Carbon Cycling

Carbon is the fourth most abundant element found on Earth, and is essential to all life as we know it. It is found in all living substances, and is essentially the key element for life. Because the carbon atom has the ability to form bonds with up to four other atoms, it can help form solid minerals (such “ limestone), ‘squishy’ organisms (such as plants and animals), and it can be dissolved in water. Carbon is also present in rocks, dissolved in rivers, lakes and oceans, and is in the atmosphere as carbon dioxide. The exchange of carbon between these reservoirs is identified as the ‘carbon cycle’. The paths taken by carbon atoms in this cycle are known as ‘sinks’, and are extremely complex, as they may take millions of years to come full circle. In this essay I will demonstrate understanding on how carbon is added to, and removed from, the atmosphere and how it is stored. I will explore the main processes in the carbon cycle – photosynthesis, respiration, plants, animals, decomposition, oceans, fossil fuels, and volcanism – and how they interlink together to form a complete and full cycle.

Photosynthesis is a complex reaction, where plants (and some bacteria) release oxygen to change water and carbon dioxide to sugar for food. During photosynthesis plants and phytoplankton take carbon dioxide from the atmosphere by absorbing it into their cells. And by using energy from the sun, they combine carbon dioxide and water to form sugar (C6H12O6) and oxygen. This is shown through the chemical equation: 6CO2 + 6H2O  C6H12O6 + 6O2. The conversion of sunlight energy into chemical energy is associated with the green pigment chlorophyll (contained in the chloroplasts of a cell.) This is the compound that traps the sun’s light to start the process of photosynthesis. Glucose molecules are very simple sugars, and carbon atoms are locked up in them. The sugars are then converted into other molecules such as starch, fats, proteins, enzymes, and DNA. The sugar is