A little message about water. Water in human life
Water
Take a look at the world map. Most of all it has blue paint on it. A blue color water is depicted on the cards, without which no one can ever do without, and there is nothing to replace it with.
In nature, the water cycle is constantly going on. From the surface of the seas, oceans, rivers and lakes, it evaporates, clouds form. They rain down, snow down, and return water to land and oceans again.
It was in the water that the first living beings arose. They were small single-celled protein lumps floating at the behest of the waves in the ocean. Gradually, over millions of years, they changed and improved. First, they gave rise to plant organisms, then forms arose that stood on the verge between plants and animals. And finally, the simplest animals appeared. Many more millions of years passed before, fighting for existence, part of the plants and animals "came out" on land and continued their development there.
Water is one of the most important substances for humans. His body, blood, brain, body tissues are more than half composed of water. And in some plants it is even more. Water - in the oceans and seas, rivers and lakes, underground and in the soil. On high mountains, in the Arctic, Antarctica, water is in the form of snow and ice. This is solid water. Ice can be seen on our rivers and lakes when they freeze in winter. There is a lot of water in the atmosphere: these are clouds, fog, steam, rain, snow. On the surface of the land is not all the water available on Earth. Deep in the ground there are underground rivers and lakes. Are you surprised that both solid ice and light, like gas, steam are also water? This is its property: it is liquid, solid and gaseous.
Water has another important property: it can easily dissolve many substances in itself. You have, of course, seen how table salt dissolves in soup. Water also dissolves various salts found in earth layers, and many other solids and even gases.
There is absolutely no pure water in nature. It can only be obtained in the laboratory. Such water is tasteless, it does not contain salts needed by a living organism. And in sea water there are too many different salts, so it is also not suitable for drinking. With a lack of water, the vital activity of organisms is severely disrupted. Only resting forms of life - spores, seeds - tolerate prolonged dehydration well. Plants in the absence of water wither and may die. Animals, if deprived of water, die quickly: for example, a well-fed dog can live without food for up to 100 days, and without water - less than 10. Loss of water is more dangerous for the body than starvation: a person can live without food for more than a month, without water - only only a few days. Organic and inorganic substances important for the life of the body are dissolved in water. A person's need for water, which he uses with food and drink, depending on the climate, is 3-6 liters per day. Water is a good friend and helper of man. She is a convenient road: ships sail on the seas and oceans. That is why many cities arose on the banks of rivers.
Water conquers drought, revitalizes deserts, increases the yield of fields and orchards. She obediently rotates turbines at hydroelectric power plants. The water of mineral springs has a healing effect. Many of the springs are hot. And people use not only the healing properties of these waters, but also heat. In Kamchatka, where there are a lot of such sources, vegetables are grown in greenhouses at any time of the year. This is what an extraordinary substance is ordinary water - the beauty of nature, as the wonderful Russian writer S. T. Aksakov once said.
The total amount of water on Earth does not change. From the surface of the seas and oceans, rivers and lakes, water evaporates, and then returns to Earth in the form of rain or snow. But there is less and less clean water on Earth. Its lack is already being felt in many countries. However, this is not because water supplies are depleted. The threat of pollution loomed over the water. Plants and factories, power plants consume large amounts of water and at the same time pollute it with various waste products. Various toxic substances enter rivers and lakes with wastewater from enterprises. Life perishes in the water. Fish, crayfish, plants - all living things die in such water. Decaying waters poison the air and become sources of serious diseases. The river is sick, its waters cannot be used by man. Water must be saved! This must be understood and remembered by everyone. Conserving water means protecting life, health, and the beauty of the surrounding nature. Our country has adopted a number of laws aimed at protecting water. Their implementation is monitored by the state authorities. This made it possible to reduce the risk of pollution on many rivers and improve the sanitary condition of cities and towns. But the problem of water protection is still acute.
Bibliography
For the preparation of this work, materials from the site http://www.5.km.ru/
Table of contents of the subject "Water. Carbohydrates. Lipids.":Without water life on our planet could not exist. Water important to living organisms for two reasons. Firstly, it is a necessary component of living cells, and, secondly, for many organisms it also serves as a habitat. For humans, only drinking water is of value. To obtain drinking water, they are used, which allow you to purify it of harmful impurities, make it suitable for drinking and cooking. That is why a few words should be said about its chemical and physical properties.
These properties are rather unusual and are mainly due to the small size of the molecules. water, their polarity and the ability to combine with each other by hydrogen bonds. Polarity refers to the uneven distribution of charges in a molecule. In water, one end of the molecule (the "pole") carries a small positive charge, while the other end carries a negative charge. Such a molecule is called a dipole. The ability of an oxygen atom to attract electrons is more pronounced than that of hydrogen atoms, so the oxygen atom in a water molecule tends to pull the electrons of two hydrogen atoms towards itself. The electrons are negatively charged, in connection with which the oxygen atom acquires a small negative charge, and the hydrogen atoms acquire a positive one.
As a result, between water molecules a weak electrostatic interaction occurs and, since opposite charges attract, the molecules seem to “stick together”. These interactions, which are weaker than ordinary ionic or covalent bonds are called hydrogen bonds. Hydrogen bonds are constantly forming, breaking up, and re-emerging in the water column. And although these are weak bonds, their combined effect determines many of the unusual physical properties of water. Given this feature of water, we can now proceed to consider those properties that are important from a biological point of view.
