AP Environmental Science World Map Review and Analysis Study Guide

Atmosphere and Aquatic Degradation: Ozone, Coral Bleaching, and Dead Zones

The Ozone Hole

• Description and Occurrence: The ozone hole is a significant thinning of the ozone layer ($O_3$) primarily located over Antarctica. It occurs during the Southern Hemisphere's spring when stratospheric clouds facilitate chemical reactions that release chlorine.

• Chemicals Involved: The primary culprits are Chlorofluorocarbons (CFCs), such as $CFCl_3$ and $CF_2Cl_2$. When these reach the stratosphere, Ultraviolet (UV) radiation breaks them down, releasing chlorine atoms ($Cl$). A single chlorine atom can destroy upwards of $100,000$ ozone molecules.

• Stopping and Reversal: The primary mechanism for stopping the depletion was the Montreal Protocol ($1987$), an international treaty that phased out the production of CFCs and other ozone-depleting substances. Reversal is a slow, natural process as existing CFCs gradually leave the atmosphere.

Coral Bleaching

• Description and Occurrence: This phenomenon happens when coral polyps expel the symbiotic algae (zooxanthellae) living in their tissues. Without the algae, the coral loses its color and its primary food source, often leading to death.

• Chemicals and Physical Triggers: The main causes are increased ocean temperatures due to climate change and ocean acidification caused by absorbed $CO_2$. When $CO_2$ dissolves in seawater, it forms carbonic acid ($H_2CO_3$), decreasing the concentration of carbonate ions ($CO_3^{2-}$) needed for coral skeletons.

• Stopping and Reversal: Mitigation requires global efforts to reduce greenhouse gas emissions ($CO_2$, $CH_4$) to stabilize ocean temperatures and pH levels.

Ocean Dead Zones

• Description and Occurrence: Also known as hypoxic zones, these are areas in the ocean where oxygen levels are too low to support most marine life. A prominent example is the dead zone in the Gulf of Mexico.

• Chemicals Involved: Excess Nitrogen ($N$) and Phosphorus ($P$) from agricultural runoff (fertilizers) and sewage reach the ocean, causing massive algal blooms. When the algae die, bacteria decompose them, consuming nearly all dissolved oxygen ($DO$) in the process.

• Stopping and Reversal: This can be addressed by improving agricultural practices (buffer strips, reduced fertilizer application) and upgrading wastewater treatment plants to remove limiting nutrients before discharge.

Terrestrial Degradation: Desertification and Deforestation

Desertification

• Causes: The primary causes include overgrazing of livestock, depletion of groundwater, and climate change-induced drought. These actions remove vegetation cover and degrade soil structure.

• Problems Caused: It lead to the loss of arable land, increased dust storms, and food insecurity for local populations.

• Methods to Stop: Restoration efforts include planting "green walls" (reforestation), rotational grazing for livestock, and improved irrigation techniques like drip irrigation to conserve water.

Deforestation

• Causes: Large-scale clearing is driven by agriculture (cattle ranching, soy and palm oil plantations), logging for timber, and infrastructure development. Specific locations include the Tropical Rainforests of South America and Southeast Asia.

• Problems Caused: It results in massive habitat loss, disruptions to the water cycle (reduced evapotranspiration), and increased atmospheric $CO_2$ since trees act as carbon sinks.

• Methods to Stop: Solutions include implementating sustainable forestry practices, legal protection of forest reserves, and REDD+ (Reducing Emissions from Deforestation and Forest Degradation) programs.

Biological Threats and Conservation: Species and Diseases

Invasive Species

• Significance: These are non-native species that spread rapidly and cause ecological or economic harm. Examples include Zebra Mussels in the Great Lakes or Kudzu in the Southern US. They lack natural predators in their new environment and outcompute native species for resources.

• Management: Control methods include mechanical removal, chemical pesticides, and biological control (introducing a natural predator from the native range).

Endangered Species

• Significance: Species at risk of extinction represent a loss of biodiversity and genetic heritage. Examples include the Bengal Tiger or the Blue Whale. The loss of a single keystone species can cause a trophic cascade.

• Management: The primary tool is the Endangered Species Act (ESA) in the US and CITES internationally. Habitat restoration and captive breeding programs are also critical.

Diseases

• Spread and Importance: Diseases like Malaria, Zika, and Ebola have specific geographic ranges but can spread via global travel and climate change (expanding the range of vectors like mosquitoes). They pose severe threats to human health and economic stability.

• Management: Prevention includes vaccination programs, vector control (mosquito netting, insecticides), and international health surveillance by organizations like the WHO.

