Bioaccumulation - DDT & Mercury
Science: KS3, topic 1.3.23
Bioaccumulation
In food webs, toxins can enter the system and build up in organisms. The build up of these toxins in organisms is called bioaccumulation. Mercury and DDT can bioaccumulate.
Bioaccumulation of DDT
- Chemicals that have been researched to bioaccumulate in the environment include DDT.
- DDT is an insecticide.
- DDT caused the shell weakening of birds of prey it bioaccumulated in.
Bioaccumulation of mercury
- Mercury can bioaccumulate.
- Mercury is used to prevent barnacles growing on ship hulls.
- Mercury found its way into fish and has even been discovered in humans.
- Mercury has also entered the marine ecosystem from burning fossil fuels.
Mercury in humans
- Mercury levels in tuna have been monitored since the 1970s.
- Mercury levels are reported as being stable.
- Stable mercury levels are a concern as humans eat a lot of tuna.
- Higher levels of mercury affect the nervous system and the brain.
- Mercury can also affect the development of unborn babies if accumulated in pregnant women.
How mercury bioaccumulates
- Mercury is absorbed by plankton once it reaches their environment.
- Small fish eat the plankton.
- Tuna eat the small fish.
- Tuna are caught and eaten by humans.
Test yourself on Bioaccumulation - DDT & Mercury
Which of these organisms is eaten by tuna?
Select the true statement
Why is it still a concern that mercury levels in tuna have stayed stable since the 1970s?
How could mercury from ship hull paint end up inside a tuna?