The ocean in the life of the earth. Importance of oceans and seas in human life. When the ocean came

Water is the most abundant substance on earth. The water shell of the Earth developed along with the lithosphere, atmosphere and wildlife. Almost all processes on our planet proceed with the participation of water. The hydrosphere consists of the oceans, land waters and groundwater. The bulk of the water is concentrated in the oceans.

The World Ocean is the blue mirror of our planet, the cradle of life on Earth. It contains not only the past, but also the future of our planet. To understand the great role of the ocean, it is necessary to know the features of its nature: the properties of water masses, to understand the role of currents, the significance of the interaction of the ocean with the atmosphere and land. You will learn about all this by studying this topic.

§ 9. Waters of the oceans

1. What is called the hydrosphere? World Ocean?
2. What do you already know about the nature of the ocean?
3. Make a characterization of the map of the oceans (see the plan in the appendix).

The role of the ocean in the life of the Earth. The ocean occupies almost 3/4 of the surface of our planet (Fig. 22). Water is one of the most amazing substances on Earth, a precious liquid, a gift of nature to our planet. In such quantities as on Earth, it is not found anywhere in the solar system.

Rice. 22. The area of ​​land and ocean: a) in general on Earth; b) in the Northern Hemisphere; c) in the southern hemisphere

The ocean... It is hard to imagine how great its importance in the life of the Earth. Clouds in the sky, rain and snow, rivers and lakes, springs - all these are particles of the ocean that have only temporarily left it.

The ocean determines many features of the nature of the Earth: it gives the atmosphere the accumulated heat, nourishes it with moisture, part of which is transferred to the land. It has a great influence on the climate, soil, flora and fauna of the land. Its role in human economic activity is great. The ocean is a healer, giving medicines and taking millions of vacationers to its shores. He is a source of seafood, many minerals, energy; he is the "kitchen of the weather", and the most spacious road in the world connecting the continents. Thanks to the work of bacteria, the ocean has the ability (up to a certain limit) to cleanse itself, and therefore many of the waste generated on Earth is destroyed in it.

The history of mankind is inextricably linked with the study and development of the ocean. Its knowledge began in ancient times. (When? By whom?) Especially a lot of new data has been obtained over the past decades with the help of the latest technology. Research carried out on scientific ships, collected by automatic oceanographic stations, as well as artificial Earth satellites, helped to detect eddies in the waters of the ocean, deep countercurrents, and prove the existence of life at great depths. The study of the structure of the ocean floor made it possible to create a theory of the movement of lithospheric plates.

Origin of the waters of the oceans. The ocean is the main custodian of water, the most common substance on Earth, which has long amazed researchers with its unusual properties. Only water under normal terrestrial conditions can be in three states. This property ensures the omnipresence of water. It permeates the entire geographic shell and performs a variety of work in it.

How did water appear on Earth? Finally, this “survey” has not yet been resolved by science. It is assumed that water either released immediately during the formation of the lithosphere from the upper mantle, or accumulated gradually. Water is still released from magma, falling on the surface of the planet during volcanic eruptions, during the formation of oceanic crust in the zones of stretching of lithospheric plates. This will continue for many millions of years. Part of the water comes to Earth from space.

properties of ocean waters. Their most characteristic properties - salinity and temperature - are already known to you. (Recall their key figures from Year 6.) Oceanic mode is a weak solution in which almost no chemicals are found. Gases, mineral and organic substances, formed as a result of vital activity of organisms, are dissolved in it.

The main changes in salinity are observed in the surface layer. The salinity of waters depends mainly on the ratio of atmospheric precipitation and evaporation, which varies depending on the geographical latitude. At the equator, the salinity is about 34%.., near the tropics - 36%, and in temperate and polar latitudes - about 33%. Salinity is less where the amount of precipitation exceeds evaporation, where there is a large influx of river waters, where ice melts.

You know that the waters of the ocean are heated, like the land, from the influx of solar heat on its surface. Occupying a large area, the ocean receives more heat than land. The temperature of surface waters varies and is distributed depending on the latitude (Fig. 23). In some areas of the ocean, this regularity is disturbed by ocean currents, and in coastal parts, by the runoff of warmer waters from the continents. The temperature of the ocean water also changes with depth. At first, its decrease is very significant, and then it slows down. At depths of more than 3-4 thousand meters, the temperature usually ranges from +2 to 0 °C.

