1. POLLUTION

2. Physical Thermal (Heat)  Global Warming
Sound (Sonar)  Disrupts marine mammals
Light  Disrupts bird navigation
Garbage  Chokes & suffocates animals

3. Chemical
Acid precipitation  Acidification of soil and water (pages 70 to 75)
Heavy Metals  Biomagnification (p. 79)
Pesticides  Biomagnification (p. 80)
Fertilizers  Eutrophication (p. 78)

4. Pesticides

5. What ARE They?

6. Pesticides
Pesticides are chemicals that kill unwanted organisms, usually those that attack crops. Therefore, they are intended to help us by killing the species we don’t want.
They affect many processes of living things:
Growth
Reproduction
Neurological Development
Immune System

7. Why are they BAD for the environment?

8. Why are they BAD for the environment?
They remain in the environment for a long time, and often kill much more than what they are “intended” to kill
When humans first started to use pesticides

9. Bioaccumulation & Biomagnification
When substances (like pesticides) build up in an organism’s body throughout its lifetime, this is called bioaccumulation.
As we move up a food chain, a pesticide becomes more and more concentrated. This is known as biomagnification.

10. Biomagnification
When humans use pesticides, goes into abiotic components of the ecosystem (e.g. water, soil). It starts here in low concentration.
The producers that live in water or soil absorb these toxins into their bodies. When the primary consumers eat the producers, they are also eating the toxins, and the toxins accumulate in their body.
Every trophic level has a higher concentration of toxins, making it fatal.

11. How do pesticides affect humans?
As you have been learning throughout this course, we are very connected to ecosystems.
Think about the food we eat… how is it possible that it contains toxins from pesticides?
Video:
Note that this video is from Europe, and they have stricter rules about pesticide use that we do

12. DDT
DDT (dichlorodiphenyltrichloroethane) was a pesticide used in Canada and throughout the world up until 1970.
It was considered a miracle chemical because it killed insects that spread diseases and ruined crops. It was considered safe for humans because there were no short-term toxic effects
Therefore, it was applied to everything in mass quantities.

13. Dangers of DDT
In 1962, conservationist Rachel Carson wrote a book, Silent Spring, warning of the dangers of using pesticides such as DDT. She warned that pesticides kill species in ecosystems and would also affect human health.
Her book changed people’s attitudes towards the environment
Throughout the 1960’s, most people realized these dangers as DDT caused a huge amount of devastation because it would accumulate in top consumers
The peregrine Falcon almost became extinct because of DDT

14. Mallard Duck Eggs Affected by DDT
The DDT causes the eggs laid by many different birds to have soft shells that crack.
The baby birds then die before they hatch.

15. Consumption of DDT
While microorganisms are affected by DDT, many tend to keep it inside of them rather than dying immediately (bioaccumulation)
This causes a chain reaction, up the food chains they are in (biomagnification)
Likewise, many small creatures on land (ex. Earthworms) can accumulate DDT in their systems, which is harmful to predators that eat them

16. Effects of DDT In birds, DDT causes the thinning of eggshells.
Humans can also accumulate DDT in their bodies, where it is stored in fatty organs and can be harmful to bodily functions
Results: dizziness, seizures, respiratory illness, and immune system dysfunction

17. The DDT ban
Since the 1970s, DDT was banned in North America. Since 2001, most other countries in the world agreed to ban it.
DDT is still used in some regions, such as Africa, to kill mosquitoes that spread the disease Malaria
Some argue that the Malaria kills more humans than the DDT, so they would rather be exposed to DDT. Therefore, they still use DDT, but in small quantities.
Banning DDT has been blamed for the increase of other insects too, such as bed bugs

18. Video: http://youtu.be/kyYpwOTtaLI
Considering the benefits of DDT, do you think it is justifiable to still use it?

19. Overuse of Fertilizers leads to Eutrophication
Runoff of these chemicals into aaquatic ecosystems leads to high nitrate and phosphate concentrations which stimulate algal growth
The algae die in large numbers, decompose and deplete oxygen
Many fish die due to lack of oxygen

20. Homework
p. 80 #3 & 5
p. 85 #7, 9 to 16