Water resources of the earth.

Starting the story about natural sources of water, it is worth explaining why we have added the definition “conditionally” to the title of the article. The fact is that there is very little truly clean drinking water on Earth, and the number of such sources is steadily decreasing every year. But let's leave our introduction, which is unpleasant for humanity, and go directly to the very topic of our conversation, noting the approximate amount of drinking water on our planet. According to the estimates of environmental scientists, the share of fresh water on Earth is only 3%, most of which are mountain and cover glaciers found at the North and South Poles, as well as in a number of northern regions, in particular in Greenland, which is considered one of the largest places of occurrence of clean drinking water on the planet. The rest, conditionally suitable for drinking, is concentrated in rivers and lakes, as well as in surface and groundwater, which is extracted with the help. Also, an insignificant share of fresh water falls on precipitation. However, no matter how large the water reserves of rivers and lakes, in their total mass, it is impossible to use it for drinking without preliminary purification, because human economic activity has gone so far that almost all such sources of drinking water on Earth have long been contaminated with not just harmful , and even substances hazardous to human health. Therefore, in most cases, surface and underground waters are used for water supply to the population, which we will talk about in detail, touching upon in the conclusion of the article the methods of extracting fresh water from icebergs and desalination of salty sea and ocean water.

Surface sources

Surface springs are called rivers and lakes, which account for only 0.01% of the volume of all fresh water on Earth. At the same time, most of it is in rivers, and only 1.47% is in lakes. Most rivers on the planet have such a course that it is not possible to provide water from them in a natural way. Therefore, many of them are blocked by dams, which form artificial open reservoirs for storing fresh water, which in some cases are used to generate electricity, which is generated when water is discharged from the storages onto turbines. There are not so many rivers in the world that are capable of discharging large volumes of water per unit of time. These include: in Russia - the Yenisei, in South America - the Amazon, in the USA - Missouri and Mississippi, in South Asia - Brahmaputra and the Ganges, in China - the Yangtze, in Africa - Congo (Zaire). In second place in importance as sources of drinking water, after rivers and reservoirs, are lakes, which in total hold up to 125 thousand cubic kilometers of water. In addition to supplying water from them directly to household needs, part of the fresh water from the lakes is used to support human economic activities - this is irrigation of agricultural land, fish farming, industrial, and most often food, production, etc. Sometimes, uncontrolled intake of fresh water from lakes that cannot replenish its supply as quickly as rivers can lead to the complete drying up of lakes. A striking example is the Aral Sea, which is essentially a lake, and has almost disappeared from the surface of the Earth. Also, there are situations when new freshwater lakes are formed, for example, as a result of seismic activity, but such cases are quite rare.

Unlike rivers, most of which are fed by many small streams and springs, even in "safe" lakes during the year significant fluctuations in water level are possible. This is due to various factors, the main ones of which are: an increase in the natural discharge of water through rivers flowing from water bodies, evaporation of water and its seepage into the ground. However, if the lake is "healthy", then, as a rule, the water level does not drop to critical levels, and the reservoir is replenished due to atmospheric precipitation, as well as rivers and springs flowing into it. This process has been going on for millennia, and a number of fairly old lakes on Earth will soon lose their potential as natural reservoirs of fresh water. The fact is that as a result of the evaporation of water, salts gradually accumulate in such reservoirs, the percentage of which at a certain moment becomes so high that a fresh lake turns into salty, which means that it is no longer possible to use water from it for drinking. Of course, it is possible, when taking water from such reservoirs, to pass it through special desalination installations. But as practice shows, the introduction of such equipment makes the produced fresh water so expensive that its desalination is not profitable. As for freshwater bogs, which are essentially the closest relatives of lakes, their potential as sources of fresh water is very little used. Scientists believe that in the near future, the problem of fresh water will become so acute that swamps, the conservation of which must be thought about today, will be one of the sources of drinking water.

Underground springs

According to the most rough estimates, about 98% of all fresh water on Earth is located in its bowels. Moreover, almost half of its volume lies at depths exceeding 800 meters, which makes its production extremely costly, and in some cases, even impossible. And those 50% that are available are so thoughtlessly taken away that if the situation is not drastically corrected, then in 40-50 years, mankind will have to drill wells more than a kilometer deep in order to provide themselves with drinking water. An example is the underground waters of the Sahara Desert, the volume of which, according to the last estimates, is up to 625 thousand cubic kilometers. But the trouble is that the area of \u200b\u200btheir occurrence is such that the replenishment of the underground reservoir does not occur naturally, and the pumping is very intensive. In addition, recent geological processes in this area have led to the fact that groundwater began to come to the surface in the form of springs, only a small part of which falls on places where people live. The rest of the water literally goes into the sand. As the scientists explain, this is because the huge freshwater reservoir under the Sahara consists of several large lakes, the surface of which, after the movements of the earth's crust, crossed in some places with the surface of the Earth. From which springs and even artesian springs were formed, especially where the water was under significant hydrostatic pressure. When there is no water in the depths of the Sahara at all, it is impossible to say for sure, but that this moment is not far off, ecologists say for sure about this. In addition, it would not hurt to pass such water through, but this is not always possible.

Extraction of underground fresh water is proceeding at a much faster pace than was possible even 20-30 years ago. And this is due to the emergence of high-tech drilling equipment and powerful pumps for lifting water from great depths, which makes it possible to extract significant volumes of water per unit of time. However, in some regions of the world, the growing water consumption has negative consequences. The fact is that underground reservoirs are practically not replenished with water naturally, and its pumping leads to a decrease in the water level, which entails an increase in the cost of its extraction. Moreover, in places where underground reservoirs are completely depleted, subsidence of the earth's surface is observed, which makes it impossible for its further exploitation, for example, as agricultural land. In coastal areas, the situation is even more dramatic. Depleted aquifers, even those that can be recovered for several more years, mix with saline sea or ocean water, resulting in salinization of the soil, and the small amount of fresh water remaining in the coastal region. The problem of salinization of fresh water has another reason associated with human economic activity. After all, the source of salt can be not only the seas and oceans, but also fertilizers or water with a high salt content, which is used to irrigate fields and gardens. Such processes of salinization of groundwater and soil are called anthropogenic, and more and more civilized countries are faced with them.

