bioaccumulation and biomagnification. bioaccumulation vs. biomagnification bioaccumulation: the...
TRANSCRIPT
Bioaccumulation vs. Biomagnification
Bioaccumulation: 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
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
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:
Year Amount Remaining
0 100 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 kgSo, after 100 years, there will still be about a kg of DDT in the environment!
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
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
Since the next organism (beetle) will eat several water boatmen, it will accumulate greater concentrations of DDT
Bioaccumulation
17 ppm
Notice how the DDT concentration increases it moves up the Food chain
Biomagnification occurs across the food chain
• 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.
Biomagnification of Other Pollutants
Substance Use and Problems
PCB’s insulators in transformersFire retardantImpairs reproductionWidespread in aquatic systems
Heavy MetalsMercury, Copper, Cadmium, Chromium, Lead, Nickel, Zinc, Tin
Mercury from gold miningMany from metal processingMay affect nervous systemMay affect reproduction
Cyanide Used in leaching of goldUsed in fishingToxic
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.
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
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."