Unit 5 APES Land and Water Use Review- AP Environmental Science

Tragedy of the Commons

• Definition: A common resource available for all humans, often exploited unsustainably.

  • Examples include the ocean, atmosphere, and public rangelands.

• Key Issues:

  • Exploitation leads to depletion of resources.

  • Overfishing transforms oceans, creating dead zones (like near Louisiana due to fertilizer runoff).

  • Groundwater is commonly overdrafted due to a lack of regulation, leading to depletion.

Water Resources

• Ogallala Aquifer:

  • Largest aquifer in the U.S., running from Texas through the Midwest.

  • Overdrafted and nearing depletion due to human usage.

• Freshwater Accessibility:

  • Only a small percentage of Earth's water is accessible as freshwater; pollution and misuse are major concerns.

• Aquifer Types:

  • Confined Aquifers: Under pressure.

  • Unconfined Aquifers: At atmospheric pressure.

• Overdraft Consequences:

  • Subsidence: Land sinks due to water withdrawal.

  • Saltwater Intrusion: Near coastlines, saltwater can encroach upon fresh groundwater, making it unusable.

Irrigation Methods

• General Usage:

  • 70% of Earth's freshwater is used mainly for irrigation (agriculture/sod).

• Types of Irrigation:

  • Furrow Irrigation: High evaporation (40% loss).

  • Flood Irrigation: Significant evaporation and water loss.

  • Spray Irrigation: Moderate evaporation.

  • Drip Irrigation: Most efficient, least evaporation, helps mitigate salinization.

• Salinization:

  • Occurs when water evaporates, leaving salts behind in soil, hindering plant growth.

  • Flushing methods can alleviate salinization, but risk adding more minerals.

Agricultural Impacts

• Tillage:

  • Increases erosion by loosening topsoil.

• Cover Crops:

  • Used to prevent soil erosion by holding soil in place with roots.

• Desertification:

  • Nutrient loss leads to land being unable to support plant life, often caused by overgrazing.

• Integrated Pest Management:

  • Combines crop rotation, natural predators, and GMOs to reduce chemical pesticide use.

Mining

• Key Terms:

  • Ore: Rock containing minerals worth mining (e.g., iron ore).

  • Reserves: Known sources available for mining.

  • Depletion Time: Estimated time until reserves are used up (approx. 80%).

• Mining Processes:

  • Overburden: Soil removed during mining.

  • Spoils: Waste generated by mining operations.

  • Tailings: Residue left from water use in mining.

• Environmental Impacts:

  • Disruption of landscapes and habitats, pollution of waterways due to eroded materials, and potential for catastrophic events like dam failures (e.g., Samarco dam collapse).

Fishing Impacts

• Bycatch:

  • Non-target marine organisms caught unintentionally, often resulting in death.

• Fishery Collapse:

  • Population decline of over 90%, making recovery difficult due to genetic bottlenecks.

• Ocean Pollution:

  • Fishing gear impacts ecosystems, leads to pollution.

• Regulations:

  • Important for sustainable practices; includes catch limits and seasonal restrictions.

• Aquaculture:

  • Fish farming; potential for environmental and health issues due to density and waste accumulation.

Forest Benefits and Deforestation Drawbacks

• Forest Benefits:

  • Stabilizes soil, prevents erosion, slows runoff, purifies water, and acts as a carbon sink.

• Deforestation Impacts:

  • Erosion, habitat destruction, carbon release into the atmosphere, and increased runoff.

• Controlled Burning:

  • Methods to prevent uncontrolled fires by clearing undergrowth.

• Clear-Cutting vs. Selective Cutting:

  • Clear-cutting destroys habitats; selective cutting maintains ecosystems by leaving some trees standing.

Rangeland Management

• Issues:

  • Overgrazing can lead to desertification and nutrient loss, exacerbating erosion.

• Solutions:

  • Fencing off streams and sustainable grazing practices avoiding overconsumption of grass.

Urbanization Effects

• Impervious Surfaces:

  • Increased runoff, leading to erosion, flooding, and waterway pollution.

  • Runoff carries pollutants to waterways, contributing to eutrophication.

• Eutrophication Process:

  • Nutrients from runoff cause excessive algae growth, leading to hypoxia.

Meat Production

• CAFOs (Concentrated Animal Feeding Operations):

  • High-density animal farming that is resource-efficient but raises health concerns.

  • Issues include antibiotic resistance, concentrated waste leading to eutrophication, and ethical concerns over animal treatment.