4.8 Impact of water pollution

Question 1

What are the Impacts of water pollution?

(6)

Answer 1

• global inequalities in sewage and water treatment
• risk of infectious bacterial diseases, typhoid and cholera
• accumulation of toxic substances from industrial processes in lakes and rivers
• bioaccumulation of toxic substances in food chains
• the effect of acid rain on organisms in rivers and lakes
• nutrient enrichment leading to eutrophication

Question 2

global inequalities in sewage and water
treatment

Answer 2

developing countries have difficulty treating water and sewage compared to developed countries (they have the technology and resources to construct one) as people aren’t educated and can’t put pressure on the government.

Question 3

risk of infectious bacterial diseases, typhoid and cholera

Answer 3

• water-borne diseases are caused by drinking contaminated water
• once contaminated, bacteria have room to thrive, increase in population

Question 4

accumulation of toxic substances from industrial processes in lakes and rivers

Answer 4

reduces oxygen in lakes and rivers, causing reduction in photosynthesis and death of fish and insect larvae.

Question 5

bioaccumulation of toxic substances in food chains

Answer 5

• Biomagnification of toxic substances in food chains: increases concentration of a toxic substance (e.g. mercury and pesticides) in the tissues of organisms at successively higher levels in a food chain, causing illness.
• Bioaccumulation: accumulation of a toxic chemical in the tissue of a particular organism.

Question 6

Formation of acid rain

Answer 6

1. burning fossil fuels such as coal and oil produce sulfur dioxide (SO2) and oxides of nitrogen (NOx) that are blown long distances and react with water in the atmosphere.
2. SO2 dissolves in water to form sulfuric acid, and NOx dissolves to form nitric acid that fall in the form of rain.

Question 7

the effect of acid rain on organisms in rivers and lakes

4

Answer 7

• lower pH makes the environment intolerable for aquatic life;
• Fish egg-laying is reduced, and young fish are malformed;
• Leaching of heavy metals such as aluminum and lead from the soil into the water; Aluminum clogs fish gills and causes suffocation;
• Minerals essential for life, notably calcium and potassium, are washed out of the lake or river, reducing algae growth and leaving less food for fish and other animals.

Question 8

Nutrient enrichment leading to eutrophication:

Answer 8

The process of eutrophication initiates with the overuse of fertilizer. The excess fertilizer runs off into the rivers and enter waterbodies such as lakes. The fertilizers encourages the rapid growth of algae which is referred to as algae bloom. This then results in the sunlight being blocked and reducing photosynthesis. Which directly causes aqautic plants to die. Bacteria then decomposes the dead plants which uses up oxygen present in the waterbody. This leads to fishes and other organisms dying due to lack of oxygen.