Rice. 23. The average annual water temperature on the surface of the oceans. Compare water temperatures at the same latitudes. Explain the result

Ice in the ocean. The formation of ice depends on the temperature of ocean waters. You already know that sea water freezes at -2°C. As salt water cools, the density of salt water increases, its upper layer becomes heavier and sinks down, and warmer layers of water rise to the surface. This mixing of the water prevents the formation of ice. Ice forms only in arctic and subarctic latitudes, where winters are long and very cold. Some shallow seas located in the temperate zone also freeze. Distinguish between annual and multi-year ice. Ocean ice can be immobile if it is connected to the land, or floating, i.e. drifting. In the ocean, there are ices that have broken off from the glaciers of the land and descended into the ocean - icebergs (Fig. 24).

Rice. 24. Melting icebergs in the ocean

The ice cover of the ocean has a huge impact on the climate of the Earth, on life in it. Ice reflects the sun's rays, cools the air, and contributes to the formation of fogs. They impede navigation and marine fisheries.

water masses. Water is the main component of the nature of the ocean. Large volumes of water that form in certain parts of the ocean and differ from each other in temperature, salinity, density, transparency, the amount of oxygen, the presence of certain living organisms, are called water masses. These properties are preserved throughout the space occupied by one or another water mass.

In the ocean, surface, intermediate, deep, and bottom water masses are distinguished. In surface fashionable masses up to a depth of 200 m, equatorial masses are distinguished. tropical, temperate and polar water masses. They are formed as a result of the uneven supply of solar heat at different latitudes and the influence of the atmosphere. In the same latitudes, the properties of surface water masses may differ, therefore, coastal and intra-oceanic masses are also distinguished.

Water masses actively interact with the atmosphere: they give it heat and moisture, absorb carbon dioxide from it, and release oxygen. When mixed, they change their properties.

1. What determines the salinity of ocean waters?
2. What are the differences in ocean water temperature?
3. Where does ice form in the ocean? How do they affect the nature of the Earth and human economic activity?
4. What is a water mass? Name the main types of water masses. What water masses are isolated in the surface layer of the ocean?

The ocean can be different: calm and gentle, roaring and raging. But, whatever it may be, there is always a mystery and mystery in it. Its depths still keep many secrets today. The mysterious life in the ocean attracts and attracts researchers so far.

Its history is inseparable from the history of living organisms. There are so many white spots in it! We can assume that their filling began quite recently and will continue for many, many more years. Only now begins the search for an answer to the question of what is the role of the ocean in the life of the entire planet.

Birth and development

More than four billion years ago, an important event took place - the Ocean was born. As a result, the face of our planet has changed radically. The atmosphere was formed, the climate was formed. First, life began in the ocean, and then on land. Now it occupies most of the entire surface of the planet.

Where did it all begin? It is assumed that water came out of stones and ore, from the bowels of the Earth. Under high pressure, it was squeezed out from within the planet in the form of water vapor. The hot steam cooled, cooling the Earth. It fell out in the form of precipitation.

Over time, a huge ocean formed from small puddles and lakes. He changed the appearance and climate of the planet so that the origin of life became possible.

Importance of the ocean in human life

To assess the role played by the oceans in the life of humans, animals, plants, the planet, it is enough to know the following:

• Half of the oxygen necessary for breathing, for all living on the planet, is produced by the vegetation of the ocean.
• Water heats up and cools down more slowly than land. This property leads to the fact that more than half of the solar energy is stored in the ocean. He is a kind of accumulator of heat entering the planet, preventing the Earth from getting too hot or cold. The planet is constantly maintained at a comfortable temperature.
• The ocean controls the climate. Warm and cold currents provide certain weather on different continents.
• It is a supplier of moisture to land. Thanks to him, rain falls, irrigating the land. Ocean water evaporates, enters the atmosphere, is carried by the wind and pours out as precipitation on the earth.
• It contains the main biomass of the planet. The ocean is food for people and animals, a medicine, a strategic raw material for industry.

The emergence of life

It is assumed that life in the ocean began with beta cells. Over time, protein bodies appeared - primordial organisms. The ocean was filled with stromatolites, who learned to use the energy of the sun. They were the first to use photosynthesis for food. Millions of years of their work made it possible to saturate the atmosphere with the necessary amount of oxygen.

And animals that appeared later used stromatolites as food. Now these ancient protein organisms have disappeared. Remained only in the form of stone monuments of the progenitors of life.

