The use, function and importance of water. be badly in need of

Effect of water on human body Water is the source of life. Man's demand for water is second only to oxygen. If people don't take certain vitamins or minerals, they may live with diseases for weeks or years, but if there is no water, they can only live for a few days. The important component of human cells is water, which accounts for 60~70% of adults' weight and more than 80% of children's weight. What is water for? 1. People need water for all kinds of physiological activities. For example, water can dissolve various nutrients, and fat and protein can only be absorbed if they are suspended in water. Water flows endlessly between blood vessels and cells, transporting oxygen and nutrients to tissues and cells, and then discharging metabolic wastes from the body. In short, people's various metabolic and physiological activities are inseparable from water. 2. Water has a certain effect on body temperature regulation. When people breathe and sweat, they will excrete some water. For example, in the hot season, the ambient temperature is often higher than the body temperature, so people rely on sweating to evaporate some heat to lower their body temperature and avoid heatstroke. In cold weather, because of the great potential of water to store heat, the body temperature will not fluctuate obviously because of the low external temperature. Water is still the lubricant in the body. It can moisturize the skin. When the skin is short of water, it will become dry, lose elasticity and look old. Some joint capsule fluid and serosa fluid in the body can prevent organs from being damaged by friction and can rotate flexibly. Tears and saliva are also lubricants for corresponding organs. Water is the cheapest and most powerful magic medicine in the world. The health care and disease prevention functions of mineral water and electrolyte water are well known. Mainly because water contains ingredients beneficial to human body. When you have a cold or fever, drinking more boiled water can help you sweat, reduce fever and dilute toxins produced by bacteria in your blood. At the same time, the increase of urine is beneficial to accelerate the discharge of toxins. 5. Large area burns, severe vomiting, diarrhea and other symptoms, when the body loses a lot of water, it should be rehydrated in time to prevent severe dehydration and aggravate the condition. 6. Drinking a glass of water before going to bed is good for beauty. Before going to bed, drink a glass of water anyway. This glass of water has great cosmetic effect. When you are asleep, that glass of water can penetrate into every cell. After cells absorb water, the skin becomes more delicate. 7. Drink a glass of water before bathing to keep your skin youthful and energetic. Be sure to drink a glass of water before taking a bath. Sweating in the bath is twice as much as usual, and the metabolism in the body is accelerated. Drinking water can make every cell in the body absorb water and create smooth and delicate skin. It should be pointed out that for the elderly and children, drinking tap water after boiling is most beneficial to health. At present, the water purifier sold in the market will reduce the minerals in the water after purification, and the long-term drinking effect is not as good as that of natural water source. Insufficient water intake or excessive water loss will cause dehydration in the body, also known as dehydration. According to the different proportion of water and electrolyte loss, it can be divided into three types. 1, hypertonic dehydration: water loss is the main factor, and electrolyte loss is relatively small. 2. Low osmotic dehydration: electrolyte loss is the main factor, and water loss is less. 3. Isoosmotic dehydration: water and electrolyte are lost in proportion, and the osmotic pressure of body fluids remains unchanged, which is more common in clinic. Life on earth first appeared in water. Water is an important part of all living things. Water in the human body accounts for 70% of the body weight; Water is an essential substance to maintain life, and people still have quality requirements for drinking water. If the water lacks essential elements or some harmful substances, or is polluted, it can not meet the drinking requirements, which will affect human health. A large number of aquatic plants and other aquatic organisms live in the water. Water is beneficial to chemical reactions in the body and also plays the role of transporting substances in the living body. Water plays an important role in maintaining the stability of biological body temperature.

Many things can be done this way or that way, and there will always be a way. For example, lighting, without electric lights, we can light candles; Without candles, we can light oil lamps; Without oil lamps, we can light the torches of Song and Ming Dynasties. There is not even a torch, so we have to wait quietly for the night to pass and the day to come. It's different for water. Without water, we can't wash our faces and brush our teeth, we can't quench our thirst, we can't see fish and shrimp on the dining table, we can't see flowers and trees, we don't know what swimming is, all our boats and boats are scrapped, concrete can't stop, high-rise buildings can't be built, and even little dolls can't cry. ...

On earth, where there is water, there is life. All life activities originate from water. Water in human body accounts for about 65% of body weight. Among them, the brain water content is 75%, the blood water content is 83%, the muscle water content is 76%, and even the hard bones contain 22%! Without water, nutrients in food can't be absorbed, waste can't be excreted, and drugs can't reach the effective parts. Once the human body is short of water, the consequences are very serious. Lack of water 1%-2%, feeling thirsty; Lack of water 5%, dry mouth, wrinkled skin, unconsciousness, and even hallucinations; Water shortage 15% is often more than hunger. Without food, people can live for a long time (some people estimate that it is two months). If there is no water, they can live for a week at most.

