Human Influences on Ecosystems

Question 1

Acid rain

Answer 1

Acid rain:
- Causes: burning fossil fuels - contain impurities => sulfur dioxide + nitrous oxide are formed and dissolved in rainwater to produce acid rain
- Effects: leads to death of organisms. Acidification of lakes and rivers
- Solutions:
+ Catalytic converter
+ Low sulfur fuels
+ Chimney gas desulfurisation

Question 2

Eutrophication

Answer 2

• Fertilisers leach into the water surroundings
• It encourages growth of algae
• Algae grows and covers the surface of wtaer
• Sunlight is blocked and cannot reach the plants underneath
• Plants die because they cannot perform photosynthesis
• Decomposers such as bacteria feed on the dead
• Level of oxygen decreases because they use it to respire and reproduce
• Organisms are killed due to low concentration of oxygen

Question 3

Deforestation

Answer 3

• The removal of large areas of forest to provide land for
  farming and roads, and to provide timber (wood) for building, furniture and fuel.
• Effects:
• Reduction of habitats or food sources for animals, which can result intheir extinction. Animal and plant diversity is reduced, and food chains are disrupted.
• Desertification can eventually occur.
• Lack of roots and soil => flooding and mudslides. .
• Less CO2 is absorbed from the atmosphere, more
  CO2 build up à increase the greenhouse effect.

Question 4

Environmental Pollutants

Answer 4

1.12.14 the table

Question 5

Discuss the effects of non-biodegradable plastics in the environment

Answer 5

• Cannot be decomposed
• Aquatic animals may suffer from choking it or being entangled
• Relase toxins => adverse effects
• Block light for photosynthesis
• May block flow of water => reduce concentration of dissolved oxygen

Question 6

Explain how increases in greenhouse gases (carbon dioxide and methane) are thought to cause global warming

Answer 6

• Solar radiation passes through the atmosphere and warms the Earth’s surface
• Earth radiates heat energy back into space (mainly infra-red radiation)
• Heat energy is absorbed by greenhouse gases => global warming => rising sea levels in the Arctic and Antarctica => flood and natural disasters

Question 7

Describe the need for conservation of:
• species and their habitats
• natural resources (limited to water and nonrenewable
materials including fossil fuels)

Answer 7

• Ecosystems help to maintain the balance of life on the planet
• Provide food and fuels, substances such as medicines
• Wide variety of organisms => diversity

Question 8

Sewage treatment

Answer 8

• Primary treatment: remove large solids (filter or screens)
• Secondary treatment: use microbes and bacteria to decompose organic materials with aeration or trickle filter
• Tertiary treatment: remaining organic materials from sludge => sludge settles and water leaves plants. Treated with chlorine/ozone => collection of water from evaporator
  16. 3.15