Hydrogen bonds between water molecules. A. Two water molecules connected by a 6+ hydrogen bond - a very small positive charge; 6~ is a very small negative charge. B. A network of water molecules held together by hydrogen bonds. Such structures are constantly formed, broken down and re-emerged in the water that is in liquid state.The biological significance of water
Water as a solvent. Water- excellent solvent for polar substances. These include ionic compounds, such as salts, containing charged species (ions), and some non-ionic compounds, such as sugars, in which polar (weakly charged) groups are present in the molecule (in Sugars, this is the hydroxyl group carrying a small negative charge, -OH). When a substance dissolves in water, the water molecules surround the ions and polar groups, separating the ions or molecules from each other.
In solution, molecules or ions are allowed to move more freely, so that the reactivity of the substance increases. For this reason, in a cage most of chemical reactions leaks in aqueous solutions. Non-polar substances, such as lipids, are repelled by water and in its presence are usually attracted to each other, in other words, non-polar substances are hydrophobic (hydrophobic - water-repellent). Similar hydrophobic interactions play important role in the formation of membranes, as well as in determining the three-dimensional structure of many protein molecules, nucleic acids and other cellular components.
inherent water properties solvent also mean that water serves as a medium for the transport of various. It performs this role in the blood, in the lymphatic and excretory systems, in the digestive tract and in the phloem and xylem of plants.
Water is the source of life on Earth, a great natural value that covers 71% of the surface of our planet, the most common chemical compound and the necessary basis for the existence of all life on the planet. The high content in plants (up to 90%) and in the human body (about 70%) only confirms the importance of this component, which has no taste, smell or color.
Water is life!
The role of water in human life is invaluable: it is used for drinking, food, washing, various household and industrial needs. Water is life!
The role of water in human life can be determined by its share in the body and organs, each cell of which is rich in an aqueous solution of essential nutrients. Water is one of the effective means of physical education, widely used for personal hygiene, recreational physical education, hardening, and water sports.
Biochemical properties of water
Preservation of the elasticity and volume of a living cell would be impossible without water, as well as a significant part of the chemical reactions of the body that occur precisely in aqueous solutions. Such a valuable liquid is indispensable for its thermal conductivity and heat capacity, which provides thermoregulation and protects against temperature extremes.
Water in human life is able to dissolve some acids, bases and salts, which are ionic compounds and some polar non-ionic formations (simple alcohols, amino acids, sugars), called hydrophilic (from Greek literally - a tendency to moisture). Nucleic acids, fats, proteins and some polysaccharides are hydrophobic substances (from Greek - fear of moisture) beyond the power of liquid.
The biological significance of water is quite large, since this priceless liquid is the main medium for internal processes occurring in the body. In percentage terms, the presence of water in the body is as follows:
Body systems | |
Adipose tissue | |
The statement of the science fiction writer V. Savchenko, who revealed the meaning of water in one phrase, is interesting on this occasion: a person has much more motives to consider himself a liquid, in contrast, for example, to a 40% sodium solution. And among biologists, a joke is popular that water “invented” a person as a means of its own transportation, the main component of whose body it is. 2/3 of its total amount is contained inside the cells and is called "intracellular", or "structured" fluid, which is able to provide the body's resistance to the influence of negative factors external environment. The third part of the water is outside the cells, and 20% of this amount is the intercellular fluid itself, 2% and 8% - respectively, the water of the lymph and blood plasma.
Importance of water in human life
The value of the natural component in life and everyday life is simply invaluable, since without it existence is impossible in principle.
Water is essential for life because:
- humidifies the inhaled oxygen;
- helps the body in the qualitative assimilation of nutrients;
- contributes to the conversion of food into energy and normal digestion;
- participates in passing metabolism and chemical reactions;
- removes excess salts, toxins and toxins;
- regulates body temperature;
- provides skin elasticity;
- regulates blood pressure;
- prevents the formation of kidney stones;
- is a kind of "lubricant" for the joints and a shock absorber for the spinal cord;
- protects vital organs.
The water cycle in the body
One of the conditions for the existence of all living things is the constant content of water, the amount of which enters the body depends on the lifestyle of a person, his age, physical health, and environmental factors. During the day, up to 6% of the water available in the body is exchanged; half of its total amount is updated within 10 days. So, per day the body loses about 150 ml of water with feces, about 500 ml with exhaled air and the same amount with sweat and 1.5 liters is excreted in the urine. Approximately the same amount of water (about 3 liters per day) a person receives back. Of these, a third of a liter is formed in the body itself during biochemical processes, and about 2 liters are consumed with food and drinks, and the daily need for exclusively drinking water is about 1.5 liters.
IN Lately experts have calculated that a person should still drink about 2 liters of pure water per day in order to prevent even the slightest dehydration of the body. The same amount is recommended to be consumed by yogis who know the true meaning of air and water. Absolutely healthy human body ideally should have a state of water balance, otherwise called water balance.
By the way, German scientists, after a series of experiments conducted on students, found out that those who drink water and drinks more than others show greater restraint and a penchant for creativity. Water in human life plays an incentive role, filling with energy and vitality.
According to some estimates, for 60 years of life a person on average drinks about 50 tons of water, which is commensurate with almost a whole tank. It is interesting to know that ordinary food is half water: in its meat - up to 67%, in cereals - 80%, vegetables and fruits contain up to 90%, bread - about 50%.
