Lesson Notes By Weeks and Term v5 - Grade 12

Lesson Video

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Performance objectives

• Describe causes, consequences, and management of one major environmental issue.
• Explain the role of human activities in global warming and climate change.
• Discuss the impact of alien invasive species on biodiversity.
• Evaluate approaches to sustainable resource management in South Africa.

Lesson summary

This week, we delve into the critical topic of human environmental interactions and responses. This isn't just abstract science; it's about understanding the very air we breathe, the water we drink, and the future of our beautiful South Africa. From the challenges of managing our limited water resources in the face of climate change to understanding the impacts of pollution on our communities, this topic is directly relevant to the health and well-being of every South African. We will investigate how human activities affect the environment and the immediate and long-term responses needed to mitigate these impacts.

Lesson notes

2. 1.

Environmental Issues in South Africa: Water Pollution Water pollution occurs when harmful substances contaminate a body of water, degrading water quality and harming aquatic life and human health. In South Africa, water scarcity is a major concern, making water pollution an especially pressing issue.

Causes: Industrial Effluent: Factories often discharge untreated or inadequately treated wastewater containing heavy metals, chemicals, and other pollutants directly into rivers and streams.

Example: Textile industries releasing dyes and chemicals into rivers in Gauteng.

Agricultural Runoff: Fertilizers, pesticides, and herbicides used in agriculture can wash into waterways, causing eutrophication (excessive nutrient enrichment). This leads to algal blooms that deplete oxygen levels, killing fish and other aquatic organisms.

Example: Excess fertilizer from maize farms in the Free State flowing into rivers and dams.

Sewage and Wastewater: Inadequate sanitation infrastructure and malfunctioning sewage treatment plants result in the release of raw or poorly treated sewage into rivers and lakes. This introduces pathogens (bacteria, viruses) that can cause diseases like cholera and typhoid fever.

Example: Sewage spills in informal settlements lacking proper sanitation systems.

Mining Activities: Acid mine drainage (AMD) is a significant source of water pollution. When water comes into contact with exposed rock containing sulfide minerals (common in gold and coal mines), it forms sulfuric acid and dissolved heavy metals, contaminating groundwater and surface water.

Example: AMD from abandoned gold mines in the Witwatersrand region impacting the Vaal River system.

Urban Runoff: Rainwater washing over streets, parking lots, and other urban surfaces picks up pollutants like oil, grease, heavy metals, and litter, carrying them into waterways.

Consequences: Threats to Human Health: Contaminated water can cause waterborne diseases, poisoning, and other health problems.

Ecological Damage: Pollution can kill aquatic organisms, disrupt food webs, and destroy habitats.

Economic Impacts: Water pollution can harm fisheries, tourism, and agriculture, leading to economic losses.

Water Scarcity: Pollution reduces the availability of clean water for drinking, irrigation, and other uses.

Management Strategies: Stricter Environmental Regulations: Implementing and enforcing stricter regulations on industrial discharges, agricultural practices, and mining activities.

Improved Wastewater Treatment: Investing in modern and efficient wastewater treatment plants.

Sustainable Agriculture: Promoting agricultural practices that reduce fertilizer and pesticide use, such as integrated pest management and conservation tillage.

Remediation of Acid Mine Drainage: Implementing technologies to treat AMD and prevent it from contaminating water resources.

Public Awareness and Education: Educating the public about the causes and consequences of water pollution and promoting responsible water use. 2.

2. Climate Change and the Greenhouse Effect Climate change refers to long-term shifts in temperatures and weather patterns. These shifts may be natural, but since the 1800s, human activities have been the main driver of climate change, primarily due to burning fossil fuels (like coal, oil and gas) which produces heat-trapping gases.

The Greenhouse Effect: The greenhouse effect is a natural process that warms the Earth's surface. When solar radiation reaches our atmosphere, some is reflected back to space and the rest is absorbed by greenhouse gases. These absorbed gases re-emit the energy in all directions, warming the Earth. Without the greenhouse effect, the Earth would be too cold to support life.

However, human activities are increasing the concentration of greenhouse gases in the atmosphere, enhancing the greenhouse effect and causing global warming.

Key Greenhouse Gases: Carbon Dioxide (CO2): Released from burning fossil fuels, deforestation, and industrial processes.

Methane (CH4): Emitted from agriculture (livestock, rice paddies), natural gas leaks, and decomposition of organic waste.

Nitrous Oxide (N2O): Released from agricultural activities, industrial processes, and burning fossil fuels. Fluorinated Gases (HFCs, PFCs, SF6): Synthetic gases used in refrigeration, air conditioning, and industrial processes. These are potent greenhouse gases with very long lifetimes in the atmosphere.

Deforestation: Deforestation, particularly the clearing of forests for agriculture and development, contributes significantly to climate change. Trees absorb CO2 from the atmosphere during photosynthesis. When forests are cut down, this stored carbon is released back into the atmosphere, increasing greenhouse gas concentrations. Additionally, deforestation reduces the planet's capacity to absorb CO2 in the future.