Which waters are the source of fresh water. Fresh water sources

About 1500 million cubic kilometers of water are found on our planet, of which approximately 10% is fresh water.

Moreover, from 110 to 190 million cubic kilometers of water is located under the earth’s crust, these are underground reservoirs. And depending on how deep these are sources of water on earth, they are divided into surface and underground waters.

Water pools, located underground at depths from tens to hundreds of meters, are peculiar vessels surrounded by solid rock in which water is under high pressure. Water reservoirs that accumulate at depths of several meters are a favorable basis for wells from which people get water for domestic needs, but such water also has the disadvantage that due to its constant contact with the upper loose layers of the soil, it is dirtier than the water which is much deeper.

A huge source of water on earth are our glaciers located in Antarctica and Greenland. This is in the area of ​​20 to 30 million cubic kilometers of fresh water. A considerable amount of fresh water falls to the earth from the atmosphere, in the form of precipitation formed due to evaporation from natural water sources on earth, this is approximately another 13 thousand cubic kilometers.

And how much fresh water is obtained annually from the world’s oceans using various physical and chemical methods. Undoubtedly, the most used sources of water on earth for their needs by humanity today are, first of all, rivers and lakes. What is it worth - the largest (and cleanest in the world) natural fresh water storage facility in Russia, the volume of which is 20 thousand cubic kilometers of water.

The composition of water in Lake Baikal is approximately as follows:

Arsenic contains about 0.3 µg/l (MPC = 10 µg/l)

Lead around 0.7 µg/l (MPC = 10)

Mercury within 0.1 μg/l (MPC = 1)

Cadmium approximately 0.02 µg/l (MPC = 1),

6 thousand cubic kilometers of water on our planet is in you and me, living organisms, animals and plants. Thus, our water natural resources are distributed throughout the planet. You and I are 80% liquid, and a violation of the water balance leads to dire consequences. We do not pay attention to how we exchange liquid with nature through urine, sweat and exhaled tiny droplets of liquid. But in order for all this to take place, we draw this liquid from nature.

And no one wondered what if this exchange stopped? In this case, dehydration occurs - dehydration of the body. The person begins to feel weak, the heart rate increases, shortness of breath and dizziness appear. When the body loses about 10% of fluid from body weight, a person loses consciousness, his speech is impaired, and his hearing and vision also deteriorate. If fluid loss amounts to 15-20% of body weight, then irreversible processes occur in the cardiovascular and nervous systems, leading to death.

Fresh water.

Water is the basis of life on earth. Our body consists of 75% water, the brain - 85%, blood - 94%. The calorie content of water is 0 kcal per 100 grams of product. Water that does not have a negative impact on 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 found in nature as absolutely pure. 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 can 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 mineralization over 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 popular ones are Narzan and Borjomi. Mineral table waters containing 1 – 2 g/l of mineral elements. Table waters with mineralization less than a gram.

Mineral waters can be classified based on 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 undergone any additional processing. Drinking water is water artificially enriched with minerals.

The label on the bottle should be studied carefully; it should indicate:

• Well number or source name.
• Name and location of the manufacturer, 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 specifications.
• Volume, bottling date, expiration date and storage conditions.

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

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

Drinking water is water artificially enriched with minerals.

PROPER FRESH WATER

This 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, environmental situation, and 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 necessary for the life of fish, biochemical processes, and aerobic bacteria. pH is related to the concentration of hydrogen ions and gives us the idea of ​​the 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 determined by the content of calcium and magnesium ions in it. There are several types of hardness - general, carbonate, non-carbonate, removable and irremovable; but most often they talk about general rigidity. The lower the water hardness, the less harm the liquid causes to our body.

