About the sea

1, Introduction

The ocean is the source of life.

Oceans and oceans; Ocean; The sea is the ocean. In fact, there are some differences between the sea and the ocean. The difference between ocean and 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 the same thing, they are different from each other. So, what's the difference between them and what does it matter?

The ocean is the central part of the ocean and the main body of the ocean. The total ocean area in the world accounts for about 89% of the ocean area. The water depth of the ocean is generally above 3000 meters, and the deepest point can reach 10000 meters. The ocean is far from the land and is not affected by the land. Its moisture and salinity have little change. Every ocean has its own unique ocean current and tidal system. The water in the ocean is blue and transparent, and there are few impurities in the water. There are four worlds, namely, the Pacific Ocean, the Indian Ocean, the Atlantic Ocean and the Arctic Ocean.

The ocean at the edge of the ocean is an accessory part of the ocean. The area of the sea accounts for about 1 1% of the ocean. The water depth of the sea is relatively shallow, with an average depth of several meters to two or three kilometers. The sea is close to the mainland and is influenced by the mainland, rivers, climate and seasons. The temperature, salinity, color and transparency of seawater are all affected by land and have obvious changes. In summer, the sea gets warmer and the water temperature drops in winter. In some sea areas, seawater will freeze. Where the river flows into the sea, or in the rainy season, the sea water will weaken. Due to the influence of land, rivers carry sediment into the sea, and the offshore seawater is turbid and the transparency of seawater is poor. The sea has no independent tides and currents. The ocean can be divided into marginal sea, inland sea and Mediterranean sea. The marginal sea is not only the edge of the ocean, but also close to the continental front; This kind of sea is widely connected with the ocean and is generally separated from the ocean by a group of islands. China's East China Sea and South China Sea are marginal seas of the Pacific Ocean. The inland sea is a sea located on the mainland, such as the Baltic Sea in Europe. The Mediterranean Sea is a sea between several continents, and its water depth is generally deeper than that of the inland sea. There are nearly 50 major oceans in the world. The Pacific Ocean is the largest, followed by the Atlantic Ocean, and the Indian Ocean is similar to the Arctic Ocean.

2, the formation of the ocean

How did the ocean form? Where does the sea water come from?

At present, science cannot give the final answer to this question, because they are related to another common and equally unsolved problem of the origin of the solar system.

Current research proves that some large and small nebulae separated from the solar nebula about 5 billion years ago. They revolve around the sun while rotating. In the process of movement, they collided with each other, and some lumps combined with each other, from small to large, and gradually became the original earth. During the collision of nebula clusters, they shrink sharply under the action of gravity, and the radioactive elements in them degenerate, which makes the primitive earth heat up continuously. When the internal temperature reaches high enough, underground substances, including iron and nickel, begin to melt. Under the action of gravity, the weight sinks and tends to concentrate in the center of the earth, forming the core; Lighter ones float to form the crust and mantle. At high temperature, the water inside evaporates, rushes out with the gas and rises into the air. But because of gravity, they will not run away, but will only turn around the earth and become a circle of air and water.

In the process of cooling and condensation, the crust on the earth's surface is constantly impacted and squeezed by the violent movement inside the earth, so it becomes uneven and sometimes crushed, forming earthquakes and volcanic eruptions, spewing magma and hot gas. At first, this kind of situation often happens, and then it gradually decreases and tends to be stable. This division of light and heavy substances led to great turmoil and reorganization, which was completed about 4.5 billion years ago.

After the crust is cooled and shaped, the earth is like an apple that has been dried for a long time, and its surface is wrinkled and uneven. There are mountains, plains, river beds and basins.

For a long time, the water vapor in the sky coexisted with the atmosphere. Thick clouds are gathering. It's dark. With the gradual cooling of the earth's crust, the temperature of the atmosphere is also slowly decreasing. Water vapor takes dust and volcanic ash as condensation nuclei and becomes water droplets, which accumulate more and more. Due to uneven cooling and strong air convection, thunderstorms and turbidity currents were formed, and it rained harder and harder for a long time. Surging floods, through thousands of rivers and valleys, converge into a huge water body, which is the primitive ocean.

