Lesson Notes By Weeks and Term v5 - Grade 12
Human impact on the environment (Grade 12 focus) and examination preparation – Week 6 focus
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Human impact on the environment (Grade 12 focus) and examination preparation – Week 6 focus
Download the Lessonotes Mobile South Africa app for faster lesson access on Android and iPhone.
Subject: Life Sciences
Class: Grade 12
Term: Term 4
Week: 6
Theme: General lesson support
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The impact of human activities on the environment is a critical issue facing South Africa and the world. From the air we breathe to the water we drink, and the land that provides our food, human actions are dramatically altering natural ecosystems. This topic is crucial for understanding the challenges we face and developing solutions for a sustainable future. In South Africa, environmental degradation disproportionately affects vulnerable communities, exacerbating existing inequalities. Understanding these impacts is not just an academic exercise; it’s vital for informed citizenship and contributing to a more equitable and sustainable future for all South Africans.
2.1 Pollution Definition: Pollution is the contamination of the environment by harmful substances (pollutants). Types of Pollution and South African
Examples: Air Pollution: Caused by the release of pollutants into the atmosphere.
Major sources in South Africa include: Burning of fossil fuels (coal-fired power plants like those in Mpumalanga) which release sulfur dioxide (SO2), nitrogen oxides (NOx), and particulate matter (PM). SO2 and NOx contribute to acid rain, damaging ecosystems and infrastructure. Particulate matter is a major health hazard, causing respiratory problems. Industrial emissions (e.g., mining operations, chemical plants) which release heavy metals and other toxic substances. Vehicle emissions (especially in urban areas like Johannesburg and Cape Town) which release carbon monoxide (CO), NOx, and particulate matter. Household burning of coal and wood for cooking and heating (especially in low-income communities) which releases particulate matter and other harmful pollutants.
Water Pollution: Contamination of water bodies (rivers, lakes, oceans, groundwater).
Major sources in South Africa include: Agricultural runoff (fertilizers and pesticides) which leads to eutrophication (excessive nutrient enrichment) of water bodies, causing algal blooms and oxygen depletion, harming aquatic life. The Hartbeespoort Dam is a prime example. Industrial wastewater (containing heavy metals and other toxic chemicals) which contaminates water sources and poses risks to human health. Gold mining near Johannesburg has resulted in widespread heavy metal contamination. Sewage and wastewater discharges (often inadequately treated) which introduce pathogens and nutrients into water bodies. Mining activities (acid mine drainage) which releases highly acidic water containing heavy metals into rivers and streams, devastating aquatic ecosystems.
Land Pollution: Contamination of soil with harmful substances.
Major sources in South Africa include: Mining activities (mine tailings, waste rock) which contaminate soil with heavy metals and other toxic substances. Industrial waste disposal (e.g., improper storage of hazardous waste) which contaminates soil and groundwater. Agricultural practices (excessive use of pesticides and fertilizers) which contaminates soil and can leach into groundwater. Improper waste disposal (landfills, illegal dumping) which contaminates soil and poses risks to human health. 2.2 Deforestation and Desertification Deforestation: The clearing of forests for other land uses (agriculture, urbanization, timber harvesting).
Causes: Agriculture (clearing land for crops and livestock grazing). Urbanization (expanding cities and infrastructure). Timber harvesting (for fuel, construction, and paper production). Mining activities (clearing land for mines and infrastructure).
Consequences: Loss of biodiversity (destruction of habitats). Soil erosion (increased runoff and loss of topsoil). Climate change (reduced carbon sequestration and increased greenhouse gas emissions). Reduced water availability (forests play a vital role in regulating water cycles).
Desertification: The degradation of land in arid and semi-arid areas, leading to the formation of desert-like conditions.
Causes: Deforestation (loss of vegetation cover). Overgrazing (excessive livestock grazing). Climate change (increased temperatures and reduced rainfall). Unsustainable agricultural practices (e.g., intensive cultivation without proper soil conservation measures).
Consequences: Loss of agricultural productivity (reduced crop yields and livestock carrying capacity). Increased poverty and food insecurity. Migration and displacement of people. Loss of biodiversity (reduced plant and animal species). 2.3 Sustainable Resource Management Definition: Using resources in a way that meets the needs of the present without compromising the ability of future generations to meet their own needs.
Strategies: Water Conservation: Efficient irrigation techniques (e.g., drip irrigation). Water-wise gardening (using drought-tolerant plants). Reducing water consumption in households (e.g., fixing leaks, using water-saving appliances). Rainwater harvesting.
Waste Management: Reduce, reuse, and recycle. Composting organic waste. Proper waste disposal (landfills with leachate collection systems). Waste-to-energy technologies.
Renewable Energy: Solar power (photovoltaic panels, solar water heaters). Wind power (wind turbines). Hydropower (dams). Geothermal energy. Biomass energy. 2.4 Biodiversity Loss Definition: The decline in the variety of life on Earth, including the loss of species, genetic diversity, and ecosystem diversity.
Causes: Habitat destruction (deforestation, urbanization, agriculture). Pollution (air, water, and land pollution). Climate change (altered temperatures and rainfall patterns). Overexploitation of resources (overfishing, hunting, logging). Invasive species (introduction of non-native species that outcompete native species).