Bioaccumulation Lesson 6
Bioaccumulation • An increase in the concentration of a chemical in an organism over time, compared to the chemical's concentration in the environment. • Occurs naturally • And necessary for certain minerals and macromolecules
Bioaccumulation Problematic when bioaccumulate are toxins • Common toxic chemicals in our environment: • Mercury mad hatters, tuna • DDT insecticide, 1970’s,eagles • Lead gasoline • PCB whales & belugas • Strontium 90 – fallout from atomic bombs
Biomagnification • The increased concentration of a toxic chemical the higher an animal is on the food chain. • The higher an organism on the food pyramid the larger the concentration of chemicals
Example • Suppose an osprey eats 300g of fish per day. The fish tissue consumed by the osprey has an average DDT concentration of 0.0001g/g. How much DDT is the osprey consuming in one day? • 300g of fish x 0.00001 g/g of fish = 0.0003g of DDT per day for the osprey
Now, suppose a bald eagle also eats 300 g of food per day. But, the bald eagle eats seal carcasses that have washed up on the beach. • The seal had eaten fish-eating fish with 0.0001g/g of DDT in their tissue. Much of the seal’s body is made up of blubber, and DDT bioaccumulates in the seal. So, the seal now has 0.0002 g/g of DDT in its tissue.
If the bald eagle eats 300 g of seal, how much DDT does the bald eagle consume in one day? • 300g of seal x 0.0002 g/g of seal= 0.06g of DDT per day for the bald eagle
What is Mercury (Hg) • Hg is a silvery, liquid metal at room temperature • "heavy metals." • Like water, Hg can evaporate and become airborne. • Because it is an element, mercury does notbreak down into less toxic substances. • Once mercury escapes to the environment, it circulates in and out of the atmosphere until it ends up in the bottoms of lakes and oceans.
Where Does Mercury Come From? • Mercury is a naturally occurring element. • Mercury ore - cinnabar - is mined
Mercury enters the environment from: • Natural sources such as volcanoes and the weathering of rocks; • Our intentional uses of mercury; • Our unintentional releases of mercury from burning fossil fuels and smelting metals. • CFL • E-waste
Questions: • In your own words, explain what bioaccumulation is • How does biomagnifications • Develop a food chain for the James Bay low lands that could potentially have biomagnifications happening.