What do you know about the ocean?

The ocean refers to the vast and continuous body of salt water on the earth, with a total area of ??approximately 360 million square kilometers, accounting for approximately 70% of the earth's surface area. Because the ocean area is much larger than the land area, some people call the earth a "water ball." Ocean Knowledge: The lightest sea, the Baltic Sea, the deepest sea, the Bering Sea, the largest sea, the Coral Sea, the shallowest sea, the Sea of ??Azov, the smallest sea, the Sea of ??Marmara, the hottest sea, the Red Sea 1. The elements contained in sea water exceed the limit of absorption by the human body, so it cannot 2. Scientists believe that the rise and fall of sea level is caused by the movement of continental plates or the cold and warm changes in the global climate. 3. The ocean contains huge amounts of heat. In the process of constantly exchanging and transmitting its own heat with the outside world, it has an impact on the climate of the continent. It plays a regulating role in distinguishing the sea from the ocean

The vast ocean, from blue to green, is beautiful and spectacular. Ocean, ocean. People always say this, but many people don't know that the sea and the ocean are not exactly the same thing, they are different from each other. So, how are they different, and how do they relate?

The ocean is the central part of the ocean and the main body of the ocean. The total area of ??the world's oceans accounts for approximately 89% of the ocean area. The water depth of the ocean is generally more than 3,000 meters, and the deepest can reach more than 10,000 meters. The ocean is far away from the land and is not affected by the land. Its hydrology and salinity vary little. Each ocean has its own unique system of currents and tides. The water color of the ocean is blue, very transparent, and there are very few impurities in the water. There are four oceans in the world, namely the Pacific Ocean, the Indian Ocean, the Atlantic Ocean, and the Arctic Ocean.

The sea is at the edge of the ocean and is a subsidiary part of the ocean. The area of ??the sea accounts for about 11% of the ocean. The water depth of the sea is relatively shallow, with the average depth ranging from a few meters to two or three thousand meters. The sea is close to the continent and is affected by the continent, rivers, climate and seasons. The temperature, salinity, color and transparency of the sea water are all affected by the land and have obvious changes. In summer, the sea water warms and in winter the water temperature drops; in some sea areas, the sea water even freezes. Where large rivers enter the sea, or during rainy seasons, the sea water becomes fresher. Due to the influence of the land, rivers carry sediment into the sea, making the nearshore seawater turbid and unclear, and the transparency of the seawater is poor. The sea does not have its own independent tides and currents. The sea can be divided into marginal sea, inland sea and Mediterranean Sea. The marginal sea is both the edge of the ocean and the frontier of the continent; this type of sea is widely connected with the ocean and is generally separated from the ocean by a group of islands. my country's East China Sea and South China Sea are the marginal seas of the Pacific Ocean. Inland seas are seas located inside continents, such as the Baltic Sea in Europe. The Mediterranean Sea is a sea between several continents, and the water depth is generally deeper than that of inland seas. There are nearly 50 major seas in the world. The Pacific Ocean has the most, followed by the Atlantic Ocean, and the Indian Ocean and the Arctic Ocean are about the same.

The Formation of the Ocean

How was the ocean formed? Where does seawater come from?

Science is currently unable to provide a final answer to this question. This is because they are connected with another universal and equally unresolved issue of the origin of the solar system.

Current research proves that about 5 billion years ago, some large and small nebula clumps were separated from the solar nebula. They revolve around the sun and spin on their own. During the movement, they collided with each other, and some lumps combined with each other, growing from small to large, and gradually became the primitive earth. During the collision of nebula clumps, they contracted sharply under the action of gravity, and the internal radioactive elements decomposed, causing the primitive earth to be continuously heated. When the internal temperature reached a high enough level, the materials in the earth, including iron, nickel, etc., began to melt. Under the action of gravity, the heavy ones sink and concentrate towards the center of the earth, forming the core; the light ones float up, forming the crust and mantle. At high temperatures, the moisture inside vaporizes and rushes out together with the gas, flying into the air. However, due to the gravity of the earth's center, they will not run away and will only form a circle of air and water around the earth.

The layer of crust located on the surface of the earth is constantly impacted and squeezed by the violent movements inside the earth during the cooling and condensation process. As a result, it becomes wrinkled and uneven, and sometimes it is squeezed, causing earthquakes and volcanoes. Exploded, spewing out magma and hot gas. At first, this happened frequently, then gradually became less frequent and gradually stabilized. This process of differentiation of light and heavy materials, resulting in great turbulence and reorganization, was probably completed 4.5 billion years ago.

