2. Bioaccumulation
• The accumulation of a substance like
pesticides (DDT), methylmercury or other
organic chemicals in an organism or part
of an organism(tissue) is called
bioaccumulation.
● Bioaccumulation refers to the gradual
build-up of pollutants in living organisms.
3.
4. Explanation
● It is increase in concentration of a pollutant
from the environment to the first organism in
a food chain.
● Organisms at any trophic level may be
capable of bioaccumulation.
● The affected organism has a higher
concentration of the substance than the
concentration in the organism surrounding
environment.
5. ● Bioaccumulation is the net result of
the interaction of uptake,storage and
elimination of a chemical.
● The substances enter the organism
through respiration, food intake,
epidermal contact with substances and
other means.
7. Organismal accumulation
● Compounds present in an
organism's environment may
concentrate in the body over time.
● For example, fish that swim
frequently in contaminated water
may build up pollutants in their
fatty tissues.
8. Trophic transfer
● The accumulated substance transfer from
one trophic level to other
● Higher the the trophic level, highr the
concentration of pollutant
● For example: Organisms at the top of the
food chain as humans or polar bears, can
receive the highest concentrations.
9. Soil accumulation
● Accumulants, toxic substances etc
that are dumped into surrounding
from specific waste site, bind to
soil particles and persist until they
are removed through erosion,
uptake by plants or
microorganism.
10. Factors on which bioaccumulation
depends
● Uptake of substance
● Storage of substance, storage capacity
● Elimination of substance
● Hydrophobicity
● Concentration of pollutant in water
● Age, sex and type of organism
11. Rate of accumulation
● Accumulation is measured in parts per
million (ppm).
● This refers to one particle of a given
substance mixed with 999 999 other
particles.
● eg oysters can concentrate DDT from
0.001 ppm in sea-water to 700ppm in
their bodies.
12. Biomagnification
● The tendency of pollutants to concentrate as
they move from one organism to the next is
called biomagnification.
● It is the increase in concentration of a
pollutant from one link in a food chain to
another.
● It is the process in which pollutants not only
accumulate, but also become more
concentrated at each trophic level.
13. Expalanation
● Characters of pollutants:
long lives, biologicaly active,mobile, soluble
in fats
● Biomagnification is simply increase in concentration of
substance in a food chain, not in organism.
● Conservative pollutants are not metabolized and therefor
when an organism containing a pollutant is eaten, they are
simply passed on to predator and accumulate in its tissue.
14. pathway for biomagnification
● Pollutants enter organisms via
different routes eg. though the mouth
and digestive tract or across gill
surfaces.
● Small aquatic organisms absorb most
toxins directly from the water
16. Leaves eaten by
caterpillar
Caterpillar eaten by
Frog
Frog eaten
by Hawk
Seeds sprayed to
protect them from
invertebrates
Seeds eaten
by finch Finch eaten by
Hawk
Pesticide soaks
into the soil
Pesticide absorbed
by earthworm
Earthworm eaten
by Blackbird
Blackbird eaten
by Hawk
Spray lands on tree
leaves
17. The Effect of the Pollutant
● Human activity creates many harmful
pollutants.
● Pollutants are taken up by plants.
● The pollutants are then transferred
along the food chain until they reach
the highest trophic level.
18.
19. Synergism
● Organisms may ingest or absorb more than one pollutant at a time. Two
pollutants may interact to produce a toxic effect which is greater than the
combined effect of the two pollutants simply added together i.e. one of the
pollutants may increase the mortality caused by the other. This is called
synergism.
● e.g High concentrations of lead, zinc and mercury are each capable of
slightly reducing the growth rate of aquatic protozoa, but when acting
together the overall effect is much higher.
20. Important pollutants
● POP
● PCB
● Heavy metals
● POP(persistent organic pollutants)
POPs are harmful, carbon-containing compounds that
remain in water and soil for many years. E.g. DDT
21. DDT
● DDT(dichloro diphenyl trichloroethane)
● a toxic POP that was used as a pesticide to control disease carrying
mosquitoes.
● Effects:
low toxicity to humans but high toxicity to insects.
It does bioaccumulate and biomagnifies
damage the organism's health and decline in wildlife population.
potentially carcinogenic
cause type2 diabetes
pencreatic cancer
22.
23. PCBs (polychlorinated biphenyls)
● PCBs were once widely used in industrial products but are now banned in
North America. PCBs were used in the manufacture of paint, plastics and
adhesives.
● PCBs are chemically stable, hydrophobic and lipid soluble, hence they can
rapidly bioaccumulate.
● Effects :
Aquatic ecosystems are most sensitive to PCBs. Organisms at high
trophic levels, like the orca, retain high levels of the pollutant.
Caused the decline of European Otter and population of Seal.
interfere with the hormonal control of oestrus and ovulation, seriously
reducing reproductive ability and weaken the immune system of marine
mammals.
In humans, PCBs may increase the risk of anaemia and
susceptibility to infectious diseases.
24. Heavy metals
● Heavy metals enter the biosphere, they do not
degrade, and they can not be destroyed.
● Mercury, cadmium, lead and tin are the heavy
metals most frequently endangering human
health.
● All enter the food chain through industrial
waste and bioaccumulate in aquatic and
marine environments.
25. Mercury
● Almost all mercury compounds are toxic and can be
dangerous at very low levels in both aquatic and
terrestrial ecosystems.
● The most important pathway for mercury
bioaccumulation is through the food chain.
● In the water, plants and small organisms like plankton
take up mercury through passive surface absorption or
through food intake.
26. Methylmurcury
● In the environment, particularly lakes, waterways and wetlands,
mercury can be converted to a highly toxic, organic compound
called methylmercury through biogeochemical interactions.
● Methylmercury biomagnifies through the food chain as
predators eat other organisms and absorb the contaminants that
their food sources contained.
● Effects
It can cross the blood-brain and placental barriers,
allowing it to react directly with brain and fetal cells.
Methymurcury concentration in fish may also be affected
to humans.
