Form 5 Biology Bab 10: Environmental Sustainability
10.1 Threat to the Environment
Global Climate Change and Environmental Issues
Greenhouse Effect & Global Warming: Accumulation of greenhouse gases ($CO_2$, $CH_4$, $N_2O$, CFCs) in the atmosphere traps infrared thermal radiation, leading to an increase in Earth's average global temperature.
Effects: Melting of polar ice caps, rising sea levels, severe weather extremes, loss of biodiversity.
Deforestation: Large-scale clearing of forests for agriculture, urbanization, and logging.
Effects: Soil erosion, flash floods, loss of natural habitats, disruption of carbon and water cycles.
Eutrophication: Excessive enrichment of water bodies with nutrients (nitrates and phosphates from agricultural fertilizer runoff and domestic sewage).
Process: Rapid growth of algae (algal bloom) $\rightarrow$ algae block sunlight from submerged plants $\rightarrow$ death of aquatic plants $\rightarrow$ decomposition by aerobic bacteria $\rightarrow$ severe oxygen depletion (high Biochemical Oxygen Demand, BOD) $\rightarrow$ death of fish and aquatic organisms.
Acid Rain: Emissions of sulfur dioxide ($SO_2$) and nitrogen oxides ($NO_x$) from fossil fuel combustion dissolve in atmospheric moisture to form sulfuric acid and nitric acid ($pH < 5.0$).
Effects: Leaching of essential minerals ($Ca^{2+}$, $Mg^{2+}$) from soil, releasing toxic aluminum ions ($Al^{3+}$), damaging plant leaves, lowering water pH and killing aquatic life.
Thermal Pollution: Discharge of warm wastewater from industrial power plants into natural aquatic ecosystems.
Effects: Reduces dissolved oxygen concentration, accelerates metabolic rates in organisms, leading to biological stress or death.
Biomagnification: Progressive increase in the concentration of non-biodegradable toxic substances (e.g., DDT, heavy metals like mercury and lead) at higher trophic levels along a food chain.
10.2 Preservation, Conservation, and Restoration of Ecosystems
Core Environmental Management Strategies
Preservation: Protecting natural habitats and ecosystems in their original, untouched state without human exploitation (e.g., gazetting national parks, marine parks, and virgin jungle reserves).
Conservation: Sustainable management and wise use of natural resources to prevent destruction and depletion while ensuring availability for future generations.
In-situ Conservation: Protecting species in their natural habitats (e.g., wildlife sanctuaries, national parks).
Ex-situ Conservation: Protecting species outside their natural habitats (e.g., botanical gardens, zoos, seed banks, gene banks).
Restoration: Active human intervention to repair, renew, or restore damaged, degraded, or destroyed ecosystems to their natural state (e.g., reforestation, coral reef replanting).
10.3 Practices in Environmental Sustainability
Sustainable Living Practices
5R Concept: Refuse, Reduce, Reuse, Recycle, and Rot (Composting).
Sustainable Agriculture: Biological pest control, organic farming, crop rotation, and contour farming to protect soil fertility and avoid synthetic chemical runoff.
Renewable Energy Utilization: Transitioning from fossil fuels to solar, wind, hydroelectric, and biomass energy sources.
Green Technology: Development and application of products, equipment, and systems that conserve the natural environment and resources while minimizing negative human impacts.
10.4 Green Technology
Applications Across Key Sectors
Energy Sector: Solar power generation, wind energy, hydroelectric dams, fuel cells, energy-efficient LED lighting.
Waste & Wastewater Management: Anaerobic digestion of organic waste into biogas, rainwater harvesting, industrial wastewater treatment using bioremediation.
Transportation Sector: Electric vehicles (EVs), hybrid vehicles, biofuels, promotion of public transportation networks.