1. Bioaccumulation and Biomagnification

2. Bioaccumulation vs. Biomagnification
The increase in concentration of a substance greater than the outside environment
Biomagnification:
The increase in concentration of a substance as it moves through a food chain
Pro: vital nutrients such as vitamins, minerals, essential fats and amino acids
Con: pollutants, metals, pesticides

3. For Bioaccumulation to occur
The chemical must be:
Long lived – the chemical persists in the environment for long time before breaking down.
Mobile – if it will stay in one place, it is unlikely to be taken up by organisms
Fat soluble – if it soluble in water, it will be excreted by the organism
Biologically active – if it is not active biologically, it may biomagnify, but it won’t cause any problems

4. A Classic Example: DDT
DDT – dichloro-dipheny-trichloroethane (chlorinated hydrocarbon)
It has a half-life of 15 years – that means if 100 kg of DDT is used it will break down as follows:

5. Year Amount Remaining 100 kg 15 50 kg 30 25 kg 45 12.5 kg 60 6.25 kg
100 kg 15
50 kg 30
25 kg 45
12.5 kg 60
6.25 kg 75
3.13 kg 90
1.56 kg
105
0.78 kg
120
0.39 kg
So, after 100 years, there will still be about a kg of DDT in the environment!

6. DDT (cont’d) DDT – not very toxic for humans But
highly toxic to insects
In high concentrations it can cause problems in other animals
shell-thinning and feminization in birds

7. Smart Board Diagram
Students come up and interact with it

8. Here is an ecosystem, that has been exposed to DDT.
Notice how the lowest organism on the food chain has 1 part per million DDT

9. Since the next organism (beetle) will eat several water boatmen, it will accumulate greater concentrations of DDT
Bioaccumulation

10. ppm = parts per million
As the DDT moves up the food chain – there is a greater conc. 2 ppm

11. 3 ppm

12. 4 ppm

13. 7 ppm

14. 17 ppm
Bioaccumulation occurs in each organism since the DDT is in > conc. than in the environment

15. 17 ppm
Biomagnification occurs across the food chain
Notice how the DDT concentration increases it moves up the Food chain

16. The next slide takes the information from the previous slide and shows it in a trophic level diagram
Focus on the relationship between NRG pyramid and biomagnification.
Notice how as we move up the pyramid, DDT conc increase and NRG decreases.

17. Biomagnification of DDT

18. Focus on the relationship between NRG pyramid and biomagnification.

19. Biomagnification of Other Pollutants
Substance
Use and Problems
PCB’s
insulators in transformers
Fire retardant
Impairs reproduction
Widespread in aquatic systems
Heavy Metals
Mercury, Copper, Cadmium, Chromium, Lead, Nickel, Zinc, Tin
Mercury from gold mining
Many from metal processing
May affect nervous system
May affect reproduction
Cyanide
Used in leaching of gold
Used in fishing
Toxic

20. Biomagnification of Mercury
Look at the terminology.
Notice the reference to parts per million or parts per trillion.
This is a common language used to represent concentration of pollutants.

21. Internet Video Link
Biocourse Bioaccumulation Link

22. Summary Bioaccumulation and biomagnification are natural processes
Important for uptake of essential nutrients
Can also lead to build up of harmful chemicals.
In order to avoid biomagnification of undesirable substances, these substances should be immobile, water soluble, short-lived, and biologically inactive

23. Rachel Carson
"Man's attitude toward nature is today critically important simply because we have now acquired a fateful power to alter and destroy nature. But man is a part of nature, and his war against nature is inevitably a war against himself…[We are] challenged as mankind has never been challenged before to prove our maturity and our mastery, not of nature, but of ourselves."