Quackenworth Earth Science Review
SALT WATER
VS.
FRESH WATER
Where is most of the earth's water found?
More than two-thirds of the earth's water is found in its oceans and is present as
salt water. If you've ever tasted water at the beach, you've probably noticed its salty
taste. This is the same salt that people sprinkle on their food. The chemical name
for salt is sodium chloride (NaCl). The remaining water found on earth is
considered fresh and can be used by humans.
Arctic Ocean
North
America
Pacific
Ocean
Atlantic
Ocean
Africa
South
America
Pacific
Ocean
Indian
Ocean
Atlantic
Ocean
Australia
Antarctica
Where does the salt in salt water come from?
Most of the salt found in salt water came from rivers and rain that, over millions of
years, ran over rocks containing sodium chloride, or salt. The salt was then carried
into the sea by rivers and streams that flowed into the sea. This process is
continual, meaning it happens every day. Salt also enters our oceans from
underwater volcanoes, the atmosphere, and precipitation.
What is salinity?
Salinity is a measure of how much salt is in water. The water found in oceans has a
higher salinity level than fresh water, water that comes from a lake or a faucet in your
home. It should be noted that water found in your faucet or in a freshwater lake contains
salt. The salinity level, however, is not as high as the water found in our oceans.
Can you name a major ocean nearest your home?
ecosystems
estuary
fresh water
glacier
ocean
river
salinity
salt
salt water
Crossword
Puzzle
1
2
3
4
5
6
7
8
9
Use the hints to solve the puzzle.
ACROSS
5) Water found in oceans
7) Where fresh water is found
8) Found in ocean water
DOWN
1) Big body of water
2) A tributary to estuary
3) Measure of salt content
4) Where salt and fresh waters mix
9) Estuaries are important to ____________
6) Found in glaciers and icecaps
Freshwater and Saltwater Animals
Draw a picture of an animal that you find
in salt water.
Draw a picture of an animal that you find in
fresh water.
Can you think of a situation where an animal may live in fresh water and in salt water?
Explain.
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_____________________________________________________________________
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Estuaries
Estuaries are important bodies of water
where salt water from the ocean mixes with
fresh water from tributaries such as rivers,
streams, and creeks. They are generally
enclosed and are protected from the full
force of ocean winds and waves. The
Chesapeake Bay, Boston Harbor, San
Francisco Bay, Tampa Bay, and Puget
Sound are examples of estuaries in the
United States.
Typically, the salinity of an estuary is highest
where the ocean first meets the estuary
itself. As you go farther inland, the salinity
level drops and eventually, the water
becomes fresh water.
Chesapeake
Bay
Atlantic
Ocean
Estuaries are important contributors to local
ecosystems and are home to numerous
species of plants and animals. Much of the
fish and shellfish that we eat have spent
time in an estuary.
Chesapeake Bay Estuary
Answer the following questions about the map of the Chesapeake Bay Estuary.
1) According to the map, what ocean feeds into the Chesapeake Bay?
________________________________________________________________
2) What are the major tributaries to the Chesapeake Bay?
________________________________________________________________
________________________________________________________________
3) Can you identify the place on the map where the salinity level of the water would
be the highest?
________________________________________________________________
________________________________________________________________
Fresh Water
FRESH WATER
As you learned earlier, most of the earth's water is found in oceans as salt water.
Only around 3% of the Earth's water is considered fresh or usable by humans
and is found in 3 main places. Most of the fresh water, around 68%, is present in
glaciers and icecaps in Greenland and Antarctica. Groundwater is where the next
source of fresh water is found. This is water that is found deep under ground and
makes up approximately 30%. The remaining percentage of water is surface
water. This is the water that is in rivers, lakes, ponds, and swamps. Finally, a
small percentage of water is present in the atmosphere as water vapor.
THE DESALINIZATION PROCESS
Humans can drink only fresh water. However, most of the water found in the
world is composed of salt water found in oceans. Desalinization is the process of
taking salt water and turning it into drinkable fresh water. This is useful for
communities that don't have an abundant supply of fresh water. Unfortunately,
desalinization is an expensive process and is not used by many communities.
Until the high cost of desalinization decreases, humans will get most of their
water from rivers, lakes, and groundwater.
Answer the following questions about the passage above.
1) What percentage of water is fresh water?
97%
50%
3%
1%
2) Of the earth's fresh water, what percentage is
found in glaciers and icecaps?
4) A small percentage of water can also be
found in the:
atmosphere
ozone layer
space layer
target zone
5) Desalinization is a process that:
88%
turns fresh water into salt water
68%
turns drinkable water into salt water
3%
turns salt water into fresh water
97%
turns fresh water into salt water
3) Fresh water is found in glaciers, icecaps, and _______.
rivers and water plants
6) The process of desalination is not used by
many communities because it is:
old
lakes and oceans
expensive
puddles
too new
rivers, lakes, ponds, and swamps
not safe
Arctic Ocean
North
America
Salinity and Salt Water
Pacific
Ocean
Atlantic
Ocean
Africa
South
America
Pacific
Ocean
Indian
Ocean
Atlantic
Ocean
Australia
Antarctica
Salinity is a measure of how much salt is present in water. Ocean water has a
higher salinity than water found in a lake. This is true because ocean water
contains more salt.
Salinity can be measured by finding how much salt is present in 1,000 grams of
salt water. For example, if you found 2 grams of salt in 1,000 grams of salt water,
the salinity would be measured as 2 parts per thousand (ppt), or 2 ppt.
2 grams of salt per 1,000 grams = 2 ppt
Answer the following questions.
1) What does it mean if the salinity level in a sample of water was found to be 35 ppt?
2) Express the following in the proper format.
37 grams of salt in 1,000 grams of salt water: _____________________________
22 grams of salt in 1,000 grams of salt water: _____________________________
8 grams of salt in 1,000 grams of salt water: _____________________________
3) If the average salinity of salt water was 33 ppt, would a salinity level of 3 ppt
be considered salty? Explain.
Oceans and Salt Water
Land
30%
Water
70%
1) According to the graph, how much of the earth is land?
___________________________________________
2) According to the graph, how much of the earth is water?
___________________________________________
Land versus Water
on Earth
Fresh Water
(Glaciers, icecaps,
groundwater, rivers,
lakes & other)
3) Where is most of the world's water found?
___________________________________________
4) How much of the world's water is found in
glaciers, icecaps, rivers, lakes, and other bodies?
___________________________________________
Oceans
97%
Water found on Earth
5) Why is ocean water salty?