Grasping a handful of plants with your hands will make you feel wet and cold. This is because of water. Plants contain a lot of water, accounting for about 80% of their weight, vegetables contain 90%-95% of water, and aquatic plants contain more than 98% of water. Water transports nutrients for plants; Water keeps the branches and leaves of plants elegant; Water participates in photosynthesis to produce organic matter; The evaporation of water keeps plants at a stable temperature to avoid being burned by the sun. Plants are not only covered by water, but also crops consume water all their lives. 1 kg corn is irrigated with 368 kg water; Similarly, wheat is 5 13 kg water, cotton is 648 kg water, and rice is as high as 1000 kg water. One seed falls to the ground, ten thousand grains are put into storage, and agriculture gains a lot. Water has made a lot of contributions!

Water participates in a series of important links in the production of industrial and mining enterprises, and plays an important role in manufacturing, processing, cooling, purification, air conditioning and washing, and is known as the blood of industry. For example, in steel mills, production is guaranteed by cooling water; When steel ingots are rolled into steel, they should be cooled with water; Part of the dust of blast furnace converter depends on water to collect; Water is indispensable in a boiler. It takes about 25 tons of water to produce 1 ton steel. In the paper mill, water is the medicine of dissolving agent, explaining agent, washing and transporting medium and solvent. It takes 450 tons of water to make 1 ton paper. The cooling water consumption of thermal power plants is huge, and at the same time, it also consumes some water. The flour mixing, distillation, cooking, pickling and fermentation in food factories are all inseparable from water. Soy sauce, vinegar, soda and beer are simply the embodiment of water.

Most scenic spots in history are decorated with water as the protagonist. You see, the spring tide of Qiantang River, Mount Everest, the fog of Lushan Mountain, the sea of clouds in Huangshan Mountain and the ice lanterns in Harbin are all changes in water. From the geological point of view, Guilin landscape, Yunnan Shilin, loess high slope, exquisite rain flower stone, everywhere has the outstanding performance of water. Venice, Suzhou, Jinan and Yueyang are also famous for their water. West Lake in Hangzhou, Slender West Lake in Yangzhou, Kunming Lake in Beijing, Three Towns in Wuhan, Huangpu River in Shanghai and Pearl River in Guangzhou all contributed to environmental beauty. Taihu Lake is beautiful, and the beauty lies in the water. Nowadays, reservoirs and channels have become important places for people to rest; Artificial fountains and water clocks that tell the time have become the most attractive attractions; Swimming, diving, surfing and boating are people's favorite water activities.

There is little information about water.

World fresh water resources

Many people imagine the earth as a blue planet with 7 1% surface covered by water. In fact, 97.5% of the water on the earth is salt water and only 2.5% is fresh water. Nearly 70% of fresh water is frozen in the ice sheets of Antarctica and Greenland, and most of the rest is soil moisture or deep groundwater, which is difficult to exploit for human use. Water from rivers, lakes, reservoirs and shallow groundwater is easy to be exploited for human direct use, but its amount is less than 1% of the world's fresh water, accounting for about 0.007% of all water on the earth. The annual precipitation on the mainland is about1100000000000000000000 cubic meters. After deducting the water absorbed by atmospheric evaporation and plants, the global river runoff is about 42700000000000 cubic meters. According to the world population 1995, the per capita annual water consumption is 7300 cubic meters. Due to the increasing world population, this average is 37% lower than that of 1970.

National water resources queue

Due to the different geographical environment, the amount of water resources in different countries and regions of the world is also different. According to the scale of water resources, the top countries are Brazil, Russian, Canadian, China, USA, Indonesian, Bangladeshi and Indian. If per capita, that is another result. China's per capita water resources are only 1/4 of the world's per capita water resources.

Countries with severe water shortage

65% of the world's fresh water resources are concentrated in 10 countries, while 80 countries with 40% population are seriously short of water. If a country's annual per capita water consumption is below 2000 cubic meters, it is a water-deficient country. Countries with per capita water consumption below 1000 cubic meters are seriously short of water, with 15 countries: Egypt, UAE, Oman, Cape Verde, Burundi, Algeria, Yemen, Jordan, Saudi Arabia, Barbados, Singapore, Bahrain, Libya, Kuwait, Qatar and Malta (the annual per capita water consumption is only 82 cubic meters). China is not rich in water resources per capita, and it is one of the countries lacking water.

The future of water resources

The human demand for water is increasing day by day. World water consumption 1975 was 3 trillion cubic meters, 1994 was 4.3 trillion cubic meters, and in 2000 it was 7 trillion cubic meters. Some people have analyzed that after 2030, there will be a shortage of water resources in the world; There will be a water shortage of 230 billion cubic meters in 2050; In 2070, there was a water shortage of 4 10 billion cubic meters. According to the analysis of experts in China, the total water demand in China in 2050 will be 800 billion cubic meters, an increase of 240 billion cubic meters. Among them, urban domestic water consumption is 80 billion cubic meters, industrial water consumption is 300 billion cubic meters, and agricultural water consumption is 420 billion cubic meters.