tell me about the carbon cycle. what are the steps in it?
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/CarbonCycle.html
The carbon cycle is the process by which carbon moves between the atmosphere, oceans, land, and living organisms. It plays a crucial role in maintaining the carbon balance on Earth. Here are the steps involved in the carbon cycle:
1. Carbon Fixation: The process by which carbon dioxide (CO2) from the atmosphere is converted into organic carbon compounds by photosynthetic organisms, primarily plants, algae, and cyanobacteria. This occurs during photosynthesis, where plants use sunlight, water, and CO2 to produce glucose and release oxygen.
2. Respiration: All living organisms, including plants, animals, and microorganisms undergo respiration. During respiration, organic compounds are broken down to release energy for cellular processes, and carbon is returned to the atmosphere as CO2. This step releases CO2 back into the atmosphere.
3. Decomposition: When organisms die or produce waste, the process of decomposition starts. Decomposers like bacteria and fungi break down the dead organic matter, releasing CO2 into the atmosphere through respiration. Some part of the decomposed material may form fossil fuels like coal and oil, storing carbon for long periods.
4. Combustion: When organic matter such as fossil fuels is burned, combustion occurs. This process releases large amounts of CO2 into the atmosphere. Human activities, such as burning fossil fuels, contribute significantly to this step, which has led to an increase in atmospheric CO2 levels.
5. Absorption: Plants and oceans absorb CO2 from the atmosphere through photosynthesis and dissolution, respectively. Photosynthetic organisms convert atmospheric CO2 into organic carbon compounds, while the oceans take up dissolved CO2, forming carbonic acid.
6. Transfers: Through several physical processes, carbon is transferred between different reservoirs. For example, carbon can be transferred from the atmosphere to the oceans through precipitation, or from plants to animals through the food chain when organisms consume and assimilate organic carbon.
7. Geological Processes: Over millions of years, carbon can be buried and stored in sedimentary rocks through processes like sedimentation and lithification. This is known as carbon sequestration, removing carbon from the active carbon cycle for extended periods.
These steps continuously exchange carbon and help balance the natural distribution of carbon on Earth. However, human activities have disrupted this balance, leading to increased CO2 levels in the atmosphere, which contributes to climate change. It's essential to understand and mitigate the impacts of human-induced changes to the carbon cycle for the long-term health of our planet.