In fact, the fresh water resources available for human development and utilization on the earth only account for 0.77% of the total water storage capacity of the earth.
■ China's total water resources are about 2.7× 10 12 cubic meters, ranking sixth in the world, but the per capita water consumption is very small, accounting for only14 of the world's per capita, ranking 88th in the world, and it is one of the 13 water-poor countries in the world.
China is a big agricultural country. The annual water shortage in agriculture is about 300× 108 cubic meters, and the drought-affected farmland is 200-300 million mu. 80 million rural people have difficulty drinking water.
Urban water supply is insufficient. There are more than 300 water shortages in 5 17 cities nationwide, with an annual water shortage of 58× 108 cubic meters.
Water environmental capacity refers to the amount of pollutants that a water body can contain or its ability to adjust and purify itself and maintain ecological balance without affecting the normal use of water.
Water environmental capacity is one of the bases for formulating local and professional water discharge standards, and it is also used by environmental management departments to determine how many pollutants are allowed to be discharged in fixed waters.
There is about 1.36× 108 cubic kilometers of water on the earth, which is mainly distributed in the ocean, glaciers, ground, underground and atmosphere.
The water used by human beings is basically fresh water, and the quality of fresh water only accounts for 0.63% of the total water quality of the earth.
With the development of industrial and agricultural production, water consumption is increasing rapidly, and fresh water resources are becoming increasingly tense.
At the same time, due to pollution, the available water is reduced, which further aggravates the contradiction of water shortage.
The situation of water resources in China is also quite severe.
China's fresh water reserves rank sixth in the world, but due to its large population, its per capita possession is only 1/4 of the world average, ranking 88th in the world.
In the process of human metabolism, with drinking water and food, various elements in water enter various parts of the human body through the digestive tract.
When water lacks some parts or some elements necessary for human life process, it will affect human health.
For example, in some areas, water is short of iodine, and drinking this water for a long time will lead to "big neck disease", which is medically called "endemic goiter".
When water contains harmful substances, it is more harmful to human body.
Carcinogens can be brought into the human body by eating contaminated food (grains, vegetables, fish, etc.). ) and can also enter the human body through drinking water.
According to the survey, the incidence of liver cancer, gastric cancer and other cancers in people who drink polluted water is about 6 1.5% higher than that in people who drink clean water.
When mercury, cadmium and other elements in sewage are discharged into rivers and lakes, aquatic plants absorb and enrich them. After eating aquatic plants, fish are further enriched in the body. After eating poisonous fish, people are rich in mercury, cadmium and other elements, which makes people sick and die.
In this way, from aquatic plants->; -> small aquatic animals; Fish->; Big fish-> The human body forms a food chain.
The human body eventually becomes the "foothold" of elements such as mercury and cadmium.
Soil and water conservation refers to the comprehensive science and technology of preventing soil erosion, protecting, improving and rationally utilizing water and soil resources in mountainous, hilly and sandstorm areas, and maintaining and improving land productivity, so as to give full play to the economic and social benefits of water and soil resources and establish a good ecological environment.
At present, soil and water conservation includes three measures: agricultural technical measures, forest and grass measures and engineering measures.
Agricultural technical measures of soil and water conservation are mainly soil and water conservation tillage.
Combined with farming, temporary small topography with certain water storage capacity is built on sloping farmland, such as district field, border field, furrow and ridge planting, etc.
The United States, the Soviet Union and other countries have also widely adopted the mulching cultivation method, the avoiding Great Leap Forward method and the less Great Leap Forward method.
In addition, there are deep ploughing, close planting, intercropping and interplanting, fattening, grass-field rotation and so on. Are agricultural technical measures for soil and water conservation.
Measures for forest and grass conservation, or plant or biological measures for water and soil conservation.
Its main function is to improve the vegetation of the earth and increase the roughness of the surface, so as to reduce the impact of raindrops on the ground, increase soil infiltration, reduce surface runoff, slow down the flow rate and weaken the scouring force.
The main function of soil and water conservation engineering measures is to reduce or stop soil erosion and develop and utilize water and soil resources by building various projects, changing small topography, intercepting surface runoff and increasing soil infiltration.
According to the position and function, it can be divided into three categories: slope treatment engineering, river treatment engineering and bank protection engineering.