In the primitive ocean, seawater is not salty, but acidic and anoxic. Water is constantly evaporating, and clouds repeatedly cause rainfall, and then fall back to the ground, dissolving the salt in the rocks on the land and under the sea, and continuously collecting it into the seawater. After hundreds of millions of years of accumulation and integration, it has become a generally uniform salt water. At the same time, because there was no oxygen and ozone layer in the atmosphere at that time, ultraviolet rays could reach the ground directly. With the protection of seawater, life was first born in the ocean. About 3.8 billion years ago, organic matter was produced in the ocean, and lower single-celled organisms first appeared. In the Paleozoic era 600 million years ago, there were algae that photosynthesized in the sun to produce oxygen, which gradually accumulated and formed the ozone layer. At this time, creatures began to land.

In a word, after the gradual increase of water quantity and salinity and the vicissitudes of geological history, the primitive ocean gradually evolved into today's ocean.

3. Ocean-21century drug warehouse

Keywords: marine science

According to the prediction of relevant medical experts, human beings will subdue cancer in 2 1 century. So, what is the panacea for mankind? In recent years, scientists have discovered that the ocean will become a drug warehouse in 2 1 century.

Sea cucumber is a precious seafood with high protein. However, you may not have thought that several kinds of sea cucumbers will release a toxin from the anus, which has the effect of inhibiting tumors.

Oyster is a small shellfish, which is very delicious, but its greater value is because it contains antibiotics. This antibiotic has an anti-tumor effect.

At present, some drug researchers are conducting experiments to extract toxic compounds from algae and tiny marine organisms as an effective means to treat some diseases. Preliminary experiments show that toxic substances extracted from sponges can inhibit the development of cancer cells. A substance extracted from enema fish is helpful to treat diabetes. An American marine expert vividly said: "Marine life is like a consulting center, which can provide solutions to health problems."

Medical experts attach great importance to the development and utilization of coral when considering taking medicine from the ocean. Experiments show that the toxic substances extracted from coral reefs, like those extracted from some spongy creatures, also have the effect of inhibiting the development of cancer cells; Other substances extracted from coral reefs can reduce inflammation of arthritis and asthma. There is a kind of coral from Hawaii, which is very toxic and can be used to make specific drugs for leukemia, hypertension and some cancers. Soft coral purified from Nanhai, China, has the functions of lowering blood pressure, resisting arrhythmia and relieving spasm.

Shark is an ancient marine fish, widely distributed all over the world, with more than 250 species. Since the mid-1980s, many international scientists have carefully studied the pharmacology, chemistry, biochemistry and application of various parts of shark body, especially the anti-tumor active substances in shark body. According to relevant data, American biologists have investigated sharks for decades and found that sharks have almost no pathological changes and rarely get cancer, which seems to have natural immunity to cancer. Some scientists inoculate sharks with some pathogenic bacteria and cancer cells, but they can't make them sick. It seems that there are some special protective chemicals in sharks.

China experts' research on sharks is almost in step with the international research. 1985, experts from Shanghai Fisheries College and Shanghai Institute of Oncology discovered for the first time in vitro that shark serum has a killing effect on human erythroleukemia tumor cells. This scientific research achievement has opened up a broad world for human beings to find anti-tumor drugs from marine biological resources.

5. Ocean-a cornucopia of mineral resources

Keywords: marine science

The ocean is a cornucopia of mineral resources. After the "international 10 marine exploration stage" in the 1970s, people's understanding of the types, distribution and reserves of marine mineral resources was further deepened.

(1) oil and gas field

With the modernization of human economy and life, the demand for oil is increasing day by day. At present, oil occupies the first place in energy. However, because some large oil fields on land are relatively easy to exploit, some have been exhausted and some are on the verge of exhaustion. Therefore, in recent 20 ~ 30 years, many countries in the world are vigorously developing offshore oil industry.

The exploration results show that the world's oil resources reserves are 65.438+billion tons, and the recoverable amount is about 300 billion tons, of which the seabed reserves are 65.438+300 million tons.

