Lesson Notes By Weeks and Term v5 - Grade 12

Lesson Video

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Performance objectives

• Explain the causes and consequences of pollution in South Africa.
• Describe the impact of deforestation and loss of biodiversity.
• Discuss alien invasive species and their control methods.
• Analyse waste management challenges and solutions.
• Apply knowledge to answer exam-style questions.

Lesson summary

The impact of human activities on the environment is a critical issue, especially in South Africa. From our reliance on coal for energy to the challenges of water scarcity and waste management, our actions have profound consequences for the ecosystems and communities around us. Understanding these impacts is not just an academic exercise; it's essential for making informed decisions about sustainable living, resource management, and environmental conservation.

Lesson notes

2. 1. Pollution (Air, Water, and Land)

Air Pollution: Causes: Burning of fossil fuels (coal for electricity generation – Eskom power stations!), industrial emissions, vehicle emissions (especially in urban areas like Gauteng), burning of biomass (veld fires, agricultural burning), mining activities (dust).

Consequences: Respiratory illnesses (asthma, bronchitis), acid rain (damages ecosystems and infrastructure), climate change (greenhouse gas emissions – CO2, methane), smog (reduced visibility and health problems), ozone depletion (increased UV radiation).

South African Context: High levels of air pollution in industrial areas (e.g., Secunda, Sasolburg) and densely populated townships due to coal burning for heating and cooking. Acid mine drainage contributes significantly to air pollution.

Water Pollution: Causes: Industrial effluent discharge (chemicals, heavy metals), agricultural runoff (pesticides, fertilizers), sewage discharge (untreated or poorly treated), mining activities (acid mine drainage), oil spills, littering.

Consequences: Eutrophication (excessive nutrient enrichment leading to algal blooms and oxygen depletion), contamination of drinking water sources (health risks), harm to aquatic ecosystems (fish kills, loss of biodiversity), bioaccumulation (toxins building up in the food chain).

South African Context: Water scarcity is exacerbated by pollution. Acid mine drainage is a major problem in Gauteng and Mpumalanga, polluting rivers and groundwater. Illegal dumping and inadequate sanitation infrastructure contribute to water pollution in many communities. Eutrophication is an increasing problem in dams and rivers.

Land Pollution: Causes: Mining activities (land degradation, toxic waste), industrial waste disposal (hazardous chemicals), agricultural practices (pesticide overuse, soil erosion), improper waste management (landfills, illegal dumping).

Consequences: Soil contamination (reduced fertility, health risks), habitat destruction (loss of biodiversity), groundwater contamination (health risks), visual pollution (aesthetic degradation).

South African Context: Extensive land degradation due to mining (e.g., gold and coal mining), particularly in areas with historical mining activity. Inadequate waste management infrastructure leads to illegal dumping and soil contamination. 2.

2. Deforestation and Loss of Biodiversity Deforestation: The clearing of forests for other land uses (agriculture, urban development, logging).

Consequences: Habitat loss (loss of biodiversity), soil erosion, climate change (reduced carbon sequestration), altered water cycles, increased flooding.

South African Context: Deforestation occurs for agriculture (e.g., sugarcane plantations), urban expansion, and illegal logging (especially in indigenous forests). Loss of indigenous forests threatens biodiversity hotspots.

Loss of Biodiversity: The decline in the variety of life on Earth, including species, genetic diversity, and ecosystem diversity.

Causes: Habitat destruction, pollution, climate change, invasive species, overexploitation of resources (e.g., overfishing, poaching).

Consequences: Ecosystem instability, loss of ecosystem services (e.g., pollination, water purification), reduced food security, increased vulnerability to disease.

South African Context: South Africa is a biodiversity hotspot, but faces significant threats to its biodiversity due to habitat loss, pollution, and climate change. Poaching of rhino and other endangered species is a serious problem. 2.

3. Alien Invasive Species Definition: Species that are introduced to an area outside their native range and cause harm to the environment, economy, or human health.

Impacts: Competition with native species (for resources), predation on native species, habitat alteration, disease transmission, economic damage (e.g., agricultural pests).

Examples in South Africa: Water Hyacinth (Eichhornia crassipes): Clogs waterways, impedes navigation, reduces oxygen levels in water.

Black Wattle (Acacia mearnsii): Outcompetes native vegetation, depletes water resources. Australian Red Claw Crayfish (Cherax quadricarinatus): Predation on native aquatic species.

European Starling (Sturnus vulgaris): Competes with native birds for nesting sites.

Control Methods: Biological Control: Using natural enemies (e.g., insects, fungi) to control invasive species.

Chemical Control: Using herbicides or pesticides (carefully applied to minimize environmental impact).

Mechanical Control: Removing invasive species by hand or using machinery (e.g., cutting down trees, pulling out weeds). 2.

4. Waste Management Challenges: Increasing volumes of waste, limited landfill space, pollution from landfills, lack of recycling infrastructure, illegal dumping. Sustainable Solutions (The Waste Hierarchy): Reduce: Minimize waste generation at the source (e.g., use less packaging, avoid single-use items).