Oceans and Their Importance
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Oceans and Their Importance

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@Dr. K. Viswanath

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Questions and Answers

Oceans cover nearly ______ per cent of the Earth’s surface.

70

The Pacific Ocean is the largest ocean, covering about ______ per cent of the Earth's surface area.

30

The deepest point in the ocean and the whole world is the ______ Trench.

Mariana

The Atlantic Ocean is the world’s ______ largest ocean.

<p>second</p> Signup and view all the answers

There are five major oceans: the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, the Southern Ocean, and the ______ Ocean.

<p>Arctic</p> Signup and view all the answers

The average depth of the oceans is about ______ metres.

<p>4000</p> Signup and view all the answers

The primeval ocean came into existence after rain began to fall for ______.

<p>centuries</p> Signup and view all the answers

The Atlantic Ocean is roughly ______ times the size of the USA.

<p>6.5</p> Signup and view all the answers

The _____ Sea is an example of an inland sea.

<p>Baltic</p> Signup and view all the answers

Lakes usually contain _____ water but some have salt water.

<p>fresh</p> Signup and view all the answers

Lake Baikal is the world’s _____ lake.

<p>deepest</p> Signup and view all the answers

The Great Lakes collectively contain nearly 21 percent of the world’s surface _____ water.

<p>fresh</p> Signup and view all the answers

Lake _____ is the only Great Lake lying entirely in the United States.

<p>Michigan</p> Signup and view all the answers

Lake _____ is surrounded by Kenya, Uganda, and Tanzania.

<p>Victoria</p> Signup and view all the answers

Lake Titicaca is regarded as the highest _____ lake in the world.

<p>navigable</p> Signup and view all the answers

Lake Chilika is the largest water _____ in Asia.

<p>lagoon</p> Signup and view all the answers

Rivers are natural bodies of flowing _____ water.

<p>fresh</p> Signup and view all the answers

The upper course of a river is often in _____ areas.

<p>mountain</p> Signup and view all the answers

During the middle course of a river, it often _____ along its path.

<p>meanders</p> Signup and view all the answers

The lower course of a river contains muddy, slightly _____ water.

<p>warmer</p> Signup and view all the answers

More than 25 _____ empty into Lake Titicaca.

<p>rivers</p> Signup and view all the answers

Lake Erie is the _____ of all five Great Lakes.

<p>shallowest</p> Signup and view all the answers

The Selenga is the largest tributary of Lake _____ .

<p>Baikal</p> Signup and view all the answers

The Atlantic Ocean includes shallow seas such as the Caribbean Sea and the ______.

<p>Mediterranean Sea</p> Signup and view all the answers

The deepest point of the Atlantic Ocean is the ______ Deep.

<p>Milwaukee</p> Signup and view all the answers

The Indian Ocean is bordered by Africa, Asia, and ______.

<p>Australia</p> Signup and view all the answers

The lowest point in the Indian Ocean is in the ______ Trench.

<p>Java</p> Signup and view all the answers

The Southern Ocean completely surrounds ______.

<p>Antarctica</p> Signup and view all the answers

The deepest point in the Southern Ocean is found in the South ______ Trench.

<p>Sandwich</p> Signup and view all the answers

The Arctic Ocean is the smallest and ______ of the world’s five oceans.

<p>shallowest</p> Signup and view all the answers

The Arctic Ocean connects to the Atlantic Ocean via the ______ Sea.

<p>Greenland</p> Signup and view all the answers

Oceans produce more than half of the oxygen in the ______.

<p>atmosphere</p> Signup and view all the answers

Marginal seas are partially enclosed by islands or ______.

<p>peninsulas</p> Signup and view all the answers

The ______ Sea is an example of a major marginal sea.

<p>Arabian</p> Signup and view all the answers

Inland seas are less common than ______ seas.

<p>marginal</p> Signup and view all the answers

Pollutants in marginal seas are usually found in concentrations that are thousands of times greater than in ______.

<p>open oceans</p> Signup and view all the answers

Ninety per cent of the world's fisheries exists within coastal waters located less than ______ km from the shoreline.

<p>200</p> Signup and view all the answers

Ocean currents formed by winds greatly influence the water circulation in ______ seas.

<p>marginal</p> Signup and view all the answers

The Ob River flows into the Kara Sea, forming a ______.

<p>bay</p> Signup and view all the answers

The Huang He is also known as the ______ River.

<p>Yellow</p> Signup and view all the answers

A ______ is a large body of water that is almost completely surrounded by land.