China has a shallow continental shelf of nearly 2 million square kilometers. Through the geological survey of submarine oil fields, seven great basin, including Bohai Sea, South Yellow Sea, East China Sea, Pearl River Estuary, Beibu Gulf, Yinggehai and Taiwan Province Province Shoal, have been discovered successively. Among them, the East China Sea is rich in seabed reserves, comparable to the North Sea oil field in Europe.

Pinghu oil and gas field in the East China Sea is the first medium-sized oil and gas field discovered in the East China Sea of China, located 420km southeast of Shanghai. It is a medium-sized oil and gas field dominated by natural gas, with a depth of 2000 ~ 3000 meters. According to experts' estimation, the natural gas reserves are 26 billion cubic meters, 4.74 million tons of condensate oil and 8.74 million tons of light crude oil.

(2) Rare manganese nodules

Manganese nodule is a kind of rare metal ore source on the seabed. It was first discovered in the Atlantic Ocean by a British marine survey ship in 1973. However, the formal and organized survey of manganese nodules in the world began with 1958. Investigation shows that manganese nodules are widely distributed at the bottom of the deep sea from 4000 to 5000 meters. They are the largest metal mineral resources in the future. Interestingly, manganese nodules are a primitive mineral. It grows at a rate of about100000 tons every year, and it is an inexhaustible mineral.

The total reserves of marine manganese nodules in the world are about 3 trillion tons, including 400 billion tons of manganese, 8.8 billion tons of copper, 654.38+064 billion tons of nickel and 4.8 billion tons of cobalt, which are dozens or even thousands of times of the land reserves respectively. According to the current consumption level, these manganese can be used worldwide for 33,000 years, nickel for 253,000 years, cobalt for 2 1500 years and copper for 980 years.

At present, with the deepening of exploration and investigation of manganese nodules and the maturity of technology, it is predicted that by 2 1 century, it will enter the stage of commercial development and formally form a deep-sea mining industry.

(3) submarine hydrothermal deposits

In the mid-1960s, American marine survey vessels first discovered deep-sea hydrothermal deposits in the Red Sea. Then, some countries found more than 30 such mineral deposits in other oceans.

Hydrothermal deposits, also known as "heavy metal mud", are high-temperature lava ejected from cracks in sea ridges (seamounts), which are washed, precipitated and accumulated by seawater, and can grow rapidly at a rate of several centimeters per week like plants. It contains dozens of rare and precious metals such as gold, copper and zinc, and the grade of gold and zinc is very high, so it is also called "submarine gold and silver warehouse". Interestingly, heavy metals are colorful, including black, white, yellow, blue and red.

Under the current technical conditions, although submarine hydrothermal deposits can't be mined immediately, it is a potential treasure house of seabed resources. Once it can be exploited industrially, it will become one of the four major seabed minerals in 2 1 century together with submarine oil, deep-sea manganese nodules and submarine placer.

(4) Combustible ice

In 2 1 century, the amount of various energy sources is gradually decreasing. Scientists began to look for new energy sources. Combustible ice is a new energy source discovered by scientists in the ocean. It is located in the depths of the ocean, shaped like ice, can be burned, can be used as the energy source of various vehicles, and has great potential value. At present, China, the United States and other countries have made corresponding plans for the exploitation and utilization of combustible ice.

6. Ocean-the granary of the future

Keywords: marine science

Some readers may think, if the ocean can't grow food, how can it become a granary in the future?

Yes, rice and wheat can't grow in the ocean, but the fish and shellfish in the ocean can provide delicious and nutritious protein food for human beings.

As we all know, protein is the most important substance that constitutes an organism and the foundation of life. At present, only 5% ~ 10% of protein ingested by human beings is provided by the ocean. Worryingly, since 1970s, the marine catch has been stagnant and many species have been exhausted. According to a folk saying, human beings have eaten almost all the grandchildren of yellow croaker. To make the ocean a veritable granary, the output of fresh fish should be at least ten times higher than it is now. The experiment of a marine farm in the United States shows that it is entirely possible to greatly increase fish production.

