Lesson Notes By Weeks and Term v5 - Grade 12

Lesson Video

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Performance objectives

• Define and explain different types of pollution with local examples.
• Discuss the causes and consequences of deforestation in South Africa.
• Explain the impact of alien invasive species.
• Describe the greenhouse effect and climate change.
• Evaluate strategies to mitigate negative environmental impacts.

Lesson summary

The human impact on the environment is arguably the most pressing issue facing humanity today. In South Africa, this is especially critical due to our unique biodiversity hotspots, high levels of poverty, and reliance on natural resources. Understanding the consequences of our actions, from deforestation to pollution, is crucial for building a sustainable future for all South Africans. This week, we will delve into the complexities of human impact, focusing on pollution (air, water, land), deforestation, alien invasive species, and climate change. We will also dedicate time to exam-style questions and revision techniques relevant to this section of the CAPS curriculum.

Lesson notes

2.1 Pollution Pollution occurs when harmful substances (pollutants) contaminate the environment (air, water, or land).

Air Pollution: This involves the release of pollutants into the atmosphere.

Common sources in South Africa include: Burning of fossil fuels: Coal-fired power plants (like those in Mpumalanga) contribute significantly to air pollution. The burning releases sulfur dioxide (SO2), nitrogen oxides (NOx), and particulate matter (PM), which cause respiratory problems, acid rain, and smog.

Industrial processes: Factories and mines release various pollutants, including heavy metals and chemical compounds.

Vehicle emissions: Cars, trucks, and buses emit carbon monoxide (CO), NOx, and particulate matter.

Household burning: Burning wood and coal for heating and cooking in informal settlements contributes to indoor and outdoor air pollution.

Mine Dust: Dust from mine dumps can affect the surrounding areas and lead to silicosis and other respiratory ailments.

Example: A study conducted in the Vaal Triangle found that high levels of PM2.5 (fine particulate matter) were associated with increased hospital admissions for respiratory illnesses, particularly among children. This highlights the direct impact of industrial air pollution on human health in South Africa.

Water Pollution: This involves the contamination of water bodies (rivers, lakes, oceans, groundwater).

Common sources in South Africa include: Industrial effluent: Factories release untreated or poorly treated wastewater containing chemicals, heavy metals, and other pollutants.

Agricultural runoff: Fertilizers, pesticides, and herbicides used in agriculture can contaminate water sources. Eutrophication (excessive nutrient enrichment) can lead to algal blooms and oxygen depletion, harming aquatic life.

Sewage: Untreated or poorly treated sewage can contaminate water sources with pathogens (bacteria, viruses) and organic matter. This is a major problem in many South African communities.

Mining activities: Acid mine drainage (AMD) is a significant problem. AMD occurs when water flows through mine tailings (waste rock) and dissolves heavy metals and sulfates, creating highly acidic and toxic water. This pollutes rivers and groundwater.

Oil spills: Oil spills from ships or pipelines can contaminate marine environments.

Example: The pollution of the Hennops River near Johannesburg by sewage and industrial effluent is a stark example of water pollution in South Africa. The river is often choked with plastic waste and is heavily contaminated with E. coli bacteria, making it unsafe for human use.

Land Pollution: This involves the contamination of soil and land.

Common sources in South Africa include: Waste disposal: Improper disposal of solid waste (municipal waste, industrial waste, hazardous waste) can lead to soil contamination and groundwater pollution.

Mining activities: Mine tailings and slag heaps can contaminate the soil with heavy metals and other pollutants.

Agricultural practices: Excessive use of fertilizers and pesticides can contaminate the soil.

Industrial accidents: Chemical spills and leaks can contaminate the soil.

Example: The illegal dumping of industrial waste near residential areas in Gauteng poses a significant threat to human health and the environment. The waste can contaminate the soil and groundwater, potentially leading to long-term health problems. 2.2 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 farmland, especially for commercial agriculture.

Urbanization: Expanding cities and towns require land, often leading to deforestation.

Logging: Harvesting timber for construction, furniture, and other uses.

Mining: Clearing forests to access mineral resources.

Fuelwood collection: In some rural areas, people rely on wood for fuel, leading to deforestation.

Consequences of Deforestation: Biodiversity loss: Forests are home to a vast array of plant and animal species. Deforestation destroys their habitat, leading to species extinction.

Soil erosion: Trees help to hold soil in place. Deforestation increases soil erosion, which can lead to land degradation and sedimentation of rivers.

Climate change: Trees absorb carbon dioxide (CO2) from the atmosphere. Deforestation releases CO2 into the atmosphere, contributing to climate change.

Water cycle disruption: Forests play a crucial role in the water cycle. Deforestation can reduce rainfall and increase the risk of drought.

Example: The clearing of indigenous forests in KwaZulu-Natal for sugarcane plantations has resulted in significant biodiversity loss and soil erosion. This illustrates the negative impacts of deforestation on South African ecosystems.