Obtaining fresh water from icebergs

At the end of the article on conditionally clean natural sources of fresh water, we, as promised, will pay attention to the extraction of drinking water from icebergs. Scientists claim that only in the glaciers of the mainland of Antarctica is up to 93% of all fresh water reserves on Earth, which is about two thousand square kilometers of frozen moisture. And since, in a short time, there will be practically no surface and underground source of drinking water on the planet, a moment will come when mankind will be forced to turn its attention to icebergs. The idea to extract drinking water from glaciers was first expressed in the 18th century by the English navigator and discoverer James Cook, better known for being eaten by the natives. And although this is just a legend, he is remembered not for the revolutionary idea at that time - to extract water from the glaciers of Antarctica, but for the ridiculous death in the cauldron of cannibals, which in fact did not exist. Why Cook drew attention to icebergs as sources of fresh water is not known for certain. But the fact that the navigator was the first to suggest using pieces of ice in long sea voyages as natural storage of water reserves, we know for sure from a number of written sources that have survived to our days. The modern followers of Cook went even further, and propose to break off huge chunks of ice from glaciers in order to then deliver them to regions where there is a shortage of drinking water. At first glance, the idea is brilliant, but when implementing such a project, difficulties may arise that cannot be overcome, even with the modern development of technology.

Breaking a large iceberg from the glacier is quite problematic, and traditional mechanical tools, as well as a directional explosion, are not suitable here, because the iceberg can split.
It is simply impossible to deliver an iceberg to its destination without losing a significant part of it, which will simply melt in warm waters and under the scorching sun.
Even if an effective method of "conservation" of the iceberg is invented, which excludes its melting, several powerful sea vessels will be needed to move it, the work of which should be as coordinated as possible.
It is unlikely that it will be possible to process such a huge amount of ice into fresh water without significant losses.

As you can see, even if an effective way of developing a glacier and delivering its parts to their destination is invented, these works will be so costly that the cost of one liter of fresh water will turn out to be astronomical. However, scientists believe that no matter what difficulties are accompanied by the extraction of ice in Antarctica, and its delivery to consumers, in the near future we will witness the embodiment of James Cook's idea into reality. Moreover, countries such as Australia, Egypt, Saudi Arabia, France and the United States are already showing great interest in this issue.

Springs (water)

