Unit 2 Review: AP Environmental Science
Unit 2 Review: AP Environmental Science
Preparation for Unit Review
Essential preparations: Ensure you have the ultimate review packet study guide printed out.
Engagement: While watching the video, answer practice questions to solidify understanding of Unit 2 concepts.
Importance of writing style: Emphasize practicing with the mini free-response questions (FRQs) for the AP Environmental Science exam, which is considered challenging.
1.1 Environmental Problems, Their Causes, and Sustainability
Environmental Science: The study of how Earth works, how we interact with it, and how to deal with environmental problems.
Major Environmental Problems:
Resource depletion: Overuse of natural resources leading to scarcity (e.g., fossil fuels, clean water).
Pollution: Contamination of the environment by harmful substances (e.g., air, water, soil pollution).
Loss of biodiversity: Reduction in the variety of life forms, impacting ecosystem stability.
Climate change: Long-term shifts in weather patterns due to increased greenhouse gases.
Causes of Environmental Problems:
Population growth: More people consume more resources and generate more waste.
Unsustainable resource use: Consuming resources faster than they can be replenished.
Poverty: Can lead to environmental degradation due to reliance on natural resources for survival.
Lack of environmental education: Limited understanding of environmental impacts.
Sustainability: The ability to meet the needs of the present without compromising the ability of future generations to meet their own needs.
Three Pillars of Sustainability: Economic, social, and environmental considerations.
Overview of Biodiversity
Definition: Biodiversity refers to the diversity of different life forms found in an ecosystem.
Common Misunderstanding: Students may think they understand biodiversity, but the concept is complex and essential for passing the exam.
Three Levels of Biodiversity
Genetic Biodiversity
Definition: Variance of genes or traits within a population.
Benefits: High genetic diversity increases the chances of survival when environmental disturbances occur. Example: In a population of sparrows, genetic diversity could lead to some birds having traits (e.g., larger beaks) that enable them to survive drought conditions.
Species Biodiversity
Definition: The diversity of different types of organisms within an ecosystem.
Measurement Methods:
Species Richness: Total count of different species in an ecosystem.
Species Evenness: Distribution and balance of population sizes of different species. Example: Forests with the same species richness may exhibit different species evenness, indicating one forest is more resilient to disease than another.
Ecosystem Biodiversity
Definition: Variance in different ecosystems within a specific area.
Example: Tropical rainforests exhibit high ecosystem diversity due to their various habitats whereas deserts have lower biodiversity due to harsher conditions.
3.1 Generalist vs. Specialist Species
Generalist Species:
Characteristics: Can thrive in a wide variety of environmental conditions and utilize diverse resources.
Advantages: More adaptable to environmental changes; less prone to extinction.
Examples: Raccoons, coyotes, white-tailed deer.
Specialist Species:
Characteristics: Can only thrive in a narrow range of environmental conditions or have a limited diet.
Disadvantages: Highly vulnerable to environmental changes; more prone to extinction.
Examples: Panda (bamboo diet), Koala (eucalyptus diet).
Benefits of Biodiversity
Ecosystem Services: Financial benefits derived from ecosystems categorized into four key areas:
Provisioning Services: Directly provides resources (e.g., wood for furniture, food).
Supporting Services: Ecosystem processes that enhance human activities (e.g., bee pollination of crops).
Regulating Services: Ecosystems stabilize climate and environmental factors (e.g., trees sequester CO2 to mitigate climate change).
Cultural Services: Recreational and intellectual advantages gained from nature (e.g., tourism, research).
Example of Disruption: The Deepwater Horizon oil spill's adverse effects on ecosystem services, including disrupted fishing industries and coastal habitat degradation.
Theory of Island Biogeography
Principles:
Distance from Mainland: Islands closer to the mainland tend to have higher species richness due to easier migration of species.
Size of Island: Larger islands generally support more species due to their habitat diversity.
Illustration of Concepts:
Graph Relationships:
Inverse relationship between distance from mainland and number of species.
Direct relationship between island area and number of species supported.
Unique Adaptations: Island species often have specialized adaptations due to limited food and habitat choices, making them vulnerable to invasive species (e.g., dodo bird's extinction following human arrival).
Ecological Tolerance
Definition: The range of environmental conditions an organism can tolerate before suffering harm.
Example: Human body temperature optimal range is 97 to 99°F; moving outside this range leads to physiological stress or intolerance.
Importance of Genetic Diversity in Tolerance
Variation in tolerance ranges exists within populations, providing resilience against environmental changes.
Natural Disturbances and their Effects on Ecosystems
Types of Disturbances:
Periodic Events: Regular occurrences (e.g., rainy or dry seasons).
Episodic Events: Irregular but predictable events (e.g., hurricanes, forest fires).
Random Events: Unpredictable occurrences (e.g., volcanic eruptions, asteroid impacts).
Long-term Climate Change: Natural climate changes due to Malankovich Cycles influence Earth's temperature and sea levels which can reshape ecosystems over thousands of years.
Malankovich Cycles: Refers to changes in Earth's orbit that affect climate:
Eccentricity: Changes in the shape of Earth's orbit.