THE SMELL OF WATER

It is caused by the presence of volatile odorous substances in it, which enter the water naturally or with wastewater. The smell is divided into 2 groups according to its character, describing it subjectively according to your feelings. Of natural origin (from living and dead organisms, from the influence of soil, aquatic vegetation, etc.) earthy, putrid, moldy, peaty, grassy, ​​etc. And of artificial origin - such odors usually change significantly during water treatment; petroleum products (gasoline, etc.), chlorine, vinegar, phenolic, etc. The odor is assessed on a five-point scale (zero corresponds to the complete absence of odor):

• VERY WEAK, almost imperceptible odor;
• THE SMELL is WEAK, noticeable only if you pay attention to it;
• THE SMELL IS EASILY NOTICED and causes disapproval of the water;
• The SMELL is DISTINCT, attracts attention and makes you refrain from drinking;
• The SMELL is so STRONG that it makes the water unfit for consumption.

For drinking water, an odor rating 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 - “meat” taste, the taste of high-protein substances... Reacting to light, these receptors caused sensations similar to the taste of water. Scientists have named the taste of water as the 6th taste – Newspaper. Ru /News/. A new study published in the journal Nature Neuroscience by specialists from the California Institute of Technology may put an end to many years of controversy. It turned out that the same receptors react to water as to sour taste. Scientists plan to continue the research. First of all, they will have to find out what mechanisms underlie the work of “acidic” receptors in detecting the presence of water.

COLOR OF WATER

The color of water perceived by the eye. Although small volumes of water appear clear, as the thickness of the sample increases, the water takes on a blue tint. This is due to the intrinsic properties of water to selectively absorb and scatter light. RIVER WATER – the following types are distinguished:

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

Be healthy!

Starting the story about natural sources of water, it is worth explaining why we included the definition “conditionally” in the title of the article. The fact is that there is very little truly clean drinking water left 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 move directly to the very topic of our conversation, noting the approximate amount of drinking water on our planet. According to the calculations 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 clean drinking water on the planet. The rest of the water, which is conditionally suitable for drinking, is concentrated in rivers and lakes, as well as in surface and underground waters, which is produced using. Also, a small proportion of fresh water comes from precipitation. However, no matter how large reserves of water rivers and lakes have, 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 only harmful , and even substances hazardous to human health. Therefore, in most cases, surface and underground waters are used to provide water to the population, which we will discuss in detail, touching upon in the conclusion of the article methods for extracting fresh water from icebergs and desalinating salty sea and ocean water.

Surface sources

Surface sources are 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 flow in such a way that it is not possible to provide water from them naturally. Therefore, many of them are blocked by dams that form artificial open reservoirs for storing fresh water, which in some cases are used to generate electricity, which is generated by releasing water from the reservoirs to turbines. There are not 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 - the Brahmaputra and Ganges, in China - the Yangtze, in Africa - the 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 for domestic needs, part of the fresh water from the lakes is used to support human economic activities - irrigation of agricultural land, fish farming, industrial, and most often food production, etc. Sometimes, uncontrolled intake of fresh water from lakes, which as quickly as rivers cannot replenish its supply, leads to complete drying out of the lakes. A striking example is the Aral Sea, which is essentially a lake and has almost disappeared from the surface of the Earth. There are also situations when new fresh lakes form, for example, as a result of seismic activity, but such cases are quite rare.

