ecosystem dynamics - the impact of pollutants

Question 1

eutrophication

Answer 1

-process that occurs when excess nutrients, particularly nitrogen & phosphorous enter a body of water and become highly concentrated, leading to excess growth of organisms such as algae

Question 2

eutrophication process

Answer 2

1. farms deal with nutrient-deficient soils using fertilisers
2. fertilisers are usually enriched in nitrogen and phosphorous
3. excess nitrogen and phosphorous not absorbed by roots often are leached from soil by run off
4. run off reaches local water bodies and causes algal blooms
5. algal blooms are rapid increases in population of algae or microorganisms at the surface of a water body that blocks sunlight, causing autotrophs under the surface to die
6. algae die and are decomposed by bacteria
7. as bacteria decompose dead algae, they use large amounts of oxygen from the water. water becomes hypoxic or possibly anoxic
8. low oxygen levels do not meet respiration needs aquatic organisms die

Question 3

biomagnification

Answer 3

-sequence of processes by which higher concentrations of non-biodegradable chemical reach organisms in higher trophic levels
-occurs because biomass at a trophic level is produced from biomass ingested from lower trophic level
-concentration of chemical increases in tissue at each trophic level
-example is DDT, a pesticide

Question 4

plastic

Answer 4

-large amounts of plastic rubbish enter waterways
-many aquatic animals mistake plastic for food e.g. sea turtles
-plastic can be consumed by wildlife, causing disease & death