Various measures, especially engineering measures and forest and grass measures, have always been interdependent and complementary.
Soil and water conservation is of great significance to the development of production and construction in mountainous, hilly and sandstorm areas, the improvement of land, the regulation of rivers and the mitigation of drought and sandstorm disasters.
Because human life or production activities have changed the physical, chemical or biological properties and components of natural water, thus affecting the utilization value of water or endangering human health, it is called water pollution.
Under natural circumstances, the quality of natural water often changes, but this change is a natural phenomenon, not water pollution.
Common water pollutants are:
(1) Pathogenic microorganisms, such as typhoid Bacillus, Shigella dysenteriae and Vibrio cholerae, cause the epidemic and spread of infectious diseases;
(2) Plant nutrients, such as nitrogen, phosphorus and potassium. , resulting in eutrophication of water quality, thus deteriorating water quality;
(3) inorganic salts.
Inorganic compounds such as acid, alkali and salt enter the water body, which affects the water quality of life, production and agriculture;
(4) Various oils affect the sensory characteristics of water, hinder the reoxygenation ability of water and destroy the self-purification ability of water;
(5) Toxic chemicals, mainly heavy metals and refractory organics, such as mercury, cadmium, lead, chromium, arsenic, selenium, alum, aragonite, organic chlorides, aromatic amines and polycyclic organic compounds;
(6) radioactive substances.
Common pollution routes are as follows:
(1) Sewage discharged from industrial production;
(2) Urban domestic sewage;
(3) Polluted irrigation, spraying pesticides and applying chemical fertilizers in agriculture are washed away by rain and enter water bodies with surface runoff;
(4) Harmful substances in solid waste flow into water after being dissolved in water;
(5) The smoke and dust wastewater discharged from industrial production directly falls or flows into the water body after being leached by rain;
(6) Rainfall and surface runoff after rain bring pollutants from urban surface atmosphere and soil into water bodies;
(7) Backwashing or infiltration of seawater pollutes groundwater sources or water bodies in coastal areas;
(8) Natural pollution sources affect the background content of water bodies. For example, the arsenic pollution in the middle reaches of the Yellow River is serious, because 90% of the sediment concentration in the Yellow River comes from the Loess Plateau, and the arsenic background in the Loess Plateau is very high, resulting in serious arsenic pollution in the water body of this reach.
The ocean is the cradle of human civilization.
The ocean, which accounts for 7 1% of the earth's total area, has a magnificent area of more than 360 million square kilometers and a total volume of about136,000 cubic kilometers.
Some people say that the ocean is an air conditioner, a treasure house of all kinds of resources, the birthplace of living things, a godsend golden waterway and an inexhaustible scenic spot for human beings.
Is it really beautiful, big sea water!
However, the waves on the shore are the crying of the sea, and the churning of the peaks and valleys is the telling of the sea. Now, the whole sea has not escaped all kinds of bad luck made by human beings.
Humans have not paid attention to the protection of fresh water resources, let alone salt water resources.
Waste water and waste residue on land, whether toxic or non-toxic, reasonable or unreasonable, are led or dumped into the sea through thousands of rivers.
As a result, the new york Bay, Tokyo Bay, Gulf of Mexico, Hangzhou Bay, Azov Sea, Mediterranean Sea, Baltic Sea and other sea areas that have suffered greatly from it are on the verge of emergency and almost become lifeless "dead seas".
The eclipsed Mediterranean is in a very difficult situation.
Although the ocean only accounts for 1% of the world's waters, more than 5% of the world's wastes are continuously poured into the sea.
Due to man-made destruction and waste pollution, a large number of marine animals cannot reproduce, and even seals and turtles will disappear.
It will take at least 200 years if the Atlantic Ocean is allowed to mitigate and deal with pollution naturally.
Most of the fish on the British market come from the North Sea.
But in recent years, environmentalists have called it "poison soup".
At 1989, thousands of seals died of pollution on the North Sea coast.
The direct pollution of the ocean is destroyed by the developed marine transportation industry and offshore oil mining industry.
Of course, the "shit" brought by amazing industrialization is incalculable.
According to preliminary calculations, 6.5438+million tons of oil, 25,000 tons of polychlorinated biphenyls, more than 3.9 million tons of zinc and 250,000 tons of copper flow into the ocean every year. In addition, there are 20 million curies of radioactive materials in the ocean.