Energy and Mineral Resources

Minerals and Fossil Fuels

• Mining Methods:

  • Surface Mining: Includes strip mining and mountaintop removal. Used for coal and mineral ores near the surface.

  • Subsurface Mining: Tunneling deep underground for resources like coal or gold.

  • Fracking (Hydraulic Fracturing): Injecting pressurized water, sand, and chemicals into shale rock to release natural gas and oil.

• Purpose: These resources are mined to provide energy for electricity, fuel for transportation, and raw materials for construction and technology.

Coal Ash and Environmental Hazards

• Metals Present: Coal ash contains heavy metals such as Lead ($Pb$), Mercury ($Hg$), and Arsenic ($As$).

• Human Health Effects:

  • Lead ($Pb$): Acts as a neurotoxin; causes developmental delays and brain damage, especially in children.

  • Mercury ($Hg$): Accumulates in the food chain (biomagnification); damages the nervous system and kidneys.

Geological and Meteorological Events

Earthquakes and Tsunamis

• Formations: Earthquakes occur due to the sudden release of energy at plate boundaries (e.g., the San Andreas Transform Fault). Tsunamis are often formed by subduction zone earthquakes (e.g., the Indian Ocean Tsunami) where the seafloor shifts vertically, displacing a massive volume of water.

• Problems: They cause catastrophic loss of life, destroy infrastructure, and can lead to secondary disasters like the Fukushima nuclear meltdown.

Hurricanes

• Formation: Driven by warm ocean waters (usually above $26.5^{\circ} C$) and low atmospheric pressure. As air rises and cools, it releases latent heat, fueling the storm's rotation. Examples include Hurricane Sandy and Hurricane Matthew.

• Problems: High winds, storm surges, and intense flooding cause billions in damages and displace populations.

Nuclear Disasters and Safety

Three Mile Island (USA, 1979)

• Problem: A partial meltdown of the reactor core. While there were no immediate deaths, it caused massive public fear and stopped the expansion of the US nuclear industry for decades.

Chernobyl (Ukraine/USSR, 1986)

• Problem: A massive explosion and fire released a plume of radioactive isotopes into the atmosphere, contaminating large swaths of Europe. It was caused by a combination of reactor design flaws and operator error.

Fukushima Daiichi (Japan, 2011)

• Problem: Following a massive earthquake and tsunami, the backup generators failed, leading to the loss of cooling and subsequent meltdowns in three reactors.

Safety Measures

• Modern nuclear plants utilize passive safety systems that don't require power to function, improved containment structures, and more stringent international oversight by the IAEA.

Demographics and Industrialization

Pre-Industrial Countries

• Characteristics: High birth rates and high death rates resulting in slow population growth. The economy is primarily based on subsistence agriculture.

• Concerns: High infant mortality, lack of clean water (spread of water-borne diseases), and indoor air pollution from burning biomass.

Post-Industrial Countries

• Characteristics: Low birth rates and low death rates. The population might stabilize or decline. High levels of affluence and service-based economies.

• Concerns: High per-capita resource consumption, massive carbon footprints, and health issues related to sedentary lifestyles and processed diets.

Oil Infrastructure and Global Patterns

Oil Spills and Pipelines

• Problems: Oil spills (Exxon Valdez, BP Deepwater Horizon) coat bird feathers and mammal fur, destroying insulation and buoyancy. They are toxic to fish and larvae and ruin coastal economies.

• Cleanup Methods: Using booms to contain oil, skimmers to remove it from the surface, dispersants to break it down, and bioremediation (using bacteria to eat the oil).

• Pipelines: Projects like the Keystone XL Pipeline transport oil (e.g., from Alberta Tar Sands) but pose risks of leaks over major geographic areas like the Ogallala Aquifer.

El Niño (ENSO)

• Occurrence: Occurs when trade winds weaken, allowing warm water from the western Pacific to flow eastward toward South America.

• Food Web Problems: The warm water prevents the upwelling of cold, nutrient-rich water off the coast of South America. Without these nutrients, primary productivity drops, causing fish populations to crash and starving the predators that rely on them.

Key Locations and Biomes

• Yellowstone National Park: The world's first National Park ($1872$), established for conservation and public enjoyment.

• Galapagos Islands: Crucial site for understanding natural selection due to its unique endemic species.

• North Atlantic Cod Moratorium: A total ban on cod fishing in Newfoundland ($1992$) due to the collapse of the fishery from overexploitation.

• Tropical Rainforest: High biodiversity, high precipitation, found near the equator.

• Tundra: Characterized by permafrost, low biodiversity, and cold temperatures.

• Mangrove Forests: Coastal ecosystems that protect shorelines from erosion and serve as nurseries for marine life.