Lesson Notes By Weeks and Term v5 - Grade 12
Human environmental interactions and responses – Week 9 focus
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Human environmental interactions and responses – Week 9 focus
Download the Lessonotes Mobile South Africa app for faster lesson access on Android and iPhone.
Subject: Life Sciences
Class: Grade 12
Term: 3rd Term
Week: 9
Theme: General lesson support
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This week we delve into the critical topic of how humans interact with and respond to their environment. This is incredibly relevant in South Africa, a country grappling with the impacts of climate change, pollution, and resource scarcity. Understanding these interactions and responses is crucial for developing sustainable practices and policies to protect our environment and ensure a healthy future for all South Africans. We will explore various ways humans impact the environment, the consequences of these actions, and the physiological and behavioral responses we exhibit to environmental changes.
2.1 Pollution: Pollution is the introduction of contaminants into the natural environment that causes instability, disorder, harm or discomfort to the ecosystem, i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light.
Major types include: Air Pollution: This refers to the contamination of the air by various pollutants, such as particulate matter, sulphur dioxide (SO2), nitrogen oxides (NOx), carbon monoxide (CO), and ozone (O3).
Sources: Industrial emissions (e.g., power plants, factories, mining activities), vehicle exhaust, burning of fossil fuels (coal, oil, gas), and agricultural practices (e.g., fertilizer use, burning of crop residues). In South Africa, coal-fired power stations are a significant contributor to air pollution, particularly in the Highveld region.
Impacts: Respiratory illnesses (asthma, bronchitis, lung cancer), cardiovascular problems, acid rain, smog, and damage to ecosystems. The Vaal Triangle and eThekwini (Durban) areas have historically suffered from severe air pollution, impacting public health.
Example: The burning of coal for electricity production in Mpumalanga releases sulphur dioxide, which can cause respiratory problems and contribute to acid rain, damaging ecosystems and infrastructure.
Water Pollution: This involves the contamination of water bodies (rivers, lakes, oceans, groundwater) by pollutants such as sewage, industrial waste, agricultural runoff, and plastics.
Sources: Untreated or poorly treated sewage discharge, industrial effluent, agricultural fertilizers and pesticides, mining runoff (acid mine drainage), and littering. In South Africa, acid mine drainage is a major concern in the Witwatersrand region.
Impacts: Waterborne diseases (cholera, typhoid), eutrophication (excessive nutrient enrichment leading to algal blooms and oxygen depletion), harm to aquatic life, and contamination of drinking water sources. Many informal settlements in South Africa lack proper sanitation, leading to water pollution and health problems.
Example: Agricultural runoff containing fertilizers and pesticides enters rivers, causing excessive algal growth (eutrophication), which depletes oxygen levels and harms fish and other aquatic organisms in the Hartbeespoort Dam.
Land Pollution: This includes the contamination of soil by pollutants such as solid waste (litter, garbage), hazardous waste (industrial chemicals, pesticides), and mining waste.
Sources: Landfills, illegal dumping, industrial spills, agricultural practices, and mining activities.
Impacts: Soil degradation, contamination of groundwater, harm to plants and animals, and health risks to humans.
Example: Improper disposal of electronic waste (e-waste) releases heavy metals into the soil, contaminating groundwater and posing health risks to communities living near disposal sites. 2.2 Resource Depletion: Resource depletion refers to the consumption of a resource faster than it can be replenished.
Water Scarcity: South Africa is a water-stressed country, facing increasing water scarcity due to factors such as climate change, population growth, and inefficient water management.
Impacts: Reduced agricultural productivity, water shortages for domestic use, increased competition for water resources, and potential for conflict.
Example: Prolonged droughts in the Western Cape have led to severe water restrictions and impacted the agricultural sector, particularly the wine industry.
Deforestation: The clearing of forests for agriculture, urbanization, and logging leads to deforestation, with negative consequences for biodiversity, climate change, and soil erosion.
Impacts: Loss of habitat for many species, increased greenhouse gas emissions, soil erosion, and reduced water availability.
Example: Illegal logging of indigenous forests in KwaZulu-Natal contributes to habitat loss and threatens endangered species like the Cape Parrot.
Overfishing: Unsustainable fishing practices deplete fish stocks, threatening marine ecosystems and the livelihoods of fishing communities.
Impacts: Loss of biodiversity, disruption of food chains, and economic hardship for fishing communities.
Example: Overfishing of certain fish species, like snoek, has led to declines in their populations, impacting the commercial fishing industry. 2.3 Climate Change: Climate change refers to long-term shifts in temperatures and weather patterns, primarily caused by human activities that release greenhouse gases into the atmosphere.
Causes: Burning of fossil fuels (coal, oil, gas), deforestation, industrial processes, and agricultural practices.
Greenhouse Gases: Carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and fluorinated gases.
Impacts in South Africa: Increased Temperatures: Higher average temperatures lead to heat waves, increased evaporation, and water stress.