High Water Consumption Situations
Usually a person receives about 2-3 liters of water per day, but there are situations in which the need for it increases. This:
- Increased body temperature (more than 37 ° C). With each increasing degree of water, 10% more of the total is required. .
- heavy physical labor in the fresh air, in which you need to drink 5-6 liters of liquid.
- Work in hot shops - up to 15 liters.
Deficiency of valuable fluid is the cause of many diseases: allergies, asthma, overweight, high blood pressure, emotional problems (including depression), and its absence leads to disruption of all body functions, undermining health and making vulnerable to disease.
Loss of water up to 2% of the total body weight (1 - 1.5 liters) will cause a person to feel thirsty; loss of 6 - 8% will lead to a semi-conscious state; 10% will cause the appearance of hallucinations and impaired swallowing function. Deprivation of 12% of water from the total body weight will lead to death. If without food a person is able to survive for about 50 days, subject to the consumption of drinking water, then without it - a maximum of 5 days.
In fact, most people drink less than the recommended amount of water: only a third, and the ailments that appear are not at all associated with a lack of fluid.
Signs of lack of water in the body
The first signs of dehydration:
A stable intake of water in the body in the required amount helps to ensure vitality, get rid of ailments and many serious diseases, improve thinking and coordination of the brain. Therefore, the emerging thirst should always be tried to quench. It is better to drink little and often at the same time, since a large amount of liquid for the purpose of a one-time replenishment of the daily norm will be completely absorbed into the blood, which will give a noticeable load on the heart until the water is removed from the body by the kidneys.
Water balance of the body - a direct path to health
In other words, water in human life, with a properly organized drinking regime, can create acceptable conditions for maintaining the necessary water balance. It is important that the liquid is High Quality with essential minerals. The situation of the modern world is paradoxical: water, the source of life on Earth, can be dangerous for life itself, carrying various infections with almost every drop. That is, only pure water can be useful for the body, the quality problem of which is modern world very relevant.
Water scarcity is a scary future for the planet
Rather, the very problem of the availability of drinking water becomes vitally important, every day turning into an increasingly scarce product. Moreover, the importance of water on Earth and its lack in international relations discussed at highest level and often in a conflicting way.
Now more than 40 countries are experiencing water shortages due to the aridity of many regions. In 15 - 20 years, even according to the most optimistic forecasts, every person will understand the importance of water on Earth, since the problem of its shortage will affect 60 - 70% of the planet's population. In developing countries, water deficit will increase by 50%, in developed countries - by 18%. As a result, international tensions around the topic of shortages will increase. water resources.
Polluted water as a result of human activities
This is due to geophysical conditions, human economic activity, often ill-conceived and irresponsible, which significantly increases the burden on water resources and leads to their pollution. Great amount water goes to the needs of cities and industry, which not only consume, but also pollute water, dumping about 2 million tons of waste into water bodies every day. The same goes for agriculture, where millions of tons of waste products and fertilizers flow into waterways from farms and fields. In Europe, out of 55 rivers, only 5 are considered clean, while in Asia, all rivers are extremely littered with agricultural waste and metals. In China, 550 out of 600 cities are experiencing water shortages; due to severe pollution, fish do not survive in water bodies, and some rivers that flow into the ocean simply do not reach it.
What flows from the taps
And why go far if the quality of water, which leaves much to be desired, concerns almost every person. The importance of water in human life is great, this is especially true when it is consumed, when sanitary standards go against the quality of the consumed liquid, which contains pesticides, nitrites, oil products, and salts that are harmful to health heavy metals. Half of the population receives hazardous water, which causes about 80% of all known diseases.
Chlorine is dangerous!
To avoid possible infection with any infection, the water is chlorinated, which in no way diminishes the danger. On the contrary, chlorine, which destroys many dangerous microbes, forms unhealthy chemical compounds and provokes diseases such as gastritis, pneumonia, oncology. When boiled, it does not have time to dissolve completely and combines with the always present in water. organic matter. In this case, dioxins are formed - very dangerous poisons, surpassing even potassium cyanide in their strength.
Water poisoning is much worse than food poisoning, because water in human life, unlike food, takes part in all biochemical processes of the body. Dioxins accumulated in the body decompose very slowly, almost tens of years. Causing disorders of the endocrine system, reproductive functions, they destroy the immune system, cause cancer and genetic abnormalities. Chlorine is the most dangerous killer of our time: killing one disease, it gives rise to another, even worse. After global water chlorination began in 1944, epidemics of heart disease, dementia and cancer began to appear massively. The risk of cancer is 93% greater than that of those who drink non-chlorinated water. There is only one conclusion: tap water should never be drunk. The ecological significance of water is the No. 1 problem in the world, since if there is no water, there will be no life on Earth. Therefore, an indispensable condition for maintaining health is its cleaning and compliance with sanitary and epidemiological standards.
Water (hydrogen oxide) is a transparent liquid that has no color (in a small volume), smell and taste. Chemical formula: H2O. In the solid state it is called ice or snow, and in the gaseous state it is called water vapor. About 71% of the Earth's surface is covered with water (oceans, seas, lakes, rivers, ice at the poles).
It is a good highly polar solvent. IN natural conditions always contains dissolved substances (salts, gases). Water is of key importance in the creation and maintenance of life on Earth, in the chemical structure of living organisms, in the formation of climate and weather.