Unlike rivers, a significant part of which is fed by many small streams and springs, even in “prosperous” lakes, significant fluctuations in water level are possible throughout the year. This is due to various factors, the main of which are: an increase in the natural discharge of water through rivers flowing from reservoirs, evaporation of water and its seepage into the ground. However, if the lake is “healthy”, then, as a rule, the water level does not fall to critical levels, and the reservoir is replenished by 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 water evaporation, salts gradually accumulate in such reservoirs, the percentage of which at a certain point becomes so high that the fresh lake turns into salt water, which means it is no longer possible to use water from it for drinking. Of course, when drawing water from such reservoirs, it is possible to pass it through special desalination plants. But as practice shows, the introduction of such equipment makes the resulting fresh water so expensive that its desalination is not profitable. As for freshwater swamps, which are essentially the closest relatives of lakes, their potential as sources of fresh water is very poorly 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 found in its depths. Moreover, almost half of its volume lies at depths exceeding 800 meters, which makes its extraction extremely costly, and in some cases, completely impossible. And those 50% that are available are taken away so thoughtlessly that if the situation is not radically corrected, then in 40-50 years, humanity will have to drill wells more than a kilometer deep in order to provide itself with drinking water. An example is the groundwater of the Sahara Desert, the volume of which, according to recent estimates, is up to 625 thousand cubic kilometers. But the trouble is that the area where they occur is such that the underground reservoir does not replenish naturally, and pumping is very intensive. In addition, recent geological processes in this area have led to the fact that groundwater began to emerge to the surface in the form of springs, only a small part of which occurs in places where people live densely. The rest of the water literally goes into the sand. As scientists explain, this is because the huge freshwater reservoir under the Sahara consists of several large lakes, the surface of which, after movements of the earth’s crust, intersected in some places with the surface of the Earth. This is how springs and even artesian springs were formed, especially where the water was under significant hydrostatic pressure. It is impossible to say for sure when there will be no more water in the depths of the Sahara, but environmentalists say for sure that this moment is not far off. In addition, it would not hurt to pass such water through, but this is not always possible.

The extraction of underground fresh water is proceeding at a much faster pace than was possible 20-30 years ago. And this is due to the advent 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 planet, increasing water consumption has negative consequences. The fact is that underground reservoirs are practically not replenished with water naturally, and pumping it out 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 its further exploitation impossible, for example, as agricultural land. In coastal areas the situation is even more dramatic. Drained aquifers, even those from which water can still be extracted for several years, mix with salty sea or ocean water, resulting in salinization of the soil and what little fresh water remains in the coastal region. The problem of salinization of fresh water has another reason related to human economic activity. After all, the source of salt can be not only seas and oceans, but also fertilizers or water with a high salt content, which is used to water fields and gardens. Such processes of salinization of groundwater and soil are called anthropogenic, and more and more civilized countries are facing them.

Getting fresh water from icebergs

In conclusion of the article about natural conditionally clean sources of fresh water, we, as promised, will pay attention to the extraction of drinking water from icebergs. Scientists claim that the glaciers of mainland Antarctica alone contain up to 93% of all fresh water reserves on Earth, which amounts to about two thousand square kilometers of frozen moisture. And since, soon, there will be practically no surface and underground sources of drinking water left on the planet, a moment will come when humanity will be forced to turn its attention to icebergs. The idea of ​​extracting 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 aborigines. 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 his absurd death in a cauldron of cannibals, which in fact never existed. Why Cook paid attention to icebergs as sources of fresh water is not known for certain. But the fact that the navigator was the first to propose using pieces of ice on long sea voyages as natural storage facilities for water reserves, we know for sure from a number of written sources that have survived to this day. Cook's modern followers have gone even further and propose breaking off huge pieces of ice from glaciers in order to 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 modern technological developments.

1. It is quite problematic to break off a large iceberg from a glacier, and traditional mechanical tools, as well as a directed explosion, are not suitable here, because the iceberg can split.
2. 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.
3. Even if an effective method of “preserving” an iceberg is invented, preventing its melting, moving it will require several powerful sea vessels, the work of which must be as coordinated as possible.
4. It is unlikely that such a huge amount of ice can be processed into fresh water without significant losses.

As we see, even if an effective way to develop a glacier and deliver its parts to its destination is invented, this work will be so expensive that the cost of one liter of fresh water will be astronomical. However, scientists believe that no matter how difficult the extraction of ice in Antarctica and its delivery to consumers may be, 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 USA are already showing great interest in this issue.

In addition to rivers, sources of fresh water are groundwater, lakes, and glaciers.

The groundwater are least used by humans, mainly used for drinking and for treatment. More often, groundwater is used indirectly, as it feeds some rivers and lakes.

Glaciers- fresh water frozen into ice. This is the most important fresh water reserve on Earth, but methods for harnessing glacial water are just being developed. Glaciers form when water freezes during the cold season, but does not have time to melt during the warm season. This can occur near the north or south poles (, northern islands) or high in the mountains. Glaciers move slowly - on average about 200 m per year, but with warming or, for example, the speed of their movement can increase sharply.

