How Polluted Water Gets Clean Again

Ocean Science Experiment Form
Title of Activity_________________________
Question: What do I want to find out?
Hypothesis: What do I think we will find out?
Procedure: How will I find out? (List step by step)
1. _____________________________________________
2. _____________________________________________
3. _____________________________________________
4. _____________________________________________
Result: What actually happened? _____________________
Conclusions: What did I learn?
How Polluted Water Gets Clean Again Experiment
Purpose: To demonstrate how natural materials in our environment act as
natural filters to clean contaminates from water.
Pollution – An unnatural addition to an environment or habitat. Oil is a
pollutant to soil and water. Chemicals are pollutants to soil and water as
Runoff – rainwater that flows into lakes and streams instead of soaking into
the ground.
Sediment – particles of soil
Background: Water quality is a concern for all of us. Since we use the
same water over and over again in our water cycle, communities must provide
clean drinking water for their citizens. With all of our cars, fertilizers,
garbage, and other chemical wastes, this process, which happens naturally in
nature, must be reproduced in a controlled environment.
In an ocean environment, runoff from streams and rivers bring sediment into
the ocean. Too much fresh water and sediment brought into the bays and
estuaries can upset the balance of the marine life in these areas. Small fish
that are hatched in these shallow waters can not survive these changes.
Fresh water that is contaminated with sediment, can suffocate fish, and
when it sinks to the bottom of the ocean, it covers the plants and blocks the
sunlight that they need.
This investigation simulates two methods used to solve this problem. One
methods traps the water in holding ponds where the sediment is given time
to settle to the bottom before the water is released into the river or ocean.
The 2nd method provides enough distance between the farms and cities and
the river to allow the land to filter the sediment from the water.
Materials Needed:
2 plastic funnels
Four jars
Food coloring
Gravel or pebbles
1. Mix soil and water in one jar. This water is muddy with sediment.
Mix green food coloring and water in the 2nd jar. The water
should be as green as possible. This represents dissolved
contamination in water.
2. Place one funnel over a collecting jar and fill ii with gravel. Place
the other funnel on the last jar, and fill it with wet sand (wet
sand keeps the sand from going directly into the jar).
3. Slowly pour some of the muddy water in the funnel with the
gravel. Let it seep into the jar. Did the water change? Now pour
some of the muddy water into the funnel with the sand. Let it
seep into the jar. Did the water change? Pour some of the food
coloring and water in the other funnel. Did the water change?
4. Repeat the entire procedure with the colored water. Record
their findings.
Discussion Questions (answer in Conclusions section):
Which filter sand, or gravel, cleaned the water most effectively of the mud?
Which filter cleaned the colored water most effectively? What does a
filter do?
What other types of filters could you use in the funnel (cotton, coffee
filters, charcoal)?
Buoyancy of Salt Water Experiment
Guiding Question: What does the word “buoyancy” mean? It means having
the ability or tendency to float. Why is it easier to swim in salt water than
in fresh water? Discuss with students any experience they have had
swimming in an ocean and compare it to swimming in a pool. Objects float
more easily in salt water because salt water is “thicker” or denser. There is
1 ounce of salt in every 35 ounces of water in the ocean. In the Dead Sea
the water is so salty that when the water is evaporated by the sun, the salt
that is left forms hard white columns and lumps.
Materials Needed:
Two identical glasses or clear plastic cups
Tap water
Salt water (prepare some ahead of time by adding 1 tablespoon of salt to 1
cup of water) Make sure that all of the salt dissolves.
Two fresh eggs
Data collection sheet
1. Fill one cup with tap water and the second cup with an equal amount of
salt water.
2. Have child predict what will happen when you place an egg in the tap
water. He/she should fill this in on the collection sheet.
3. Place the egg in the tap water. What happens? Record the results.
4. Have child predict what will happen when you put the other egg in the salt
water. Have him/her record the predictions.
5. Place the egg in the cup with salt water. What happens? Child should
record the results. If the egg doesn’t float add more salt.
6. Have child write their conclusions on the collection sheet.
Extensions: Try adding more salt. The egg should float higher in the cup.
Ask students how the amount of salt in water would affect a person’s ability
to swim.