<p>gulf</p> Signup and view all the answers

The largest gulf in the world is the Gulf of ______.

<p>Mexico</p> Signup and view all the answers

Sewage water carries harmful ______ that can cause health problems.

<p>bacteria</p> Signup and view all the answers

Industrial waste contains toxic ______ that can pollute water bodies.

<p>chemicals</p> Signup and view all the answers

Marine dumping refers to the disposal of garbage into oceans, seas, and ______.

<p>rivers</p> Signup and view all the answers

Oil spills present a serious threat to local marine ______.

<p>life</p> Signup and view all the answers

Burning fossil fuels releases carbon ______, which contributes to global warming.

<p>dioxide</p> Signup and view all the answers

Leakage from ______ can pollute underground water with contaminants.

<p>landfills</p> Signup and view all the answers

The ______ River has the third largest river basin in the world.

<p>Mississippi</p> Signup and view all the answers

The ______ River is the largest river in the world by volume.

<p>Amazon</p> Signup and view all the answers

The Nile River meets the Mediterranean Sea at the Nile River ______.

<p>delta</p> Signup and view all the answers

The Mackenzie River Basin is the second largest river basin in North America after the ______ River basin.

<p>Mississippi</p> Signup and view all the answers

The Ganges River is about ______ km long.

<p>2,525</p> Signup and view all the answers

The ______ River connects the Great Lakes to the Atlantic Ocean.

<p>St Lawrence</p> Signup and view all the answers

The Rhine River flows about ______ km from the Swiss Alps to the Netherlands.

<p>1,233</p> Signup and view all the answers

The Indus River is the ______ longest river in Asia.

<p>9th</p> Signup and view all the answers

The Danube River flows through ______ modern-day European nations.

<p>ten</p> Signup and view all the answers

The ______ River is considered to be the longest river in Russia.

<p>Ob</p> Signup and view all the answers

The Amazon River produces about ______ per cent of all the freshwater that flows into the world’s oceans.

<p>20</p> Signup and view all the answers

The River Nile has two main tributaries - the Blue Nile and the ______ Nile.

<p>White</p> Signup and view all the answers

The Ganges River system includes three large rivers - the Ganges, the ______, and the Meghna.

<p>Brahmaputra</p> Signup and view all the answers

The ______ River is loaded with suspended sediments and dissolved solids due to snowmelt.

<p>Mackenzie</p> Signup and view all the answers

The Rhine River watershed is about ______ km² in size.

<p>185,000</p> Signup and view all the answers

Study Notes

Importance of Water

  • Water is essential for life; Earth is home to various bodies of water, including rivers, streams, and lakes.
  • Oceans cover approximately 70% of Earth's surface and contain nearly 97% of the planet's water.

Oceans

  • The average depth of oceans is about 4,000 meters, with some areas being deeper than the tallest mountains.
  • There are five major oceans: Pacific, Atlantic, Indian, Southern, and Arctic.

Formation of Oceans

  • Earth's oceans formed after cooling from a cloud of dust and hot gases, allowing rain to fill large depressions in the surface.

The Five Oceans

  • Pacific Ocean: Largest ocean, covering about 30% of Earth's surface; average depth of 4,300 meters. Home to the Mariana Trench, the deepest point on Earth.
  • Atlantic Ocean: Second largest; occupies 25% of Earth's surface, containing many shallow seas and fewer islands. Average depth is 3,300 meters.
  • Indian Ocean: Covers approximately 14% of Earth's surface; bordered by Africa, Asia, and Australia. Known for the warmest ocean waters.
  • Southern Ocean: Surrounds Antarctica, covering about 4% of Earth's surface, with a depth of 7,235 meters at its deepest point.
  • Arctic Ocean: Smallest and shallowest ocean, located around the North Pole. Deepest point is the Eurasian Basin at 5,450 meters.

Importance of Oceans

  • Oceans regulate Earth's temperature, produce over half the atmospheric oxygen, and absorb significant carbon dioxide.
  • They are critical for trade and have a diverse range of ecosystems.

Seas

  • Seas are large bodies of saline water, can be marginal (partially enclosed) or inland (shallow and inland).
  • Marginal seas, like the Mediterranean and Red Sea, are more vulnerable to pollution due to proximity to human activities.

