water
pollution experiment
The plumbing system in most homes
carries the water that has been used and is flushed or drained away
to the sewage treatment works. In Cornwall the company responsible
for supplying water and treating it after use is South West Water
- click here
to visit SWW website
Sometimes waste gets into the
water cycle and cannot be treated by the water company because it
enters a river or the sea directly. In this case water can become
polluted and cause problems for plants and animals living in and
near the water, and all the life that relies upon water to survive.
Here is an experiment for you
to do that will help show how this happens.
For this experiment you will
need:
• A glass jar half filled
with tap water
• A couple of drops of car engine oil
• Some cotton wool
• Some washing-up liquid
• A pipette
Your glass jar half filled with tap water represents your local
river. What is this river called? Look on an OS Explorer map to
find out the name or look on the Cornwall Rivers map (B04k).
At the moment the river is not
polluted and it could provide a home for many different animals
if the other conditions around the river offer the right habitat
for them. Aquatic invertebrates, birds, fish and mammals would not
be an unlikely sight.
• Rub the unpolluted water
between your fingers, remember what this feels like. Look closely
at the surface of the water, remember how clear it is.
• Write down what the water
felt and looked like.
• Now put a couple of drops
of engine oil into the water. This represents someone putting oil
directly into a river or dumping it in a place where it will find
its way into a river, for example through fly tipping (W02).
Engine oil should be taken to
a council rubbish site where it will be disposed of properly. You
might have heard about oil spills caused by large ships off the
coast of Britain and other parts of the world. This can cause a
tremendous amount of suffering to sea birds, fish and other sea
creatures not to mention the effect on animals that use the beaches
where oil is washed ashore. For more information go to the Ocean
Link website or Global
Marine Oil Pollution website
• Using the pipette and
the cotton wool you are going to try and carry out a ‘clean
up’ operation to take out all of the oil from the water. You
will have to be very careful in doing this. The oil will settle
on top of the water after a few moments (why is this?) this will
help you to remove it.
• Rub the water between
your fingers after you have completed your ‘clean up’
operation. Does the water feel like it did before the oil was put
into it or can you feel the oil in it? Can you see a film on the
top of the water?
• Write down how the water
feels and looks now.
• How might the oil affect
the birds landing on the surface of the water?
Even if you have done a really
careful job of cleaning up all the oil, there will still be some
left in the water. Think about how difficult it would have been
to remove any of the oil if the water had been flowing like in a
river or if there had been waves and tides like in the sea!
Sometimes detergent is used to
break up oil when there has been a spill.
• Add some washing up liquid
into the water and feel the water. Keep on adding detergent until
the water no longer feels oily. How much did you need to use? Compare
this to the amount of oil that was put into the water.
The detergent might have broken
down the power of the oil to create a film over the water and to
coat plants and animals but it hasn’t made the oil go away
and now there is detergent in the water as well!
• What affect might detergent
have on the plant and animal life found in a river? (W05)
It is better to prevent pollution
than try and clean it up after it has happened.
• Use your findings to
create a poem about the way oil affects water and the plants and
animals that live in watery habitats like ponds, lakes, rivers,
streams and other wetland areas.
• You can send your
poem to the Westcountry Rivers Trust (B05)
and the best ones will appear on the website.
|