keys, or springs, - are waters directly leaving the bowels of the earth to the day surface; they are distinguished from wells, artificial structures, with the help of which they either find ground water, or take over the underground movement of spring waters. The underground movement of spring waters can be expressed in extremely diverse ways: either it is a real underground river flowing over the surface of the water-resistant layer, then it is a barely moving brook, or a stream of water escaping from the bowels of the earth as a fountain (griffin), then these are separate drops of water gradually accumulating in the basin key. Keys can come out not only on the surface of the earth, but also on the bottom of lakes, seas and oceans. Cases of the latter kind of key outputs have long been known. Regarding the lakes, it can be noted that the accumulation of some mineral sediments (lacustrine iron ores) at the bottom of Lake Ladoga. and the Finnish hall. forces to allow the exit at the bottom of these pools-springs, mineralized by known substances. In the Mediterranean, the Anavolo spring is remarkable, into the hall. Argos, where a column of fresh water up to 15 m in diameter beats from the bottom of the sea. The same keys are known in the Hall of Tarentum, in San Remo, between Monaco and Menton. In the Indian Ocean, there is a spring rich in fresh water gushing among the sea 200 km from Chittagont and 150 km from the nearest coast. Of course, such cases of fresh water coming out in the form of springs from the bottom of the seas and oceans is a rarer phenomenon than on land, since a significant force of fresh water is needed to be found on the surface of the sea; in most cases, such jets mix with sea water and disappear for observation without a trace. But some ocean sediments (the finding of manganese ores) are also capable of suggesting that I. can also be exposed at the bottom of the oceans. Since the underground movement of water depends on the meeting at depths of waterproof layers and on the inclination and bending of these latter, as well as and from the presence of cracks in rocks that change the direction of water movement, then initially, to get acquainted with the keys, it is necessary to analyze the question of their origin. Already by the very shape of the key's exit to the day surface, one can distinguish whether it will be descending or ascending. In the first case, the direction of movement of the water goes down, in the second, the stream hits upward, like a fountain. True, sometimes an ascending key, meeting an obstacle to its direct exit to the day surface, for example. in the overlying water-resistant layers, it can go along the slope of the aquifers and be exposed somewhere lower in the form of a descending spring. In such cases, they can be mixed with each other if the immediate exit point is masked by something. In view of the above opinions, when meeting with I., you can enter, as a classifying principle, the very method of their origin. In this last respect, all known I. can be divided into several categories: 1) I., feeding on river water. This is the case when a river flows through a valley formed by loose material that is easily permeable to water. It is clear that the river water will penetrate into this loose rock, and if a well is laid somewhere at a certain distance from the river, it will find river water at a certain depth. In order to be completely sure that the water found is, in fact, the water of the river, it is necessary to make a series of observations on the change in the water level in the well and in the neighboring river; if these changes are the same, then we can conclude that the water of the river was found by the well. It is best for such observations to choose the moments when the rise in the water level in the river was caused by rainfall somewhere in the upper reaches of the river. and if at this time there was an increase in the water level in the well, then you can get. firm belief that the water found by the well is river water. 2) I., originating from the concealment of rivers from the surface of the earth. Theoretically, one can imagine a twofold possibility for their formation. A stream or river can meet on the way of its current either a crack, or loose rocks, where they will hide their waters, which can somewhere further, in lower-lying places, are again exposed to the surface of the earth in the form of I. The first of these cases has a place where rocks are developed on the surface of the earth, broken by cracks. If such rocks are easily soluble in water, or if they are easily eroded, then the water prepares an underground bed for itself and somewhere, in lower-lying places, will be exposed in the form of I. Such cases are represented by a significant surface of the coast of Estonia, Ezel Island, etc. . terrain. For example, you can point to the Erras stream, a tributary of the river. Isenhof, which is originally a stream, abundant in water, but as it approaches the Erras manor, it gradually becomes poorer in it and, finally, one has to see the bed of the stream, free of water, filled only during high water. At the bottom of this free bed, holes have been preserved in the limestone, with the help of which one can make sure that water is moving underground, which is again exposed on the day surface to the bank of the river. Izenhof is a mighty source. The same example is presented by the Ohtias brook on the Ezele Island, which is originally a rather abounding creek, which, not reaching 3 km to the sea shore, hides in a crack and is already exposed on the very shore of the sea by a high water I. Carinthia is an extremely interesting country in this respect. where, thanks to the numerous cracks and the presence of vast cavities in the rocks, the fluctuation of the surface water level is surprisingly diverse. For example, you can point to the Cirknitskoe Lake, which is up to 8 km long and about 4 km wide; it often completely dries up, that is, all its water goes into the holes at its bottom. But once the rain falls in the neighboring mountains, the water will again come out of the holes and fill the lake with itself. Here, obviously, the lake bed is connected by holes with vast underground reservoirs, in case of overflow of which water again flows to the surface of the earth. The same concealment of streams and rivers can be caused by the meeting by them of significant accumulations of loose, easily permeable, rocks, among which the entire water supply can seep and in this way disappear from the surface of the earth. As an example of the latter kind of key formation, we can point to some keys of Altai. Here, on the shore of a salt lake, you can often find a fresh spring plentiful either on the shore, or sometimes near the shore, but from the bottom of the salt lake. It is easy to see that from the side where the I. are exposed, a valley opens up from the mountains to the lake, to the mouth of which one has to climb a wide wedge-shaped embankment, and only after climbing it can one see a number of separate streams heading to the lake and being lost in loose material, obviously inflicted by the river itself and filled up its mouth with it. Further up the valley, a real and often abundant stream is already visible. 3) I., feeding on water glaciers. The glacier, sinking below the snow line, is exposed to a higher temperature, and its firn or ice, gradually melting, gives rise to numerous I. Such L. sometimes run out from under the glacier in the form of real rivers; an example of this is pp. Ron, Rhine, some rivers flowing from Elbrus, like Malka, Kuban, Rion, Baksan and friend. 4) Mountain I. have long been the subject of controversy. Some scientists put them in exclusive dependence on volcanic forces, others - on special huge cavities inside the earth, from where, under the influence of pressure, water from them is delivered to the surface of the earth. The first of these opinions held for a long time in science, thanks to the authority of Humboldt, who observed I. at the top of the Tenerife peak, originating from water vapor escaping from the two holes of the peak; Due to the rather low air temperature at the top of the mountain, these vapors turn into water and feed I. The studies of Arago in the Alps have quite clearly proved that there is not a single I. at the very peaks, but there is always above them either a supply of snow, or generally significant surfaces that collect atmospheric waters in sufficient quantities to feed I. The dependence of I. on overlying lakes is Lake Daubenskoe in Switzerland, which lies at an altitude of about 2,150 m and feeds a multitude of I. emerging in the underlying valleys. If we imagine that the massif of rocks on which the lake lies is broken by cracks that reach the underlying valleys and capture the bottom or the shore of the lake, then water can seep down through these cracks and feed I. There may be another case: when this massif is formed by rocks layered, among which there are rocks that are permeable to water. When such a permeable layer lies obliquely and comes into contact with the bottom or with the shores of the lake, then here too there is a full opportunity for water to seep and feed the underlying springs. It is just as easy to explain the periodicity in the activity of mountain springs feeding on the overlying lakes. Cracks or a permeable layer may come into contact with the water of the lake somewhere near its level, and in the case of a decrease in the latter, for example. from drought, the supply of the underlying keys is temporarily interrupted. In case of rain or snow on the mountains, the water level in the lake rises again and the possibility of feeding the underlying springs opens up. Sometimes it is possible to observe the outcrops of ice on the mountains from under the snow covers - as a direct result of the melting of snow reserves. But especially interesting are the cases when there are no snow reserves on the mountains, but where the I. running out at the foot of these mountains owe their food in any case to snow accumulations. Such a case is presented by the I. of the southern coast of Crimea. The chain of the Crimean or Tauride mountains is all composed of layered rocks, which have an inclined position, falling from south to north. This position of the layers also forces underground waters to drain in the same direction. Nevertheless, to the south. On the Crimean coast, right from the foot of the mountain chain, which rises up to 1400 m, to the sea coast, you can observe numerous I. Some of them run out directly from the sheer cliff, with which the chain of mountains opens towards the Black Sea. Such I. sometimes appear in the form of a waterfall, like I. Uchan-su, near Yalta, feeding the river of the same name. The temperature of different I. is different and ranges from 5 ° - 14 ° C. It was noted that the closer the I. is exposed to the chain of mountains, the colder it is. In the same way, observations were made on the amount of water delivered by various I. at different times of the year. It was found that the higher the air temperature, the more water supplied by the key, and vice versa, the lower the temperature, the less water. Both these observations clearly show that the nutrition of I. yuzhn. the coast of Crimea owes to the reserves of overlying snow. However, the aforementioned height of the Tauride Mountains chain is far from reaching the snow line and, indeed, if you climb to their plateau-like summit, called Yaila, then no snow reserves are observed here. Only with a careful acquaintance with Yaila can one notice in some of its places the pit holes, sometimes occupied by small lakes, or filled with snow. Quite often the depth of such pits reaches up to 40 m. During the winter snow is filled with winds into these pits, and in the spring, summer and autumn it gradually melts and, of course, its melting is stronger in warm seasons, and therefore ice gives more water; for this reason, the constant water temperature of I. is also lower as their exit points approach the reserves of melting snow. This conclusion is also confirmed by another circumstance. Most of the waters of I. southern. the shores of the Crimea are hard, that is, calcareous, even though they are sometimes exposed from clay shale. Such a content of lime in them finds an explanation in the fact that the snow reservoirs lie in limestones, from which water borrows lime. five) Ascending, or hitters, keys require quite definite conditions for their formation: they need a cauldron bending of rocks and the alternation of waterproof layers with permeable ones. Atmospheric water will penetrate into the exposed wings of the aquifers and accumulate at the bottom of the basin under pressure. If cracks form in the upper waterproof layers, then water will gush out of them. On the basis of the study of ascending I., artesian wells are arranged (see the corresponding article).

