Environmental issues concerning use of nitrogen - containing fertilisers

Question 1

How do nitrogen - containing fertilisers improve crop productivity?

Answer 1

They increase nitrogen availability, which boosts growth, photosynthesis, and crop yield, providing cheaper food

Question 2

What is one benefit of nitrogen - containing fertilisers?

Answer 2

They have significantly contributed to providing cheaper and more abundant food supplies

Question 3

What is a major drawback of nitrogen - containing fertilisers on biodiversity?

Answer 3

They reduce species diversity by promoting the growth of fast - growing plants like grasses and nettles, which outcompete other species

Question 4

Why do species - rich hay meadows require low soil nitrogen concentrations?

Answer 4

Low nitrogen levels allow a variety of species to compete with grasses, preserving biodiversity

Question 4

What is eutrophication, and how is it related to nitrogen - containing fertilisers?

Answer 4

Eutrophication is the over - enrichment of water with nutrients, often caused by fertiliser leaching, leading to excessive algal growth and ecosystem damage

Question 5

What is leaching?

Answer 5

Leaching is the process by which nutrients are removed from the soil by rainwater dissolving and carrying them away

Question 5

How does leaching affect plant roots?

Answer 5

Soluble nutrients, like nitrate ions, are carried deep into the soil beyond the reach of the plant roots

Question 6

Where do leached nitrate ions end up?

Answer 6

They enter watercourses, such as streams and rivers, and may drain into freshwater lakes

Question 7

How can leached nitrate ions affect human health?

Answer 7

High nitrate concentrations in drinking water can impair oxygen transport in babies and have been linked to stomach cancer

Question 8

What environmental issue is cause by leached nitrate ions?

Answer 8

They contribute to eutrophication, which damages aquatic ecosystems

Question 8

What is eutrophication?

Answer 8

Eutrophication is the process by which nutrient concentrations, such as nitrates, increase in bodies of water, often leading to ecological changes

Question 9

Where does eutrophication mostly occur?

Answer 9

It occurs primarily in freshwater lakes and the lower reaches of rivers

Question 10

What is the initial limiting factor for plant and algal growth in most lakes and rivers?

Answer 10

The naturally low concentration of nitrate ions

Question 10

What happens when nitrate ion concentration increases due to leaching?

Answer 10

Nitrate ions cease to a limiting factor, leading to increased growth of plants and algae

Question 11

What is an algal bloom?

Answer 11

An algal bloom occurs when algae grows densely at the surface of the water, forming a thick layer

Question 12

What is the process of eutrophication?

Answer 12

1) In most lakes and rivers there are low concentrations of nitrate, so nitrate ions are a limiting factor for plant.algal growth

2) Nitrate ion concentration increases due to leaching, ceases to be limiting factor, algal/plant populus grows

3) Algae mostly grows at surface of water, creating a dense layer of algae - “algal bloom”

4) Dense layer of algae absorbs light and prevents penetration to lower depths

5) Light becomes limiting factor for plant/algal growth at lower depths, death

6) Saprobiontic bacterias grow due to the increase of dead plants/algae, using them as food

7) They require oxygen for respiration, creating a demand for 02

8) Conc of oxygen in water is reduced and nitrates are released from decaying organisms

9) Oxygen becomes limiting factor for aerobic organisms, ultimately dying as oxygen used up entirely

10) Without aerobic organisms, less competition for anaerobic organisms

11) Anaerobic organisms further decompose dead material, releasing more nitrates and some toxic wastes which contaminate water