In nature, there are countless food chains. In the ocean, if there are algae, there are shellfish, and if there are shellfish, there are small fish or even big fish ... The total area of the ocean is more than twice that of the land, and most of the few fishing grounds in the world are offshore. This is because algae growth needs sunlight and compounds such as silicon and phosphorus, and these conditions are only available near land. Now, an algae has been developed, which can reproduce in 1 hectare of seawater, and it can produce more than 20 tons of protein. Marine survey shows that in the deep-sea water below 1000 meters, the contents of silicon and phosphorus are very rich, but they cannot float to the warm surface. Therefore, only a few small sea areas, due to the action of natural forces, the deep sea water automatically rises to the surface, thus making these sea areas full of algae and dense fish, becoming a rare fishing ground.

Inspired by these sea areas, oceanographers use the principle of updraft to artificially pump deep seawater to the surface in those sunny sea areas, then cultivate algae there, feed shellfish with algae, and feed lobsters with processed shellfish. Surprisingly, this series of experiments have been successful.

Experts optimistically pointed out that the ocean granary has great potential. At present, the annual output per hectare of land crops with the highest yield is only 0.7 1 ton in protein. However, scientific experiments show that the maximum output of mariculture in the same area can reach 27.8 tons, and the commercially competitive output is 16.7 tons.

Of course, there will be many difficulties from scientific experiments to actual production. Most importantly, pumping water from the deep sea below 1000 meters requires considerable electricity. Where does such a huge amount of electricity come from? Obviously, under today's conditions, these energy needs cannot be met.

However, scientists have found the trick: they intend to use the temperature difference between the tropical and subtropical ocean surface and the deep sea to generate electricity. This is the so-called seawater temperature difference power generation. In other words, the designed marine farm will be combined with the seawater temperature difference power station.

According to the calculation of relevant scientists, due to the strong light in tropical and subtropical waters, there are as many as 6,250 trillion cubic meters of warm water available for power generation in this sea area. If people use 1% warm water to generate electricity every time, and then pump the same amount of deep seawater to cool down, they can get 750 million tons of various seafood every year by using this electricity for aquaculture. It is equivalent to four times the total amount of fish and meat consumed by human beings in the mid-1970s.

Through these simple calculations, it is not difficult to see that it is completely feasible for the ocean to become the granary of mankind in the future.

Western viewpoint

Ocean ocean

Ocean ocean

Excerpted from the Encyclopedia Britannica

China enters the ocean.

Foreign language entrance ocean

Knowledge classification: geography > ocean

Endless salt water is distributed in huge basins on the surface of the earth. The area is about 362,000,000 square kilometers (65,438+040,000,000 square miles), which is close to 765,438+0% of the earth's surface area. The global ocean is generally divided into several oceans and smaller oceans. The three oceans are the Pacific Ocean, the Atlantic Ocean and the Indian Ocean (the Arctic Ocean is regarded as an extension of the Atlantic Ocean), and most of them are bounded by land and seabed topographic lines. The three oceans are connected in a large area around the Antarctic continent, that is, the Antarctic Sea (also known as the "Southern Ocean"). Traditionally, the Antarctic Sea has also been divided into three parts, belonging to three oceans. Including the corresponding part of the Antarctic Sea, the Pacific Ocean, the Atlantic Ocean and the Indian Ocean account for 46%, 24% and 20% of the total sea area of the earth respectively. Most of the important marginal seas are distributed in the northern hemisphere, and they are partially surrounded by continents or island arcs. The largest are the Arctic Ocean and its offshore waters, the Mediterranean Sea in Asia (between Australia and Southeast Asia), the Caribbean Sea and its adjacent waters, the Mediterranean Sea (Europe), the Bering Sea, the Sea of Okhotsk, the Yellow Sea, the East China Sea and the Sea of Japan.

The average depth of the ocean is about 3.7 kilometers (2.3 miles). Starting from the continental shelf slope with a depth of 100 ~ 00 meters (330 ~ 660 feet), the continental slope was reduced to a vast deep-sea plain. About 75% of the seabed is between 3 and 6 kilometers deep, only about 1% deeper. The deepest waters are distributed in narrow trenches, and most of them are related to the Pacific island arc. At present, the deepest water is Mariana Trench11.034m..