Who lives in the ocean

All living organisms of the oceans are divided into three fundamentally different groups:

1. Plankton. It exists only in water, sizes - from fractions of a millimeter to a meter.
2. Nekton - fish, squid, crabs, mammals.
3. Benthos. Lives at the bottom.

As you can see, the inhabitants of the ocean are diverse, their species change depending on the depth at which they live. But how many of them exist? Biologists give only an approximate answer to this question - more than 200 thousand. After all, the ocean has not been fully explored and scientists regularly discover more and more new species. Especially closer to the bottom, at great depths.

Most of all living beings are distributed in the upper layers, close to the coast, on the shelves. Thanks to solar energy, the most comfortable living conditions are here. Good light is necessary for plants for photosynthesis. The variety of plants provides food for fish, crabs, molluscs.

Away from the coast, on the surface, plankton dominates. It is the main food not only for fish, but also for mammals. And at the bottom you can meet crayfish, mollusks, lobsters, crabs. Even at the deepest depths there is life.

The connection of the ocean with life on Earth

Some people think that the life of mankind will be eternal. However, science knows several stages in the development of our planet, after which a huge number of living beings inhabiting it disappeared. Life on Earth and the life of the seas and oceans are firmly and forever connected with each other. There is an established fact of their mutual influence.

If climate warming occurs, the water temperature at depth and surface levels off. The water cycle stops. On the surface of the seas and oceans, bacteria intensively multiply, which block the access of oxygen. All life perishes in water. Hydrogen sulfide is released. It, spreading over land, poisons the plants and animals of the land.

Alas, it has already happened. Scientists attribute these phenomena to the disappearance of a number of plants and animals, which occurred on Earth at least four times. Today, the problem of warming is widely discussed. Many countries around the world have come together to fight climate change.

ocean protection

Marine and ocean fish are still prey. They are hunted on a large scale. Consumption of fish products is reaching record highs. But life in the ocean is rich and inexhaustible only at first glance. Many species of plants and fish are on the verge of extinction. Therefore, more and more attention is paid to the protection of the oceans.

So, whale hunting has been banned for several decades. Limited permission remained only among the northern peoples. For them, whale hunting is vital. There is a distribution order for catching crabs, the extraction of certain varieties of algae.

There is an acute problem with the use of chemical toxic compounds in agriculture. Getting through the rivers, sewage pollutes the ocean, killing its inhabitants.

Accidents on ships carrying oil, fertilizers, and hazardous chemical products have a significant impact on the level of pollution.

Various scientific studies and geological surveys do not pass without a trace. Mechanical, electromagnetic waves harm the inhabitants of the ocean. affect reproduction and offspring.

Finding out what life is in the ocean, the seas, how much it needs protection is the duty of all developed countries. The future depends on his condition. How secure the ocean is, how secure humanity is!

The World Ocean occupies 3/4 of the Earth's surface (the area is 361 million km2, or 70.8%) and contains 96.4% of the volume of water in the hydrosphere (1.38 billion km3).
The World Ocean is a part of the biosphere, a geographical object with a special geological and geomorphological structure, a special nature of heat and mass transfer with atmospheric air, sedimentary deposits of the bottom and flora and fauna peculiar only to it.

The oceans are the main link in the water cycle in nature. It determines the water balance of the Earth, is an important source of renewal of water bodies on the earth's surface and atmospheric moisture. The World Ocean is the cause of many processes and phenomena that have occurred on the earth's surface and are currently taking place, and is an active participant in them. It is associated with the interaction of atmospheric air and ocean waters, the formation of climate. It absorbs almost half of the solar energy falling on its surface and spends it on heating the waters. The heated waters of the equatorial latitudes reach the polar regions by ocean currents, give off their heat and play the role of the "heating system" of the planet.
The role of the World Ocean is great in ensuring the stability of the gaseous composition of the atmosphere, the biochemical cycle of chemical elements, and the process of photosynthesis. At any point on the land, living organisms, including humans, are continuously affected by the World Ocean, therefore, in general, it is difficult to overestimate its importance in the ecological system of the Earth.

We all know that ocean waters are salty. The average salinity of the oceans is 35 0/00 (ppm), in other words, 1000 grams of ocean water contains 35 grams of dissolved salts. If we single out the salts of the World Ocean, then their total mass will be 48 billion tons. If these salts are evenly distributed over the earth's surface, a layer 133 m thick would be obtained. The chemical composition of these salts contains 76 elements of the periodic table. It should be noted here that the salinity of sea water can change, but the ratio between salts never changes, it is constant.

