Lesson Notes By Weeks and Term v5 - Grade 12

Lesson Video

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Performance objectives

• Define and explain different types of pollution in a South African context.
• Explain the causes and consequences of deforestation.
• Understand the impact of acid rain.
• Link human activities to the loss of biodiversity.
• Apply these concepts to answer exam questions.

Lesson summary

Human impact on the environment is arguably the most pressing issue facing humanity today. From the air we breathe to the water we drink and the food we eat, our actions directly and indirectly affect the delicate ecosystems that sustain us. In South Africa, this is particularly relevant. We face unique environmental challenges related to our diverse biodiversity, water scarcity, reliance on coal-fired power plants, and the legacy of historical land use practices. Understanding these impacts and developing sustainable solutions is crucial for our future. This topic builds on concepts covered in earlier grades, demanding a deeper understanding of the processes and interconnectedness involved.

Lesson notes

2.1 Pollution: Pollution refers to the contamination of the environment with harmful substances. It can affect the air, water, and soil, with severe consequences for human health and ecosystems.

Air Pollution: Air pollution is caused by the release of pollutants into the atmosphere.

Common sources include: Burning of fossil fuels: Coal-fired power plants (like those in Mpumalanga), vehicle emissions, and industrial processes release greenhouse gases (e.g., carbon dioxide, methane) and particulate matter (e.g., soot, dust). In South Africa, reliance on coal for electricity contributes significantly to air pollution.

Industrial emissions: Factories release various pollutants, including sulfur dioxide (SO2), nitrogen oxides (NOx), and heavy metals, which can cause respiratory problems and other health issues.

Agricultural activities: Ammonia emissions from livestock farming and fertilizer use contribute to air pollution.

Burning of biomass: Burning wood for cooking and heating, especially in informal settlements, releases particulate matter and other harmful pollutants.

Dust from mining activities: Often containing heavy metals like lead and mercury, impacting local communities.

Example: A community living near a coal-fired power plant in Mpumalanga experiences high rates of respiratory illnesses due to the high levels of particulate matter and sulfur dioxide in the air.

Water Pollution: Water pollution occurs when harmful substances contaminate water bodies.

Common sources include: Industrial effluent: Factories release untreated wastewater containing chemicals, heavy metals, and other pollutants into rivers and lakes.

Agricultural runoff: Fertilizers and pesticides used in agriculture can wash into water bodies, causing eutrophication (excessive nutrient enrichment) and harming aquatic life.

Sewage discharge: Untreated or poorly treated sewage can contaminate water with pathogens (disease-causing microorganisms) and organic matter, leading to oxygen depletion.

Mining activities: Mining operations can release heavy metals and other pollutants into water bodies, contaminating drinking water sources. Acid mine drainage is a huge issue in S

A. Oil spills: From ships and industrial facilities contaminate marine ecosystems.

Example: A river downstream from a factory is heavily polluted with chemicals, resulting in the death of fish and other aquatic organisms.

Soil Pollution: Soil pollution occurs when harmful substances contaminate the soil.

Common sources include: Industrial waste: Factories can contaminate soil with heavy metals and other pollutants.

Agricultural practices: Excessive use of fertilizers and pesticides can contaminate soil with harmful chemicals.

Mining activities: Mining operations can contaminate soil with heavy metals and other pollutants.

Improper waste disposal: Landfills and illegal dumping sites can contaminate soil with leachate (contaminated liquid).

Example: Soil near a gold mine is contaminated with mercury, posing a risk to human health through consumption of contaminated crops.

Acid Rain: Acid rain forms when sulfur dioxide (SO2) and nitrogen oxides (NOx) react with water, oxygen, and other chemicals in the atmosphere to form sulfuric and nitric acids. These acids fall to the earth as acid rain. It damages forests, acidifies lakes and streams, and corrodes buildings and monuments. Acid rain is worsened by the burning of fossil fuels, particularly coal. The high concentration of coal-fired power plants in Mpumalanga contribute to acid rain and the destruction of ecosystems in the area. 2.2 Deforestation: Deforestation is the clearing of forests for other land uses, such as agriculture, urbanization, and mining.

Causes of Deforestation: Agriculture: Clearing forests for farmland is a major driver of deforestation, especially for cattle ranching and crop production.

Logging: Harvesting timber for construction, furniture, and paper products contributes to deforestation.

Mining: Mining operations can clear large areas of forest for access to mineral resources.

Urbanization: As cities expand, forests are cleared for housing, infrastructure, and industrial development.

Fuelwood: The use of wood as fuel, especially in developing countries, contributes to deforestation.

Consequences of Deforestation: Loss of biodiversity: Forests are home to a vast array of plant and animal species, and deforestation leads to habitat loss and extinction. South Africa's unique biodiversity is threatened by deforestation.

Climate change: Forests play a crucial role in regulating the climate by absorbing carbon dioxide from the atmosphere. Deforestation releases this stored carbon dioxide, contributing to climate change.

Soil erosion: Forests protect soil from erosion by anchoring it with their roots. Deforestation exposes soil to erosion, leading to soil degradation and reduced agricultural productivity. This can lead to increased siltation in rivers and dams.