Almost 70% of the surface of our planet is occupied by oceans and seas. Solid water - snow and ice - covers 20% of the land. Of the total amount of water on Earth, equal to 1 billion 386 million cubic kilometers, 1 billion 338 million cubic kilometers falls on the share of salty waters of the World Ocean, and only 35 million cubic kilometers falls on the share of fresh waters. The total amount of ocean water would be enough to cover it Earth layer over 2.5 km. For each inhabitant of the Earth, there are approximately 0.33 cubic kilometers of sea water and 0.008 cubic kilometers of fresh water. But the difficulty is that the vast majority of fresh water on Earth is in a state that makes it difficult for humans to access. Almost 70% of fresh water is contained in the ice sheets of the polar countries and in mountain glaciers, 30% is in aquifers underground, and only 0.006% of fresh water is simultaneously contained in the channels of all rivers. Water molecules have been found in interstellar space. Water is part of comets, most planets solar system and their companions.
The composition of water (by mass): 11.19% hydrogen and 88.81% oxygen. Pure water is clear, odorless and tasteless. It has the highest density at 0°C (1 g/cm3). The density of ice is less than the density of liquid water, so ice floats to the surface. Water freezes at 0°C and boils at 100°C at a pressure of 101,325 Pa. It is a poor conductor of heat and a very poor conductor of electricity. Water is a good solvent. The water molecule has an angular shape; hydrogen atoms form an angle of 104.5° with respect to oxygen. Therefore, the water molecule is a dipole: that part of the molecule where hydrogen is located is positively charged, and the part where oxygen is located is negatively charged. Due to the polarity of water molecules, electrolytes in it dissociate into ions.
In liquid water, along with ordinary H20 molecules, there are associated molecules, i.e., combined into more complex aggregates (H2O)x due to the formation of hydrogen bonds. The presence of hydrogen bonds between water molecules explains the anomalies of its physical properties: the maximum density at 4 ° C, heat boiling (in the series H20-H2S - H2Se) anomalously high heat capacity. As the temperature rises, hydrogen bonds break, and a complete break occurs when water changes into steam.
Water is a highly reactive substance. Under normal conditions, it interacts with many basic and acid oxides, as well as with alkali and alkaline earth metals. Water forms numerous compounds - crystalline hydrates.
Obviously, water-binding compounds can serve as desiccants. Other drying agents include P205, CaO, BaO, metallic Ma (they also chemically interact with water), and silica gel. To important chemical properties water is its ability to enter into reactions of hydrolytic decomposition.
Physical properties of water.
Water has a number of unusual features:
1. When ice melts, its density increases (from 0.9 to 1 g/cm³). For almost all other substances, the density decreases when melted.
2. When heated from 0 °C to 4 °C (more precisely, 3.98 °C), water contracts. Accordingly, as it cools, the density decreases. Thanks to this, fish can live in freezing waters: when the temperature drops below 4 ° C, more cold water as the less dense one remains on the surface and freezes, while a positive temperature remains under the ice.
3. High temperature and specific heat of fusion (0 °C and 333.55 kJ/kg), boiling point (100 °C) and specific heat of vaporization (2250 kJ/kg), compared to hydrogen compounds with similar molecular weight.
4. High heat capacity of liquid water.
5. High viscosity.
6. High surface tension.
7. Negative electric potential water surface.
All these features are associated with the presence of hydrogen bonds. Due to the large difference in the electronegativity of hydrogen and oxygen atoms, electron clouds are strongly shifted towards oxygen. Because of this, as well as the fact that the hydrogen ion (proton) does not have internal electron layers and has small dimensions, it can penetrate into the electron shell of a negatively polarized atom of a neighboring molecule. Due to this, each oxygen atom is attracted to the hydrogen atoms of other molecules and vice versa. A certain role is played by the proton exchange interaction between and within water molecules. Each water molecule can participate in a maximum of four hydrogen bonds: 2 hydrogen atoms - each in one, and an oxygen atom - in two; in this state, the molecules are in an ice crystal. When ice melts, some of the bonds break, which allows the water molecules to be packed more densely; when water is heated, the bonds continue to break, and its density increases, but at temperatures above 4 ° C, this effect becomes weaker than thermal expansion. Evaporation breaks all remaining bonds. Breaking bonds requires a lot of energy, hence the high temperature and specific heat of melting and boiling and high heat capacity. The viscosity of water is due to the fact that hydrogen bonds prevent water molecules from moving at different speeds.
For similar reasons, water is a good solvent for polar substances. Each solute molecule is surrounded by water molecules, and the positively charged parts of the solute molecule attract oxygen atoms, and the negatively charged parts attract hydrogen atoms. Because the water molecule is small, many water molecules can surround each solute molecule.
This property of water is used by living beings. In a living cell and in the intercellular space, solutions of various substances in water interact. Water is necessary for the life of all unicellular and multicellular living beings on Earth without exception.
Pure (free of impurities) water is a good insulator. Under normal conditions, water is weakly dissociated and the concentration of protons (more precisely, hydronium ions H3O+) and hydroxide ions HO− is 0.1 µmol/L. But since water is a good solvent, certain salts are almost always dissolved in it, that is, positive and negative ions are present in water. As a result, water conducts electricity. The electrical conductivity of water can be used to determine its purity.
