2.3 Effects of Bioaccumulation on Ecosystems

Question 1

What is bioaccumulation?

Answer 1

The accumulation of a substance, such as a toxic chemical, in various tissues of a living organism

• many harmful chemicals cannot be decomposed naturally
• chemicals can be eaten or absorbed and sometimes cannot be removes from the organism effectively

Question 2

What are keystone species? Give an example.

Answer 2

• species that can greatly affect population numbers and the health of an ecosystem
• eg. salmon in many B.C. forest ecosystems

Question 3

What is Biomagnification?

Answer 3

• process where chemicals not only accumulate, but become more concentrated at each trophic level
• at each level, chemicals that don’t get broken down build up in organisms
• when the next animal consumes the organism with the chemical accumulation, the animal will receive a huge dose of chemical(s)

Question 4

What are PCBs?

Answer 4

• compounds that are produced by replacing hydrogen atoms in biphenyl with chlorine
• poisonous environmental pollutants that tent to accumulate in animal tissues

Question 5

What were PCBs used for and when were they banned and why?

Answer 5

• industrial and electrical appliances
• banned in 1977
• banned because of the negative environmental impact

Question 6

Why are PCBs so bad? Which animal has the largest load of PCBs?

Answer 6

• PCBs stay in organisms and environments for a very long time, suppressing the immune system and probably causing cancer in humans
• orcas

Question 7

What is a DDT?

Answer 7

A pesticide introduced in 1941 to control Mosquito populations and is still used in some places

Question 8

What is a pesticide?

Answer 8

A substance used to control populations of plant and animal pest

Question 9

Why is DDT so dangerous?

Answer 9

• it binds to soil, bioaccumulates in plants, and bioaccumulates in the fatty tissue of the fish, birds , and mammals that eat the plants

Question 10

What is chemical accumulation measured in and explain how the system works?

Answer 10

Parts per million (ppm)

- one ppm means one particle of a given substance mixed with 999,999 other particles

Question 11

What are POPs?

Answer 11

Persistent Organic Pollutants - harmful carbon containing compounds that remain in water and soil for many years

Question 12

What are heavy metals? What are 3 dangerous heavy metals?

Answer 12

• Metals that have no known vital or beneficial effects organisms, and accumulation over time in the bodies of mammals can cause serious illness
• Lead, Cadmium, Mercury

Question 13

Is lead considered safe? Where does lead come from? What can lead in humans cause? How can lead be absorbed?

Answer 13

• NO
• electronic devies (which should be recycled with caution)
• anemia (blood condition) and nervous & reproductive system damage
• absorbed through the skin, inhaled, or ingested

Question 14

What is cadmium used for? Why is cadmium dangerous? What is the main exposure to cadmium in humans?

Answer 14

• manufacture of plastics and nickel-cadmium batteries
• it is toxic to earthworms and causes many problems with fish, in humans it causes lung diseases, cancer, and nervous & immune system damage
• cigarettes

Question 15

How has mercury entered ecosystems? What adds most of the mercury in the atmosphere? Why is mercury so dangerous? (2)

Answer 15

• the burning of fossil fuels, waste incineration, mining, and the manufacture of items like batteries
• coal burning: adds 40% to the mercury in the atmosphere
• mercury bioaccumulates in the brain, heart, and kidneys in many animals
• fish bioaccumulate methyl mercury compounds, adding wish for any organisms that eat the fish, including humans

Question 16

What is bioremediation? Give an example.

Answer 16

• the use of micro-organisms or plants to help clean up chemical pollution
• eg. oil industry sometimes use bacteria to “eat” oil spills