The glaciers of Greenland and Antarctica are cover glaciers, since they cover the entire territory, regardless of the topography. The same glaciers that form on the tops of mountains are called mountain glaciers.

Monuments of the hydrosphere

There are also real monuments that delight you with the beauty of the landscapes and the huge reserves of fresh water. These include lakes such as Baikal, Constance, and Geneva.

More than five hundred different watercourses flow into the lake, annually bringing about 60 cubic kilometers of water into it. The age of this miracle - the lake - is more than 25 million years.

Lake Geneva is the second largest (after Lake Balaton) freshwater lake in the central region, located in and. It is the largest in the Alps. Its area is about 600 square kilometers, its volume is about 100 cubic kilometers. It is deservedly considered one of the most beautiful and cleanest in Europe.

Hydrosphere monuments are also considered waterfalls.

A waterfall is formed when water flows freely from a steep cliff. Many waterfalls consist of a series of small falls, or cascades, where water falls from one ledge to another.

Waterfalls, as a rule, are formed as a result of the destruction of soft soil rocks, which leads to the erosion of a layer of hard rocks and its periodic collapse. For example, the famous Niagara Falls was formed, located on the border between and.

In mountainous areas, high waterfalls often occur where mountain tributaries flow into the main river stream.

The role of waterfalls in human life

Waterfalls, cascades and rapids pose serious obstacles to navigation. In order to bypass them, canals are built with locks that allow ships to gradually rise or fall from one level to another. For example, the Welland Ship Canal in the province. Ontario (Canada), bypassing Niagara Falls. This canal carries ocean liners to the Great Lakes. And at the stage of early development and settlement of North America, waterfalls significantly impeded the advance of pioneers; they had to be bypassed, and loads had to be dragged.

Waterfalls are an exceptional source of electricity, production volume

which depends on the height of the fall and the volume of water directed at the rotation of the turbines. In the past, industrial facilities in many countries were built near waterfalls. Thus, for example, such large cities as Richmond, Baltimore and Philadelphia arose.

Water is the most abundant substance on our planet: although in varying quantities, it is available everywhere, and plays a vital role for the environment and living organisms. Fresh water is of greatest importance, without which human existence is impossible, and nothing can replace it. Humans have always consumed fresh water and used it for a variety of purposes, including domestic, agricultural, industrial and recreational use.

Water reserves on Earth

Water exists in three states of aggregation: liquid, solid and gaseous. It forms oceans, seas, lakes, rivers and groundwater located in the upper layer of the Earth's crust and soil cover. In its solid state, it exists in the form of snow and ice in polar and mountainous regions. A certain amount of water is contained in the air in the form of water vapor. Huge volumes of water are found in various minerals in the earth's crust.

Determining the exact amount of water reserves around the world is quite difficult because water is dynamic and in constant motion, changing its state from liquid to solid to gaseous and vice versa. As a rule, the total amount of water resources in the world is estimated as the totality of all waters in the hydrosphere. This is all the free water that exists in all three states of aggregation in the atmosphere, on the Earth's surface and in the earth's crust to a depth of 2000 meters.

Current estimates have shown that our planet contains a huge amount of water - about 1386,000,000 cubic kilometers (1.386 billion km³). However, 97.5% of this volume is salt water and only 2.5% is fresh. Most of the fresh water (68.7%) is found in the form of ice and permanent snow cover in the Antarctic, Arctic, and mountainous regions. Further, 29.9% exists as groundwater, and only 0.26% of the Earth's total fresh water is concentrated in lakes, reservoirs and river systems where it is most easily available for our economic needs.

These figures were calculated over a long period of time, but if shorter periods are taken into account (one year, several seasons or months), the amount of water in the hydrosphere may change. This is due to the exchange of water between the oceans, land and atmosphere. This exchange is usually called the global hydrological cycle.

