1. Unit E: Fresh and Saltwater Systems
Science 8
Science 8 Unit E Section 1.0

2. Humans depend on water supply and quality.
Section 1.0
Humans depend on water supply and quality.
Science 8 Unit E Section 1.0

3. The Distribution of Water on Earth
Topic 1.1
Science 8 Unit E Section 1.0

4. A Unique Planet
Earth is unique among the planets because _____of its surface is covered with water.
It is often called the “water planet” or the “blue planet.”
Science 8 Unit E Section 1.0

5. Drinking Water
Water that humans can drink safely is called _____________.
Only a tiny amount of water on Earth is potable. In fact, only about ______% of all the water on Earth is available for humans to drink.
Science 8 Unit E Section 1.0

6. Water on Earth _______% of the water on Earth is salt water.
_______% of the water on Earth is fresh water.
Most of the fresh water is locked in icecaps and sea ice in the Arctic and the Antarctic.
And not all of the water underground, and in lakes, rivers, and wetlands is accessible.
The remaining fresh water may be too far below Earth’s surface or in places where humans don’t live.
_______% of the water on Earth is salt water.
Water on Earth
Science 8 Unit E Section 1.0

7. Imagine that you had 1000 glasses of water in front of you, representing all the water on Earth. Less than one-third of one glass would represent all of the drinking water that humans have access to!
Science 8 Unit E Section 1.0

8. Earth’s Water Distribution
Science 8 Unit E Section 1.0

9. Fresh Water = 3% Salt Water = 97%
Science 8 Unit E Section 1.0

10. Of the 3% fresh water, 77% is ice 22% is groundwater
1% water in lakes, rivers, and wetlands
Science 8 Unit E Section 1.0

11. Homework!
Workbook
Page 2
# 5 - 7
Unit A - Section 1.0

12. Water Quality
Topic 1.2
Science 8 Unit E Section 1.0

13. Water Quality
When you turn on your tap, you expect your glass to fill up with clear water that has no unpleasant odour or taste.
In Canada, we expect the quality of our water to be good all the time.
Water quality describes how pure the water is.
You can determine water quality by measuring the amount of substances besides water that are in a water sample.
Science 8 Unit E Section 1.0

14. Substances Dissolved in Water
Many different substances are dissolved in both fresh and salt water. Most of these substances are called salts.
The most common salt dissolved in water is sodium chloride—the same mineral we use for table salt.
The total amount of all salts dissolved in water is called its _________.
Seawater (water in the oceans) has a much higher salinity than fresh water.
Seawater’s average salinity is 3.5%.
Seawater also contains many other substances in much smaller amounts – including gold and silver!
Science 8 Unit E Section 1.0

15. Hard Water
____________ contains a high concentration of the minerals _______ and ________ .
You can tell that you have hard water if soap doesn’t lather properly. Hard water also leaves mineral deposits in appliances such as kettles and hot water heaters.
Science 8 Unit E Section 1.0

16. Organisms in Drinking Water
__________also contains organisms and other organic matter.
Some of the substances and organisms that may be found in water are harmful and some are not.
For example, Escherichia coli, known as E. coli, is a type of bacteria that can cause sickness and even death. Usually, our water treatment processes prevent these organisms from becoming a problem.
Science 8 Unit E Section 1.0

17. Water Quality Testing
Well water comes from ______ __________, and so it is protected from most pollutants—both natural and human- made.
Most cities and towns get their drinking water from surface sources, either lakes or rivers. They then filter this water and treat it with __________.
This processing brings it to a level of quality that is safe for human use.
Such water must be tested regularly to make sure that it is potable.
Science 8 Unit E Section 1.0

18. Let me introduce you to my little friend…_______!
Named after French zoologist Alfred Mathieu Giard.
Giardia lives inside the intestines of infected humans or other animals. Individuals become infected through ingesting or coming into contact with contaminated food, soil, or water.
The symptoms of Giardia, include violent diarrhea, excess gas, stomach or abdominal cramps, upset stomach, and nausea. Resulting dehydration and nutritional loss may need immediate treatment.
Giardia causes a disease called Giardiasis (or “Beaver Fever”,  which causes the villi of the small intestine to atrophy and flatten, resulting in malabsorption in the intestine. Lactose intolerance can persist after the eradication of Giardia from the digestive tract.
Science 8 Unit E Section 1.0

19. Water Testing Criteria
______ ________is not always a sign of clean water! So, drinking water is tested for:
taste and odour
turbidity (cloudiness) and colour
toxic substances and other pollutants
_______
hardness or mineral content
pH (how acidic or basic the water is)
___________ oxygen
solids, including floating materials
_________ __________
Science 8 Unit E Section 1.0

20. Recall: Salt Water
Much of the fresh water is locked up in icecaps and glaciers. Only a _______ percentage of liquid fresh water is available for drinking.
In some areas of the world, very little fresh water is available, but there is lots of salty water.
Is there a way to use salty water for drinking?
Salt water must be processed to remove the salt to make the water potable. The two most common processes used for producing fresh water from salt water are ___________ and_______ _______.
Science 8 Unit E Section 1.0

21. Distillation
Distillation equipment produces pure water (_______ ______) from water that may contain minerals, such as salt, and other substances.
In ____________, the solution is boiled so that the water evaporates and leaves the salt behind. Liquid fresh water is then formed from the water vapour.
Science 8 Unit E Section 1.0

22. Distillation Apparatus
Science 8 Unit E Section 1.0

23. Reverse Osmosis
_________ ________ operates by forcing salt water through a filter or membrane with holes too small for the salts to pass through.
Recall that _________ is the movement of water particles through a membrane.
The particles move from an area of higher water concentration to one with a lower water concentration.
In reverse osmosis, the water moves from an area of ______ water concentration to one of ________water concentration.
In this way, the water leaves behind the unwanted dissolved substances.
Science 8 Unit E Section 1.0

24. Reverse Osmosis
Science 8 Unit E Section 1.0

25. Homework!
Workbook
Page 4
# 16 – 20
Unit A - Section 1.0