The above pollutants have accounted for 80% of all marine pollutants.
People ask for oil from the sea, but throw it into the sea.
This seems puzzling.
1On February 25th, 990, at the seminar held by the International Federation for the Prevention of Oil Tanker Pollution in Abu Dhabi, Tunisia, the research report stated that the amount of oil flowing into the sea every year is huge, and the oil leakage caused by oil tanker accidents accounts for 12%.
Since the 1960s, serious oil spills in the world have become more and more serious.
1967 March 18, "Tory Yang Kan" hit the rocks at Lance Point, England, and the oil leaked about 9 19000 barrels; On June 1968 and 13, the hull of "Glory of the World" was damaged in South Africa, leaking about 322,000 barrels of oil. 1969165438+1On October 4th, an oil storage tank in Sevolan, New Jersey, USA broke and leaked about 200,000 barrels of oil. 1969165438+10. On 5 October, Keo, the coast of Massachusetts, USA, was damaged, and the oil leaked about 2 10000 barrels. 1970 On March 20th, the Othello was hit in Trent Vista Bay, Sweden, leaking about 438,000 barrels of oil. 1972 19 February 19, the starfish was hit in the Gulf of Oman, leaking about 840,000 barrels of oil. 1976 may 12, the "urqui Ola" ran aground on the coast of La Coruna, Spain, leaking 730,000 barrels of oil. 1976 15 February 15, Argo ran aground off the coast of Massachusetts, USA, leaking about 183000 barrels of oil. 1On February 25th, 977, the Hawaiian Patriot caught fire in the North Pacific Ocean, leaking about 723,000 barrels of oil. 1August 978 16 "Amoli kadiz" ran into a rock near French bourbon sal, leaking about10.6 million barrels of oil; 1On June 3rd, 979, the oil well "Axdock 1" in the south of the Gulf of Mexico exploded, leaking about 4.4 million barrels of oil. 1979 July19, the "Atlantic Queen" and "Aegean Captain" collided off the coast of Trinidad and Tobago, leaking about 2.2 million barrels of oil; 1 979165438+1October1day, two oil tankers collided in Galveston Bay, Texas, USA, leaking about 25.5 barrels of oil; 1August 6, 983, the "Castillo belleville" exploded and caught fire off Cape Town, leaking about 1.8 million barrels of oil; 1June 365438+July 3, 9841day, a general-purpose tanker ran aground on the coast of Melenchin, Louisiana, USA, leaking about 67000 barrels of oil. 1985165438+1On October 6th, an oil well in Lange, Texas, USA exploded, leaking about150,000 barrels. 1On June 23rd, 988, the miracle of the world ran aground on the coast of Rhode Island, USA, leaking about 24,000 barrels of oil. 1990 65438+1October19 or so. During the Gulf War, most oil wells in Kuwait were destroyed, and about 500,000 tons flowed into the Gulf waters.
These data show that the oil slick caused by tanker accidents only accounts for 12% of oil pollution, while the pollution caused by industrial or public garbage accounts for 37%, the pollution caused by normal shipping accidents accounts for 7%, the pollution caused by natural oil mines accounts for 9%, and the pollution caused by oil exploitation and exploration accounts for 2%.
In recent years, it has also been found that plastic garbage in the ocean has also become a killer of marine resources.
According to the survey report, ocean-going merchant ships throw 639,000 pieces of plastic garbage into the sea every day, and the fishing gear scattered or abandoned in the sea every year is about 6,543,800 tons.
These plastic wastes not only pollute beaches and scenic spots, but also seriously threaten the survival of marine mammals, seabirds and turtles, and also cause serious damage to the ecological environment.
Dumping and discarding plastic waste into the sea has become a pollution source that cannot be ignored.
According to the report published by the World Environmental Protection Organization, human pollutants dumped in the sea have damaged the health of seawater workers and swimmers, and bacteria and viruses in the pollutants may cause people to suffer from hepatitis, cholera, gastroenteritis and polio.
This is the retribution of human rudeness in the ocean.
The pollution of the ocean has buried a "time bomb" for mankind.
I didn't answer this. I copied it. You won't mind, will you?
Anyway, I still hope you can adopt me, O(∩_∩)O Thank you ~