Bioaccumulation Biodegradable Substances Substances that break down naturally
Bioaccumulation
Biodegradable Substances • Substances that break down naturally in the environment • Examples: – sewage, food scraps, dead organisms
Non-biodegradable Substances • Either broken down very slowly or not at all by natural means • Once they enter an ecosystem they are very hard to get rid of • Examples: – certain chemicals (eg pesticides), mercury, glass some types of plastic
Bioaccumulation • Producers can absorb non-biodegradable substances from the environment • Because they don’t break down they get stored inside the plants • Animals eat they plants and begin to store the pollutants in their body fat – over time there are stronger concentrations because the animals need to eat a lot of plants to survive • Next secondary consumers eat the primary consumers and end up with even higher concentrations • This moves up the food chain to tertiary consumers who have the highest concentration • This process is called bioaccumulation
Bioaccumulation • At each trophic level the amount of toxin increases • Eventually the levels become so high that the health of secondary and tertiary consumers is harmed – poisoning, weakness, disease, easier prey and death
Example: DDT • A very common example is DDT • Pesticide sprayed on crops for insects (1940 s) • 1950 s and 60 s birds of prey began to die out – falcons, hawks, eagles • It was banned in Canada in the 1970 s but is still present in the environment
Mad Hatters • Felt hats used to be processed using mercury. • The hatters who worked in the process built up mercury in their systems (nonbiodegradable toxin) that poisoned their nervous systems: – tremors, mood and personality alterations
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