All information about water 5, all information about water

The world's freshwater resources.

Many people imagine the Earth as a blue planet with 71% of its surface area covered in water. In fact, the water on the earth is saltwater, only fresh water. Of the freshwater, nearly 70 percent is frozen in the ice sheets of Antarctica and Greenland, and most of the rest is soil water or deep groundwater, which is difficult to extract for human use.

Rivers, lakes, reservoirs and shallow groundwater are easier to exploit for direct human use, but their amount is less than 1 of the world's freshwater, accounting for about all water on the planet. The amount of precipitation that falls on the continents is about 110 trillion cubic meters per year, and the amount of river runoff in the world, excluding the amount of water that evaporates from the atmosphere and is absorbed by plants, is about one trillion cubic meters, and the average amount of water available to each person per year is 7,300 cubic meters based on the world population in 1995. As a result of the growing world population, this average has fallen by 37 from 1970.

Water resources queue up in various countries.

Due to the different geographical environments of countries and regions, the amount of water resources available varies greatly. The top ones are: Brazil, Russia, Canada, China, the United States, Indonesia, Bangladesh, and India.

If averaged over the population, it's a different result. The per capita water resources of Chinese are only 1 4 of the world's per capita resources.

Countries with severe water scarcity.

Sixty-five of the world's freshwater resources are concentrated in 10 countries, while 80 countries, which account for 40 of the population, are experiencing severe water scarcity. If a country's annual per capita water volume is less than 2,000 cubic meters, it is a water-scarce country. There are 15 countries with a per capita water volume of less than 1,000 cubic meters, which are seriously water-deficient

Egypt, United Arab Emirates, Oman, Cape Verde, Burundi, Algeria, Yemen, Jordan, Saudi Arabia, Barbados, Singapore, Bahrain, Libya, Kuwait, Qatar, Malta (82 cubic meters per capita per year). Chinese people are not rich in water per capita, and they are one of the countries with water shortages.

The future of water.

The human demand for water is increasing day by day. World water consumption was 3 trillion cubic metres in 1975, trillion cubic metres in 1994 and 7 trillion cubic metres in 2000. Some people analyze that after 2030, the world's water resources will be in short supply; In 2050, there will be a water deficit of 230 billion cubic meters; In 2070, there will be a water deficit of 410 billion cubic meters.

According to the analysis of Chinese experts, China's total water demand in 2050 will be 800 billion cubic meters, an increase of 240 billion cubic meters over the current level. Among them, 80 billion cubic meters of urban domestic water, 300 billion cubic meters of industrial water, and 420 billion cubic meters of agricultural water.

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1. Water (abbreviation: dihydrogen monoxide, chemical formula: h?)o) It is an inorganic substance composed of hydrogen and oxygen, which is non-toxic and drinkable. It is a colorless and odorless transparent liquid at room temperature and pressure, and is known as the source of human life.

2. Water can be divided into natural water (rivers, lakes, atmospheric water, seawater, groundwater, etc.) [containing impurities], distilled water [theoretically pure water], and artificial water (water obtained by combining hydrogen and oxygen atoms through chemical reactions).

3. Water is one of the most common substances on the earth, an important resource for the survival of all life, including inorganic synthesis and human beings, and the most important component of living organisms. Water has played an important role in the evolution of life. It is a narrowly non-renewable, broadly defined renewable resource.

4. Pure water can conduct electricity, but it is very weak (conductivity can be ignored in daily life), and it is an extremely weak electrolyte. Water in daily life has more positive and negative ions due to the dissolution of other electrolytes, and the conductivity is enhanced.

Good things: for electricity, for drinking.

Bad thing: flooding fields, crops.

The importance of water:

1. On the earth, if there is water, there will be life. All life activities originate from water.

2. The water in the human body accounts for about 65% of the body weight. Among them, the cerebral marrow contains 75% water, the blood contains 83% water, the muscles contain 76% water, and even the hard bones contain 22% water!

3. Without water, the nutrients in the food cannot be absorbed, the waste cannot be discharged from the body, and the drug cannot reach the site where it works.

4. Once the human body is short of water, the consequences are very serious. Lack of water 1%-2%, feeling thirsty; Dehydration 5%, dry mouth, wrinkles, confusion, and even visual hallucinations; A 15% lack of water is often worse than starvation.

5. Without food, people can live for a long time (some estimate that it is two months), and if they don't even have water, they can live for about a week at most.

Properties of water: 1. Water is a colorless and odorless transparent liquid at room temperature and pressure. In nature, pure water is rare, and water is usually a solution of acids, alkalis, salts and other substances, and it is customary to call this aqueous solution water.

2. Pure water can be obtained by several distillations in platinum or quartz utensils, of course, this is also pure water in a relative sense, and it is impossible to be absolutely free of impurities.

3. Water is a substance that can be converted between liquid, gaseous and solid. Water in a solid state is called ice; The gaseous state is called water vapor. When the water vapor temperature is higher, the gaseous water cannot be converted into liquid water by pressurization.

1. Water (chemical formula H O) is an inorganic substance composed of hydrogen and oxygen, which is non-toxic and drinkable. It is a colorless and odorless transparent liquid at room temperature and pressure, which is known as the source of human life and is an important substance to maintain life.

2. Water is one of the most common substances on earth. 71% of the Earth's surface is covered by water. It is an important resource for the survival of all life, including inorganic chemistry and human beings, and it is also the most important component of living organisms.

3. The conductivity of pure water is very weak, and it is a very weak electrolyte. Water in daily life has more anions and cations due to the dissolution of other electrolytes, so it has more obvious conductivity.

1.Overview of China's water resources: China's total water resources are trillions of cubic meters.

Among them, trillions of cubic meters of surface water and trillions of cubic meters of groundwater. China's total water resources rank sixth in the world, and the distribution of regions is uneven, and water and land resources do not match. The annual distribution of the Yangtze River basin is uneven, and drought and flood disasters are frequent.

In most areas, the precipitation for four consecutive months accounts for more than 70% of the year, and consecutive wet or dry years are common.

2.The main problems in the development and utilization of water resources: the contradiction between supply and demand is intensifying; low water use efficiency and deterioration of the water environment; Lack of rational allocation; The degree of water resources development in North China is already very high, and the lack of water has affected the ecological environment and the development and productivity of the oak layout.

Considering the insufficient water resources, under the planned economic system, the layout of industries in the past did not fully consider the conditions of water resources, and many industries with large water consumption were arranged in water-scarce areas; However, rice, which consumes a lot of water, is blindly developed in water-scarce areas, which artificially exacerbates the contradiction of rational allocation of water resources. To sum up, the total amount of water resources in China is not abundant, the regional distribution is uneven, and the distribution is concentrated during the year.