Lakes

  • Lakes are inland bodies of water, mostly freshwater, with some saline. They can be endorheic (no natural outflow).
  • Major examples include:
    • Lake Baikal: Deepest and cleanest freshwater lake, located in Russia, holds 20% of Earth's freshwater.
    • Great Lakes: Comprises five interconnected lakes in North America, covering 21% of surface freshwater.
    • Lake Victoria: One of the largest tropical lakes, bordered by Kenya, Uganda, and Tanzania.
    • Lake Chilika: Largest lagoon in Asia, located in India, rich in biodiversity.

Rivers

  • Rivers are flowing bodies of freshwater, originating typically from mountains through melting snow and rain.
  • The river's course includes three stages:
    • Upper course: characterized by fast, cold flow and steep gradients.
    • Middle course: marked by meandering and moderate flow.
    • Lower course: slower flow, often resembling wetlands.

Major Rivers

  • Mississippi River: Third largest river basin in the world, crucial for biodiversity and commercial waterway.
  • Amazon River: Largest river by volume, producing 20% of the world’s freshwater; rich in unique wildlife.
  • Nile River: Longest river globally at over 6,853 km, vital for agriculture and freshwater supply in Africa.
  • Mackenzie River: Second largest basin in North America, connected to important lakes.
  • Ganges River: Integral for agriculture in India and Bangladesh, known for its fertile delta.
  • St. Lawrence River: Connects the Great Lakes to the Atlantic, critical for international trade.
  • Rhine River: Major transportation route in Europe since Roman times, flows through multiple countries.
  • Indus River: Flows through Pakistan, crucial for agriculture and home to unique species.
  • Danube River: Longest river in the EU, flows through ten countries and vital for transport and trade.### Key Transport Routes in Europe
  • The Danube River serves as an essential transport route across Europe, known as 'Corridor VII' of the European Union.
  • Facilitated the connection between the North Sea in western Europe and Black Sea ports through the Rhine-Main-Danube Canal and the Danube-Black Sea Canal.

The Ob River

  • Longest river in Russia, stretching approximately 3,650 km.
  • Formed by the confluence of the Altai Biya and Katun rivers; flows into the Kara Sea, creating Ob Bay (around 800 km long).
  • Acts as a significant navigable waterway for cargo transport within Russia, serving major trade centers.
  • The river basin hosts a substantial portion of Siberia's oil and natural gas fields, contributing two-thirds of Russia's production.
  • Major industrial hubs, including Novosibirsk and Barnaul, are located along its banks.

Huang He River

  • Sixth-longest river in the world at 5,464 km.
  • Originates from the Kunlun Mountains in western China and empties into the Gulf of Bohai.
  • Also referred to as the Yellow River due to the silt that imparts a yellow hue to its waters.

Gulfs and Bays

  • Gulfs are large water bodies with narrow mouths, mostly surrounded by land; the Gulf of Mexico is the world's largest example.
  • A bay is a broader inlet set apart from larger water bodies, formed when land curves inward; examples include San Francisco Bay and the Bay of Bengal.

Causes of Water Body Pollution

  • Pollution occurs when harmful substances are discharged into water bodies, adversely affecting plant and animal life.

Industrial Waste

  • Industries contribute significant waste containing toxic pollutants, which often enter rivers and seas without proper treatment.

Sewage and Waste Water

  • Sewage carries harmful bacteria and chemicals, posing health risks and leading to disease propagation in contaminated water bodies.
  • Household waste water should be chemically treated before being released into water systems.

Marine Dumping

  • Household waste, including plastics and other materials, is sometimes dumped into water bodies, creating long-term pollution.
  • Decomposition of waste can take from weeks to centuries, harming aquatic life and ecosystems.

Accidental Oil Leakage

  • Oil spills present severe threats to marine life, including fish and seabirds, disrupting ecosystems.

Burning of Fossil Fuels

  • The combustion of coal and oil releases ash and carbon dioxide into the atmosphere, causing acid rain and contributing to global warming.
  • Global warming destabilizes ocean currents and raises sea levels, impacting marine environments.

Chemical Fertilizers and Pesticides

  • Rainwater runoff containing chemicals from fertilizers and pesticides presents significant risks to aquatic ecosystems.

Leakage from Landfills

  • Rain can lead to landfill leakage, contaminating underground water sources with hazardous materials.

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Explore the significance of water on Earth and the characteristics of the five major oceans. Learn about the formation, depth, and unique features of the Pacific, Atlantic, Indian, Southern, and Arctic Oceans. Test your knowledge on the vital role oceans play in our planet's ecosystem.

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