Water has a refractive index n=1.33 in the optical range. However, it strongly absorbs infrared radiation, and therefore water vapor is the main natural greenhouse gas responsible for more than 60% of the greenhouse effect. Due to the large dipole moment of the molecules, water also absorbs microwave radiation, on which the principle of the microwave oven is based.
aggregate states.
1. According to the state, they distinguish:
2. Solid - ice
3. Liquid - water
4. Gaseous - water vapor
Fig.1 "Types of snowflakes"
At atmospheric pressure, water freezes (turns into ice) at 0°C and boils (turns into water vapor) at 100°C. As the pressure decreases, the melting point of water slowly rises and the boiling point falls. At a pressure of 611.73 Pa (about 0.006 atm), the boiling and melting points coincide and become equal to 0.01 ° C. This pressure and temperature is called the triple point of water. At lower pressures, water cannot be in a liquid state, and ice turns directly into steam. The sublimation temperature of ice decreases with decreasing pressure.
With an increase in pressure, the boiling point of water increases, the density of water vapor at the boiling point also increases, and liquid water decreases. At a temperature of 374 °C (647 K) and a pressure of 22.064 MPa (218 atm), water passes through critical point. At this point, the density and other properties of liquid and gaseous water are the same. With more high pressure there is no difference between liquid water and water vapor, hence no boiling or evaporation.
Metastable states are also possible - supersaturated vapor, superheated liquid, supercooled liquid. These states can exist for a long time, but they are unstable and a transition occurs upon contact with a more stable phase. For example, it is not difficult to obtain a supercooled liquid by cooling clean water in a clean vessel below 0 °C, however, when a crystallization center appears, liquid water quickly turns into ice.
Isotopic modifications of water.
Both oxygen and hydrogen have natural and artificial isotopes. Depending on the type of isotopes included in the molecule, the following types of water are distinguished:
1. Light water (just water).
2. Heavy water (deuterium).
3. Superheavy water (tritium).
Chemical properties of water.
Water is the most common solvent on Earth, largely determining the nature of terrestrial chemistry as a science. Most of chemistry, at its inception as a science, began precisely as the chemistry of aqueous solutions of substances. It is sometimes considered as an ampholyte - both an acid and a base at the same time (cation H + anion OH-). In the absence of foreign substances in water, the concentration of hydroxide ions and hydrogen ions (or hydronium ions) is the same, pKa ≈ approx. 16.
Water itself is relatively inert under normal conditions, but its strongly polar molecules solvate ions and molecules, form hydrates and crystalline hydrates. Solvolysis, and in particular hydrolysis, occurs in animate and inanimate nature, and is widely used in the chemical industry.
Chemical names for water.
From a formal point of view, water has several different correct chemical names:
1. Hydrogen oxide
2. Hydrogen hydroxide
3. Dihydrogen monoxide
4. Hydroxy acid
5. English hydroxic acid
6. Oxidane
7. Dihydromonoxide
Types of water.
Water on Earth can exist in three basic states - liquid, gaseous and solid, and in turn acquire the most different forms which are often adjacent to each other. Water vapor and clouds in the sky, sea water and icebergs, mountain glaciers and mountain rivers, aquifers in the earth. Water is able to dissolve many substances in itself, acquiring one or another taste. Because of the importance of water, "as a source of life," it is often divided into types.
Characteristics of waters: according to the peculiarities of origin, composition or use, they distinguish, among other things:
1. Soft water and hard water - according to the content of calcium and magnesium cations
2. Groundwater
3. Melt water
4. Fresh water
5. Sea water
6. Brackish water
7. Mineral water
8. Rain water
9. Drinking water, Tap water
10. Heavy water, deuterium and tritium
11. Distilled water and deionized water
12. Waste water
13. Storm water or surface water
14. By isotopes of the molecule:
15. Light water (just water)
16. Heavy water (deuterium)
17. Super heavy water (tritium)
18. Imaginary water (usually with fabulous properties)
19. Dead water - a type of water from fairy tales
20. Living water - a kind of water from fairy tales
21. Holy water - a special kind of water according to religious teachings
22. Polivoda
23. Structured water is a term used in various non-academic theories.
World water reserves.
The huge layer of salt water that covers most of the Earth is a single entity and has a roughly constant composition. The oceans are huge. Its volume reaches 1.35 billion cubic kilometers. It covers about 72% earth's surface. Almost all water on Earth (97%) is in the oceans. Approximately 2.1% of the water is concentrated in polar ice and glaciers. All fresh water in lakes, rivers and groundwater is only 0.6%. The remaining 0.1% of the water is part of the saline water from wells and saline waters.
The 20th century is characterized by an intensive growth of the world's population and the development of urbanization. Giant cities with a population of more than 10 million people appeared. The development of industry, transport, energy, industrialization of agriculture have led to the fact that the anthropogenic impact on the environment has assumed a global character.
Improving the effectiveness of protection measures environment is primarily due to the widespread introduction of resource-saving, low-waste and waste-free technological processes, and a decrease in air and water pollution. Environmental protection is a very multifaceted problem, which is dealt with, in particular, by engineering and technical workers of almost all specialties that are associated with economic activities in settlements and industrial enterprises, which can be a source of pollution mainly of the air and water environment.
Water environment. The aquatic environment includes surface and ground waters.
