Environmental Science: Carbon and Nitrogen Cycles

Carbon Cycle

• The carbon cycle moves carbon through Earth, the atmosphere, and living things.
• Photosynthesis removes carbon dioxide from the atmosphere and incorporates it into plants.
• Respiration releases carbon dioxide into the atmosphere.
• Combustion (burning fossil fuels) releases carbon dioxide.
• Carbon dioxide dissolves in oceans as carbonic acid.
• Oceans are a large carbon reservoir, including limestone.
• Human activity disrupts the carbon cycle by increasing atmospheric carbon dioxide.

Nitrogen Cycle

• The nitrogen cycle moves nitrogen between the atmosphere, land, and living things.
• Nitrogen fixation (lightning or bacteria) converts atmospheric nitrogen to ammonia.
• Nitrifying bacteria convert ammonia to nitrates and nitrites.
• Legumes (like soybeans) have symbiotic relationships with nitrogen-fixing bacteria.
• Plants absorb these forms of nitrogen and incorporate them into biomolecules.
• Humans disrupt the nitrogen cycle through eutrophication (excess nitrogen).

Water Cycle

• The water cycle recycles freshwater on Earth.
• Main processes: evaporation, condensation, precipitation.
• Water transitions between liquid, solid, and gas forms.
• Evaporation, sublimation, and transpiration return water to the atmosphere.
• Condensation leads to precipitation (rain, snow, etc.).
• Runoff carries water to lower elevations.
• Infiltration returns water to groundwater.

Renewable and Non-Renewable Resources

• Energy resources power homes, vehicles, and more.
• Renewable resources can be replenished (wind, water, geothermal, biomass).
• Non-renewable resources are finite (fossil fuels).
• Fossil fuels (coal, oil, natural gas) form from decomposed organic matter over millions of years.
• Conservation is key for sustainable use.

Environmental Sustainability

• Environmental sustainability manages resources for future use.
• Renewable resources can be replenished; non-renewable resources cannot.
• Sustainable development combines environmental protection with economic growth.
• Sustainable agriculture practices (crop rotation) preserve soil quality.
• Sustainable forestry practices (selective logging) reduce environmental impact and loss compared to clear-cutting.

Natural Disasters

• Natural disasters include hurricanes, earthquakes, tornadoes, mudslides, volcanoes, and tsunamis.
• Preparation methods include warning systems, evacuation plans, and community preparedness.
• Preventative methods include identifying flood plains, building dams, and planting trees.