Mineral springs. There is no water in nature that does not contain in solution a certain amount of various gases, or various mineral substances, or organic compounds. In rainwater, sometimes up to 0.11 g of mineral substances are found per liter of water. Such a finding is made quite understandable if we remember that there are many minerals in the air that are easily soluble in water. Numerous chemical analyzes of waters of various springs show that, apparently, even the purest spring waters still contain a small amount of mineral substances. For example, you can point to the Barege springs, where 0.11 g of minerals were found per liter of water, or to the Plombier water, where they were found 0.3 g. Of course, this amount varies significantly in different waters: there are spring waters containing in the solution some minerals in amounts close to saturation. Determination of the amount of mineral substances dissolved in water is of very great scientific interest, since it indicates which substances can be dissolved in water and transferred from one place to another. Such definitions received particular importance when spectral analysis was applied to precipitation falling out of spring waters at the point of their emergence on the earth's surface; such an analysis made it possible to detect very small amounts of minerals in solutions of various keys. By this method it was found that most of the known mineral substances are in the solution of spring waters; gold was even found in the waters of Luesh, Gotl and Gisgübel. Greater dissolution is facilitated by a higher temperature, and it is known that in nature there are warm springs, the waters of which in this way can be further enriched with minerals. Fluctuations in the water temperature of various springs are extremely significant: there are spring waters whose temperature is close to the point of snow melting, there are waters - with temperatures exceeding the boiling point of water and even - in an overheated state - like the water of Geysers. According to the water temperature, all springs are subdivided into cold and warm or thermal springs. Among the cold ones are distinguished: normal keys and hypotherms; in the former, the temperature corresponds to the average annual temperature of a given place, in the latter, it is lower. Among the warm springs, local warm springs or baths and absolute baths are distinguished in the same way; the first include such springs, the water temperature of which is slightly higher than the average annual temperature of the area, the second - at least 30 ° C. The finding of absolute terms in volcanic areas gives an explanation for their high temperature. In Italy, near volcanoes, jets of water vapor, called staffs, often erupt. If an ordinary key meets such jets of water vapor, then it can be heated to a very different degree. The origin of the higher temperature of local baths can be explained by various chemical reactions taking place inside the earth and the temperature rise caused by them. For example, one can point to the relative ease of decomposition of pyrite, in which a significant release of heat is detected so much that it may be quite enough to raise the temperature of the spring water. In addition to the high temperature, pressure should also have a strong influence on the enhancement of dissolution. The waters of the springs, moving at depths, where the pressure is much higher, must dissolve in a larger amount both various mineral substances and gases. That, in fact, an increase in dissolution proceeds in this way, is proved by the fallout of precipitation from the waters of the springs in the places of their exits to the day surface, where the springs are exposed at the pressure of one atmosphere. This is also confirmed by the keys containing gases in the solution, sometimes even in an amount exceeding the amount of water in volume (for example, in carbon dioxide sources). Water saturated under pressure is an even stronger solvent. In water containing carbon dioxide, the average lime salt dissolves extremely easily. Taking into account that in the immediate vicinity of both currently active and extinct volcanoes of some localities, there is sometimes a fairly abundant release of various acids, for example, carbon dioxide, hydrochloric, etc., it is easy to imagine that if such secretions are met with jets of spring water, then it can dissolve a more or less significant amount of released: gas (assuming the above pressure, such waters must be recognized as extremely strong solvents). In any case, the strongest mineral springs should be found more often in the vicinity of currently active or extinct volcanoes, and often a significantly mineralized and warm spring serves as the last indicator of volcanic activity that was once in a given area. Indeed, the strongest and warmest springs are confined to the neighborhood of typical volcanic rocks. The classification of mineral springs is very difficult, since it is difficult to imagine the presence in nature of waters containing only one chemical compound in solution. On the other hand, the same difficulty in classification is presented by the lack of clarity among chemists themselves and the grouping of the constituents dissolved in water of the keys, and a significant proportion of arbitrariness. Nevertheless, in practice, for the convenience of viewing mineral springs, it is customary to group them in a known way, which will be discussed. said further. A detailed consideration of all mineral springs would take us out of the scope of this article, and therefore we will dwell only on some of the most common ones.

Lime wrenches, or hard water keys. This name is understood as such key waters, in the solution of which there is acidic carbonic lime. They got the name of hard waters from the fact that soap dissolves with great difficulty. Carbonic lime in water dissolves very little, and therefore some favorable conditions are needed for its dissolution. Such a condition represents the presence of free carbon dioxide in solution in water: in its presence, the average salt turns into acidic and in this state becomes soluble in water. Nature promotes the borrowing of carbon dioxide by waters in two ways. There is always free carbon dioxide in the atmosphere, and therefore rain falling out of the atmosphere will dissolve it; this is confirmed by analyzes of the air before and after rain: in the latter case, carbon dioxide is always found less. Rainwater finds another supply of carbon dioxide in the vegetation layer, which is nothing but a product of the weathering of rocks, into which organic matter is introduced - the decomposition product of plant roots. Chemical analyzes of the air of soils have always revealed the presence of free carbon dioxide in them, and therefore water that has passed through the air and soil must certainly contain a more or less significant amount of carbon dioxide. Such water, meeting limestones, which, as you know, are composed of medium salt of carbonate lime, will convert it into acidic salt and dissolve. In this way, cold lime springs usually occur in nature. Their activity in the gesture of coming out to the day surface is revealed by the formation of a kind of sediment, called lime tuff and consisting of a porous mass in which the pores are extremely irregular; This mass consists of medium coal-lime salt. The precipitation of this precipitate is due to the release of semi-bound carbon dioxide from hard waters and the transfer of acidic salt to medium. Calcareous tuff deposits are a common occurrence because limestone is a very common rock. Lime tuff is used for burning and making caustic lime, as well as directly used in lumps to decorate stairs, aquariums, etc. Sediment from hard waters takes on a slightly different character if it is deposited somewhere in the cavities of the earth or in caves. The process of sedimentation here is the same as in the above case, but its nature is somewhat different: in this last case it is crystalline, dense and solid. If hard water seeps on the ceiling of the cave, then streaky masses are formed that descend from the ceiling of the cave down - such masses in the geological literature are called stalactites, a to those that are deposited at the bottom of the cave, due to the fallout of hard water from the ceiling downwards, - stalagmites. In Russian literature they are sometimes called, droppers. With the growth of stalactites and stalagmites, they can merge with each other, and thus artificial columns can appear inside the cave. Such a sediment, due to its density, is an excellent material for the preservation of all objects that can get into it. He cloaks these objects with a continuous and continuous veil that protects them from the destructive effects of the atmosphere. Thanks, in particular, to the stalagmite layer, it became possible to preserve the bones of various animals, in the form of bone breccia, to the products of man, once, in prehistoric times, who lived in these caves. Taking into account that both the settlement of the cave and the deposition of the stalagmite layer proceeded gradually, one should expect that an extremely interesting picture of the past should be revealed in the successive layering of the caves. Indeed, the excavation of the caves has yielded extremely important material for the study of prehistoric man and ancient fauna. If a cold source of hard water, when it comes out to the surface of the earth, must fall in the form of a waterfall, then the average coal-lime salt will fall out of the water and line the bed of the waterfall. Such a formation resembles, as it were, a frozen waterfall, or even a number of them. Potanin, on his trip to China, describes a very interesting series of such waterfalls, where one could count up to 15 separate terraces, from which water flows in cascades, forming on the way of its flow a series of pools made up of carbonic lime. Hot springs are even more energetic in depositing medium coal-lime salt. Such keys, as mentioned earlier, are associated with volcanic countries. As an example, one can point to Italy, in which there are many places of outlets of such springs: in this respect, a particularly vigorous deposition of carbonic lime is observed near San Filippo, in Tuscany; here the key is deposited in four months a layer of sediment one foot thick. In Campania, between Rome and Tivoli, there is a lake. Solfataro, from which carbon dioxide is released with such energy that the water of the lake seems to be boiling, although its water temperature is far from reaching the boiling point. Parallel to this release of carbon dioxide is the precipitation of the average salt of lime carbonate from the water; it is enough to stick a stick under the water level for a short time so that in a short time it is covered with a thick layer of sediment, the sediment deposited under such conditions is much denser than tuff, although it contains pores, these latter are arranged in parallel rows. This sediment was named in Italy travertine. It serves as a good building stone and, where there is a lot of it, breakages are laid in it and its production is carried out. Many buildings in Rome were erected from such a stone and, by the way, the Cathedral of St. Peter. The abundance of strips of travertine in the vicinity of Rome testifies that in the basin in which Rome now stands and where the river flows. The Tiber was once a vigorous activity of warm lime springs. Even more original is the deposition of the same sediment composition from hot lime springs, if they appear in the form of ascending or gushing springs, that is, in the form of a fountain. Under these conditions, under the influence of a vertically gushing jet of water, small foreign objects can be mechanically carried away by the water and float in it. Carbon dioxide is released more vigorously from the surface of solids. In a short time, carbonic lime will begin to be deposited around the floating particle, and in a short time a ball floating in the water is formed, consisting of concentrically-shell deposits of carbonic lime and supported in the water by a vertically beating stream of water from below. Of course, such a ball will float until its weight increases and it falls to the bottom of the key. This way is the accumulation of the so-called pea stone. In the Carlsbad Key, sowing. Bohemia, the accumulation of pea stone occupies a very significant area.

