Teaching GEOG NOTES GEOG 211 CYCLIC PROCESSES OF THE ATMOSPHERIC GASES (1)

CYCLIC PROCESS OF THE ATMOSPHERIC GASES

• Overview of main atmospheric gas cycles:

  • Carbon cycle

  • Oxygen cycle

  • Carbon dioxide cycle

  • Other cycles: Phosphorous cycle, Water cycle

CARBON CYCLE

1. Carbon Presence

   • Carbon exists in the atmosphere primarily as carbon dioxide (CO2).

   • Atmosphere serves as the source of carbon for living beings.

2. Photosynthesis

   • Green plants absorb CO2 and utilize sunlight to produce carbohydrates, a form of food.

   • Carbohydrates serve as a vital energy source for all living organisms.

3. Carbon Dissolution

   • CO2 dissolves in water bodies, leading to lime accumulation on Earth.

   • The dissolution process known as carbonization causes CO2 to re-enter the atmosphere.

4. Carbon Release

   • CO2 is produced through respiration by plants and animals, decomposition of organic matter, and combustion of fossil fuels (coal, petroleum, natural gas).

   • This continuous cycle maintains the balance of carbon and the biosphere.

OXYGEN CYCLE

1. Oxygen Proportion

   • Oxygen makes up approximately 21% of the atmosphere; essential for respiration in all living beings.

2. Role in Combustion

   • Oxygen is crucial for the combustion of fuels (wood, coal, gas), producing CO2 in the process.

3. Sources of Oxygen

   • Oxygen is predominantly produced by plants and trees; more vegetation leads to higher oxygen availability.

4. Cycle Continuity

   • Oxygen produced via photosynthesis is cycled back into the atmosphere through respiration by animals and plants.

NITROGEN CYCLE

1. Atmospheric Nitrogen

   • Comprises 78% of the atmosphere, crucial for life.

2. Sources of Nitrogen

   • Primary sources are nitrates in the soil.

3. Biological Transformation

   • Nitrogen enters biological components through biological (nitrogen fixation) and industrial processes.

4. Food Chain Transfer

   • Nitrogen compounds are transferred from plants to animals through the food chain.

5. Decomposition

   • Decomposition of organic matter by bacteria returns nitrogen gas to the atmosphere, completing the nitrogen cycle.

PHOSPHORUS CYCLE

1. Unique Characteristics

   • Unlike other cycles, the phosphorus cycle is sedimentary, without a gaseous phase.

2. Sources

   • The largest reservoir is in sedimentary rocks; phosphorous enters the cycle through weathering and erosion.

3. Transportation

   • Phosphates are transported to water bodies where they are utilized by aquatic plants and algae.

   • Excess phosphates can lead to environmental issues like eutrophication.

4. Human Impact

   • Commercial fertilizers, mining, deforestation, and agricultural runoff contribute to nutrient overload in aquatic ecosystems.

EUTROPHICATION

1. Definition

   • Nutrient enrichment (eutrophication) leads to serious environmental issues in aquatic ecosystems.

2. Consequences

   • Algae blooms consume dissolved oxygen, resulting in anoxic conditions.

   • Decomposition of algae further depletes oxygen, affecting fish survival.

WATER CYCLE

1. Process Overview

   • Also known as the hydrologic cycle; encompasses evaporation, condensation, precipitation, and runoff.

2. Evaporation

   • Water transforms from liquid to gas due to solar energy, including transpiration from plants.

3. Condensation

   • Vapors cool and consolidate into clouds, essential for precipitation.

4. Precipitation

   • Returns water to Earth in forms such as rain, snow, sleet, or hail.

5. Infiltration and Run-off

   • Water seeps into the ground forming aquifers or flows into bodies of water; crucial for recharging groundwater supplies.

6. Main Learning Objectives

   • The cycle facilitates the natural circulation of water, influences climate, and impacts weather patterns.

   • Highlights the importance of water availability and ecosystem health.