Surface water is mainly concentrated in the ocean, with a content of 1 billion 375 million cubic kilometers - about 98% of all water on Earth. The surface of the ocean (water area) is 361 million square kilometers. It is about 2.4 times more area land area, occupying 149 million square kilometers. The water in the ocean is salty, and most of it (more than 1 billion cubic kilometers) retains a constant salinity of about 3.5% and a temperature of approximately 3.7oC. Noticeable differences in salinity and temperature are observed almost exclusively in the surface layer of water, as well as in marginal and especially in mediterranean seas. The content of dissolved oxygen in water decreases significantly at a depth of 50-60 meters.
Groundwater can be saline, brackish (lower salinity) and fresh; existing geothermal waters have an elevated temperature (over 30 °C). For the production activities of mankind and its household needs, fresh water is required, the amount of which is only 2.7% of the total volume of water on Earth, and a very small share of it (only 0.36%) is available in places that are easily accessible for extraction. Most of the fresh water is found in snow and freshwater icebergs found in areas primarily in the Antarctic Circle. The annual global river flow of fresh water is 37.3 thousand cubic kilometers. In addition, a part of groundwater equal to 13 thousand cubic kilometers can be used. Unfortunately, most of the river flow in Russia, amounting to about 5,000 cubic kilometers, falls on the marginal and sparsely populated northern territories. In the absence of fresh water, salty surface or underground water is used, producing its desalination or hyperfiltration: it is passed under a large pressure drop through polymer membranes with microscopic holes that trap salt molecules. Both of these processes are very energy intensive, therefore, the proposal is of interest, which consists in using freshwater icebergs (or parts of them) as a source of fresh water, which for this purpose are towed along the water to shores that do not have fresh water, where they organize their melting. According to the preliminary calculations of the developers of this proposal, the production of fresh water will be about half as energy-intensive as compared to desalination and hyperfiltration. An important circumstance inherent in the aquatic environment is that it is mainly transmitted through it infectious diseases(approximately 80% of all diseases). However, some of them, such as whooping cough, chickenpox, tuberculosis, are also transmitted through the air. To combat the spread of disease through aquatic environment The World Health Organization (WHO) has declared the current decade the decade of drinking water.
Fresh water. Fresh water resources exist thanks to the eternal water cycle. As a result of evaporation, a gigantic volume of water is formed, reaching 525 thousand km per year. (due to font problems, water volumes are indicated without cubic meters).
86% of this amount falls on the salt waters of the World Ocean and inland seas - the Caspian. Aralsky and others; the rest evaporates on land, half of which is due to the transpiration of moisture by plants. Every year, a layer of water about 1250 mm thick evaporates. Part of it again falls with precipitation into the ocean, and part is carried by winds to land and here feeds rivers and lakes, glaciers and groundwater. The natural distiller feeds on the energy of the Sun and takes about 20% of this energy.
Only 2% of the hydrosphere is fresh water, but they are constantly renewed. The rate of renewal determines the resources available to mankind. Most of the fresh water - 85% - is concentrated in the ice of the polar zones and glaciers. The rate of water exchange here is less than in the ocean, and is 8000 years. Surface water on land is renewed about 500 times faster than in the ocean. Even faster, in about 10-12 days, the waters of the rivers are renewed. Fresh waters of the rivers have the greatest practical value for mankind.
Rivers have always been a source of fresh water. But in the modern era, they began to transport waste. Waste in the catchment area flows down the riverbeds into the seas and oceans. Most of the used river water is returned to rivers and reservoirs in the form of wastewater. So far, the growth of wastewater treatment plants has lagged behind the growth in water consumption. And at first glance, this is the root of evil. In fact, everything is much more serious. Even with the most advanced treatment, including biological treatment, all dissolved inorganic substances and up to 10% of organic pollutants remain in the treated wastewater. Such water can again become suitable for consumption only after repeated dilution with pure natural water. And here, for a person, the ratio of the absolute amount of wastewater, even if it is purified, and the water flow of rivers is important.
The global water balance has shown that 2,200 km of water per year is spent on all types of water use. Almost 20% of the world's fresh water resources are used to dilute wastewater. Calculations for 2000 assuming that water consumption rates will decrease and treatment will cover all wastewater, have shown that, anyway, 30-35 thousand km of fresh water will be required annually to dilute wastewater. This means that the resources of the total world river flow will be close to exhaustion, and in many parts of the world they have already been exhausted. After all, 1 km of treated waste water "spoils" 10 km of river water, and not treated - 3-5 times more. The amount of fresh water does not decrease, but its quality drops sharply, it becomes unsuitable for consumption.
Mankind will have to change the strategy of water use. Necessity forces us to isolate the anthropogenic water cycle from the natural one. In practice, this means a transition to a closed water supply, to a low-water or low-waste, and then to a "dry" or waste-free technology, accompanied by a sharp decrease in the volume of water consumption and treated wastewater.
Fresh water reserves are potentially large. However, in any part of the world, they can be depleted due to unsustainable water use or pollution. The number of such places is growing, covering entire geographical areas. The need for water is not met by 20% of the urban and 75% of the rural population of the world. The volume of water consumed depends on the region and standard of living and ranges from 3 to 700 liters per day per person. Water consumption by industry also depends on economic development of this area. For example, in Canada, the industry consumes 84% of the total water intake, and in India - 1%. The most water-intensive industries are steel, chemical, petrochemical, pulp and paper, and food. They take almost 70% of all water used in industry. On average, industry consumes about 20% of all water consumed in the world. The main consumer of fresh water is agriculture: 70-80% of all fresh water is used for its needs. Irrigated agriculture occupies only 15-17% of the area of agricultural land, and provides half of all production. Almost 70% of cotton crops in the world are supported by irrigation.
