A Guide to the Scientific Method and Environmental Science
The Scientific Method
- Observation: Detect patterns or events, often guided by a question.
- Hypothesis: A possible explanation for the observation.
- Independent Variable: The “predictor” variable that seems to be causing the pattern in the observation.
- Dependent Variable: The “response” variable, or the pattern being caused.
- Controlled Experiment: Set up artificial conditions: a “treatment” with the hypothesized cause and a “control” without the causal factor.
- Comparison: Compare two natural settings that differ in the independent variable.
- Predictive (Computer Model): Create a mathematical representation of reality.
- Theory: A hypothesis that has been tested many times and never disproven.
- Natural Law: A theory that holds true everywhere.
Mining Methods and Impacts
Underground Mining
- Tunnels to access resources.
- Destroys less surface area than other methods.
- Risks of miner fatalities from cave-ins and explosions.
- Liquid minerals can be pumped out (e.g., petroleum, lithium).
Surface Mining
- Strip Mining: Digging long rows, removing top layers to access resources close to the surface (e.g., coal, aluminum, sand).
- Open-Pit Mining: Extracting massive beds of metal ores.
- Mountaintop Removal: Scraping off mountaintops and dumping the debris into valleys (e.g., coal).
Environmental Impacts of Mining
- Water Pollution: Acid mine drainage occurs when water seeps into mines, mixes with sulfides, and carries toxic heavy metals and acid into streams, harming aquatic life. Toxic heavy metals can also contaminate groundwater and drinking water.
- Habitat destruction, soil erosion, air pollution, greenhouse gas emissions, and human health effects.
Waste Disposal Methods
- Open Dumps/Burn Piles: Large piles of garbage exposed to wind and rain, polluting air and water. Illegal in most developed countries but common in less developed ones.
- Sanitary Landfills: Account for 54% of US waste. Carefully designed structures with liners and clay to isolate polluted water from groundwater. They require significant space, are expensive, and often face local opposition. Anaerobic decomposition of wet trash produces methane, a greenhouse gas, which can be captured and burned to generate electricity.
- Incineration: Accounts for 12% of US waste. Burning garbage generates electricity but produces CO2, toxic ash, and some air pollution.
- Exporting Waste: Garbage is a major US export. 14% of US electronic waste goes to developing countries for recycling.
- Ocean Dumping: Illegal by international treaty but still occurs. The Great Pacific Garbage Patch is a massive floating island of plastic debris.
Energy Sources
Natural Gas
Composed mainly of methane, along with ethane, propane, and other gases. Found alongside coal and oil deposits. Obtained by pumping or fracking (hydraulic fracturing).
Advantages of Natural Gas
- Large supply.
- Less air pollution than coal.
Disadvantages of Natural Gas
- Fracking fluids are toxic and can contaminate water supplies.
- Methane leaks contribute to greenhouse gas emissions.
- Drilling and sand mining damage land.
- Processing and burning natural gas create toxic gases.
- Transporting natural gas requires pipelines and large ports, leading to habitat destruction.
Nuclear Power
Nuclear fission splits uranium atoms, releasing energy as heat and radioactivity. The heat boils water to generate steam, which turns a turbine to produce electricity.
Advantages of Nuclear Power
- Large uranium reserves (estimated 200 years).
- High energy output from a small amount of fuel.
- Minimal air pollution from reactors, no greenhouse gas emissions during operation, and no direct toxin release.
Disadvantages of Nuclear Power
- High construction costs and energy requirements for power plants.
- Warm water discharge into rivers and oceans can reduce oxygen levels.
- Challenges in storing radioactive waste.
- Potential for environmental and health disasters.
- Complex and costly decommissioning of old plants.
Hydroelectric Power
Dams harness water pressure to turn turbines and generate electricity.
Advantages of Hydroelectric Power
- Low air pollution.
- Reservoirs created by dams offer recreational opportunities, flood control, and irrigation.
- Relatively low electricity generation costs.
Disadvantages of Hydroelectric Power
- Reservoirs flood habitats, displacing people and wildlife.
- Potential for mercury release into water.
- Greenhouse gas emissions from flooded areas (methane).
- Disruption of river-based recreation and migratory fish.
- High construction costs for dams.