Axial Precession: Changes in the tilt of Earth's axis.
Obliquity: Variation in Earth's tilt affecting seasonal climates.
Implications for Ecosystems: Changes can lead to flooding of low-lying coastal ecosystems and alterations in coral reef habitats due to rising sea levels.
Adaptations and Environmental Change
Definition of Adaptation: A genetic mutation that enhances an organism's ability to survive and reproduce.
Example of the Evolution of Opposable Thumbs: Early Homo habilis developed thumb muscle arrangements that allowed tool manipulation, leading to dietary advantages and increased survival rates.
Ecological Succession and Keystone Species
Types of Succession:
Primary Succession: Starts with bare rock and pioneer species (e.g., moss, lichen) gradually leading to soil formation and a climax community.
Secondary Succession: Follows a disturbance with existing soil; pioneer species help reestablish the ecosystem quickly.
Keystone Species: Species vital to ecosystem structure. Removal can lead to ecosystem collapse.
Example: Wolves (predators) regulate deer populations which in turn affects vegetation health, soil structure, and overall ecosystem integrity.
Further examples include ecosystem engineers like beavers and mangroves that shape landscapes significantly.
Waste Management
8.2 Sewage Treatment
Purpose: To remove pollutants from wastewater before it is returned to the environment or reused.
Process Steps:
Primary Treatment: Physical removal of large solids via screens and sedimentation tanks. (e.g., grit, fats, oils, greases).
Secondary Treatment: Biological treatment to break down organic matter using bacteria and aeration. (e.g., activated sludge system).
Tertiary Treatment (Advanced Treatment): Further removal of specific pollutants like nitrogen, phosphorus, and sometimes medications or hormones. Can include filtration, disinfection (chlorine, UV, ozone).
Disinfection: Killing pathogens before discharge, commonly using chlorine, ozone, or UV light.
Sludge Treatment: Remaining solid waste (sludge) is treated through anaerobic digestion, dewatering, and often used as fertilizer or landfilled.
9.8 Solid Waste Disposal Methods
Landfills (Sanitary Landfills):
Description: Designed to minimize environmental impacts by containing waste (lining, leachate collection, methane recovery).
Advantages: Can generate electricity from methane, job creation.
Disadvantages: Leachate contamination of groundwater, methane emissions (if not captured), NIMBY (Not In My Backyard) opposition.
Incineration:
Description: Burning waste to reduce volume and sometimes generate energy (Waste-to-Energy facilities).
Advantages: Reduces waste volume significantly, can produce electricity.
Disadvantages: Air pollution (dioxins, heavy metals), ash disposal, high capital costs.
Recycling:
Description: Processing used materials into new products.
Advantages: Reduces demand for virgin resources, saves energy, decreases landfill volume, reduces pollution.
Disadvantages: Market fluctuations for recycled materials, contamination of recyclables.
Composting:
Description: Decomposition of organic matter (food scraps, yard waste) into nutrient-rich soil amendment.
Advantages: Creates valuable fertilizer, reduces landfill waste, improves soil structure.
Disadvantages: Requires proper management to avoid odors and pests.
9.9 Waste Reduction Methods
The 3 R's Hierarchy (in order of preference):
Reduce: Decreasing the amount of waste generated in the first place.
Examples: Buying durable goods, choosing products with minimal packaging, consuming less.
Reuse: Using a product multiple times for its original purpose or a new purpose.
Examples: Refillable containers, second-hand clothing, repair broken items.
Recycle: Processing materials to be used in new products (as described in 9.8).
Other Strategies:
Composting: Diverting organic waste from landfills (as described in 9.8).
Extended Producer Responsibility (EPR): Manufacturers are responsible for the entire life cycle of their products, including disposal.
Pay-as-you-throw (PAYT): Residents pay for waste disposal based on the amount they generate, incentivizing reduction.
9.10 Hazardous Waste
Definition: Waste that is dangerous or potentially harmful to human health or the environment.
Characteristics of Hazardous Waste (CRIT):
Corrosivity: Can corrode metal containers.
Reactivity: Unstable under normal conditions and can explode or produce toxic fumes.
Ignitability: Flammable liquids or substances that can catch fire easily.
Toxicity: Harmful to human health or the environment when ingested, inhaled, or absorbed.
Sources of Hazardous Waste:
Industrial processes, households (batteries, cleaners), medical facilities, agriculture (pesticides).
Management Methods:
Incineration: High-temperature burning to destroy hazardous components.
Landfills (Hazardous Waste Landfills): Specially designed landfills with multiple liners and extensive monitoring to prevent leakage.
Bioremediation: Using microorganisms to break down hazardous substances.
Phytoremediation: Using plants to absorb and accumulate toxic materials from soil.
Deep-well Injection: Injecting liquid hazardous waste into porous rock formations deep underground.
Conclusion of Unit 2
Reflection: Understanding the complexities of biodiversity, ecosystem services, and environmental changes is crucial for environmental science. Encouragement to keep using learned skills and knowledge as they move deeper into their studies.