Iron, or ferruginous, keys contain iron oxide in the solution of their waters, and therefore for their formation it is necessary to have either ready-made iron oxide in the rocks or conditions under which iron oxide can also turn into nitrous oxide. Some rocks do have ready-made ferrous oxide, for example. in rocks containing magnetic iron ore, and therefore, if water containing free carbon dioxide in solution flows to such a rock, then iron nitrous oxide can be easily borrowed from the magnetic iron ore. In this way carbonic iron waters occur. Sulfur pyrite, or pyrite, is quite common in rocks, which is a combination of one iron share with two sulfur shares; this last mineral, undergoing oxidation, gives ferrous sulfate, which is quite easily soluble in water. In this way, iron sulfate springs are formed, and as an example of such, one can point to the Koncheozersk mineral waters of the Olonets lips. Finally, there may be cases when there is no ready-made iron oxide in the rock, but there is oxide: it turns out that here, too, nature is able to practice the well-known method in which iron oxide turns into nitrous oxide. This method was observed on red-colored sandstones, the upper surface of which was overgrown with plant roots; it turned out that where the roots came into contact with the sandstone, it became discolored, that is, under the influence of decomposition of the roots without access to air and due to the formed carbohydrates, the iron oxide was reduced to nitrous oxide. In any case, the content of carbonic ferrous oxide in iron keys is very small: it ranges from 0.196 to 0.016 grams per liter of water, and in mixed waters, as in the iron-alkaline waters of Zheleznovodsk - only 0.0097 g. Iron keys are easy to recognize by the appearance on the surface of their waters, at the point of exit, an ocher-brown film consisting of aqueous iron oxide, which is, as a result of the oxidation of iron oxide by atmospheric oxygen, into oxide. This is the path in nature for the accumulation of various. iron ores, called brown iron ores, the varieties of which are: sod, swamp and lake ores. Of course, in previous geological times, nature practiced in the same way the accumulation of brown iron ore in ancient sediments.

Sulfur keys contain hydrogen sulfide in the solution, recognizable by an unpleasant odor; in its distribution on the surface of the earth, sulfur springs are confined to areas where gypsum or anhydrides are developed, i.e., water or anhydrous sulphate salt of lime. Such a close proximity of the sulfur springs with the above rocks involuntarily suggests that there are some processes in nature by which the sulfur-salt is reduced to a sulfur compound. An incident in one of the laboratories helped explain this process. In a jar filled with a solution of ferrous sulfate. or ferrous sulfate, a mouse accidentally hit; after quite a long time, the corpse of the mouse became covered with crystals with a metallic, brassy-yellow sheen of sulfur pyrite. The last mineral could occur in solution only by reduction, that is, by taking oxygen from the sulfur salt, and this could only happen from the decomposition of a mouse corpse in solution and without access to air. At the same time, carbohydrates develop, which act in a reducing way on sulfur-salt, take oxygen from it and convert it into a sulfur compound. In all likelihood, the same process occurs with gypsum or anhydride with the assistance of carbohydrates; at the same time, lime sulphide is converted into calcium sulphide, which, in the presence of water, quickly decomposes and gives hydrogen sulfide.This way can be explained why the waters of some wells sometimes begin to emit the smell of rotten eggs (hydrogen sulfide), whereas before these waters were odorless Gypsum is a very widespread mineral, and therefore its presence in a solution of various waters should also be common. Imagine that there is gypsum in the water of this well and that the frame of the well has rotted: when a tree decays without access to air, carbohydrates develop here, which act in a reducing way on gypsum, take oxygen from it and convert it into a sulfur compound. Since this process takes place in the presence of water, decomposition immediately takes place and hydrogen sulfide is formed. One has only to change the rotten logs of the well and the nasty smell will disappear. This process of formation of sulfur springs is confirmed by the presence of some sulfur compounds in solution in their waters, as well as the frequent proximity of oil sources to them. However, the content of hydrogen sulfide in the water of sulfur springs is not particularly significant - it ranges from barely noticeable traces to 45 kb. cm per liter (i.e. 1000 kb. cm) of water. To Europe. Sulphurous springs are known in Russia in the Ostsee region, in Lithuania, in the Orenburg province. and in the Caucasus.

