Lesson Notes By Weeks and Term v5 - Grade 12

Lesson Video

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Performance objectives

• Explain the causes & consequences of water and air pollution in SA.
• Discuss the impact of deforestation & loss of biodiversity.
• Describe climate change and its potential impact on South Africa.
• Analyse waste management strategies.
• Evaluate conservation efforts and sustainable development.

Lesson summary

The impact of human activities on the environment is one of the most pressing issues facing our world today. As Grade 12 Life Sciences learners in South Africa, you are inheriting a country and a planet facing significant environmental challenges. From water scarcity exacerbated by pollution and climate change, to the loss of biodiversity in iconic landscapes like the Kruger National Park due to poaching and habitat destruction, these issues directly affect your future. Understanding the science behind these problems, and potential solutions, is crucial for you to become informed and responsible citizens.

Lesson notes

2.1 Water Pollution: Water pollution occurs when harmful substances contaminate water bodies, making it unsafe for drinking, irrigation, and other uses. In South Africa, key sources of water pollution include: Industrial Effluent: Factories release chemicals, heavy metals, and other toxins into rivers and streams.

Example:* Mining activities, particularly gold and coal mining, often release acid mine drainage (AMD). AMD contains sulfuric acid and heavy metals, contaminating water sources and harming aquatic life.

Agricultural Runoff: Fertilisers, pesticides, and herbicides used in agriculture can be washed into water bodies during rainfall.

Example:* Excess nitrates from fertilisers can lead to eutrophication, where excessive nutrients cause algal blooms that deplete oxygen levels in the water, killing fish and other organisms.

Sewage and Wastewater: Untreated or inadequately treated sewage contains pathogens and organic matter that can contaminate water sources.

Example:* Many informal settlements lack proper sanitation, leading to untreated sewage entering rivers and posing a serious health risk.

Oil Spills: Accidental spills from ships or pipelines can contaminate water bodies, harming marine life and ecosystems.

Consequences of Water Pollution: Human Health: Contaminated water can cause diseases like cholera, typhoid, and dysentery.

Ecosystem Damage: Pollution can kill aquatic life, disrupt food chains, and damage habitats.

Economic Losses: Water pollution can harm fisheries, agriculture, and tourism. 2.2 Air Pollution: Air pollution is the contamination of the atmosphere by harmful substances, such as particulate matter, gases, and fumes. In South Africa, major sources of air pollution include: Industrial Emissions: Power plants, factories, and mines release pollutants into the air.

Example:* Coal-fired power plants, which are prevalent in South Africa, release sulfur dioxide, nitrogen oxides, and particulate matter, contributing to acid rain and respiratory problems.

Vehicle Emissions: Cars, trucks, and buses release pollutants like carbon monoxide, nitrogen oxides, and particulate matter.

Example:* Traffic congestion in urban areas like Johannesburg and Cape Town leads to high levels of air pollution.

Burning of Fossil Fuels: Burning coal, wood, and other fossil fuels for heating and cooking can release pollutants into the air, particularly in informal settlements.

Mining Activities: Dust and other pollutants are released during mining operations.

Consequences of Air Pollution: Human Health: Air pollution can cause respiratory problems, heart disease, and cancer.

Environmental Damage: Acid rain can damage forests, lakes, and buildings.

Climate Change: Some air pollutants, like greenhouse gases, contribute to climate change. 2.3 Deforestation: Deforestation is the clearing of forests for other land uses, such as agriculture, urbanization, and logging. In South Africa, deforestation is driven by: Agriculture: Clearing forests for farming and grazing land.

Urbanization: Clearing forests for housing and infrastructure development.

Logging: Harvesting timber for construction and other purposes.

Firewood Collection: Collecting firewood for fuel, especially in rural areas.

Consequences of Deforestation: Loss of Biodiversity: Forests are home to a wide variety of plants and animals, and deforestation leads to habitat loss and species extinction.

Soil Erosion: Trees help to hold soil in place, and deforestation can lead to soil erosion and land degradation.

Climate Change: Forests absorb carbon dioxide from the atmosphere, and deforestation releases carbon dioxide into the atmosphere, contributing to climate change.

Water Scarcity: Forests play a crucial role in regulating water cycles, and deforestation can disrupt water supplies and increase the risk of droughts. 2.4 Loss of Biodiversity: Biodiversity refers to the variety of life on Earth, including plants, animals, and microorganisms. Loss of biodiversity is a major environmental problem in South Africa, driven by: Habitat Loss: Deforestation, urbanization, and agricultural expansion destroy habitats and reduce biodiversity.

Pollution: Water and air pollution can harm or kill plants and animals.

Climate Change: Changing temperatures and rainfall patterns can alter habitats and threaten species survival.

Overexploitation: Overfishing, hunting, and poaching can deplete populations of certain species.

Example:* Rhino poaching for their horns remains a severe problem in South Africa, driving the species towards extinction.

Invasive Species: Introduced species can outcompete native species and disrupt ecosystems.

Consequences of Loss of Biodiversity: Ecosystem Disruption: The loss of species can disrupt food chains and other ecosystem processes.

Economic Losses: Biodiversity provides valuable ecosystem services, such as pollination, water purification, and climate regulation.