1. BIOACCUMULATION

2. Chemical Pollutants
Humans have been introducing synthetic (man-made) chemicals into the environment.
Some examples are:
PCBs (polychlorinated biphenyls) widely used in paints, plastics, lubricants up to 1977
DDT (an insecticide for mosquitos) now banned in many countries
Dichloro-diphenyl trichloroethane

3. Bioaccumulation
Bioaccumulation: a slow build up of chemicals in the bodies of organisms.

4. Some chemicals are persistent in the environment – meaning they last a long time!
These chemicals are taken up into environments and food chains and stored in fatty tissues.
DDT was used to kill insects – it persists for a long time in the environment
Spraying DDT, 1958

5. DDT
first used in WWII to protect against diseases such as typhus and malaria.
cheap and effective insecticide – was manufactured for home use.
Before it was banned in 1972 by the EPA for use in agriculture, 1,350,000,000 pounds of DDT had been made in North America.

10. Biomagnification
Biomagnification: consumers in each trophic level receive larger doses of accumulated chemicals than the one before it. .

11. Measuring Toxins Parts per 10 One in every 10 parts is contaminated
ppt
Parts per 100
pph
ppm?
ppb?
One in every 10 parts is contaminated

15. Some metals also bioaccumulate.
Lead not considered safe at any level, can cause anemia, nervous & reproductive system damage.
Cadmium is toxic to earthworms & causes many health problems in fish. Cadmium
causes lung diseases, cancer,
nervous & immune system damage
in humans
Mercury bioaccumulates in the
brain, heart & kidneys of many
animals

16. Bioaccumulation - EFFECTS
How it affects organisms:
Birth defects
Failure to reproduce
Amphibians live on both land and in the water.
Amphibians are sensitive to chemical changes in the environment and are valuable indicators species for ecosystem health

19. How BIOACCUMULATION affects ecosystems:
If an important part of the food chain cannot reproduce, the whole food chain is affected.
Keystone species = species that can greatly affect population numbers & health of ecosystem.

21. Undoing the Damage

22. Rhodococcus bacteria can biodegrade PCBs Bacteria can be used to clean
up oil spills and underground leaks

24. Bioremediation With Plants
Plants can also be used to help trap hazardous wastes such as heavy metals
The plants uptake the metals and trap them in their tissues
Plants also help stabilize by reducing wind and water erosion (that would spread contaminants).