Salty keys are found where there is in rocks or deposits of table salt, or where the latter forms inclusions in them. Table salt or rock salt belongs to substances easily soluble in water, and therefore, if water flows through such rocks, it can be largely saturated with salt; that is why keys of such varied salt content are found in nature. There are keys that are close to saturation, and there are keys that show up only with a weak salty taste. Some salt springs are also admixed with calcium chloride or magnesium chloride, sometimes in quantities so significant that in this way mineral springs of a completely new composition are formed; the latter type of springs is recognized as rather important from a medical point of view, and the Druskenik mineral waters belong to this category (see the corresponding article). The purest salt springs are found in Europe. Russia in the provinces of Vologda, Perm, Kharkov and Poland. In the areas of distribution of salt springs, drilling has recently been quite often used, with the help of which either the presence of rock salt deposits is discovered at depths, or stronger salt brines are extracted. In this way, the famous Stasfurt deposit was discovered, near Magdeburg, or our Bryantsovskoe salt deposit in the Yekaterinoslavskaya lips. By drilling, as indicated above, stronger brines can be produced. A spring rising naturally from the depths can meet fresh water on its way, which will dilute it to a large extent. Placing a borehole and accompanying it with a pipe, it is possible in this way to adopt stronger solutions at depths; the well pipe protects the rising water from mixing with fresh water. But it is necessary to use drilling in order to increase the concentration of mineral springs waters with great care, one must first study this key well, find out exactly those rocks through which it breaks to the surface of the earth and, finally, determine the value of the mineral key. If you want to use the key for commercial purposes, for example. a salt key for boiling salt out of it, it can be recommended to increase its concentration by drilling. Many mineral springs are exploited for medical purposes, for which their significant strength is often not so much important as their specific composition. In this latter case, it is often better to completely abandon the desire to increase the concentration of the key by drilling, because otherwise you can spoil its mineral composition. Indeed, in medicine, especially in balneology, often minimal amounts of a substance play a significant role in the composition of mineral waters (as an example of this, the insignificant content of ferrous oxide in iron waters was indicated above), and there are some waters, such as ., iodine, which sometimes contain only traces of iodine and despite this not only are considered useful, but actually help patients. Any key, making its way naturally to the surface of the earth, must go through a wide variety of rocks, and its solution can enter into exchange decomposition with the constituent parts of the rocks; in this way the key, initially of very simple composition, can obtain a significant variety in terms of mineral constituents. By laying a borehole and accompanying it with a pipe, you can get stronger solutions, but not of the same composition as before.

Carbonic I. It was already indicated above that in volcanic countries there is a release of carbon dioxide and other gases along cracks; if the waters of the spring meet such gases on their way, then they can dissolve them in more or less significant quantities, which, of course, largely depends on the depth at which such a meeting took place. At great depths, where the pressure is also great, the waters of the spring can dissolve a lot of carbon dioxide under high partial pressure. For example, you can point to the Marienbad carbonate I., where 1514 kb are dissolved in a liter of water. cm, or to Narzan Kislovodsk, where 1062 kb are dissolved in the same amount of water. see gas. Such springs are easily recognized on the surface of the earth by the abundant release of gas from the water, and sometimes the water seems to be boiling.

Oil I. Oil is a mixture of liquid carbohydrates, among which the limiting ones with a specific gravity, less than water, prevail, and therefore oil will float on it in the form of oily spots. The waters that carry oil are called oil springs. Such I. are known in Italy, in Parma and Modena, very strong along the river. Irrawaddy, in the Burmese Empire, in the vicinity of Baku and on the Absheron Peninsula, on the bottom and islands of the Caspian Sea. On one island Cheleken, in the Caspian Sea, there are up to 3500 oil springs. The famous oil region of the river is especially remarkable. Allegheny, in the North. America. As a rule, the places of natural outcrops of oil springs are chosen for drilling wells at these points in order to get a larger supply of oil at great depths. Drilling in oil areas has provided quite a lot of interesting data. It discovered the presence of sometimes significant cavities in the ground, filled with gaseous carbohydrates under pressure, which, when they reach them with a borehole, sometimes break out with such force that they throw out the drilling tool. In general, it should be noted that the areas of outlets of oil sources themselves exhibit gaseous carbohydrates. Thus, in the vicinity of Baku, there are abundant outlets of such gases in two places; one of the exits is on the mainland, where in the past there was a temple of fire worshipers above the exit site, and now the Kokorev plant; if you ignite this gas, protecting it from the wind, then it will constantly burn. Another outlet of the same gases is found from the bottom of the sea, at a fairly significant distance from the coast, and in calm weather you can also make it burn. The same drilling discovered that the oil springs in their distribution are subject to a known law. When drilling in the valley of the river. It was proved by the Alleghenies that oil deposits are located in strips parallel to the Allegheny Mountains chain. The same, apparently, is found in our Caucasus, both in the Baku region, and in sowing. slope, in the vicinity of Grozny. In any case, when the drill reaches the oil-bearing layers, water together with oil appears in the form of an often grandiose fountain; with this appearance, a very strong splashing of its jet is usually observed. The latter phenomenon did not find an explanation for a long time, but now, apparently, it has been quite satisfactorily explained by Sjögren, in whose opinion this sputtering of the fountain water depends on the fact that at depths, under high pressure, oil condensed a large amount of gaseous carbohydrates and upon the arrival of such of material on the surface of the earth, under the pressure of one atmosphere, gaseous products are released with considerable energy, causing this splashing of a water jet. Indeed, at the same time, a lot of gaseous carbohydrates are released, which forces the oil fields to take, when a fountain appears, a number of precautions in case of a fire that might occur. Together with water and oil, the fountain sometimes throws out a very large amount of sand and even large stones. For a long time little attention was paid to the nature of the water carrying oil. Thanks to the labors of Potylitsin, it was proved that these waters are quite significantly mineralized: in a liter of water he found from 19.5 to 40.9 g of mineral substances; the main component is table salt, but of particular interest lies in the presence of sodium bromide and iodide in these waters. In nature, there is a significant diversity in the composition of mineral I., and therefore it is not possible to consider all of them here, but it can be noted that, in general, other I. occur in ways similar to those described above. Water always circulating in rocks can meet in them various substances soluble in water and, either directly, or by exchange decomposition, or oxidation, or reduction, mineralize at their expense. Finding mixed I., as indicated above, significantly complicates their classification; nevertheless, for convenience of review, mineral I. is subdivided into several categories, meaning mainly pure keys: 1) chloride keys (sodium, calcium, and magnesium), 2) hydrochloric keys, 3) sulfurous or hydrogen sulfide keys, 4) sulfate (sodium, lime, magnesia, alumina, iron and mixed), 5) carbonate (sodium, lime, iron and mixed) and 6) silicate, that is, containing various salts of silicic acid in the solution; the last category represents a wide variety. To get some idea about the composition of the keys, we present a table of analyzes of the most famous mineral keys.

Fresh water.

Water is the basis of life on earth. Our body is 75% water, brain 85%, blood 94%. The calorie content of water is 0 kcal per 100 grams of product. Water that does not adversely affect human health is called drinking water or unpolluted water. Water must comply with sanitary and epidemiological standards, it is purified using water treatment plants.

Fresh water.

The main sources of fresh water are rivers and lakes. Lake Baikal is rightfully considered the largest reservoir. The water of this lake is considered the cleanest. Fresh water is divided into 2 types according to its chemical composition:

PROPERLY FRESH - fresh water is not absolutely pure in nature. It always contains a small percentage of minerals and impurities.

MINERAL WATER - drinking water, which contains trace elements and mineral salts. Due to the unique properties of mineral waters, it is used in the treatment of various diseases and prevention. Mineral water is able to maintain the health of the body. Mineral water is divided into 4 groups according to the content of mineral components in it. Mineral medicinal waters with a mineralization of more than 8 g / l, such water should be taken as prescribed by a doctor. Mineral medicinal table waters with mineralization from 2 to 8 g / l. They can be used as a drink, but not in large quantities. Among the most popular are Narzan and Borjomi. Mineral table waters containing 1 - 2 g / l of mineral elements. Table water with a mineralization of less than a gram.