The total runoff of the rivers of the CIS (USSR) for the year is 4720 km. But water resources are distributed extremely unevenly. In the most populated regions, where up to 80% of industrial production lives and 90% of land suitable for agriculture is located, the share of water resources is only 20%. Many parts of the country are not sufficiently supplied with water. This is the south and southeast of the European part of the CIS, the Caspian lowland, south Western Siberia and Kazakhstan, and some other areas Central Asia, south of Transbaikalia, Central Yakutia. The northern regions of the CIS, the Baltic states, the mountainous regions of the Caucasus, Central Asia, the Sayan and Far East.
The flow of rivers varies depending on climate fluctuations. Human intervention in natural processes has already affected river runoff. IN agriculture most of the water does not return to the rivers, but is spent on evaporation and the formation of plant mass, since during photosynthesis, hydrogen from water molecules passes into organic compounds. To regulate the flow of rivers, which is not uniform throughout the year, 1,500 reservoirs have been built (they regulate up to 9% of the total flow). To the drain of the rivers of the Far East, Siberia and the North of the European part of the country economic activity so far it hasn't had much of an effect on humans. However, in the most populated areas, it decreased by 8%, and near such rivers as the Terek, Don, Dniester and Ural, by 11-20%. The water runoff in the Volga, Syr Darya and Amu Darya has noticeably decreased. As a result, the inflow of water to the Sea of Azov decreased by 23%, to the Aral Sea - by 33%. The level of the Aral fell by 12.5 m.
Limited and even scarce in many countries, fresh water supplies are being significantly reduced due to pollution. Usually, pollutants are divided into several classes depending on their nature, chemical structure and origin.
Pollution of water bodies. Fresh water bodies are polluted mainly as a result of the discharge of wastewater into them from industrial enterprises and settlements. As a result of wastewater discharge, the physical properties of water change (temperature rises, transparency decreases, color, tastes, odors appear); floating substances appear on the surface of the reservoir, and sediment forms at the bottom; changes chemical composition water (the content of organic and inorganic substances, toxic substances appear, the oxygen content decreases, the active reaction of the environment changes, etc.); the qualitative and quantitative bacterial composition changes, pathogenic bacteria appear. Polluted reservoirs become unsuitable for drinking, and often for technical water supply; lose their fishery importance, etc. The general conditions for the release of sewage of any category into surface water bodies are determined by their national economic significance and the nature of water use. After the release of wastewater, some deterioration in the quality of water in reservoirs is allowed, but this should not noticeably affect his life and the possibility of further use of the reservoir as a source of water supply, for cultural and sports events, and fisheries.
Supervision over the fulfillment of the conditions for the discharge of industrial wastewater into water bodies is carried out by sanitary and epidemiological stations and basin departments.
The water quality standards for reservoirs of domestic and drinking cultural and household water use establish the quality of water for reservoirs for two types of water use: the first type includes sections of reservoirs used as a source for centralized or non-centralized domestic and drinking water supply, as well as for water supply of food industry enterprises; to the second type - sections of reservoirs used for swimming, sports and recreation of the population, as well as those located within the boundaries of settlements.
The assignment of water bodies to one or another type of water use is carried out by the bodies of the State Sanitary Supervision, taking into account the prospects for the use of water bodies.
The water quality standards for water bodies given in the rules apply to sites located on flowing water bodies 1 km upstream of the nearest water use point, and on stagnant water bodies and reservoirs 1 km on both sides of the water use point.
Much attention is paid to the prevention and elimination of pollution of the coastal areas of the seas. Sea water quality standards, which must be ensured when discharging wastewater, refer to the water use area within the allotted boundaries and to sites at a distance of 300 m away from these boundaries. When coastal areas of the seas are used as a receiver of industrial wastewater, the content of harmful substances in the sea should not exceed the MPC established for sanitary-toxicological, general sanitary and rganoleptic limiting indicators of harmfulness. At the same time, the requirements for the discharge of wastewater are differentiated in relation to the nature of water use. The sea is considered not as a source of water supply, but as a medical, health-improving, cultural and household factor.
Pollutants entering rivers, lakes, reservoirs and seas make significant changes to the established regime and disrupt the equilibrium state of water ecological systems. As a result of the processes of transformation of substances polluting water bodies, occurring under the influence of natural factors, in water sources there is a complete or partial restoration of their original properties. In this case, secondary decomposition products of pollution can be formed that have a negative impact on water quality.
Self-purification of water in reservoirs is a set of interrelated hydrodynamic, physicochemical, microbiological and hydrobiological processes leading to the restoration of the original state of a water body.
Due to the fact that wastewater from industrial enterprises may contain specific contaminants, their discharge into the city drainage network is limited by a number of requirements. Industrial wastewater released into the drainage network should not: disrupt the operation of networks and structures; have a destructive effect on the material of pipes and elements of treatment facilities; contain more than 500 mg/l of suspended and floating substances; contain substances that can clog networks or deposit on pipe walls; contain combustible impurities and dissolved gaseous substances capable of forming explosive mixtures; contain harmful substances, preventing biological wastewater treatment or discharge into a reservoir; have a temperature above 40 °C.
Industrial wastewater that does not meet these requirements must be pre-treated and only then discharged into the city drainage network.
