Carbon, Nitrogen, Phosphorus and Sulfur Cycles

Carbon Cycle

Carbon is one of life’s most essential elements.  It is needed in everything living.  It also dictates the temperature of our earth.  The carbon cycle is very delicate, as a slight offset can drastically change earths temperature, like in global warming.  Plants and other living things on the producer level of the food chain remove CO₂ from the atmosphere and convert it into glucose through photosynthesis.  Through a process called aerobic respiration, this glucose is then converted back into CO₂ by consumers and decomposers.  Decomposers also convert CO₂ stored in producers back into CO₂ once producers are dead.  Other natural occurrences like forest fires

Today, most CO₂ is released back into the atmosphere through the burning of fossil fuels.  Fossil fuels are formed over the course of millions of years as dead organic matter, like animals and plants, is trapped and compressed under earth’s surface.  Usually, the CO₂ in these deposits are not released into the atmosphere unless exposed to air.  Humans, though, are offsetting the natural carbon process by digging up these deposits and prematurely releasing the stored carbon, causing too much carbon in earth’s atmosphere and thus an increase in it’s temperature.  My family offsets the carbon cycle because of our automobile use and our natural gas use to heat our stove and our home.  We contribute to it by having an abundant garden and by leaving trees on our property so that they can absorb our atmosphere’s carbon dioxide.

Nitrogen Cycle

Nitrogen is important in many living structures, such as DNA.  The largest deposit of nitrogen is in earth’s atmosphere where it is stored as an unreactive gas.   Animals and plants cannot use naturally occurring nitrogen until it is processed.  One of these processes is when bacteria converts nitrogen into a form that is usable by other organisms.  This process is called nitrogen fixation.  Hydrogen and nitrogen are combined to create ammonia, which is released by the bacteria into the environment and is then converted yet again into ammonium ions, which are consumed by plants.  The left over ammonia goes through nitrification, which creates a different form of nitrogen that is able to be consumed by plants.  As the plants are eaten, the nitrogen is brought up the food chain.  Nitrogen is released through two bacterial processes, called ammonification and denitrification, as well as through animal and plant waste, and animal and plant decomposition.  Humans alter the nitrogen cycle through the burning of fossil fuels, the destruction of forests, waste runoff, unnatural nitrogen removal and the destruction of forests.

Sulfur Cycle

Sulfur, though less important than nitrogen and carbon, stills plays a large role in earth’s ecosystems.  Most sulfur is stored beneath earths surface in soil and fossil fuels.  It is absorbed by living things as plants extract it from the soil.  Sulfur then makes its way up the food chain, and is deposited back into the ground as the living things that consumed it are decomposed by bacteria.  Large quantities of sulfur enter the atmosphere through volcanic eruptions.  These eruptions release hydrogen sulfide and sulfur dioxide.  Small amounts of sulfur can be released through dust storms, forest fires, sea spray and other natural occurrences.  Marine algae produce dimethyl sulfide, which is a form of sulfur that acts as a building blocks for water condensation and the formation of clouds.  Excess sulfur in the atmosphere leads to acid rain.  Acid rain and volcanic eruptions return sulfur back into earth’s surface, where it becomes a part of soil, completing the process.

Phosphorus Cycle

The phosphorus cycle is unique because it does not involve the atmosphere at all.  Most phosphorus is stored in phosphate salts, which occur in rock formations and ocean sediments.  Phosphorus is released from these rocks and sediments when water flows over them.  These phosphate ions are then excreted by plants, and thus it makes its way up the food chain.  Phosphorus is essential to the formation of nucleic acids and other types of molecules, as well as bones and teeth.  Phosphorus can be stored in the ocean for long periods of time.  Phosphorus is essential to plant life, and an absence of it can halt any from happening.