Quick Links

Home / IAS Preparation / Horizontal And Vertical Distribution of Salinity: Geography NCERT Notes For UPSC

Horizontal And Vertical Distribution of Salinity: Geography NCERT Notes For UPSC

Last Updated on Jun 17, 2021

IMPORTANT LINKS

Agriculture Notes For UPSC Public Administration UPSC Notes Modern History Books For UPSC Overseas Citizen Of India Caste System & Panchayati Raj Godavari River Federalism Indira Point New Development Bank Battle Of Sinhagad Sankalp And Strive Schemes Digital India High Yielding Varieties Economic Growth Development League Of Nations Ease Of Doing Business Mid Day Meal Scheme Wildlife Protection Act 1972 UPSC Notes International Union Conservation Nature

Horizontal And Vertical Distribution Of Salinity is considered to be one of the important topics for UPSC Civil Services exam. In these NCERT notes, the topics that are covered are: salinity and its horizontal and vertical distribution. By keeping all these things in mind, Testbook prepares the best quality NCERT notes for UPSC aspirants.

These notes on Horizontal And Vertical Distribution Of Salinity will also be fruitful for those students who are preparing for exams like banking SSC, state civil services exams and so on. Know what is salinity and study vertical distribution of salinity in ocean, Salt budget of ocean, Salinity of Indian Ocean, Factors affecting salinity of ocean water, etc.

Ocean Salinity
The term salinity refers to the total content of dissolved salts in seawater. Its calculation is done as the amount of salt (in gm) dissolved in 1,000 gm (1 kg) of seawater and expressed as ppt or part per thousand. If the salinity level is 24.7 then it is considered to be the upper limit to demarcate ‘brackish water’.
Check the detailed UPSC Mains Syllabus here!

Horizontal And Vertical Distribution of Salinity (UPSC Geography) NCERT Notes: Download PDF Here!

FREEMentorship Program by

Ravi Kapoor, Ex-IRS

UPSC Exam-Hacker, Author, Super Mentor, MA

100+ Success Stories

Key Highlights

Achieve your Goal with our mentorship program, offering regular guidance and effective exam strategies.

Cultivate a focused mindset for exam success through our mentorship program.

UPSC Beginners Program

Get UPSC Beginners Program SuperCoaching @ just

₹50000

Claim for free

Role of Ocean Salinity

Salinity determines various factors like compressibility, thermal expansion, temperature, density, absorption of insolation, evaporation and humidity.

Along with that it shows major influence on the composition and movement of the sea: water and the distribution of fish and other marine resources.

Check the NCERT notes on Ocean Waves here.

Share of Different Salt in Ocean Salinity
Concentration or percentage of salt is different in ocean salinity, they are:
sodium chloride — 77.7%
magnesium chloride—10.9%
magnesium sulphate —.4.7%
calcium sulphate — 3.6%
potassium sulphate — 2.5%
You might also like: NCERT notes on Salinity of Ocean water

Factors Affecting Salinity of Ocean

Some of the common factors which affects the salinity of ocean are listed below:

The salinity of water in the surface layer of the ocean is determined by evaporation and precipitation.
Surface salinity is greatly influenced in coastal regions by the freshwater flow from rivers, whereas in polar regions by the processes of freezing and thawing of ice.
Salinity is also influenced by wind as it transfers water to other areas.
Oceanic current also has a major contribution in the salinity of the ocean.
As temperature, density and salinity of water are interlinked with each other. So, change in any of them can cause change in the salinity of an area.

Check the NCERT Notes Geography on Structure of Atmosphere here.

Sources of Oceanic Salinity

As the salts which are dissolved in water originate from continental landmasses. Further they are carried through rain, rivers, groundwater table, sea-waves, winds, and glaciers.

Along with that there are some salts which originate from the ocean bottom. As the layer beneath the Earth crust contains minerals in a molten state. These minerals reach the crust either due to volcanic activity or due to their outgassing from the fissures present at the bottom of the ocean.