Mineral waters can be classified on the basis of their chemical composition: hydrocarbonate, chloride, sulfate, sodium, calcium, magnesium and mixed composition;

By gas composition and individual elements: carbon dioxide, hydrogen sulfide, bromide, arsenic, ferruginous, silicon, radon:

Depending on the acidity of the medium: neutral, slightly acidic, acidic, strongly acidic, slightly alkaline, alkaline. “Mineral water” on the labels means that it is bottled directly from the source and has not been subjected to any further processing. Drinking water is artificially mineral-enriched water.

The bottle label should be read carefully, it should indicate:

Well number or source name.
The name and location of the manufacturer, the address of the organization authorized to accept claims.
Ionic composition of water (the content of calcium, magnesium, potassium, bicarbonates, chlorides is indicated)
GOST or technical conditions.
Volume, date of bottling, shelf life and storage conditions.

GOST guarantees the standards for the safe presence of such pollutants as mercury, cadmium or lead, radionuclides in water are not exceeded, there is no bacterial contamination.

“Mineral water” on the labels means that it is bottled directly from the source and has not been subjected to any further processing. Artesian springs are used for water intake. They are well protected from industrial, agricultural and bacterial contamination. This water is checked for chemical composition, purified using industrial and household filters. Spring water is also used.

Drinking water is artificially mineral-enriched water.

PURE FRESH WATER

It is a natural solvent, it contains particles of substances surrounding it. It has indicators of acidity and hardness. Water can also have taste, smell, color and transparency. Its indicators depend on the location, the ecological situation, and on the composition of the reservoir. Fresh water is considered to be water that contains no more than 0.1% salt. It can be in a variety of states: in the form of liquid, steam, ice. The amount of oxygen dissolved in water is an important indicator of its quality. Oxygen is essential for fish life, biochemical processes, and aerobic bacteria. PH is related to the concentration of hydrogen ions and gives us an idea of \u200b\u200bthe acidity or alkaline properties of water as a solvent. Rn< 7 – кислая среда; рН=7 – нейтральная среда; рН>7 - alkaline environment. Hardness is a property of water due to the content of calcium and magnesium ions in it. There are several types of hardness - general, carbonate, non-carbonate, removable and irreparable; but most often they talk about general rigidity. The lower the water hardness, the less harm the liquid does to our body.

ODOR OF WATER

It is caused by the presence of volatile odors in it, which enter the water naturally, or with wastewater. The smell is subdivided into 2 groups by nature, describing it subjectively by its sensations. Natural origin (from living and dead organisms, from the influence of soil, aquatic vegetation, etc.) earthy, putrefactive, moldy, peaty, herbaceous, etc. And artificial - such odors usually change significantly during water treatment; petroleum products (gasoline, etc.), chlorine, acetic, phenolic, etc. Evaluate the smell on a five-point scale (zero corresponds to the complete absence of smell):

VERY WEAK, almost imperceptible smell;
ODOR WEAK, noticeable only if you pay attention to it;
SMELL IS EASILY NOTICE and causes disapproval of water;
THE SMELL IS PERFECT, draws attention to itself and makes you refrain from drinking
The odor is so strong that it makes the water unusable.

For drinking water, a smell of no more than 2 points is allowed.

TASTE OF WATER.

Previously, it was believed that a person is able to distinguish 4 tastes: sour, sweet, salty, bitter. Later, umami was added to them - the “meaty” taste, the taste of high-protein substances ... Reacting to light, these receptors evoked sensations similar to the taste of water. Scientists have named the taste of water 6 taste - Newspaper. Ru / News /. The new study, published in the journal Nature Neuroscience by experts at the California Institute of Technology, may put an end to years of controversy. It turned out that the same receptors react to water as to sour taste. Scientists plan to continue research. First of all, they have to find out what mechanisms underlie the work of "acidic" receptors in determining the presence of water.

WATER COLOR

The color of the water perceived by the eye. Although small volumes of water appear transparent, the water turns blue as the sample is thicker. This is due to the inherent properties of water to selectively absorb and scatter light. RIVER WATER - the following types are distinguished:

TRANSPARENT (no color) - near mountain and high-mountain rivers;
YELLOW (yellow-red) - near flat and especially desert rivers;
DARK or BLACK, which is especially typical for rivers flowing in the jungle;
WHITE (white-gray) - air bubbles give the water white color when the water foams on rapids and waterfalls.
SEA WATER - the color of the sea depends on the color of the sky, the amount and nature of the clouds, the height of the sun above the horizon, as well as other reasons.
ICE - ideal ice is transparent, but any irregularities lead to absorption and scattering of light and, accordingly, a color change.

Be healthy!

The main source of fresh water is precipitation, but two other sources can also be used for consumer needs: groundwater and surface water.

Underground springs

Approximately 37.5 million km 3, or 98% of all fresh water in a liquid state falls on groundwater, with about 50% of which lies at depths of no more than 800 m. However, the volume of available groundwater is determined by the properties of aquifers and the capacity of pumping water pumps. Groundwater reserves in the Sahara are estimated at about 625 thousand km 3. In modern conditions, they are not replenished at the expense of surface fresh water, but are depleted when pumped out. Some of the deepest groundwaters are never included in the general water cycle at all, and only in areas of active volcanism such waters erupt in the form of steam. However, a significant mass of groundwater nevertheless penetrates the earth's surface: under the influence of gravity, these waters, moving along waterproof inclined layers of rocks, come out at the foot of the slopes in the form of springs and streams. In addition, they are pumped out by pumps, and also extracted by the roots of plants and then, in the process of transpiration, enter the atmosphere.

Fig. 1. Exit of an underground source to the surface

The groundwater table is the upper limit of the available groundwater. In the presence of slopes, the groundwater table intersects with the earth's surface, and a source is formed. If groundwater is under high hydrostatic pressure, then artesian springs are formed in the places where they exit to the surface. With the advent of powerful pumps and the development of modern drilling technology, the extraction of groundwater has become easier. Pumps are used to supply water to shallow wells installed on aquifers. However, in wells drilled to a great depth, up to the level of pressure artesian waters, the latter rise and saturate the overlying groundwater, and sometimes come to the surface. Groundwater moves slowly, at a speed of several meters per day or even a year. They are usually saturated with porous pebble or sandy horizons or relatively impermeable strata of shale, and only rarely are they concentrated in underground cavities or underground streams. To choose the right location for drilling a well, information about the geological structure of the territory is usually required.