Most of the "living matter" in the World Ocean is plankton, which, according to their chemical data, repeats the salt composition of sea water. The origin, death and decomposition of plankton are in balance, so there is no excess of organic matter in the ocean. The World Ocean contains approximately 2,000 billion tons (2 trillion) of organic matter in dissolved form. In the open ocean, up to 2 mg of dissolved organic matter is present in 1 liter of water. In inland seas, especially near the coasts of the continents, the concentration of dissolved organic substances reaches up to 10 mg per liter.

The largest volumes of gases dissolved in sea water are oxygen, nitrogen, carbon dioxide. Oxygen is essential for life in the ocean. There is a lot of dissolved oxygen in the oceans, its concentration in sea water is 1.5 times greater than the concentration of oxygen in the atmosphere. In the oceans, 35 billion tons of oxygen are annually consumed and the same amount is returned to the water due to the green plants of the ocean and atmospheric air.

Every year, 27,080 million tons of various substances enter the World Ocean with river flows, glacial melt, groundwater, and winds. Most of them come with the flowing waters of rivers: solid particles - 17444 million tons, dissolved substances - 3403 million tons. brought by groundwater - 1000 million tons. These substances have entered the ocean in approximately the same volume for a long time and will continue to do so in the future. But in recent years, substances of anthropogenic origin have been added to the natural supply of substances to the ocean. The ocean is a natural reservoir, since all substances, except gases, that are in motion, eventually fall into the ocean. Ocean waters are polluted only due to the influx of anthropogenic substances. Ocean pollution is one of the global environmental problems of our time. To preserve the purity of the waters of the World Ocean means to preserve the purity of the biosphere.

There is a fair assertion that people incorrectly named our planet, giving it the name Earth, while it should have been called the Ocean, since more than 70 percent of its area is occupied by water. In the entire solar system, only the Earth has a sufficient amount of water and thermal conditions, which, combined, ensure the existence of a vast World Ocean.

The aquatic environment - the hydrosphere - occupies a significant part biosphere- areas of life, consisting of land, air and water. The main part of the hydrosphere is the ocean. Water and substances dissolved in it are found in the seas, rivers, lakes and glaciers, and are also hidden at different depths underground.

A diver explores the continental rift in Silfra, Iceland, 2010.
The photograph won the highest award in the Diving category at the 4th International Underwater Photography Competition in Indonesia.

The role of the World Ocean in the life of the Earth is difficult to overestimate. The ocean is the cradle and source of life on our planet. More than half of the oxygen needed for breathing comes from photosynthesis in the upper layer of ocean waters. If the interaction of the ocean and the sun were suddenly interrupted, all life on Earth would cease.

The ocean is a heat accumulator, creator and regulator of climate. Its role in maintaining the constancy of the climate is enormous. It is the interaction of the World Ocean and the atmosphere that determines the weather on our planet.

The ocean is a convenient and cheap road that connects continents and islands, industrial centers, agricultural regions, and sources of raw materials. Tens of thousands of ships carry out sea transportation of passengers and all kinds of cargo, annually transporting hundreds of millions of tons of cargo.

The ocean is an inexhaustible treasure trove of chemicals. Almost all the elements of the Periodic Table of Mendeleev are dissolved only in sea water. It has literally everything - from table salt to uranium and gold. Innumerable riches hide the bottom of the oceans. Coal, iron ore, tin, sulfur are extracted from the primary deposits of the seabed. Placer deposits of tin, platinum, rare earth elements are already being developed in the beach and coastal zones. Serious attention is paid to the development of deep-water ore deposits. Large deposits of phosphorites are located on the shelf and continental slope of the World Ocean. The vast bottom plains of the ocean are covered with ferromanganese nodules, in the development of which the first steps are already being taken. The extraction of building materials - sand, gravel, shell rock - is in full swing.

The most valuable mineral raw materials currently mined from wells at the bottom of the seas are undoubtedly oil and gas. To date, the world's offshore oil production has amounted to 30 percent.

And finally, the ocean is an inexhaustible source of renewable energy. These are the reserves of heavy hydrogen contained in the water - deuterium - the thermonuclear fuel of the future, and the energy of sea waves, currents, tides, the temperature difference between deep and surface waters ...