After the crust is cooled and shaped, the earth is like a long-dried apple, with densely wrinkled and uneven surfaces. Mountains, plains, river beds, ocean basins, all kinds of terrain are available.

For a long period of time, water vapor and the atmosphere in the sky coexisted together; there were dense clouds. The sky is dark and the earth is dark. As the earth's crust gradually cools, the temperature of the atmosphere also slowly decreases. The water vapor uses dust and volcanic ash as condensation nuclei and turns into water droplets, accumulating more and more. Due to uneven cooling and violent air convection, thunder and lightning winds were formed, and heavy rain and turbid currents were formed. The rain became heavier and heavier, and it continued to rain for a long time. The torrential floods passed through thousands of rivers and ravines and gathered into a huge body of water. This is the primitive ocean.

In the primitive ocean, seawater is not salty, but acidic and anoxic.

The water continues to evaporate, causing rain due to repeated topography, and then falls back to the ground, dissolving the salt in the land and seabed rocks, and continuously collecting it in the sea water. After hundreds of millions of years of accumulation and fusion, it turned into generally uniform salt water. At the same time, because there was no oxygen and no ozone layer in the atmosphere at that time, ultraviolet rays could reach the ground directly. With the protection of sea water, life was first born in the ocean. About 3.8 billion years ago, organic matter was produced in the ocean, and first there were lower single-celled organisms. In the Paleozoic Era 600 million years ago, seaweeds began to photosynthesize in the sun, producing oxygen, which slowly accumulated to form the ozone layer. At this time, creatures began to land on land.

In short, through the gradual increase in water volume and salt content, as well as the vicissitudes of geological history, the primitive ocean gradually evolved into today's ocean. Coast People often think that the place where the ocean and land meet is called the "coastline". In fact, this line is a "belt" with a certain width. It is 440,000 kilometers long in the world and can circle the earth's equator 11 times. This coastal zone is not only rich in natural resources, but also the area with the most frequent human activities. It is currently the most economically and culturally developed area in the world. Two-thirds of the world's population lives here. It has the functions of a three-dimensional sea, land and air transportation system and transshipment system. Especially for maritime traffic, there are currently 2,300 ports located on the coast. The coast is a coastal zone where waves and tides play a significant role. It is a zone where the ocean and land interact and come into contact with each other. Its width can range from tens of meters to dozens of kilometers. It can generally be divided into three parts: the upper zone, the middle zone (intertidal zone) and the lower zone. The upper zone, also known as the land shore zone, is generally not affected by wind, waves and tides. It may be due to the terrace terrain formed by the action of sea water in the past, the erosion and accumulation of onshore rivers, and the action of coastal winds to form sand dunes. It is characterized by sea cliffs, sea caves, sea erosion terraces and platforms. The intertidal zone consists of two parts: the beach and the tidal flat. This area is the area where wave activity is most active and has the strongest effect. The lower zone is also called the underwater bank slope zone, which is the place where the coast used to be and has now sunk under the sea water. It is generally counted from the place where the sea water reaches at low tide to the zone where waves and tides have no significant effect. There are many types of coasts, including flat, steep, hard rocky shores and soft mud and sand shores. According to its formation dynamics, climate and other reasons, it can be divided into several types of coasts: erosion coast, accumulation coast, moraine-ice erosion coast, tectonic coast, biological coast and so on. Physical Characteristics of Seawater The reason why the ocean constitutes a unique environmental system is inseparable from the characteristics of seawater. Seawater is water first, because for most seawater, its salinity is between 32 and 35‰, with the average being close to 35‰. This fact shows that pure water accounts for the vast majority of seawater, so the physical properties of seawater are very similar to pure water. And this also explains why the ocean itself is an inexhaustible large "fresh water reservoir". Water has many distinct anomalies compared to other liquids. Evaporates into steam, shrinks and freezes. There is flowing liquid water between 0°C (melting point) and 100°C (boiling point), and water at 4°C and ice formed by water float on the water, and water at 4°C is always at the top. Ground floor. This characteristic is very important to the organisms living in it. On the other hand, water is a solvent and can dissolve many substances. This is the basis for another property of sea water. It is different from ordinary fresh water, but contains a mixture of many inorganic salts, and also contains a variety of dissolved gases, especially oxygen and carbon dioxide, as well as a large amount of organic and inorganic suspended substances. These substances have varying degrees of impact on the physical properties of seawater, and more importantly, provide good nutrients for the growth of organisms. The salinity of seawater is generally around 35‰. Many phenomena that occur in the ocean are closely related to the distribution and changes of salinity, so salinity is a basic characteristic of seawater. In some sea areas, such as the Red Sea, due to strong sunshine and large evaporation, the salinity can be as high as over 40‰; in the Gulf of Bothnia in the northern Baltic Sea, where rainfall is heavy and rivers flow into more, the salinity can be as low as 3‰. Even in the same sea area, the salinity of seawater changes differently in the horizontal and vertical directions. The color of sea water is also called sea color. Undersea Landforms Just like on land, the underwater world has mountains, plains, and deep trenches and canyons. This world is not as peaceful and peaceful as people imagine or as it appears on the surface. On the contrary, it is the most active and turbulent area on earth. Earthquakes and volcanic activities are frequent, forming high mountains and ridges, but everything is hidden under the sea water. Although the ocean floor shapes of the world's oceans are different, they are basically composed of continental shelves, continental slopes, island arc trenches, ocean basins, and mid-ocean ridges (undersea mountains). The coastline we usually see is not the dividing line between the continent and the ocean. In fact, below the sea surface, the continent still extends at an extremely gentle slope to the seafloor about 200 meters deep. This part is the continental shelf - the coastal plain submerged by sea water. It has become a paradise for marine life. You can find many marine animals and plants living and thriving here. Below the continental shelf is the transition slope from the continental shelf to the ocean floor. The slope increases suddenly, generally 3-4 degrees, and some even exceed 10 degrees. The water depth increases sharply, generally 200-2500 meters. This is the relatively narrow continental slope, and its bottom is the real dividing line between the continent and the ocean. Beyond the continental slope, there is a deep trench or island arc-trench system.

