Heavy Metal Pollution
- Heavy metals may be present in some types of pollution, e.g.
- Industrial processes such as mining can release metals such as lead, arsenic and copper into the environment
- Arsenic and lead, among other heavy metals, have also been found in chemical pesticides
- These heavy metals can be washed from mining sites and agricultural fields into the natural environment, e.g. into lakes and ponds
- The metals enter food chains when they are taken up by plants and passed on to animal consumers
- Heavy metals do not degrade inside cells, so when organisms take up or consume these elements over extended time periods they can build up inside the tissues; this is known as bioaccumulation
- While heavy metals may not be harmful in small doses, they can become toxic to living organisms at higher concentrations, resulting in fertility loss and/or death
Bioaccumulation diagram
Bioaccumulation is the build up of pollution inside the tissues of an organism over time
Examiner Tip
Note that heavy metals can also build up as they are passed up the food chain; organisms higher up the food chain are likely to receive a higher dose as they eat several organisms from the trophic level below. This is slightly different to bioaccumulation, and is known as biomagnification; this can also result in the death of organisms from heavy metal toxicity.