Freshwater resources

Fresh water contains a minimal amount of salts (no more than 0.1%) and is suitable for human needs. However, not all resources are available to people, and even those that are are not always suitable for use. Consider sources of fresh water:

• Glaciers and snow covers cover about 1/10 of the world's land mass and contain about 70% of fresh water. Unfortunately, most of these resources are located far from populated areas and are therefore difficult to access.
• Groundwater is by far the most common and accessible source of fresh water.
• Freshwater lakes are mainly located at high altitudes. Canada contains about 50% of the world's freshwater lakes. Many lakes, especially those in dry areas, become salty due to evaporation. The Caspian Sea, Dead Sea, and Great Salt Lake are among the world's largest salt lakes.
• Rivers form a hydrological mosaic. There are 263 international river basins on Earth, which cover more than 45% of the planet's landmass (with the exception of Antarctica).

Water resources objects

The main objects of water resources are:

• oceans and seas;
• lakes, ponds and reservoirs;
• swamps;
• rivers, canals and streams;
• soil moisture;
• groundwater (soil, groundwater, interstratal, artesian, mineral);
• ice caps and glaciers;
• precipitation (rain, snow, dew, hail, etc.).

Problems of water use

For many hundreds of years, human impact on water resources was insignificant and of an exclusively local nature. The excellent properties of water - its renewal due to the cycle and the ability to be purified - make fresh water relatively purified and possessing quantitative and qualitative characteristics that will remain unchanged for a long time.

However, these features of water gave rise to the illusion of the immutability and inexhaustibility of these resources. Out of these prejudices arose a tradition of careless use of extremely important water resources.

The situation has changed greatly over the past decades. In many parts of the world, the results of long-term and mismanagement of such a valuable resource have been discovered. This applies to both direct and indirect water use.

Around the world, over the course of 25-30 years, there has been a massive anthropogenic change in the hydrological cycle of rivers and lakes, affecting water quality and their potential as a natural resource.

The volume of water resources, their spatial and temporal distribution, are determined not only by natural climate fluctuations, as before, but now also by the types of economic activities of people. Many parts of the world's water resources are becoming so depleted and heavily polluted that they can no longer meet ever-increasing demands. It may
become a major factor hindering economic development and population growth.

Water pollution

The main causes of water pollution are:

• Wastewater;

Domestic, industrial and agricultural wastewater pollutes many rivers and lakes.

• Disposal of waste in seas and oceans;

Burying garbage in the seas and oceans can cause huge problems, because it negatively affects living organisms that live in the waters.

• Industry;

Industry is a huge source of water pollution, producing substances harmful to people and the environment.

• Radioactive substances;

Radioactive pollution, in which there is a high concentration of radiation in the water, is the most dangerous pollution and can spread into ocean waters.

• Oil spill;

An oil spill poses a threat not only to water resources, but also to human settlements located near a contaminated source, as well as to all biological resources for whom water is a habitat or a vital necessity.

• Leaks of oil and petroleum products from underground storage facilities;

Large quantities of oil and petroleum products are stored in tanks made of steel, which corrode over time, causing harmful substances to leak into the surrounding soil and groundwater.

• Precipitation;

Precipitation, such as acid precipitation, occurs when air is polluted and changes the acidity of water.

• Global warming;

Rising water temperatures cause the death of many living organisms and destroy a large number of habitats.

• Eutrophication.

Eutrophication is a process of reducing the quality characteristics of water associated with excessive enrichment with nutrients.

Rational use and protection of water resources

Water resources require rational use and protection, ranging from individuals to enterprises and states. There are many ways we can reduce our impact on the aquatic environment. Here are some of them:

Saving water

Factors such as climate change, population growth and increasing aridity are increasing pressure on our water resources. The best way to conserve water is to reduce consumption and avoid increased wastewater.

At the household level, there are many ways to save water, such as taking shorter showers, installing water-saving appliances, and washing machines with low water consumption. Another approach is to plant gardens that do not require much water.