Table 1
World water reserves
No. p / p | Name of objects | Distribution area in million cubic km | Volume, thousand cubic meters km | Share in world reserve, |
1 | World Ocean | 361,3 | 1338000 | 96,5 |
2 | The groundwater | 134,8 | 23400 | 1,7 |
3 | including underground: fresh water |
10530 | 0,76 | |
4 | soil moisture | 82,0 | 16,5 | 0,001 |
5 | Glaciers and permanent snows | 16,2 | 24064 | 1,74 |
6 | underground ice | 21,0 | 300 | 0,022 |
7 | lake water | |||
8 | fresh | 1,24 | 91,0 | 0,007 |
9 | salty | 0,82 | 85.4 | 0,006 |
10 | swamp water | 2,68 | 11,5 | 0,0008 |
11 | river water | 148,2 | 2,1 | 0,0002 |
12 | Water in the atmosphere | 510,0 | 12,9 | 0,001 |
13 | Water in organisms | 1,1 | 0,0001 | |
14 | Total water supply | 1385984,6 | 100,0 | |
15 | Total fresh water | 35029,2 | 2,53 |
Conclusion.
Water is one of the main wealth on Earth. It is hard to imagine what would happen to our planet if fresh water disappeared. A person needs to drink about 1.7 liters of water per day. And about 20 times more daily is required for each of us for washing, cooking and so on. The threat of disappearance of fresh water exists. All living things suffer from water pollution, it is harmful to human health.
Water is a familiar and unusual substance. The famous Soviet scientist academician I.V. Petryanov called his scientifically popular book about water "The most extraordinary substance in the world." And the doctor of biological sciences B.F. Sergeev began his book "Entertaining Physiology" with a chapter on water - "The substance that created our planet."
Scientists are right: there is no substance on Earth more important for us than ordinary water, and at the same time there is no other substance of the same kind, in whose properties there would be as many contradictions and anomalies as in its properties.
Bibliographic list:
1. Korobkin V. I., Peredelsky L. V. Ecology. Tutorial for universities. - Rostov /on/Don. Phoenix, 2005.
2. Moiseev N. N. Interaction between nature and society: global problems // Bulletin of the Russian Academy of Sciences, 2004. V. 68. No. 2.
3. Environmental protection. Proc. allowance: V 2t / Ed. V. I. Danilov - Danilyan. - M.: Publishing house MNEPU, 2002.
4. Belov S. V. Environmental protection / S. V. Belov. – M. graduate School, 2006. - 319 p.
5. Derpgolts VF Water in the universe. - L .: "Nedra", 2000.
6. G. A. Krestov, From Crystal to Solution. - L .: Chemistry, 2001.
7. Khomchenko G.P. Chemistry for entering universities. - M., 2003
Russian State Hydrometeorological University
Department of Oceanology
Discipline "Chemistry"
Essay on the topic: "Properties of water"
Fulfilled Art. gr. O-136
Gusev M.V.
Saint Petersburg
I. Introduction ............................................... ................................................. .............3
II. Main part................................................ ................................................. .3
physical properties. ................................................. .................................4
Heavy (deuterium) water .............................................. .............................5
Magnetized water. ................................................. ....................................7
Chemical properties of water .............................................................. ......................7
Bibliography: ............................................... ..............................................10
I Introduction
Almost ¾ of the surface of our planet is occupied by oceans and seas, and about 20% of the land is covered with snow and ice. Of the total amount of water on Earth, equal to 1 billion 386 million cubic kilometers, 1 billion 338 million cubic kilometers falls on the share of salty waters of the World Ocean, and only 35 million cubic kilometers falls on the share of fresh waters. Almost 70% of fresh water is contained in the ice sheets of the polar countries and in mountain glaciers, 30% is in aquifers underground, and only 0.006% of fresh water is simultaneously contained in the channels of all rivers.
Water is the only substance on Earth that exists in nature in all three states of aggregation - liquid, solid and gaseous.
Water molecules have been found in interstellar space. Water is part of comets, most of the planets of the solar system and their satellites.
There are nine stable isotopic varieties of water. Keeping them in fresh water on average the following:
1 H 2 16 O - 99.73%, 1 H 2 18 O - 0.2%, 1 H 2 17 O - 0.04%, 1 H 2 H 16 O - 0.03%.
The remaining five isotopic species are present in water in negligible amounts.
II. Main part
The structure of the molecule.
As you know, the properties of chemical compounds depend on what elements their molecules consist of, and change naturally. Water can be considered as hydrogen oxide or as oxygen hydride. Hydrogen and oxygen atoms in a water molecule are located at the corners of an isosceles triangle with an O-H bond length of 0.958 nm; bond angle H - O - H 104 o 27 '(104.45 o).
But since both hydrogen atoms are located on the same side of the oxygen, the electric charges in it disperse. The water molecule is polar, which is the reason for the special interaction between its different molecules. Hydrogen atoms in a water molecule, having a partial positive charge, interact with the electrons of oxygen atoms of neighboring molecules (hydrogen bond). It combines water molecules into a kind of spatial structure polymers. In the liquid and solid phases, each water molecule forms four hydrogen bonds: two as a proton donor and two as a proton acceptor. The average length of these bonds is 0.28 nm, the H - O - H angle tends to 180 o. The four hydrogen bonds of a water molecule are directed approximately to the vertices of a regular tetrahedron.
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