13.5 environmental issues of using Nitrogen containing fertilisers

Question 1

species diversity reduction

Answer 1

nitrogen rich soils favour the growth of grasses, nettles and other rapidly growing species. outcompete many other species which die as a result

Question 2

leaching

Answer 2

process by which nutrients are removed from the soil
Rainwater dissolves soluble nutrients e.g. nitrate ions carrying them deep into the soil beyond the reach of plant roots
Leached nitrate ions find their way into water courses

Question 3

dangers of leaching

Answer 3

if river or lake is a source of drinking water high nitrate ion concentration can prevent efficient oxygen transport in babies and is linked to stomach cancer
can also cause eutrophication

Question 4

eutrophication

Answer 4

nutrient increase in bodies of water

1. most lakes and rivers have a low concentration of nitrate ions (nitrate ions are a limiting factor for plant and algal growth)
2. leaching causes an increase in nitrate ion concentration. plant and algal growth
3. algae mostly grow at the surface of water. upper layer of water becomes densely populated with algae (algal bloom)
4. algal bloom absorbs light preventing it penetrating lower depths
5. light becomes a limiting factor for plant and algal and they die
6. saprobiontic bacteria eat dead algae and plants- population grows.
7. saprobiontic bacteria require oxygen for respiration-increased demand for oxygen
8. concentration of oxygen reduced and nitrates released from dead organisms
9. oxygen becomes a limiting factor for aerobic organisms (fish) causing them to die
10. without aerobic organisms less competition for anaerobic organisms whose population now rises
11. anaerobic organisms further decompose dead material, releasing more nitrates and some toxic wastes such as hydrogen sulphide. water is now putrid

Question 5

main cause of eutrophication

Answer 5

artificial fertilisers