Most of the seabed surface is covered by loose sediments, and there are consolidated sediments and crustal igneous rocks below. Although most of the seabed is quite flat, there are many mountain-like landforms, such as seamounts. The so-called mid-ocean ridge is a major landform, and its trunk and branches extend to all oceans. The peak of the ridge is 2 ~ 3 kilometers higher than the deep seabed, and its volcanic activity area is where the new submarine basalt crust is formed, which plays a key role in the submarine expansion movement (see [plate structure]). The recent study on the Pacific Ridge found that in the active area formed by the new crust, seawater would circulate among basalts and react at high temperature, resulting in drastic changes. The solution after the interaction of these hot water will pass through the pores in the earth's crust and return to the ocean. In some pores, the temperature can be as high as 350℃(660℉).

According to the standard of geochronology, compared with the average life span of deep-sea water molecules ranging from hundreds of years to about 1000 years, the general water circulation in the ocean can be said to be very rapid. On the ocean surface, wind pressure rubs the upper seawater to produce ocean currents. The main wind system determines the initial flow direction of the main ocean currents, but the flow direction will also change due to the influence of the earth's rotation and topography. An example is the clockwise rotation of tropical and temperate regions in the North Atlantic, including the strong western boundary current joining the Gulf Stream. Similar eddy currents are generated in other areas. Near the eastern continental margin of the main ocean, the surface seawater is usually driven away from the coast and replaced by seawater from a medium depth, with lower seawater temperature and richer nutrients. These coastal areas where seawater gushes upward are often rich in ecology and popular in fisheries. Wind-induced circulation affects the oceans at different depths, but the seawater characteristics of most medium depths and all deepest waters depend on thermohaline circulation. Hot-salt circulation starts from the sinking of high-latitude seawater due to cooling, and then flows laterally until it sinks to a certain depth, and the water density is the same, thus forming a few water bodies with unique temperature and salinity. The mixing of these water bodies produces water masses with different properties, which are filled at specific depths in different areas of the ocean. Most of the water that is not affected by the surface circulation moves from south to north or from north to south, but there are some obvious exceptions, such as seawater generated in the Mediterranean appearing in the middle. The Atlantic region, where the valley is today.

Many important features of the ocean are determined by the temperature and salinity of seawater. In addition, the pressure determines the density of seawater. The heat of seawater mainly comes from the solar energy absorbed by its surface, and the water temperature on the surface will be obviously different with the latitude. However, the distribution of surface temperature is obviously influenced by other regional characteristics such as heat conduction and upwelling of surface ocean currents. The temperature of the vast ocean ranges from below-1℃ to 28℃ (30 ~ 82 ℉). In tropical and temperate latitudes, the most obvious drop in ocean seawater temperature is thermocline (below the surface layer where seawater is fully mixed, the depth is about 100 m). When the water depth exceeds 1 km, the water temperature changes slowly and tends to the bottom water temperature below 2℃. According to the total amount, about 50% of the ocean water temperature is between 65438 0.3 ~ 3.8℃. The salinity of the surface layer of seawater-that is, the proportion of dissolved salt in seawater-is changing, which mainly depends on the comparison between evaporation loss of local seawater and rainfall. The average salinity of the ocean is 34.7. In areas where rivers inject a lot of fresh water or a lot of icebergs melt, the salinity of seawater will be slightly lower; In areas where the amount of evaporated water is extremely high, the salt concentration will be higher.

Seawater contains all kinds of dissolved inorganic substances, gases and organic substances. In addition to the above dissolved components, it also contains suspended particles (such as plankton). Besides water, the most abundant inorganic components are chloride, sodium, sulfate, magnesium, calcium, potassium and bicarbonate. Unlike many trace substances, the concentrations of these main components are different, but they are almost fixed in proportion to salinity. Marine seawater is slightly alkaline, and its pH value is close to 8. Geochemists believe that despite the continuous increase and decrease of substances, the main composition characteristics of seawater have remained basically unchanged for at least the past 600 million years.

The ocean seems to have formed at the beginning of the earth's history. When the earth's temperature rises and is divided into three main zones (core, mantle and crust), volcanism will release a large amount of water vapor from the interior of the earth and bring it to the surface of lava together with other excess volatile substances. Water vapor forms a hot cloud and overflows lava, and then condenses into enough water to form an ocean.