In some parts of the world, the growing consumption of groundwater is having serious consequences. Pumping a large volume of groundwater, incomparably exceeding their natural replenishment, leads to a lack of moisture, and lowering the level of these waters requires large expenditures on expensive electricity used to extract them. In places of depletion of the aquifer, the earth's surface begins to sink, and there it is difficult to restore water resources in a natural way.

In coastal areas, excessive abstraction of groundwater leads to the replacement of fresh water in the aquifer with sea salt, and thus degradation of local fresh water sources occurs. The gradual deterioration of groundwater quality as a result of salt accumulation can have even more dangerous consequences. Sources of salts are both natural (for example, dissolution and removal of minerals from soils) and anthropogenic (application of fertilizers or excessive watering with water with a high salt content). Rivers fed by mountain glaciers usually contain less than 1 g / L of dissolved salts, but the salinity of water in other rivers reaches 9 g / L due to the fact that they drain saline-bearing areas over a long distance.

As a result of the indiscriminate discharge or burial of toxic chemicals, they seep into aquifers that are sources of drinking or irrigation water. In some cases, just a few years or decades is enough for harmful chemicals to get into groundwater and accumulate there in tangible quantities. However, if the aquifer was once contaminated, it will take 200 to 10,000 years to naturally cleanse itself.

Surface sources

Only 0.01% of the total volume of fresh water in a liquid state is concentrated in rivers and streams and 1.47% in lakes. For the accumulation of water and the constant supply of it to consumers, as well as to prevent unwanted floods and generate electricity, dams have been built on many rivers. The Amazon in South America, Congo (Zaire) in Africa, the Ganges with Brahmaputra in southern Asia, the Yangtze in China, the Yenisei in Russia, and the Mississippi with Missouri in the United States have the highest average water flow rates and, consequently, the greatest energy potential.

Fig. 2. Freshwater lake Baikal

Natural freshwater lakes containing about 125 thousand km 3 of water, along with rivers and artificial reservoirs, are an important source of drinking water for people and animals. They are also used for irrigation of agricultural land, navigation, recreation, fishing and, unfortunately, for the discharge of domestic and industrial wastewater. Sometimes, due to the gradual filling of sediments or salinization, the lakes dry up, however, in the process of evolution of the hydrosphere, new lakes are formed in some places.

The water level even in "healthy" lakes can decrease throughout the year as a result of water runoff through the rivers and streams flowing from them, due to water seepage into the ground and its evaporation. Their level is usually restored due to precipitation and the influx of fresh water from rivers and streams flowing into them, as well as from springs. However, as a result of evaporation, salts are accumulated that come from the river runoff. Therefore, after millennia, some lakes can become very salty and unsuitable for many living organisms.

As you know, water is the source of life, and it has its own holiday. Every year on March 22, the planet celebrates World Water Day or World Water Day, designed to draw public attention to issues related to the protection of water resources. But there are problems.

Thus, in 2006, about 1.1 billion people did not have normal and safe drinking water, and more people died from floods and droughts than from other natural disasters.

Thoughtlessly pouring drinking water in the kitchen and bathroom? These photos will make you think.
Let's see where people get their water. This is how they collect water from a well in Zimbabwe. Compared to the options below, this is still fairly clear water.

Queue at a huge water well in the Indian state of Gujarat.

According to the World Health Organization, infections caused by a lack of clean water kill one person every minute somewhere in the world.

In this area in Kenya, people go to the swamp for drinking water.

In Mumbai, drinking water can also be drawn from a puddle. The main thing is not to run over the train.

A picturesque column in the northern Indian city of Allahabad.

Designer from Caracas, Venezuela. Installation for collecting rainwater.

The water from the reservoir in Dhaka seems to be quite clear. Against the background of the next option ...

Collecting drinking water from a puddle in Somalia.

Let's take a closer look at the process.

Many scientists believe that the problem is not a lack of water, but its irrational use. One of the most pressing issues of our time is the excessive consumption of water in the production of food.

So, a person drinks 2-3 liters of water per day, while 2000-5000 liters of water are required to produce food for one person.
Sea in Karachi, Pakistan. Slightly dirty.

In a slum area in the capital of Indonesia, Jakarta, there is such a canal with water.

Fresh water resources on our planet are extremely unevenly distributed. The arid or semi-arid regions of the world, which make up 40% of the land, use only 2% of the world's water reserves.

The main source of all fresh water is the oceans, from which about 500 thousand square kilometers evaporate annually. water. 80% of all precipitation goes back to the oceans and falls.
A body of water in Manila.

The largest reserves of fresh water are found in the polar ice. The ratio of the amount of the world's fresh water to the volume of all water on Earth is only 3%.
Water trip in Tacloban, Philippines. It is difficult to drive through mountains of garbage.

Myanmar. Drinking rainwater is a relatively good option.

In this area of \u200b\u200bSana'a, Yemen, everyone goes to a single pump, trying to fill as many containers as possible.

Crossing the sewer canal in the slums of Mumbai.

Filling barrels with water from a tank truck, Lima, Peru.

Textured pump in the Khyber Pakhtunkhwa province of Pakistan.

A bridge over a polluted canal in eastern Bangalore, India. It is difficult to pass here without plugging the nose.

Carrying water near the capital of South Sudan. And saves from the sun.

Drinking water from South Sudan.

When thirsty

Bath in a slum in Jakarta, Indonesia.

Drinking water from a pit in the Baghdad area. It smells very strong.

A hand pump of questionable quality water in the Indian state of Assam.

Laundry in the Yamuna River in New Delhi. No, it's not snow, it's pollution foam.

Some kind of questionable water reservoir in southwest China in Sichuan province.

According to international experts, the problem of the shortage of fresh water will become one of the most acute by the middle of the 21st century. Thus, by 2025, 3.2 billion people on our planet will suffer from water shortages.
Collected drinking water from a pit, South Sudan.

Hike for water on a bombed street in Aleppo, Syria.

On the banks of the "river" in Jakarta, Indonesia.

Never give up. A volunteer clears debris from a river in Jakarta.

Doing laundry on the banks of a luxury canal in a slum in Nairobi.

Piggy and dirty canal in eastern Bangalore, India.

We don't need to worry for now. Russia is the world's leader in terms of fresh water reserves - we have more than 20% of the world's resources.

There are 2.5 million rivers and 2.7 million lakes in Russia. Lake Baikal alone contains 20% of the world's fresh water. In addition, 2,290 large and medium-sized reservoirs have been created in Russia.

No, this is not Baikal, this oil spilled near the resort town of the Red Sea in Eilat, Israel.

I could not. Sea of \u200b\u200bdead fish in the Gulf of Mexico, Mexico.