Thermal Pollution and Its Effect
on Dissolved Oxygen Lab
What is Thermal Pollution?
• What causes it?
• What does it effect?
Fish Safety
• No fish will be harmed in this lab. If your fish
dies due to your negligence, you get a zero! And
you will be known as the kid who killed their fish
for the rest of the year, so be careful!!!
• Tips to keep your fish alive:
– Be careful putting ice in the beaker….don’t give your
fish a concussion
– Do not turn the hot plate setting above 2
– Use the stir rod to keep the fish moving around
– Be careful that the temp does not go above 30
degrees C!
Tech Tips
• When using the DO probe, take the
beaker off of the hot plate
• You may not get a stable reading……if it
hovers around a range of numbers, that’s
okay, go with that
• Store the DO probe properly when not in
use
Procedure:
1.Put 500 mls of dechlorinated water to a 1000 ml beaker
2.Add one goldfish to the beaker and find the temperature of the water.
3.Using just a few pieces of ice at a time, slowly cool the goldfish down until the
temperature of the water is 15 C.
4.Allow the goldfish to calm down and carefully count how many breaths the fish
takes in a minute. (Count how many times it opens and closes the operculum, the
covering of the gills)
5.Using the dissolved oxygen probe record the percent dissolved oxygen at 15 C.
6.Place the goldfish on the hotplate and SLOWLY heat it up to 20 C. Stir the water
using the thermometer slowly so the goldfish does not lie on the bottom of the
beaker and warm up too fast. Once the water has reached 20 C take the beaker off
the hotplate and set on the lab table.
7.After allowing the goldfish to settle down, again count how many breaths the fish
takes in a minute.
8.Using the dissolved oxygen probe record the percent dissolved oxygen at 20 C.
9.Repeat steps 6 – 8 bringing the temperature to 25 C and 30 C.
10.Do not allow the water to go above 30 C or the fish could be harmed or die.
11.Allow the fish to cool back down to room temperature as you complete the
analysis.
Analysis:
1. Graph the results
2. What is the relationship between the two lines on
the graph above?
3. What is the effect of thermal pollution on aquatic
organisms?
4. What does the term anthropogenic mean?
5. What are some ways that each of us could lessen
the effect of thermal pollution on a body of water?
6. How might the presence of biological or chemical
pollution affect the outcome of the experiment?
Post-Lab Instructions
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Return the fish to the buckets
Store the DO probes as directed
Log off of the laptops
Empty the beakers
Turn off and unplug the hotplates
You can come back at 3:45 to pick up your new
pet goldfish 