Transcript Bioaccumulation and Biomagnification

Bioaccumulation
and
Biomagnification
Bioaccumulation vs. Biomagnification

Bioaccumulation:


Biomagnification:



The increase in concentration of a substance
greater than the outside environment
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
0
15
30
45
60
75
90
105
120
Amount Remaining
100 kg
50 kg
25 kg
12.5 kg
6.25 kg
3.13 kg
1.56 kg
0.78 kg
0.39 kg
So, 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
ppm = parts per million
As the DDT moves up the food chain – there is
a greater conc. 2 ppm
3 ppm
4 ppm
7 ppm
17 ppm
Bioaccumulation occurs in each
organism since the DDT is in > conc.
than in the environment
17 ppm
Biomagnification occurs across the food chain
Notice how the DDT concentration increases it moves
up 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 DDT
Biomagnification of Other Pollutants
Substance
Use and Problems
PCB’s

Heavy Metals
Mercury, Copper, Cadmium,
Chromium, Lead, Nickel, Zinc,
Tin
Mercury
Cyanide
Used
insulators in transformers
Fire retardant
Impairs reproduction
Widespread in aquatic systems
from gold mining
Many from metal processing
May affect nervous system
May affect reproduction
in leaching of gold
Used in fishing
Toxic
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.
Internet Video Link

Biocourse Bioaccumulation Link
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."