The dead and decomposing organic matter are also considered to be important sources of the salinity of the oceans.

Check the NCERT Notes Geography on Continental Drift for UPSC.

Horizontal Distribution of Salinity
As the surface salinity of oceans decreases from both sides of the tropics. On the basis of their salinity levels, seas across the world can be categorized as follows:

The salinity range is between 33o/oo and 37 o/oo for normal open ocean.

The highest salinity is seen between the range of 15° and 20° latitudes.

Sometimes in the hot and dry regions where evaporation rate is very high, their salinity reaches upto 70 o/oo in the hot and dry regions where evaporation is high.

In Pacific ocean variation in salinity is maximum because of its shape and larger areal stretch.

In the landlocked Red Sea, the salinity is 41o/oo which is considered to be high.

There is seasonal variation in salinity in the estuaries and the Arctic from 0 – 35 o/oo.

Because the influx of melted water is observed from the Arctic region, the salinity level decreases from 35 o/oo – 31 o/oo on the western parts of the northern hemisphere.

Salinity level in the North Sea is considered to be higher because more saline water is brought by the North Atlantic Drift in the North sea, despite its location in higher latitudes.

Salinity record of the Baltic sea is less because of the influx of rover water in large amounts.

Because of the high evaporation rate in Mediterranean sea, salinity level is also high.

In the Black sea salinity level is very low because of massive freshwater influx by rivers.

The average recorded salinity of the Indian Ocean is 35 o/oo.

Salinity level is low in Bay of Bengal because of the influx of river water whereas in the Arabian Sea salinity level is high because of the low influx of fresh water and high evaporation.

Study the NCERT Notes Geography on Extra Tropical Cyclones for UPSC exam.

Vertical Distribution of Salinity

As there is change in salinity level with depth, but this change in salinity level depends on the position of the sea.

Salinity level at the surface of the sea is decreased with the input of fresh waters or increased by the loss of water to ice or evaporation.

Salinity level at the depth is constant as there is neither addition of water nor salt to it.

There is a huge difference in the salinity level between the surface zones and the deep zones of the oceans.

The lower saline water is always present above the higher saline dense water.

There is an increase in salinity level with increase in depth and there are several distinct zones where salinity level increases tremendously. Such zones are called halocline.

With increase in salinity, density of water also increases.

High salinity seawater, usually, sinks below the lower salinity water and causes stratification by salinity.

Attempt the UPSC IAS Test Series here!
Prepare for your UPSC IAS exam and other government or competitive exams with Testbook. Solve mock tests, take the test series, attempt previous year’s papers and get all exam related information. Download the Testbook App now!

Horizontal And Vertical Distribution of Salinity FAQs

What is the significance of salinity?

The significance of salinity is that it effects the physical property of seawater and other aspects of the oceans like freezing and boiling points. It also shows major influence on the composition and movement of the sea.

What are the factors affecting the salinity of the ocean?

Factor which affects the salinity of the ocean are: rate of evaporation, degree of water mixing by current, amount of fresh water added by precipitation, streams and icebergs.

Which region has a high salinity level?

Landlocked Red Sea has a high salinity level and 41 along with hot and dry regions, where evaporation is high, their salinity level reaches to 70 sometimes.

What is the term salinity?

Salinity is expressed as the amount of salt in grams dissolved in seawater per 1000 gm.

What are the controlling factors of salinity?

The factors affecting the amount of salt in different oceans are called controlling factors of oceanic salinity. Evaporation, precipitation, the influx of river water, prevailing winds, ocean currents and sea waves are significant controlling factors.

Report An Error

UPSC Exams

Latest Update

Coaching

UPSC Current Affairs

Syllabus

UPSC Notes

Previous Year Papers

Mock Tests

UPSC Editorial

Bilateral Ties

Books

Government Schemes

Topics