From time immemorial, the ocean served as a source of food for man, who obtained fish, crustaceans, molluscs, marine animals and plants in it. Throughout the centuries-old history of mankind, the methods and tools of coastal fishing have not changed much. Oceanic fisheries, which fish far from the coast, have undergone tremendous changes. Especially in recent decades. A real revolution in the development of ocean fishing was made by the invention of the steam engine and the internal combustion engine, the use of synthetic materials for the manufacture of fishing gear, and the equipping of fishing vessels with fish-searching equipment. Modern trawls, purse seines, longlines are quite complex engineering structures that provide the possibility of catching a large amount of fish - up to several tens of tons per trawl!

For a long time there was an opinion about the inexhaustibility of the ocean's fish resources. This has been greatly facilitated by the rapid growth in global fish catches, especially in recent years. If in a century, from 1850 to 1950, the catch of sea fish and other products of the ocean increased 10 times, increasing by an average of 25 percent per decade, then from 1950 to 1960 it doubled! The subsequent doubling of the world catch occurred from 1960 to 1970. World fish production by this time approached 100 million tons.

Already since 1970, the pace of the world catch of fish and seafood began to slow down, despite the ever-increasing intensity of fishing. In some traditional fishing areas, fish production began to decline, the species composition of catches changed, the average size of fish decreased, and some commercial species were threatened with extinction.

Thus, mankind was personally convinced of the limited fish resources of the seas and oceans.

Most scientists involved in determining the annual fish production of the ocean agree that it is 100 - 200 million tons. The annual fish catch achieved so far (about 100 million tons) is close to the amount that can be taken from the ocean without disturbing the natural reproduction process.

One of the most acute problems on Earth is the problem of providing the population of our planet with a sufficient amount of protein food, part of which a person takes in the ocean, catching marine animals. This problem becomes even more important if we take into account the natural increase in the population of our planet. So, according to scientists' forecasts, by the beginning of the third millennium the population of the Earth will approach 6 billion people. It is known that the physiological need of a person for fish is on average 20 kilograms per year.

How to ensure the natural reproduction of biological resources in the seas and oceans?

Some prospects for increasing the catch of fish are laid in fresh waters, but so far they provide only a tenth of the world's catch. The possibilities for expanding fisheries in the seas and oceans are much richer.

Great importance is currently being attached to the development of scientific fishing methods that take into account the peculiarities of the biology of commercial fish species, the nature of their distribution, age composition, abundance and other indicators. Not the last word also belongs to the improvement of fishing gear, fish processing technology.

In this case, the development of new areas and objects of fishing is of particular importance. First of all, this applies to the fishing of the inhabitants of the upper layer of the ocean - the epipelagic zone, such as mackerel pike, flying fish, small tuna, squid. The fishery of small-sized fish is promising - luminous anchovies, gonostomas, living in the intermediate layer of ocean waters - mesopelagial. Significant progress has been made in the development of deep-water uplifts of the World Ocean with relatively large fishing depths - 800-1000 meters, where powerful accumulations of grenadier, doryfish, smooth-headed and other fish species have been found.

Critical to increasing the harvest of the biological resources of the oceans will belong to objects of a lower trophic level than fish, such as Antarctic krill, which is now fished by many countries.

Until now, speaking about the possibilities of increasing the catch of fish and seafood, we meant only the rational use of the natural food resources of the World Ocean, showing some ways to improve the traditional “gathering or hunting”, which until recently was, in fact, fishing. Scientists in many countries are working on how to move from "gathering and hunting" to marine management.

According to some scientists, the transition of the fishing industry from the extraction of fish to the cultivation of marine plants and animals can cause changes in human civilization, in importance not inferior to the emergence of agriculture, when a person moved from "gathering and hunting" to cultivating the soil. Such a reorganization of the fish industry will be, in fact, a "blue revolution". The onset of such a revolution is not far off. Successful experiments on artificial breeding of fish have already been carried out. Work is underway to increase the biological productivity of sea waters by lifting deep, nutrient-rich layers to the surface. The creation of artificial reefs, the breeding of new, more productive species of plants and animals, the achievements of genetics and ethology, the science that studies the behavior of animals - these are the ways of the uninterrupted and man-controlled growth of the gifts of the ocean.

The future of mankind is closely connected with the use of the resources of the oceans. The growing demand for mineral raw materials, energy and food resources makes people more and more often turn their attention to the ocean. The problems of the development of the World Ocean are complex, closely interconnected and must be solved in a comprehensive manner, by the combined efforts of various specialists from all countries. The ocean belongs to everyone, and we are all responsible for its fate!