Here, the oceanic plate subducts beneath the continental plate, and the intersecting zone forms a "V"-shaped trench, which is the deepest place in the ocean and forms the largest height difference on Earth with the adjacent island arcs. For example, the Peru-Chile Trench is 8,000 meters deep, and the Andes Mountains on its back are more than 6,500 meters above sea level. The intersection between them is 14,500 meters. If it were not covered by sea water, this would be the most majestic and spectacular sight! Because this area is located on the edge of two plates, earthquakes and volcanic activities occur frequently. Across the trench and deeper into the ocean, you will reach the vast ocean basin. Its depth is between 2,500-6,000 meters, and most of it is an abyssal plain, accounting for 77% of the total seabed area. It is vast and flat, but the scenery is unremarkable. Around the plain, there are thousands of miles of sea ridges, steep sea peaks and flat-topped mountains as smooth as a knife. There are also deep sea valleys, fault zones and troughs. Sea ridges and seamounts are all composed of volcanoes, and seamounts can even be exposed to the sea. Become islands, such as the Hawaiian Islands in the Pacific. Going deeper into the ocean floor, we come to mid-ocean ridges. Unlike ordinary ridges, they are the center of seafloor spreading. Moreover, the mid-ocean ridge is a worldwide system that traverses all oceans. It starts from the Arctic Ocean, passes through the Atlantic Ocean, passes through the Indian Ocean, and enters the Pacific Ocean. It meanders for more than 70,000 kilometers. It is like the backbone of the ocean. No land mountain range can compete with it. Comparable to it. Marine biological resources The ocean is the cradle of life. Since the birth of the first viable cell, more than 200,000 species of organisms still live in the ocean, including about 100,000 species of marine plants and about 160,000 species of marine animals. From lower plants to higher plants, herbivores to carnivores, plus marine microorganisms, they form a special marine ecosystem that contains huge biological resources. It is estimated that the annual production of global marine plankton (fresh weight) is 500 billion tons. Without destroying the ecological balance, it can provide humans with aquatic products for human consumption by 30 billion people every year. This is an extremely attractive future for mankind. Food bank! Marine biological resources have their own characteristics: they are living, self-proliferating, and constantly updated resources. But on the other hand, because they reproduce and develop through living animals and plants, the resources are renewed and Supplement has a certain ability of spontaneous adjustment and is a dynamic balancing process. But once the balance of its ecosystem is destroyed, it means the destruction of marine biological resources.

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